Development of a Quantitative Safety Risk Assessment Model for Rail Safety Management System Its Application towards Assessing and Prioritising Safety Risks at Interfaces of Railway and Highway by RAJALINGAM RAJAYOGAN M.Sc., University of South Bank, London (1994) B.Eng. (Mech), University of Peradeniya, Sri Lanka (1982) A Thesis Submitted in Partial Fulfilment of the Requirements for the Degree of Doctor of Philosophy School of Business University of Western Sydney Australia February 2012
Transcript
Development of a Quantitative Safety Risk Assessment Model for Rail Safety Management System
Its Application towards Assessing and Prioritising Safety Risks
at Interfaces of Railway and Highway
by
RAJALINGAM RAJAYOGAN M.Sc., University of South Bank, London (1994)
B.Eng. (Mech), University of Peradeniya, Sri Lanka (1982)
A Thesis Submitted in Partial Fulfilment of the Requirements for the Degree of
Doctor of Philosophy
School of Business University of Western Sydney
Australia
February 2012
ii
Dedication
I dedicate this thesis to my almighty God ‘Lord Ganesha’ and to
my beloved Bhagawan ‘Sri Sathiya Sai Baba’, who gave me love and huge blessings
to initiate and to successfully complete my doctoral studies.
(Aum Ganeshaya Namaha & Aum Sai Ram)
iii
Declaration of Originality
This is to certify that the research work reported in this thesis is, to the best of my
knowledge and belief, original and has not been submitted to any other University or
Institution for the award of a higher degree.
Rajalingam Rajayogan
iv
Acknowledgment
During my doctoral studies at the University of Western Sydney, I have had a great
opportunity to work on my favourite topic which is directly related to the nature of
my current employment at RailCorp-NSW. Through this study I have gained very
interesting and valuable experiences while meeting many local and international
people, colleagues and friends who helped me with my research along the way, either
directly or indirectly. I therefore take this opportunity to express my sincere
appreciation and gratitude to them.
First and foremost, I am deeply grateful to my principal supervisor Dr Premaratne
Samaranayake for his gentle encouragement and guidance, and my co-supervisor
Dr Kenan Matawie for his assistance in the statistical analysis of this study. I would
like to thank my former supervisors Dr K Ramanathan, Dr V Jayaraman and
Dr R Agrawal. I also thank my friends Dr P Jayakumar and Dr D Jeyaraman who
initiated the wonderful idea about PhD studies in my mind.
I express my sincere thanks to Dr Siriyani Dias, Ms Maria Lozano and Mr Tony
Davies from my previous employment at WorkCover-NSW, who assisted me in
learning the statistical analysis system in order to conduct statistical research work. I
also thank Mr Ian Cooke for helping me in the initial preparation of data. It is also
necessary to thank my current employer (RailCorp-NSW) and my work supervisors
Mr Matthew Coates and Ms Mandie Thomas for allowing me to take considerable
time off from my work to undertake this study at the University.
I offer my sincere salutes to my beloved leader late Dr M G Ramachandran (MGR)
who gave me courage and self confidence indirectly. My sincere appreciations go to
Prof. E. Ambikairajah and my family friends (including the members of our music
group ‘Sydney Geetha Saagara’) who provided assistance in various ways.
Finally, I would like to especially thank my wife Naguleswary (Rahini), my daughter
Sujanthini and my son Shayanthan who offered me love, patience and moral support
during my studies.
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Table of Contents
PAGE
Dedication ............................................................................................................................................. ii
Declaration of Origina lity................................................................................................................... iii
Acknowledgement ............................................................................................................................... iv
Table of Contents ................................................................................................................................. v
List of Tables ........................................................................................................................................ x
List of Figures.................................................................................................................................... xiii
Abbreviations ..................................................................................................................................... xv
Nomenclature .................................................................................................................................... xvi
Abstract............................................................................................................................................. xvii
Chapter 1: Introduction to the Research...............................................................................................................1
1.0 Introduction .................................................................................................................................1 1.1 Overview of Risk and Occupational Health & Safety.................................................................1 1.2 Safety Management System (SMS).............................................................................................4 1.3 Background of Rail Safety Risk Potentials and Rail SMS ..........................................................5 1.4 Significance of the Study.............................................................................................................8 1.5 Objectives of the Study .............................................................................................................10 1.6 Target of the Study ....................................................................................................................11 1.7 Benefits of the Study .................................................................................................................12 1.8 Limitations of the Study ............................................................................................................13 1.9 Structure of the Thesis...............................................................................................................14
Chapter 2: Literature Review...............................................................................................................................18
2.0 Introduction ...............................................................................................................................18 2.1 Definitions of Terms Used in Relations to Safety .....................................................................18
2.2 Safety Management System (SMS) at Organisational Level ....................................................24 2.2.1 The Four ‘P’ Principles of Safety Management System....................................................25 2.2.2 Safety Culture ....................................................................................................................27 2.2.3 Organisational Involvement in SMS..................................................................................28 2.2.4 Comparison of Current SMS with Traditional Approach ..................................................29 2.2.5 Major Modules of SMS .....................................................................................................30 2.2.6 Initiatives to Build an SMS................................................................................................ 31
2.2.6.1 Employer’s Responsibilities ......................................................................................31 2.2.6.2 Leadership Skills........................................................................................................ 32 2.2.6.3 Communicating Safety Critical Information..............................................................33 2.2.6.4 Elements of a Safe Working Environment.................................................................34
2.2.7 Measurements on Effectiveness of SMS ...........................................................................37 2.3 Risk Management within SMS.................................................................................................. 38
2.3.1 Major Processes in Risk Management...............................................................................39 2.3.2 Hazard Identification .........................................................................................................40
2.3.2.1 Dividing Hazard Identification into Manageable Portions.........................................40 2.3.2.2 Developing an Inventory of Tasks .............................................................................41 2.3.2.3 Analysing Tasks......................................................................................................... 41
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2.3.2.4 Identifying the Hazards Involved...............................................................................42 2.3.2.5 Considering the People Factor ...................................................................................42 2.3.2.6 Aiding Hazard Identification .....................................................................................43 2.3.2.7 Hazard Identification as Ongoing Process .................................................................45 2.3.2.8 Recording Hazard Identification Data........................................................................45
2.3.3 Undertaking Risk Assessment ...........................................................................................46 2.3.3.1 Risk Assessment ........................................................................................................46 2.3.3.2 Risk Assessment Matrix.............................................................................................48 2.3.3.3 Recording Results of Risk Assessment......................................................................51 2.3.3.4 Considering Current Controls ....................................................................................52 2.3.3.5 Setting Times Limits for Action ................................................................................52
2.3.4 Risk Control or Elimination............................................................................................... 53 2.3.4.1 Risk Control Involvement..........................................................................................53 2.3.4.2 Hierarchy of Controls ................................................................................................54 2.3.4.3 Sequence of Risk Control ..........................................................................................55 2.3.4.4 Undertaking Monitoring and Review.........................................................................57
2.4 Safety Risk Potentials in Railways............................................................................................ 58 2.4.1 Priority Issues Identified in Rail Safety .............................................................................60
2.4.1.1 System Based Safety Issues .......................................................................................61 2.4.1.2 People Based Safety Issues ........................................................................................64
2.4.2 Challenges of Safety Faced in Rail Sector.........................................................................68 2.5 Rail Safety Management System............................................................................................... 70
2.5.1 Rail SMS as a Central System to All Rail Operations.......................................................71 2.5.2 Development and Management of Rail Safety ..................................................................74 2.5.3 Key Components of SMS Managed by Rail Sectors .........................................................74 2.5.4 External Bodies Assisting in Rail Safety ...........................................................................79 2.5.5 Need for Measuring Rail Safety ........................................................................................81 2.5.6 Risk Assessment in Rail SMS ...........................................................................................82
2.6 Major Safety Issues at Railway-Highway Interfaces.................................................................84 2.6.1 Statistical Overview of Global Level Crossing Collisions and Consequences ..................85 2.6.2 Global Comparison of Level Crossing Accidents..............................................................87
2.7 Background of Research Problem .............................................................................................89 2.7.1 Significance of Safety Improvement at Level Crossings...................................................90
2.7.2 Previous Research on Risk Assessment at Grade Crossings.........................................90 2.7.3 The Need for Improving Railway Grade Crossings Safety ...............................................91
2.8 Summary ...................................................................................................................................93 Chapter 3: Research Methodology.......................................................................................................................94
3.0 Introduction ...............................................................................................................................94 3.1 Fundamental Concepts on Safety Risks Evaluation ..................................................................94
3.1.1 Identification of General Risks ..........................................................................................95 3.1.2 Evaluation of Risks............................................................................................................96 3.1.3 Analysis of Risk.................................................................................................................97 3.1.4 Types of Risk Analysis Methods .......................................................................................98
3.2 Developing Theoretical Framework on Safety Risk Evaluation at Rail Grade Crossings.......103 3.2.1 Development of a Quantitative Risk Assessment Model for Safety Evaluation at Rail Crossings - Safety Risk Index (SRI).........................................................................................104
3.2.1.1 Basic Concepts Used in Developing SRI.................................................................105 3.2.1.2 Numerical Example on Application of SRI .............................................................107 3.2.1.3 Major Steps to Achieve Objectives of Study ...........................................................108 3.2.1.4 Grade Crossing Accidents Data for Analysis...........................................................110
3.2.2 Major Factors Influencing Accident Risks at Grade Crossings .......................................111 3.2.2.1 Crossings Characteristics .........................................................................................113 3.2.2.2 Railway Characteristics............................................................................................114
3.3 Overview of Current Statistical Models for Predicting Accidents and Consequences at Grade Crossings .......................................................................................................................................116
3.3.2 Overview on Existing Models Developed for Prediction of Collisions at Railway-Highway Interfaces ..................................................................................................................................123
3.3.3 Overview of Existing Models in Predicting Consequences of Collisions at Railway-Highway Interfaces...................................................................................................................131
3.3.3.1 USDOT Consequence Model (1987).......................................................................132 3.3.3.2 Canada - University of Waterloo Consequence Model (2003) ................................133
3.3.4 Overview of Existing Models in Predicting Overall Safety Risks at Railway-Highway Interfaces ..................................................................................................................................134
3.4 Evaluation of Risk at Grade Crossings with Application of Safety Risk Index (SRI).............134 3.4.1 Identifying Worst Accident Crossing Locations (Black-Spots).......................................135 3.4.2 Developing an Improved Quantitative Method for Black-Spots Identification with Application of SRI....................................................................................................................136
3.5 Summary .................................................................................................................................138 Chapter 4: Data Collection and Consolidation ................................................................................................. 140
4.0 Introduction .............................................................................................................................140 4.1 Source of Rail Crossing Accidents Data and Information.......................................................140
4.1.1 Database of Railway-Highway Crossings Data and Information (Inventory Database)..141 4.1.1.1 Attributes and Variables in Inventory Database.......................................................142 4.1.1.2 Selection of Appropriate Variables from Inventory Database .................................143 4.1.1.3 Extraction of Public Grade Crossings from Inventory Database .............................146
4.1.2 Database of Railway-Highway Crossing Accidents Information (Occurrence Database)149 4.1.2.1 Attributes and Variables in Occurrence Database....................................................149 4.1.2.2 Selection of Appropriate Variables for Developing Models....................................150 4.1.2.3 Selection of Appropriate Records from Occurrence Database.................................152
4.1.3 Consolidated Database by Combining Inventory and Occurrence Databases .................154 4.2 Preliminary Data Analysis on Rail Crossings Accidents.........................................................155
4.2.1 Accidents at All Railway-Highway Crossings.................................................................156 4.2.1.1 Annual Accident Rates for All Rail Crossings Relations to Travel .........................157 4.2.1.2 Annual Accident Frequency Rates for Rail Crossings.............................................159 4.2.1.3 Reasons for Research Focus on Public Grade Crossings .........................................160
4.2.2 Accidents and Consequences at Public Grade Crossings ................................................163 4.2.2.1 Reasons for Grouping Public Grade Crossings by Protection Types for Model Development........................................................................................................................164 4.2.2.2 Inventory Data on Public Grade Crossings by Protection Type...............................164 4.2.2.3 Statistics of Accident Frequency and Consequence for Public Grade Crossings by Protection Type (2001 – 2005) ............................................................................................165 4.2.2.4 Statistics of Variables Used in Models by Protection Types ...................................166
4.3 Summary .................................................................................................................................166 Chapter 5: Development and Validation of Grade Crossing Accidents and Consequences Prediction Models............................................................................................................................................................168
5.0 Introduction .............................................................................................................................168 5.1 Overview of Current Safety Risk Assessment Models............................................................169
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5.2 Common Models of Accident Frequency Prediction ..............................................................170 5.2.1 Poisson Models................................................................................................................171
5.3 Common Models of Accidental Consequences Prediction......................................................190 5.3.1 Consequence Model by US Department of Transportation .............................................191 5.3.2 Consequence Model by Canada Transport Development Centre ....................................192
5.4 Major Steps in the Process of Model Development ................................................................193 5.4.1 Functional Form of Model...............................................................................................196 5.4.2 Model Distribution Structure ...........................................................................................197
5.4.3 Selection of Explanatory Variables for a Best-Fit Model................................................199 5.4.4 Procedures for Selecting Appropriate Variables for a Model ..........................................200 5.4.5 Assessment of Final Model for Goodness-of-Fit .............................................................201 5.4.6 Procedures for Selecting Final Model..............................................................................202
5.4.6.1 Step-1: Developing a GLM Poisson Regression Model ..........................................202 5.4.6.2 Step-2: Developing a GLM Negative Binomial Regression Model.........................202 5.4.6.3 Step-3: Selection of Appropriate Model - Poisson or Negative Binomial ...............202 5.4.6.4 Step-4: Utilising Empirical Bayesian Models..........................................................203
5.5 Results on Models Developed for Each Protection Type ........................................................208 5.5.1 Generating Models Predicting Accident Frequencies......................................................209
5.5.1.1 Crossing Protection Type 1 (No Signs or No signals) .............................................210 5.5.1.2 Crossing Protection Type 2 (Stop Signs or Cross-bucks) ........................................217 5.5.1.3 Crossing Protection Type 3 (Signals, Bells or Warning Devices) ...........................226 5.5.1.4 Crossing Protection Type 4 (Gates or Full Barrier) .................................................234
5.5.2 Generating Models Predicting Accidental Consequences ...............................................242 5.5.2.1 Crossing Protection Type 1 (No Signs or No signals) .............................................245 5.5.2.2 Crossing Protection Type 2 (Stop Signs or Cross-bucks) ........................................253 5.5.2.3 Crossing Protection Type 3 (Signals, Bells or Warning Devices) ...........................260 5.5.2.4 Crossing Protection Type 4 (Gates or Full Barrier) .................................................267
5.6 Summary .................................................................................................................................274 Chapter 6: Development of Safety Risk Index (SRI) for Risks Assessment at Grade Crossings .................276
6.0 Introduction .............................................................................................................................276 6.1 Development of Safety Risk Index (SRI) Model.....................................................................277
6.1.1 Defining Safety Risk Index (SRI)....................................................................................277 6.1.2 Identifying Safety Status of a Crossing using Graphical Method....................................278
6.2 Identifying Black-Spots (Crossings with Unacceptable Higher Safety Risk Index Values) ...280 6.2.1 Introducing Threshold Curves of Safety Risk Index........................................................280 6.2.2 Selecting Safety Risk Index Threshold Value .................................................................281 6.2.3 Identifying Black-Spots in Each Protection Type............................................................284
6.2.3.1 Crossing Protection Type 1 (No Signs or No signals) .............................................284 6.2.3.2 Crossing Protection Type 2 (Stop Signs or Cross-bucks) ........................................286 6.2.3.3 Crossing Protection Type 3 (Signals, Bells or Warning Devices) ...........................287 6.2.3.4 Crossing Protection Type 4 (Gates or Full Barrier) .................................................289
6.2.4 List of All Black-Spots Identified in the Study................................................................291 6.2.5 Validation of Safety Risk Index (SRI) Model .................................................................305 6.2.6 Analysis of Black-spot Cluster Regions (All Protection Types)......................................307
7.2.1 Effects of Highway Characteristics on Four Protection Types........................................313 7.2.2 Effects of Railway Characteristics on Four Protection Types .........................................315 7.2.3 Effects of Upgrading Protection Types on Collisions Related to Highway Characteristics..................................................................................................................................................318 7.2.4 Effects of Upgrading Protection Types on Collisions Related to Railway Characteristics..................................................................................................................................................321
7.3 Examining Models Predicting Consequences .........................................................................324 7.3.1 Effects of Highway Characteristics on Four Protection Types........................................325 7.3.2 Effects of Railway Characteristics on Four Protection Types .........................................325
7.4 Examining Models Predicting Safety Risk Index (SRI) ..........................................................326 7.4.1 Effects of Highway Characteristics on Four Protection Types........................................327 7.4.2 Effects of Railway Characteristics on Four Protection Types .........................................331
7.5 Summary .................................................................................................................................334 Chapter 8: Conclusions and Recommendations ...............................................................................................336
8.0 Introduction .............................................................................................................................336 8.1 Overview of Research Findings ..............................................................................................337
8.1.1 Accident Frequency Prediction Model ............................................................................339 8.1.2 Accident Consequences Prediction Model ......................................................................340 8.1.3 Estimation of Safety Risk Index (SRI) ............................................................................342 8.1.4 Black-Spots Identified Using Safety Risk Index .............................................................343
8.2 Contributions of Research Study............................................................................................. 345 8.3 Benefits of Research Study ..................................................................................................... 347 8.4 Research Limitations...............................................................................................................348 8.5 Recommendations ...................................................................................................................349 8.6 Future Research.......................................................................................................................350
Appendix 1: All Variables in USDOT FRA Databases .................................................................369
Appendix 2: Graphical Distribution of Variables Used................................................................376
Appendix 3: Descriptive Statistics on Model Variables ................................................................386
Appendix 4: List of Publications.....................................................................................................389
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List of Tables
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Chapter 2: Table 2.1: Typical Measure of Risk Exposures 49 Table 2.2: Typical Measure of Likelihood 49 Table 2.3: Typical Measure of Consequences 50 Table 2.4: A Typical Risks Assessment Matrix 50 Table 2.5: Level Crossing Accident Statistics in Selected European Countries 87 Chapter 3: Table 3.1: Group Selection for Estimating Probability of an Event 100 Table 3.2: Group Selection for Measuring Consequences of an Event 100 Table 3.3: A Typical Qualitative Risks Ranking Matrix 101 Table 3.4: Probability of Deaths by Causes 102 Table 3.5: USDOT Accident Prediction Equations for Category by Characteristic Factors 130 Table 3.6: Coefficients of Coleman-Stewart Model 131 Chapter 4: Table 4.1: Filtering Process in Selecting Appropriate Variables from Inventory Database 146 Table 4.2: Number of All Crossings by Type Vs Position (2001-2005) 147 Table 4.3: Filtering Process in Selecting Appropriate Variables from Accident Database 152 Table 4.4: All Level Crossing Accidents and Casualties (2001 – 2005) 156 Table 4.5: Number of All Level Crossing Accidents and Accident Rates (2001 – 2005) 158 Table 4.6: Accident Frequency Rates by Type of Crossings 160 Table 4.7: Accident Frequency Rates by Type by Position of Crossings 161 Table 4.8: Public Grade Crossing Accident Casualties (2001 – 2005) 163 Table 4.9: Public Grade Crossings Data by Protection Type (2001 – 2005) 165 Table 4.10: Accidents Data of Public Grade Crossings by Protection Type (2001-2005) 165 Table 4.11: Consequences Data of Public Grade Crossings by Protection Type (2001-2005) 166 Chapter 5: Table 5.1: Comparison of Accidental Crossings Predicted by Poisson Model to History 173 Table 5.2: Over-Dispersion Test Values on Number of Accidents by Crossing Types 178 Table 5.3: Comparison of Observed and Predicted Values for Accidental Crossings by ZIP 184 Table 5.4: Descriptive Statistics on Variables Used in the Model - Protection Type 1 210 Table 5.5: Pearson Correlation Between Variables Used in the Model - Protection Type 1 211 Table 5.6: Parameter Estimates of GLM Poisson Regression Model - Protection Type 1 211 Table 5.7: Goodness-of-Fit Result of GLM Poisson Regression Model - Protection Type 1 212 Table 5.8: Parameter Estimates in GLM Negative Binomial Model - Protection Type 1 213 Table 5.9: Goodness-of-Fit Result of GLM Negative Binomial Model - Protection Type 1 213 Table 5.10: Over-Dispersion Parameter and Weighting Factors Estimation - EB Model 214 Table 5.11: Goodness-of-Fit Result of NB & EB Models - Max Timetable Train Speed 215 Table 5.12: Goodness-of-Fit Result of NB & EB Models - AADT 216 Table 5.13: Top Ten Accidental Locations by EB Model Prediction in Protection Type 1 217 Table 5.14: Descriptive Statistics on Variables Used in the Model - Protection Type 2 218 Table 5.15: Pearson Correlation Between Variables Used in the Model - Protection Type 2 218 Table 5.16: Parameter Estimates in GLM Poisson Regression Model - Protection Type 2 219 Table 5.17: Goodness-of-Fit Result of GLM Poisson Regression Model - Protection Type 2 219 Table 5.18: Parameter Estimates in GLM Negative Binomial Model - Protection Type 2 220 Table 5.19: Goodness-of-Fit Result of GLM Negative Binomial Model - Protection Type 2 220 Table 5.20: Over-Dispersion Parameter and Weighting Factors Estimation - EB Model 222 Table 5.21: Goodness-of-Fit Result of NB & EB Models - Timetable Train Speed 223 Table 5.22: Goodness-of-Fit Result of NB & EB Models - Highway Speed 223 Table 5.23: Goodness-of-Fit Result of NB & EB Models - Number of Traffic Lanes 224 Table 5.24: Goodness-of-Fit Result of NB & EB Models - Daily Train Movement 224 Table 5.25: Goodness-of-Fit Result of NB & EB Models - AADT 224 Table 5.26: Top Ten Accidental Locations by EB Model Prediction in Protection Type 2 225
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Table 5.27: Descriptive Statistics on Variables Used in the Model - Protection Type 3 226 Table 5.28: Pearson Correlation Between Variables Used in the Model - Protection Type 3 227 Table 5.29: Parameter Estimates in GLM Poisson Regression Model - Protection Type 3 227 Table 5.30: Goodness-of-Fit Result of GLM Poisson Regression Model - Protection Type 3 228 Table 5.31: Parameter Estimates in GLM Negative Binomial Model - Protection Type 3 229 Table 5.32: Goodness-of-Fit Result of GLM Negative Binomial Model - Protection Type 3 229 Table 5.33: Over-Dispersion Parameter and Weighting Factors Estimation - EB Model 230 Table 5.34: Goodness-of-Fit Result of NB & EB Models - Max Timetable Train Speed 232 Table 5.35: Goodness-of-Fit Result of NB & EB Models - Highway Speed 232 Table 5.36: Goodness-of-Fit Result of NB & EB Models - Number of Traffic Lanes 232 Table 5.37: Goodness-of-Fit Result of NB & EB Models - Daily Train Movement 233 Table 5.38: Goodness-of-Fit Result of NB & EB Models - AADT 233 Table 5.39: Top Ten Accidental Locations by EB Model Prediction in Protection Type 3 234 Table 5.40: Descriptive Statistics on Variables Used in the Model - Protection Type 4 235 Table 5.41: Pearson Correlation Between Variables Used in the Model - Protection Type 4 235 Table 5.42: Parameter Estimates in GLM Poisson Regression Model - Protection Type 4 236 Table 5.43: Goodness-of-Fit Result of GLM Poisson Regression Model - Protection Type 4 236 Table 5.44: Parameter Estimates in GLM Negative Binomial Model - Protection Type 4 237 Table 5.45: Goodness-of-Fit Result of GLM Negative Binomial Model - Protection Type 4 237 Table 5.46: Over-Dispersion Parameter and Weighting Factors Estimation - EB Model 239 Table 5.47: Goodness-of-Fit Result of NB & EB Models - Number of Main Tracks 240 Table 5.48: Goodness-of-Fit Result of NB & EB Models - Number of Traffic Lanes 240 Table 5.49: Goodness-of-Fit Result of NB & EB Models - Daily Train Movement 241 Table 5.50: Goodness-of-Fit Result of NB & EB Models - AADT 241 Table 5.51: Top Ten Accidental Locations by EB Model Prediction in Protection Type 4 242 Table 5.52: Equivalent Fatality Score comparison for various accident consequences 243 Table 5.53: Descriptive Statistics on Variables Used in the Model - Protection Type 1 245 Table 5.54: Pearson Correlation Between Variables Used in the Model - Protection Type 1 246 Table 5.55: Parameter Estimates in GLM Poisson Regression Model - Protection Type 1 246 Table 5.56: Goodness-of-Fit Result of GLM Poisson Regression Model - Protection Type 1 247 Table 5.57: Parameter Estimates in GLM Negative Binomial Model - Protection Type 1 248 Table 5.58: Goodness-of-Fit Result of GLM Negative Binomial Model - Protection Type 1 248 Table 5.59: Over-Dispersion Parameter and Weighting Factors Estimation - EB Model 249 Table 5.60: Goodness-of-Fit Result of NB & EB Models - Max Timetable Train Speed 251 Table 5.61: Goodness-of-Fit Result of NB & EB Models - Total Occupants in Vehicle 251 Table 5.62: Top Ten Locations by Consequence Predicted with EB in Protection Type 1 252 Table 5.63: Descriptive Statistics on Variables Used in the Model - Protection Type 2 253 Table 5.64: Pearson Correlation Between Variables Used in the Model - Protection Type 2 254 Table 5.65: Parameter Estimates in GLM Poisson Regression Model - Protection Type 2 254 Table 5.66: Goodness-of-Fit Result of GLM Poisson Regression Model - Protection Type 2 255 Table 5.67: Parameter Estimates in GLM Negative Binomial Model - Protection Type 2 256 Table 5.68: Goodness-of-Fit Result of GLM Negative Binomial Model - Protection Type 2 256 Table 5.69: Over-Dispersion Parameter and Weighting Factors Estimation - EB Model 257 Table 5.70: Goodness-of-Fit Result of NB & EB Models - Max Timetable Train Speed 259 Table 5.71: Goodness-of-Fit Result of NB & EB Models - Total Occupants in Vehicle 259 Table 5.72: Top Ten Locations by Consequence Predicted with EB in Protection Type 2 260 Table 5.73: Descriptive Statistics on Variables Used in the Model - Protection Type 3 261 Table 5.74: Pearson Correlation Between Variables Used in the Model - Protection Type 3 261 Table 5.75: Parameter Estimates in GLM Poisson Regression Model - Protection Type 3 262 Table 5.76: Goodness-of-Fit Result of GLM Poisson Regression Model - Protection Type 3 262 Table 5.77: Parameter Estimates in GLM Negative Binomial Model - Protection Type 3 263 Table 5.78: Goodness-of-Fit Result of GLM Negative Binomial Model - Protection Type 3 263 Table 5.79: Over-Dispersion Parameter and Weighting Factors Estimation - EB Model 264 Table 5.80: Goodness-of-Fit Result of NB & EB Models - Max Timetable Train Speed 266 Table 5.81: Goodness-of-Fit Result of NB & EB Models - Total Occupants in Vehicle 266 Table 5.82: Top Ten Locations by Consequence Predicted with EB in Protection Type 3 267 Table 5.83: Descriptive Statistics on Variables Used in the Model - Protection Type 4 268 Table 5.84: Pearson Correlation Between Variables Used in the Model - Protection Type 4 268 Table 5.85: Parameter Estimates in GLM Poisson Regression Model - Protection Type 4 269 Table 5.86: Goodness-of-Fit Result of GLM Poisson Regression Model - Protection Type 4 269
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Table 5.87: Parameter Estimates in GLM Negative Binomial Model - Protection Type 4 270 Table 5.88: Goodness-of-Fit Result of GLM Negative Binomial Model - Protection Type 4 270 Table 5.89: Over-Dispersion Parameter and Weighting Factors Estimation - EB Model 271 Table 5.90: Goodness-of-Fit Result of NB & EB Models - Max Timetable Train Speed 273 Table 5.91: Goodness-of-Fit Result of NB & EB Models - Total Occupants in Vehicle 273 Table 5.92: Top Ten Locations by Consequence Predicted with EB in Protection Type 4 273 Chapter 6: Table 6.1: Summary of Proposed Threshold Critical Values by Protection Types 283 Table 6.2: List of 3 Black-Spots Identified in Protection Type 1 286 Table 6.3: List of Top Five within 129 Black-Spots Identified in Protection Type 2 287 Table 6.4: List of Top Five within 76 Black-Spots Identified in Protection Type 3 289 Table 6.5: List of Top Five within 239 Black-Spots Identified in Protection Type 4 290 Table 6.6: List of 447 Black-Spots Identified from the Study and Their Locations 292 Table 6.7: Number of Black-Spots Identified by Top Ten States 305 Table 6.8: Number of Black-Spots Identified by Top Eight Counties 305 Table 6.9: Common 17 Black-Spots Identified in All Three Circles (A, B and C) 306 Chapter 7: Table 7.1: Controlled Values for Parameters Constructing Collision Prediction Models 312 Table 7.2: Controlled Values for Parameters Constructing Consequence Prediction Models 324 Table 7.3: Controlled Values for Parameters Constructing Safety Risk Index Models 327 Chapter 8: Table 8.1: EB Modelling Equations for Accident Frequency Prediction with Variables 339 Table 8.2: Impact Effect of Railway and Highway Characteristics on Accident Prediction 340 Table 8.3: EB Modelling Equations for Consequence Prediction with Explained Variables 341 Table 8.4: Impact Effect of All Factors on Consequences Prediction by Protection Type 342
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List of Figures
PAGE
Chapter 1: Figure 1.1: A Typical Railway-Highway Crossing in Australia 8 Figure 1.2: Outcome of a Major Accident at Level Crossing (Lismore, Australia 2006) 9 Figure 1.3: Logical Flow of Research Areas Leading to the Thesis Topic 15 Figure 1.4: Flow Diagram for Developing Structure of the Thesis 17 Chapter 2: Figure 2.1: Characteristics of an Event of Accident 19 Figure 2.2: The 4 ‘P’s Principles for Safety Management System 26 Figure 2.3: The Basic Safety Management System Process 29 Figure 2.4: The 3 ‘C’ Elements of Leadership 33 Figure 2.5: Three Major Processes in Risk Management System 39 Figure 2.6: Three Elements in Determination of Risk Assessment 47 Figure 2.7: Two Major Groups Identified in Rail Safety Issues 60 Figure 2.8: Rail Safety Management System as a Central System to All Rail Operations 73 Figure 2.9: International Comparison of Annual Collision Rate for Level Crossings 88 Figure 2.10: International Comparison of Annual Fatality Rate for Level Crossings 88 Chapter 3: Figure 3.1: Three Common Types in Risk Analysis Methods 99 Figure 3.2: Three Basic Elements of Measurements in the Development of SRI 106 Figure 3.3: Graphical Representation of Three Elements of Rail Safety Risk Evaluation 107 Figure 3.4: Flow Diagram for Identifying Black-Spots Within Grade Crossings 110 Figure 3.5: Model of Accident Risk Factors and Associated Variables at Grade Crossings 112 Figure 3.6: Graphical Model of a Typical Quantitative Safety Risk Matrix 135 Figure 3.7: Flow Diagram for Procedures of Identifying Black-Spots 136 Figure 3.8: Identifying Black-Spots within Grade Crossings Based on Safety Risk Index 137 Chapter 4: Figure 4.1: Distribution of Different Categories of Variables in the Inventory Database 142 Figure 4.2: Process for Extraction of Public Grade Crossings from Inventory Database 148 Figure 4.3: Distribution of Different Categories of Variables in the Occurrence Database 150 Figure 4.4: Process for Extraction of Crossings Accidents Information 153 Figure 4.5: All Level Crossing Accidents and Casualties (2001 – 2005) 157 Figure 4.6: Number of All Level Crossing Accidents and Accident Rates (2001 – 2005) 158 Figure 4.7: Number of Level Crossing Accidents by Crossing Type (2001 – 2005) 159 Figure 4.8: Annual Accident Frequency Rate per Crossing Type 160 Figure 4.9: Number of Crossings within Each Type of Crossing (2001 – 2005) 161 Figure 4.10: Number of Accidents within Each Type of Crossing (2001 – 2005) 162 Figure 4.11: Accident Frequency Rates within Each Type of Crossing (2001 – 2005) 162 Figure 4.12: Public Grade Crossing Accidents and Casualties (2001 – 2005) 163 Chapter 5: Figure 5.1: Number of Crossings Predicted by Poisson Model for Protection Type 1 174 Figure 5.2: Number of Crossings Predicted by Poisson Model for Protection Type 2 174 Figure 5.3: Number of Crossings Predicted by Poisson Model for Protection Type 3 175 Figure 5.4: Number of Crossings Predicted by Poisson Model for Protection Type 4 175 Figure 5.5: Number of Crossings Predicted by ZIP Model for Protection Type 1 182 Figure 5.6: Number of Crossings Predicted by ZIP Model for Protection Type 2 182 Figure 5.7: Number of Crossings Predicted by ZIP Model for Protection Type 3 183
xiv
Figure 5.8: Number of Crossings Predicted by ZIP Model for Protection Type 4 183 Figure 5.9: Flow Diagram of Developing Empirical Bayesian (EB) Model 189 Figure 5.10: Flow Diagram of Better-Fit Poisson Model Building Process (Step 1) 204 Figure 5.11: Flow Diagram of Better-Fit NB Model Building Process (Step 2) 205 Figure 5.12: Flow Diagram of Comparing Poisson and NB Models (Step 3) 206 Figure 5.13: Flow Diagram of Best-Fit EB Model Building Process (Step 4) 207 Chapter 6: Figure 6.1: Flow Diagram of Developing Safety Risk Index (SRI) Model 278 Figure 6.2: Identifying Safety Status of Grade Crossings by Safety Risk Index Curve 279 Figure 6.3: Safety Risk Index Curves with Different SRI Values 280 Figure 6.4: Estimating Threshold Value for Black-Spots Identification 282 Figure 6.5: Number of Black-Spots by Protection Types Vs Standardized Score of SRI 283 Figure 6.6: Safety Risk Index Vs Percentage of Protection Type 1 Accidental Crossings 285 Figure 6.7: Black-Spots Identification in Protection Type 1 Grade Crossings 285 Figure 6.8: Safety Risk Index Vs Percentage of Protection Type 2 Accidental Crossings 286 Figure 6.9: Black-Spots Identification in Protection Type 2 Grade Crossings 287 Figure 6.10: Safety Risk Index Vs Percentage of Protection Type 3 Accidental Crossings 288 Figure 6.11: Black-Spots Identification in Protection Type 3 Grade Crossings 288 Figure 6.12: Safety Risk Index Vs Percentage of Protection Type 4 Accidental Crossing 289 Figure 6.13: Black-Spots Identification In Protection Type 4 Grade Crossings 290 Figure 6.14: All 447 Black-Spots Identified in Four Protection Type Grade Crossings 291 Figure 6.15: Graphical Demonstration on Comparison of Black-Spots to Crossings Ranked 306 Figure 6.16: Three Cluster Regions of 447 Black-Spots in All Protection Types 308 Chapter 7: Figure 7.1: Flow Diagram for Impact Analysis on Models Developed in the Study 311 Figure 7.2: Effect of AADT on Collision Prediction by Protection Type 313 Figure 7.3: Effect of Number of Traffic Lanes on Collision Prediction by Protection Type 314 Figure 7.4: Effect of Highway Speed on Collision Prediction by Protection Type 315 Figure 7.5: Effect of Daily Train Traffic on Collision Prediction by Protection Type 316 Figure 7.6: Effect of Number of Main Tracks on Collision Prediction by Protection Type 317 Figure 7.7: Effect of Train Speed on Collision Prediction by Protection Type 318 Figure 7.8: Effect of AADT on Predicted Collision Ratio 319 Figure 7.9: Effect of Number of Traffic Lanes on Predicted Collision Ratio 320 Figure 7.10: Effect of Highway Speed on Predicted Collision Ratio 321 Figure 7.11: Effect of Daily Train Traffic on Predicted Collision Ratio 322 Figure 7.12: Effect of Number of Main Tracks on Predicted Collision Ratio 323 Figure 7.13: Effect of Train Speed on Predicted Collision Ratio 324 Figure 7.14: Effect of Occupants in Vehicle on Consequences Prediction by Protection Type 325 Figure 7.15: Effect of Train Speed on Consequences Prediction by Protection Type 326 Figure 7.16: Effect of AADT on Estimation of SRI by Protection Type 328 Figure 7.17: Effect of Number of Traffic Lanes on Estimation of SRI by Protection Type 329 Figure 7.18: Effect of Highway Speed on Estimation of SRI by Protection Type 330 Figure 7.19: Effect of Occupants in Vehicle on Estimation of SRI by Protection Type 331 Figure 7.20: Effect of Daily Train Traffic on Estimation of SRI by Protection Type 332 Figure 7.21: Effect of Number of Main Tracks on Estimation of SRI by Protection Type 333 Figure 7.22: Effect of Train Speed on Estimation of SRI by Protection Type 334 Chapter 8: Figure 8.1: 447 Basic Black-Spots Identified in All Protection Types of Grade Crossings 343 Figure 8.2: Worst Black-Spots Identification in All Protection Types of Grade Crossings 344 Figure 8.3: Number of Worst Black-Spots Identified as per SRI Threshold Value Selected 345
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Abbreviations
AIC Akaike's Information Criterion ALARP As Low As Reasonably PracticableAS / NZS Australian and New Zealand StandardsATC Australian Transport Council ATP Automatic Train Protection AADT Average Annual Daily TrafficDOT Department of Transportation EB Empirical BayesianEFS Equivalent Fatality ScoreEC European Countries ETSC European Transport Safety Council FRA Federal Railroad AdministrationGLM Generalised Linear ModellingGOF Goodness-of-FitHRGC Highway-Railway Grade Crossings ITSRR Independent Transport Safety and Reliability Regulator LC Level Crossing LR Linear RegressionNB Negative BinomialOHS Occupational Health & SafetyPPE Personal Protective Equipment RSSB Rail Safety & Standards BoardRC RailCorpRSA Railway Safety ActSMS Safety Management SystemSRI Safety Risk IndexSPAD Signal Passed at Danger UN United Nation USDOT US Department of Transportation WD Warning DeviceWCA WorkCover AuthorityZIP Zero-Inflated Poisson
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Nomenclature
iP Risk score due to probability for thi hazard
iC Risk score due to consequence for thi hazard
iE Risk score due to exposure for thi hazard
SRI Safety Risk Index λ Poisson parameter (e.g. Accident occurrence rate) 2s Sample variance
_
y Sample mean
a, ib
Regression parameters
iZ ith reference variable
iR Measure of risk for a class of events X Expected accident frequency at a grade crossing Y Estimated consequences (equivalent fatalities) at a grade crossing ℜ Estimated safety risk index (SRI) value at a grade crossing
oℜ Critical (or threshold) safety risk index value
1ω, 2ω Weighting factors used in EB models Κ Over-dispersion parameter used in EB models
Var (Y) Variance of accidents )(ˆ YE Estimated mean value of accidents from Poisson / NB models
y Actual number of accidents from the accident history ),(ˆ yYE Refined estimation of accidents from EB models
)|(ˆ YCE Predicted number of equivalent fatalities by Poisson / NB Models )]|(),|[(ˆ YCYCE Refined estimation of equivalent fatalities from EB models
e Exponential function Ln Logarithm function
2R Values of determination coefficient in regression models 2χ Chi-square statistic
DT Daily Train Movement AADT Annual Average Daily Traffic MTTS Maximum Timetable Train Speed
HS Highway Speed MT Number of Main Tracks TL Number of Traffic Lanes
TCA Track Crossing Angle TOV Total Occupants in Vehicle EFS Equivalent Fatality Score FAT Number of fatalities INJ Number of Injuries PVD Property and vehicle damage in dollars
xvii
Abstract
In the global view, among other rail safety issues, highway-railway accidents
continue to be a major problem from both public health and socio-economic
perspectives. It is noted that many research studies have been conducted in the past
in relation to developing appropriate models to assess the road traffic safety through
collision prediction, but a considerable amount of work has been carried out only
regarding safety at “highway-railway” grade crossings.
The primary objective of this study is to provide an improved method for rail safety
appraisal at “railway-highway” grade crossings through the development and
application of suitable safety risk scores (called ‘Safety Risk Index’) with a
combination of both accident frequency and accidental consequences prediction
models generated for crossings, and also by using these safety risk scores to identify
the worst or most dangerous locations. The Safety Risk Index (SRI) is a simple
composite index, which can measure, compare and rank safety levels at different risk
situations and locations. These safety risk scores are designed to generate an overall
grade crossings safety risk, which is based on the combination of three basic risk
elements - namely the exposure of the crossing users, the probability of an accident
taking place, and the severity of consequences should an accident occur. This method
facilitates the assessment of the safety risks at grade crossings and also ranks,
identifies and prioritises the worst performing crossings or the problematic crossings
(Black-Spots). This model is very simple and easily understood by those with
different levels of knowledge on safety. The SRI index based on quantitative
methods and developed in this study seems very promising and has great potential to
be a major tool for safety risk assessment at grade crossings in various countries.
The secondary objective of this study is to provide an index with a single meaningful
value for assessing the risk at grade crossings, through the gathering and analysis of
data, information and knowledge (from various data sources) on rail safety. The
research study also establishes appropriate statistical methodologies in order to
develop and to construct a quantitative model for risk assessment.
1
Chapter 1
Introduction to the Research
1.0 Introduction
In the broader aspect of safety associated with various modes of transport, in
particular with rail transport, safety at railway crossings is a major area for concern
with an increasing number of accidents across various railroad infrastructures. In
recent times, the safety of rail crossings and associated safety risk assessments
across many situations of road-rail crossings have attracted increasing attention.
However, the need for further research in this area, in particular developing
comprehensive safety risk assessment models, is warranted with the increasing
demand for improved safety which can contribute to improved public health and
socio-economic benefits.
This chapter introduces the research topic and briefly discusses the initiative of the
research. It briefly presents an outline structure of the thesis and explains the
reasons why this study is of interest. The aim of the study is also highlighted and a
brief description of the developing concept of a risk assessment model (Safety Risk
Index) is discussed. It initially provides the basic definition of safety and risks and
briefly describes Occupational Health and Safety (OHS) in general industries. It
provides an overview of general safety management systems used in industries. In
addition, it elaborates the background of the existing potential of rail safety risks and
the overview of rail safety management systems. It also describes the objectives of
the research study and lists the benefits achieved in relation to this research. Finally
it outlines the structure of the thesis in detail.
1.1 Overview of Risk and Occupational Health & Safety
Human life is often put at risk when performing various activities in different ways.
Basically, risk is the chance that a safety hazard will result in an accident which
causes casualties such as loss of life, injury or property damage. Statistically, risk is
2
the probability of an untoward event or unfavourable consequence of an event. This
truism may have very distinct meanings in the individual locations and populations
of today’s world. Australian / New Zealand Standard 4360 (2004) defines
‘acceptable risk’ as “An informed decision to accept the consequences and the
likelihood of a particular risk”.
In order to understand what safety involves, it is important and necessary to know the
nature of hazards. A hazard is an activity or combination of activities or set of
circumstances which could produce an accident with the potential to harm life, health
or property. Hazard identification is the process of identifying all risks in the
workplace. Hazards are the main cause of occupational health and safety (OHS)
problems. Therefore, finding ways of eliminating hazards or controlling the
associated risks is the best way to reduce injury and illness. When attempting to
interpret what ‘safety’ means, an ambiguous situation is created. However,
Australian / New Zealand Standard 4801 (2001) provides meaning to the term
‘safety’ as “A state in which the risk of harm (to persons) or damage (to properties)
is limited to an acceptable level”.
Given the very close relationship between safety and accidents, the literature
suggests that the level of safety is inversely proportional to the number of accidents
(Dixit 2007, p.1). Safety at workplaces and also in public places continues to be one
of the major emerging concerns and issues in most developing countries. Measuring
safety is needed to assess the level of safety, and thereby to identify and improve
processes and procedures outlined in the safety management systems. Most of the
current safety accreditation procedures appear to allow the tolerance of some risks. In
various industries, employees today face a wide array of potential risks to their health
and well-being. Some hazards are reasonably apparent, whilst others are often more
insidious. Hazards are the prime identifiable cause of occupational health and safety
problems (WorkCover-NSW 1996, p.7). Some examples of occupational hazards are:
• Trip hazards in a passage or corridor;
• Lifting things in an unsafe manner;
• Using chemicals incorrectly;
• Handling of flammable liquids in the presence of ignition sources;
3
• Loose asbestos released during demolition work which has the potential to
cause lung cancer;
• Noise from an uninsulated chainsaw which can reach levels of up to 110 dB
with the potential to seriously damage hearing;
• Badly designed shovel (for example, with a short handle and very large
blade) which has the potential to cause back injury;
• Waste oil from an engine which has the potential to damage workers' health
through skin absorption, due to its carcinogenic properties.
Occupational Health and Safety (OHS) issues arise not only from physical and
chemical problems but also from other features of the operating conditions such as an
employee’s work experience. Under the OHS Acts and Regulations provided in
various countries, the employer has ultimate responsibility to ensure that a safe
workplace is maintained. To meet this requirement, employers must ensure that some
forms of safety systems are in place and that responsibility has been allocated to
managers, supervisors and workers in the organisation. In the meantime, all
employees should take responsibility for their own health and safety and for others
who may be affected by acts or omissions on their part. Safety responsibility should
be part of the daily functions of everyone in the workplace. To assign the safety
responsibilities the following are put in place for workers (NT WorkSafe 2003):
• Incorporate health and safety responsibilities into job descriptions for all
workers and encourage workers to identify unsafe work situations;
• Responsibilities and accountabilities should be assigned for such things as
induction training, first aid, emergency procedures and workplace
inspections;
• Ensure that workers fully understand their responsibilities for health and
safety. Using induction, adequate education and training programs can
achieve this aim.
A major challenge for many employers would be managing safety to meet the
specified requirements set up by government and safety regulators. In recent times,
safety management systems have been developed for managing the above challenges
with some success across various industries.
4
1.2 Safety Management System (SMS)
In general, a safety management system (SMS) is considered to be a businesslike
approach to safety. It is a systematic, explicit and comprehensive system for
managing safety risks. As with all management systems, a SMS provides for goal
setting, planning, and measuring performance. A SMS is woven into the fabric of an
organisation (Civil Aviation Safety Transport Canada 2001, p.1). In this regard, SMS
is implemented across various functional areas of an organisation, aiming to manage
and control the potential risks at workplaces. With the increased use of SMS across
various industries and organisations, it has become part of the culture, the way
people do their jobs. NT WorkSafe (2003, p.6) states that ‘Safety management is
described as a set of actions or procedures relating to health and safety in the
workplace, put in place and actively endorsed by management to achieve the
following’:
• Identification, assessment and elimination or control of all workplace hazards
and risks;
• Active involvement in health and safety matters with managers and workers
working together both formally and informally to improve health and safety;
• Providing necessary information and training for people at all levels so they
can effectively meet their responsibilities; and
• Designing and implementing company goals about health and safety.
Further, a SMS provides an organisation with the capacity to anticipate and address
safety issues before they lead to an incident or accident. A SMS also provides
management with the ability to deal with accidents and near misses effectively so
that valuable lessons are learnt and changes implemented to improve safety and
efficiency (Civil Aviation Safety Transport Canada 2001, p.5). The SMS approach
reduces losses and improves productivity. The basic safety management process is
generally accomplished with major elements of events and functions such as:
• A safety issue / concern is raised, a hazard is identified, or an incident /
accident happens;
• The concern / event is reported or brought to the attention of management;
• The event, hazard, or issue is analysed to determine its cause or source;
• Corrective action, control or mitigation is developed and implemented; and
5
• The corrective action is evaluated to make sure it is effective. If the safety
issue is resolved, the action can be documented and the safety enhancement
maintained. If the problem or issue is not resolved, it should be re-analysed
until it is resolved.
When an organisation develops a safety management policy and associated
procedures, they have to fit into the organisation in many ways. For example, safety
management has to be comprehensive, but should not be more complex than the rest
of the company's management program. Safety management must be compatible, and
preferably, integrated into the overall management scheme. A list of the
organisation’s safety system procedures is helpful to managers who want to know
more about how to make safety management a reality. Most items in this list will be
familiar to managers. They are already part of the safety landscape. The fundamental
changes are concerned with roles and accountability of company's management and
the regulator.
1.3 Background of Rail Safety Risk Potentials and Rail SMS
United Nations (2000, p.1) states that each year, accidents at level crossings not only
cause the deaths of or serious injuries to many thousands of road users and railway
passengers, but also impose a heavy financial burden in terms of interruption of
railway and road services and damage to railway and road vehicles and property.
This leads to the following phenomena:
• Many billions of dollars are paid in medical costs and disability payments;
• Medical insurance premiums are increased to meet the rising costs;
• Capacity of operations and productivity is decreased;
• Heavy loss of lives and human suffering;
• Inconvenience caused to the people injured, to others and to the environment.
The Rail Safety & Standards Board (RSSB) in the United Kingdom claims that rail is
still one of the safest forms of public transport and is nine times safer than travelling
by car. However, the railway occurrences and the rise in accidental consequences
(including fatalities, injuries and property damage) sustained by passengers, railway
6
employees and public in recent years provide a stark reminder of the potential for
hazards in railway systems worldwide. Railway occurrences include both:
• Accidents affecting life and property of passengers, public and employees;
and
• Incidents that do not result in accidents directly but have the potential to do
so (known as ‘near miss accidents’).
Railway occurrences (accidents and incidents) don’t just happen, nor are occurrences
completely accidental in nature. There may be many factors which contribute to the
railway occurrences, caused by the failure of one or more safety components of the
railway system. Identifying, prioritising and targeting the hazard potentials and
developing mitigative initiatives and controls can achieve the prevention of such
occurrences. In order to improve rail safety, railway authorities and safety agencies
keep continuously employing various rail SMS in several countries. These systems
are designed to enhance the quality of safety performance for the rail passengers,
public and rail employees.
Therefore, the Rail SMS is important in ensuring rail safety. It provides a holistic,
systematic and optimal way of managing and controlling rail safety risks to achieve
desired safe outcomes in a sustainable way. Britain’s main line railways have
become increasingly safe in recent years (Rail Safety and Standards Board 2006). At
the same time, the number of passengers is rising at an unprecedented rate, freight
traffic has grown and is set to expand even further, and performance is improving.
All this bears out what the Rail sector has always known - that high standards of
performance and safety are inextricably linked. It provides what passengers and
customers expect while creating the essential condition for growth in the traffic. As
the authority for maintaining safety, the Rail sector needs to assure itself and the
community (the public, passengers and employees) that the safety risks are being
managed to levels that are “As Low As Reasonably Practicable” (ALARP).
There are currently different approaches (national and international) to railway
safety, different targets and methods applied. Technical standards, the rolling stock
and the certification of staff and railway undertakings differ from one country to
another and have not been adapted to the needs of an integrated Rail SMS. However,
the world railway safety system covers safety requirements for the system as a
7
whole, including infrastructure and traffic management, and the interaction between
railway undertakings and infrastructure senior managers. It also focuses on the
establishment of common safety indicators in order to assess that the system
complies with the common safety targets and facilitates the monitoring of railway
safety performances. In general, the Rail SMS system has been developed to meet
overall needs based on best international knowledge and practices. A number of
initiatives taken under the Rail SMS have led to increased safety awareness and the
application of a structured, proactive approach to safety. Through external
benchmarking and external SMS reviews set up by the Australian/New Zealand
Standards 4801 (2001), the SMS is reinforced to strive for continuous improvement.
Based on state-of-the-art knowledge, international best practices and its own
experience, the Rail sector’s SMS is continuously being upgraded to meet the
challenges and needs of a modern, safe mass transit railway.
EUROPA (2004) states that safety rules and standards, such as operating rules,
signalling rules, requirements on staff and technical requirements applicable to
rolling stock, have been devised mainly nationally. Under the regulations currently in
force, a variety of bodies deals with safety. These national safety rules, which are
often based on national technical standards, should gradually be replaced by rules
based on common standards, established by technical specifications for
interoperability. The new national rules should be in line with current legislations
and facilitate migration towards a common approach to railway safety. In this way,
the Rail sector aims to ensure that:
• Railway safety is generally maintained and continuously improved, taking
into consideration the development of current legislations;
• Safety rules are laid down, applied and enforced in an open and non-
discriminatory manner;
• Responsibility for the safe operation of the railway system and the control of
risks associated with it is borne by the infrastructure managers and railway
undertakings;
• Information is collected on common safety indicators through annual reports
in order to assess the achievement of the common safety targets and monitor
the general development of railway safety.
8
One major element of SMS is to develop appropriate methodologies to assess the
safety risk in various operating sectors of railways. One of the major sectors urgently
warranting safety evaluation is the interface of railway and highway. This safety
evaluation includes a quantitative risk assessment procedure to determine the annual
collective risks due to potential accident scenarios from level crossings.
1.4 Significance of the Study
Rail Safety and Standards Board (2004, p.1) states at the outset that "Level Crossing
Risk is likely to become the largest category of train accident risk on the National
Rail network in Great Britain. It is also a significant risk for road users and
pedestrians”. Safety at level crossings is also one of the most serious safety issues
faced by the rail industry in Australia. Sochon and Piamsa-Art (2007, p.1) states that
approximately 100 level crossing crashes occur between a road vehicle and a train
each year and about 8% of these crashes result in deaths. In addition, about 22
pedestrians die each year while crossing railways on public streets. Fatalities at level
crossings are only a small proportion of the national road toll but a major contributor
to the rail toll. A typical railway level crossing in Australia is shown in Figure 1.1.
Figure 1.1: A Typical Railway-Highway Crossing in Australia
9
In recent times, the significance of level crossing safety has been highlighted in
several studies. For example, a major trend has recently emerged involving heavy
vehicles (trucks) colliding with trains and causing catastrophic damage to those trains
and the people on board. In the period between January 2006 and June 2007, there
were 11 level crossing crashes involving heavy vehicles. Tragically, 17 lives were
lost. More than $100 million in damages resulted. These major incidents include the
Kerang crash, where 11 lives were lost, and the Lismore crash, where there was one
fatality and more than $25 million in damages resulted (Sochon & Piamsa-Art 2007,
p.1). Figure 1.2 shows the consequences of a level crossing major accident which
occurred in Lismore (Australia) in May 2006. Management of safety at level
crossings falls upon individual jurisdictions. Each jurisdiction manages its own
initiatives such as level crossing infrastructure upgrades and the development of
modelling techniques to identify dangerous crossing locations. By working in
partnership, the rail and road authorities can be drawn upon as necessary, allowing
the development and delivery of better safety projects.
Figure 1.2: Outcome of a Major Accident at Level Crossing (Lismore, Australia 2006)
10
In the global view, among other rail safety issues, railway-highway accidents
continue to be a major problem both from public health and socio-economic
perspectives. These collisions are a source of concern for regulators, railway
authorities and the public. For example, each year in the USA, about 363 people lose
their lives and about 1,034 people are injured as a direct result of crossing collisions
occurring at the annual rate of 2,980 approximately (USDOT FRA accidents
database, 2005).
It is noted from the literature that many research studies have been conducted in the
past in relations to developing appropriate collision models to assess road traffic
safety, but very little work has been carried out regarding safety at “highway-
railway” grade crossings. Hence the primary aim of this study is to provide an
improved method for rail safety appraisal through the development and application
of suitable accidents and consequences prediction models for grade crossings and
also by using these models to identify the worst or most dangerous locations (black-
spots). The research involving quantitative analysis is designed and conducted using
a set of secondary data comprising of 209,975 grade crossings selected from all
states in the USA. The proposed model for prediction of accidents and consequences
at grade crossings and its parameters is a combination of a wide range of traffic and
geometric characteristic information together with the corresponding accident data
for each crossing for the five-year period 2001-2005. Potential explanatory variables
were tested and largely identified from initial analysis of the accident characteristics
and associated factors. Generalized Poisson, Negative Binomial and Empirical
Bayesian Linear models for predicting both accidents and consequences were
developed and evaluated separately for the grade crossings with different protection
types. By combining these two predictions, a single measurable index (Safety Risk
Index) is formed and estimated to assess and to prioritise the grade crossings.
1.5 Objectives of the Study
The major objective of this research is to provide a strong basis for the initial process
of developing an appropriate methodology on safety improvement at railway-
highway grade crossings. This methodology is an integral part of a comprehensive
safety management program, which consists of six interconnected steps:
11
• Developing separate models for prediction of accidents and consequences at
crossings;
• Identifying crossings where the potential risk of accidents is unacceptably
high;
• Identifying crossings where the potential risk of consequences is
unacceptably high;
• Developing a single composite index (Safety Risk Index) using the prediction
of accidents and consequences to assess and prioritise the potential risk at the
crossings;
• With the estimated values of Safety Risk Index, identifying 'black-spot
crossings' where the overall potential risk is unacceptably high; and
• Assisting in the development of comprehensive safety intervention programs
and guidelines at the state and national levels that includes prioritisation of
countermeasures at high-risk crossings by reviewing the causes of accidents
and available control measures at these locations.
The other objectives of this study is to gather, integrate and summarise available
information, data and knowledge on rail safety from various sources by meaningful
and measurable indicators, which can then be converted into a single meaningful
value for assessing the risk at grade crossings. The research study also establishes
appropriate statistical methodologies in order to develop and to construct a
quantitative model for risk assessment. It is expected that this generic model is
comprehensive and easily understandable for those with different levels of
knowledge on safety. The model is useful not only to calculate risk assessments but
also to rank rail safety at different grade railway-highway crossing locations. It is
therefore believed that the model is capable of increasing awareness of rail safety
issues and problems among the rail safety policy makers, rail users and road users.
1.6 Target of the Study
The target of this study is to explore new opportunities to enhance the evaluation
techniques in risk assessment used in support of effective rail SMS. In order to
achieve the goal, this research is designed to develop a set of statistical
12
methodologies to combine appropriate key performance indicators of rail safety into
a single value of quantitative index. The study provides an improved method for
safety appraisal at railway-highway grade crossings through the development and
application of suitable safety risk scores (called ‘Safety Risk Index’) with
combination of both accident frequency and accidental consequences prediction
models generated for crossings. The Safety Risk Index is a simple composite index,
which can measure, compare and rank safety levels at different risk situations and
locations. These safety risk scores are designed to generate an overall grade crossings
safety risk, which is based on the combination of three basic risk elements, namely
the exposure of the crossing users, the probability of an accident occurring, and the
severity of consequences should an accident occur. This method facilitates not only
the assessment of the safety risks at grade crossings but also identifies and prioritises
the worst performing crossings. These problematic crossings are called ‘black-spots’.
1.7 Benefits of the Study
Railway-highway crossing safety enhancement programs typically have three types
of benefits in relation to financial and socio-economic perspectives. The first is
clearly that of minimising (if not completely eliminating) collisions between trains
and highway vehicles at level crossings. The second benefit is minimising (if not
eliminating) the deaths, injuries, property damage and human suffering associated
with these collisions. The third is that of minimising the delays to both rail and road
traffic at level crossings as a result of imposed speed restrictions on rail operations
and of excessive barrier closure times against highway traffic. The first and second
benefits are considered as primary benefits for a country and its people while the
third provides a secondary benefit.
In this study, the primary benefits (as explained above) are gained through the
development of an improved method to assess safety risks at the different level
crossing locations and utilising the estimated single Safety Risk Index (SRI) scores.
The SRI is developed using the prediction of accident frequency and consequences
models. With the estimation of SRI scores, safety risks at the different level crossing
locations can be assessed and compared directly between them. One major advantage
in developing the Safety Risk Index is to come up with a comprehensive set of risk
13
exposure and severity indicators which includes the maximum available major
parameters in rail safety instead of considering a few isolated indicators such as
accident frequency rates. The SRI index therefore captures a broad view and picture
compared to the traditional models developed in rail safety. The Index can be useful
for researchers who work on safety assessment analysis of level crossings. It may
also be useful to railway and highway operating organisations, as the index indicates
the scale of current issues and problems that they were perhaps not aware of.
In addition, government policy makers can use this index to identify and prioritise
the most dangerous crossing locations (black-spots) in a country and to develop
appropriate policies, strategies and intervention programs in order to minimise the
risks to as low a level as possible at these worst locations. However, there may be
some issues in the quality of risk assessment. For example, incomplete information
or deteriorating quality and quantity of the data (such as accidents frequency,
accidental consequences, and train and vehicle movements) may jeopardize the
success of safety evaluation in the SMS.
Overall, the author strongly believes that this study provides useful insights into
safety at railway level crossings and a holistic approach for assessing safety risk as
part of a rail SMS, particularly risk management at different types of level crossing
locations. The quantitative risk analysis techniques developed in this study can be
applied in the rail SMS in order to indicate which grade crossing locations should be
accorded high priority for implementation of safety intervention programs, purely on
the basis of their risk-minimising potential.
1.8 Limitations of the Study
There are some limitations associated with the research study undertaken and
reported here. Firstly, this study examines the accident risks at railway-highway
grade crossings. Accidents within station or yard premises and non-crossing
locations, those due to trespassing or suicides, and near miss accidents are not
included in this study.
14
Secondly, it is noted that the number of annual accidents and the annual accidents
frequency rate for ‘Public’ railway-highway crossings are exceptionally high values
(as shown in Figure 4.8 in Chapter 4) in comparison with other types of crossings
such as ‘Private’ and ‘Pedestrian’ level crossings. Given the significance of public
railway-highway crossings with large number of accidents, this research study is
therefore focused on analysing accidents aspects of ‘Public’ railway-highway
crossings.
Finally, the development of risk assessment models is based on the US grade
crossings accidents statistical data rather than data in Australian context. This is due
to unavailability of data across all necessary indicators which are required to assess
risk at grade crossings in Australian rail networks. Even though the new approach
developed in this study is applicable for risk assessment at grade crossings in any
country, the methodology generated is considered more appropriate in the US
environment, since the US grade crossings accidents data were used to develop the
models.
1.9 Structure of the Thesis
The research study undertaken and reported herein falls within broader areas of
safety management systems and procedures. At the outset of this research, SMS and
procedures used in general industries were initially identified and discussed.
Furthermore, specific SMS procedures used in rail industry were then analysed. The
risk management system (one of the major elements of SMS) was selected for further
consideration. The risk assessment process was also recognised as an important part
of a risk management system. Finally, a risk assessment study was conducted on the
grade railway-highway crossings, as safety at these locations becomes one of the
major emerging issues. A brief outline of research areas/topics leading to the
selection of the research topic (Assessing and Prioritising Safety Risks at Interfaces
of Railway and Highway) is schematically shown in Figure 1.3.
15
INDUSTRIAL SAFETY MANAGEMENT SYSTEMS • Construction Industry • Mining Industry • Manufacturing Industry • Government Administration and Defence Industry • Transport Industry (Railway, Highway etc.) • Agriculture Industry • Education Industry • Wholesale Industry • Retail Industry • Electricity, Gas and Water Supply
RAIL SAFETY MANAGEMENT SYSTEMS • Accident Investigation • Establishing a Safety Reporting System • Accident and Incident Reporting • Safety Audit / Assessment • Risk Management System • Safety Orientation and Recurrent Training • Emergency Response Plan • Documentation • Senior Management Commitment • Safety Policy • Safety Information • Establishing Safety as a Core Value • Setting Safety Goals
RISKS MANAGEMENT SYSTEMS • Hazards Identification • Risks Assessment • Risks Control or Elimination
RISKS ASSESSMENT • Risks Exposure • Likelihood / Probability of Event • Consequences of Event
“Assessing and Priorit ising
Safe ty Risks at Interfaces of Railw ay and H ighw ay”
Figure 1.3: Logical Flow of Research Areas Leading to the Thesis Topic
16
The logical flow of chapters of the thesis is shown in Fig 1.4. There are eight
chapters organised to present the research work carried out. As indicated earlier, this
chapter (Chapter 1) briefly introduces the research work carried out, including the
importance of the selected topic and reasons why this study is of interest. It also
provides the basics of a railway SMS, an overview of current railway safety issues,
the goals and objective targets set out for the research and the point of departure.
Chapter 2 describes in greater detail the current railway SMS and safety issues, and
expands on the research topic. The chapter describes how rail safety concerns
everyone and all aspects of safety. It also reviews the literature on similar previous
studies. Chapter 3 outlines the research methodology that is adapted to develop the
appropriate statistical model in the study. Various rail safety problems and all micro-
level factors that could contribute to rail accidents are discussed. Key performance
indicators are then identified. Finally, an appropriate methodology is developed to
combine different key performance indicators and to assess the rail safety risks.
Chapter 4 presents a procedure and associated steps for extracting and utilising rail
accident data and inventory information to evaluate rail safety risks through risk
assessment models. Chapter 5 describes the development of appropriate models for
predicting accident frequencies and consequences. It explains the theoretical
framework of the model with the support of the key performance indicators, which
were identified in the previous chapter. It also provides the process of validating the
models developed. Chapter 6 describes and presents a single composite risk index
(Safety Risk Index) to assess and prioritise the rail safety performances at grade
crossings using the predictions obtained in the previous chapter. Chapter 7 is
concerned with sensitive analysis work on the models to identify and discuss the
influences of relevant factors on prediction of accident frequencies, consequences
and safety risks. Conclusions are drawn in Chapter 8 through study findings and
discussions shown in the early chapters. This chapter discusses the contributions and
the outcome from this study. It also clearly indicates the benefits and limitations of
the study. In this chapter, an indication of relevant future research work, which may
extend to the contributions made by this research study, is also supplied.
17
Figure 1.4: Flow Diagram for Developing Structure of the Thesis
CHAPTER 1 :
Introduction to the Research
CHAPTER 2 :
Literature Review
CHAPTER 3 :
Research Methodology
CHAPTER 5 :
Development and Validation of Grade CrossingAccidents and Consequences Prediction Models
CHAPTER 7 :
Impact Analysis on Risk Assessment Models
CHAPTER 8 :
Conclusions and Recommendations
CHAPTER 4 :
Data Collection and Consolidation
CHAPTER 6 : Development of Safety Risk Index (SRI) for
Risks Assessment at Grade Crossings
18
Chapter 2
Literature Review
2.0 Introduction
Rail safety management is one of the major challenges in the broader management of
safety and risks of rail operations. Given the rapid growth in infrastructure
development, and the increasing demand for rail transport (both passenger and
freight), rail safety management is constantly aiming to improve overall safety of rail
infrastructure, in particular rail-road crossings. The focus of this research is to
investigate rail safety management, from a point of view of managing complex
situations of rail crossings across a network. This involves identifying research
problems within the broader rail safety and risk assessment, and managing
complexities of rail crossings across many situations and locations.
The previous chapter provided the scope and background of the research. In order to
investigate rail safety management and associated systems, it is necessary to
consider its implementation within organisational settings. Thus, this chapter
provides a comprehensive overview of the safety management system, the risk
assessment process used in the rail safety management system and the challenges
faced in managing risks in Rail sectors. This chapter also describes the magnitude of
existing rail safety risk issues / problems in details. It provides some typical Safety
Management Systems used in many organisations. It also identifies the major safety
issues and the significance on improving safety at level crossings. Finally the
research problem for this study is broadly articulated.
2.1 Definitions of Terms Used in Relations to Safety In the Safety Management System, important terms are frequently used to describe
the system. The following are some of those terms and their definitions.
19
2.1.1 Accidents
An accident is an unwanted event that results in physical harm to people (life or
health) or damage to property. There is a reasonable degree of consensus that an
accident is some kind of unplanned event (Dixit 2007). In general, the term
"incident" describes such events where no injury occurs. However, incidents are
often wake-up calls that can alert employees and supervisors to hazards or risks that
they had not considered before. Every incident is an opportunity to learn valuable
safety lessons. Accidents are directly linked to safety (or lack of it) across various
situations. Thus, the definition of an accident is critically important for any
consideration of safety, in particular when consequences of accidents are estimated /
judged and analysed based on measures of accidents. The definition of an accident
can also influence how one could see accidents (and thereby safety) from a point of
view of what we can see and measure. In general, it can be noted from a process
viewpoint, that accidents have multiple causes such as performing bad practices and
involving risky behaviour. In general, an accident may be defined as an unplanned
event that has the potential to cause adverse consequences due to a combination of
several factors. This nature of process is shown in Figure 2.1.
• Quantifiably measures safety performance within an organisation or between
various operations.
• Improves regulatory compliance with environmental, health and safety
requirements.
Effectiveness of control measures: Risk control measures must also be maintained,
e.g. work procedures have to be monitored to ensure they are being followed,
hearing protectors have to be kept clean and checked for damage. All control
measures have to be assessed in order to determine:
• Whether or not they have had the intended effect;
• That no hazards have been created by the control measures.
Effectiveness of process: The process itself should be assessed to ensure it is
effectively managing the risks. For example, a control measure may have failed
because not all hazards were identified, or because the likelihood of a risk was
wrongly assessed. If this is the case, it may be necessary to change the way the
system is implemented in the workplace.
Effectiveness of consultation, information, in struction and training: Assessment
of consultation mechanisms would include whether safety committees are operating
effectively and if workers are really involved in the process of safety. When
considering information, instruction and training we would look at how up-to-date
and relevant they are. Also consider whether the information is reaching all who
need it, e.g. new workers, non-English speakers.
Monitoring and Review: Monitoring and review of the various components of the
SMS must be carried out to see how effective they are.
2.2.7 Measurements on Effectiveness of SMS
A senior management question is “What gets measured to improve safety at
workplaces?” Another question is “How can it be measured?” Top management is
looking for safety initiatives, with a positive impact upon the organisation’s total
38
performance (Mathebula 2001, p.7). The management wants initiatives that they can
approve and invest their time in, to effect five key measures:
• Return on Assets (ROA) – Changes in this measurement indicates how an
individual program impacts profitability.
• Value Added per Employee (VAE) – Changes in this measurement reflect
how an individual program impacts on productivity.
• Economic Value Added (EVA) – Changes in this measurement reflect how a
shareholder’s value is created or destroyed by management. EVA has been an
economic toolkit for more than two hundred years. Simply put, EVA is the
measure of corporate performance that differs from most others by including
a charge against profit for the cost of all the capital a company employs. For
example an accident, which results in the destruction of assets, is a value
destroyer and may lead into negative EVA.
• Frequency Rate (FR) and Severity Rate (SR) – Changes in this measurement
reflect lost time due to injuries. It is also valuable to track FR for medical aid
injuries and first aid injuries.
2.3 Risk Management within SMS
Risk management is part of broader SMS and links through key inputs and outputs
such as measuring, or assessing risk and developing strategies to manage it.
Strategies include transferring the risk to another party, avoiding the risk, reducing
the negative effect of the risk, and accepting some or all of the consequences of a
particular risk. Traditional risk management focuses on risks stemming from physical
or legal causes (e.g. natural disasters or fires, accidents, death, and lawsuits). It is
stated that in ideal risk management, a prioritisation process is followed whereby the
risks with the greatest loss and the greatest probability of occurring are handled first,
and risks with lower probability of occurrence and lower loss are handled later
(Kokash & D'Andrea 2006, p.11). In practice the process may be difficult. Balancing
between risks with a high probability of occurrence but lower loss versus a risk with
high loss but lower probability of occurrence can often be mishandled. Intangible
risk management identifies a new type of risk - a risk that has a 100% probability of
occurring but is ignored by the organisation due to a lack of identification ability. For
39
example, knowledge risk occurs when deficient knowledge is applied. Relationship
risk occurs when collaboration ineffectiveness occurs. Process-engagement risk
occurs when operational ineffectiveness occurs. These risks directly reduce the
productivity of knowledge workers, decrease cost effectiveness, profitability, service,
quality, reputation, brand value, and earnings quality. Intangible risk management
allows risk management to create immediate value from the identification and
reduction of risks that reduce productivity. Risk management also faces difficulties
in allocating resources. Resources spent on risk management could have been spent
on more profitable activities. Again, ideal risk management minimises spending
while maximising the reduction of the negative effects of risks.
2.3.1 Major Processes in Risk Management
In general, a Risk Management System comprises three major processes as shown in
Figure 2.5 (Australian/New Zealand Standard 4360, 2004). They are:
• Hazards Identification;
• Risks Assessment; and
• Risks Control or Risks Elimination.
1. Hazards Identification
Risk
Management System
2. Risks 3. Risks Assessment Control or . Elimination
Figure 2.5: Three Major Processes in Risk Management System
40
2.3.2 Hazard Identification
The Risk Management System emphasises that all employers must ensure that
appropriate measures are taken to identify the hazards and assess the risk to the
health and safety of every person in the workplace (Australian/New Zealand
Standard 4360, 2004). There are a number of ways in which hazards can be
identified in the workplace:
• Walk-through survey compiling a hazards list as we go;
• Check accidents, near misses and workers compensation records;
• Talk to workers, e.g. safety committee meetings, informal meetings;
• Look at how work is done, including manual handling practices such as
lifting, pushing, pulling, moving, etc.; and
• Liaise with experienced people in a similar industry
In the event of an incident, photographing workplace hazards is extremely useful, not
only for recording purposes but also when highlighting issues through discussion at
health and safety committee meetings. The hazards identification process generally
contains the following functions (Australian/New Zealand Standard 4360, 2004).
• Dividing hazard identification into manageable portions;
• Developing an inventory of tasks;
• Analysing tasks;
• Identifying the hazards involved;
• Considering the people factor;
• Aiding hazard identification;
• Hazard identification as ongoing process; and
• Recording hazard identification data
2.3.2.1 Dividing Hazard Identification into Manageable Portions
As identifying every hazard throughout the workplace can be an extremely large and
complex job, the first step is to break this job down into 'bite-sized chunks'. This can
be achieved using the following techniques:
• Breaking the workplace into work sectors or areas (and, if necessary,
breaking down further into zones);
41
• Breaking each sector down into tasks;
• Developing a list of likely hazards for the work sector; and
• Analysing the components of each task to identify the individual hazards
present.
2.3.2.2 Developing an Inventory of Tasks
Once the workplace has been divided logically into work sectors (such as the
operations, maintenance sectors etc.) and, if necessary, into zones (such as station
operations, depot maintenance, etc.), a complete inspection of all workplace tasks
should be carried out. This will develop an inventory of all the tasks performed
throughout the organisation (Australian/New Zealand Standard 4360, 2004). For
example, the task identified may be as diverse as grinding metal samples; changing
the toner in a photocopier; transporting material from one area to another;
transferring biological samples into test tubes; decanting and mixing paints and
solvents; operating machinery such as cranes, hoists and fork lift trucks; undertaking
repair work inside confined spaces; undertaking cleaning work; spraying chemicals
such as pesticides. It is also necessary to consider future tasks or situations that
involve a change to the existing premises or process, or those which are non-routine.
2.3.2.3 Analysing Tasks
Once the task inventory is completed each activity must be analysed to prepare for
the identification of all hazards involved. In order to later analyse the risks associated
with the hazards, a manageable level of detail is required and this means that some
tasks must be broken down further into component elements. Each of these elements
is then examined in terms of its activities, use of plant and equipment, use of
substances and materials, processes, and the place where it is carried out. Following
are the elements that may be included in a task:
• Individual activities;
• Substances and materials;
• Plant, tools and equipment involved;
• Characteristics of the place where the task is carried out.
42
The easiest method of breaking tasks down into elements is usually to consider how
the task is undertaken step by step (Australian/New Zealand Standard 4360, 2004).
For example, the task of diluting concentrated acid (e.g. hydrochloric acid) in a
laboratory involves:
• Preparing the work area;
• Putting on personal protective equipment (lab coat, glasses and gloves);
• Collecting the concentrated acid container;
• Pouring the acid;
• Labelling the container; and
• Clearing and cleaning up the work area.
2.3.2.4 Identifying the Hazards Involved
After breaking down the task into its elements, the next stage is to identify the
hazards involved. In undertaking the hazard identification task, there are many
different factors to consider - those related to specific hazards, individual tasks,
workplace conditions, particular people involved and unique circumstances.
2.3.2.5 Considering the People Factor
An important factor to consider is the people who may be exposed to risks from
hazards, and how any individual characteristics may impact on exposure. Gathering
this information at the hazard identification stage will assist with later risk
assessment efforts. In most cases, those affected will be the people involved in the
tasks. During hazard identification, try to take note of 'people issues' such as
(Australian/New Zealand Standard 4360, 2004):
• Any special characteristics which should be taken into account for example,
inexperience, chemical susceptibility and ergonomic issues (such as height or
prior injuries)
• Whether people other than operatives could be affected
• How these groups of people are affected by the circumstances surrounding
the task, such as normal operation, peak production, environmental factors,
maintenance activities and working alone.
43
2.3.2.6 Aiding Hazard Identification
There are a number of activities that can be carried out to assist with identifying
hazards present in the workplace. These activities may be conducted in parallel with
other risk management functions and processes such as development of task
inventory and risk assessment activities. Some of those activities include:
• Undertaking a workplace walk-through;
• Analysing available information;
• Conducting workplace inspections; and
• Maintaining and using checklists.
Undertaking a workplace walk-through: Walking through the area which the
hazard identification has targeted is an essential information-gathering exercise even
if the team or individual involved is familiar with the task. Observing how work is
carried out will reveal valuable clues about the hazards involved. Sometimes it is not
a good idea to fully rely on the organisation's standard operating procedures for
details on how specific tasks are undertaken as workplace practices may vary greatly
from the international or national standard rules.
Analysing available information: Another important aid to identify hazards is to
check all available information. In the current context, this may assist in identifying
potential hazards from the types of plant, substances and work procedures at the
workplace. Amongst the key sources of information, which may assist in indicating
how hazards have arisen in the past, and are likely to happen again, are:
• Incident and first aid records;
• Plant maintenance and breakdown records (such as service books);
• Work systems and procedures documentation;
• Safety and health policies both general and specific;
• Employee training records;
• Operators' manuals and equipment instruction booklets, which often point out
safety "dos and don'ts'';
• Injury/incident data, workers compensation statistics and guidance material
from Workplace safety monitoring organisations such as WorkCover - NSW;
44
• Australian standards which provide specifications for issues such as design,
manufacturing, inspection, testing, use and work methods.
While reading and analysing the information from these resources, take note of
hazards and conditions which may be relevant to the workplace. Developing a list of
potential hazards may prove valuable as a prompt in identifying hazards at the
workplace (Australian/New Zealand Standard 4360, 2004).
Conducting workplace inspections: One of the most important aids to hazard
identification is the workplace inspection. This may be conducted as part of, or
independent of, the workplace walk-through. Inspections can focus on specific tasks,
locations or hazards. Essentially, the inspection should be regarded as a fact-finding
mission to detect potential hazards. Before undertaking the inspection, it is vital that
those assigned to the task are fully briefed on employees’ roles. Activities undertaken
during the inspection may include:
• Taking notes;
• Interacting with employees;
• Observing work being done;
• Taking measurements (such as noise level readings); and
• Taking photos.
Maintaining and using checklists: Checklists are an invaluable aid in any safety
exercise (Australian/New Zealand Standard 4360, 2004). They assist in ensuring
that:
• Important issues are not overlooked;
• Consistency is achieved if the required activity is being undertaken by several
different people; and
• There is a formal record of efforts made.
To gain maximum benefit in hazards identification, any checklists used should be
specifically developed for the individual workplace. This will ensure that
circumstances unique to that workplace are taken into account. Examples of
checklists can be obtained from any Safety and Health web pages. These may be
used as a basis from which a customised checklist can be developed.
45
2.3.2.7 Hazard Identification as Ongoing Process
Hazard identification does not end with the initial investigation. Hazard identification
should be regarded as an ongoing, integral part of workplace operations. In general,
the legal requirement is for hazard identification to be undertaken:
• Before and during the introduction of new work systems, plant and chemicals
to the workplace
• Before and during alterations or changes to the use or location of work
systems, plant and chemicals
• Where new information on hazards or control measures becomes available.
In order to fully comply with this requirement, a hazard monitoring system should be
put in place. This will form a part of the monitoring and review element of a safety
program.
2.3.2.8 Recording Hazard Identification Data
Once gathered, the hazard identification data and information must be recorded in a
risk register database so that it can be used for risk assessment activities and in
determining appropriate control measures. In practice, the same database may be
used to update hazard identification information, risk assessment information and
details of control measures to be implemented.
Review information: In considering likelihood, it is important to review the
information, which was gathered during the hazard identification stage. This may
include, for example:
• Hazard identification checklists (which will indicate the factors taken into
consideration);
• Hazard identification record database (which will provide valuable
information on circumstances surrounding the hazard together with
comments of the identification team or individual);
• Incident and first aid records (which should reveal trends or frequencies of
injury;
• Incident investigation reports;
46
• Plant maintenance and breakdown records (such as service books);
• Work systems and procedures documentation;
• Safety and health policies both general and specific;
• Employee training records; and
• Operators’ manuals and equipment instruction booklets.
Other important sources of data include national incident, injury and workers
compensation statistics, which provide information on the numbers and frequencies
of accidents, related to type, activity and industry sector.
2.3.3 Undertaking Risk Assessment
As discussed earlier, risk is the potential outcome of a hazard. In other words, it is
the possibility that injury, illness, damage or loss will occur as a result of a hazard.
Since risk and safety are very closely related each other, there is a strong need for
evaluating risks, leading to the need for assessing the level of safety.
2.3.3.1 Risk Assessment
Risk assessment is the process of assessing all possible risks associated with each of
the hazards identified during the hazard identification process. There are a number of
different ways to assess risks. Some of the key points about assessing the risk in the
workplace are as follows (Australian/New Zealand Standard 4360, 2004).
• Assessment must cover all risks to the health and safety of employees;
• Assessment must cover risks to non-workers, such as sub-contractors and the
public, who may be affected by the employer’s actions;
• Prior to the introduction of new or changed work practices, substances or
plant, the employer must review the original assessment. A regular review is
advised as part of good management practice;
• Employers must carry out an assessment of first-aid requirements in their
workplace and ensure that appropriate equipment, facilities and trained
personnel are available and readily accessible in the workplace; and
47
• Where groups of workers are especially at risk, they must be identified as part
of the assessment, e.g. young, inexperienced, or workers with a disability.
In assessing the risks, the following three essential elements (Figure 2.6) are generally considered. • The exposure of a hazard causing an accident;
• The probability or likelihood of the accident; and
• The potential accidental consequences.
Based on the estimation of these three elements the risks are calculated and ranked,
and priority is assigned for risk control through the use of the rating of risk rank.
Risks associated with an identified hazard need to be assessed in order to determine
how severe or dangerous they are. Assessing the risks allows employers to make
decisions as to what hazards or risks need to be controlled and to set priorities for
introducing controls. When assessing the risk any controls that are already in place
need to be taken into account. Two important laws of human nature should always be
part of the assessment (NT WorkSafe 2003, p.11). Firstly, never rely solely on
common sense, as it is much less common than is generally assumed. Secondly,
always rely on Sod’s Law. i.e. ‘if someone can do it, sooner or later someone will’.
1. Risks Exposure
Risk
Assessment 2. Likelihood / 3.Consequence Probability of Event of Event
Figure 2.6: Three Elements in Determination of Risk Assessment
48
In order to undertake risk assessment, it is necessary to understand the nature of risk.
Risk assessment involves examining and evaluating the exposure of hazards, and the
likelihood and possible consequence (severity) of the potential outcomes of hazards.
Assessing risks can be carried out using a range of methodologies which are
available - from qualitative to semi-quantitative to quantitative approaches. Risks can
be quantified by determining the likelihood and consequence of a hazard against
known standards. The most common way of assessing risk by qualitative methods
includes methods using an employee’s experience and the information found on
experience and incident records. In this research, assessing the risk is approached by
quantitative methods. Risk is assessed using key measures of a hazard’s exposure,
the probability of an event occurring and its consequences.
2.3.3.2 Risk Assessment Matrix
A risk assessment matrix is a simple tool that can be used to assess a risk by
evaluating a hazard’s exposure, its likelihood of occurring and its potential
consequences. This enables the user to identify the appropriate response and
prioritise the implementation of controls. The process of risk assessment matrix
involves the following steps:
1. Measure the exposure of a hazard occurring;
2. Evaluate the likelihood of the hazard;
3. Estimate its potential consequences;
4. Quantify the risk of the hazard by combining 1, 2 and 3; and
5. Identify the risk of the hazard and the appropriate action required.
Exposure: The first step is to measure the exposure of the hazard. For example, how
many people are exposed to the hazard and for how long? This measure is required
when setting priorities for introducing controls. A typical example of measuring the
risk exposure with three descriptors ranging from hazard potential is shown in
Table 2.1.
49
Table 2.1: Typical Measure of Risk Exposures
Exposure of Risk Description
High Exposure High hazard potentials in a small size group of people
Medium Exposure Medium hazard potentials in a medium size group of people
Low Exposure Low hazard potentials in a large size group of people
Likelihood: The next step is to determine the likelihood of the hazard. The method
of determining the likelihood that injury, illness, damages or loss will occur as a
result of hazards may vary according to the type of workplace and operations
involved. A basic system of evaluating likelihood is shown in Table 2.2, the measure
of likelihood is split into five descriptors ranging from events that are considered
'Very Likely' to hazards that would be considered 'Highly Unlikely'. It may be
determined that someone would be very likely to trip over raised paving slabs of a
frequently used path and 'Highly Unlikely' for someone to trip over a lifted floor tile
in a rarely used store room.
Table 2.2: Typical Measure of Likelihood
Descriptor Desc ription
Very likely It is expected to occur at some time in the near future
Likely Will probably occur in most circumstances
Possible Might occur at some time
Unlikely Could occur at some time
Highly unlikely May occur in exceptional circumstances
Consequences: The third step is to measure the potential consequences should a
hazard be realised, and its effect on exposed people. For each hazard identified, ask
the question ‘What if?’ In other words, the question is “what is the worst likely
outcome from hazard exposure?” As shown in Table 2.3, consequence has been split
into five descriptors varying from an outcome resulting in 'Negligible' injuries for the
most minor instances to 'Fatality' should one or more people be killed. The severity
of the injury may be rated as 'major injury' if the potential result is permanent
disability of the worker or a 'first aid injury' if the result of the injury at most would
be minor cuts and scratches.
50
Table 2.3: Typical Measure of Consequences
Descriptor Description
Fatality Death
Major injury Extensive injuries, lost time injury >5 days , permanent disability (e.g. broken bones,
major strains)
Minor injury Medical treatment required, lost time injury from 1 – 5 days (e.g. minor strains)
First aid First aid treatment where medical treatment not required (e.g. minor cuts and burns)
Negligible Incident does not require medical treatment, property damage may have occurred
Measure of risk: The final step in assessing a hazards risk is to combine the
perceived likelihood and consequences determined above to identify the appropriate
action. For example, it is noticed that a storm has resulted in a power line coming
down across a footpath. The determination of the potential risk of such a hazard
would be a combination of the likelihood of a person being exposed, 'Likely' and the
potential consequences, 'Fatality'. By connecting 'Likely' and 'Fatality' on the matrix
shown in Table 2.4, it can be seen that this hazard is designated as an 'E' or 'Extreme'
risk. Immediate action is required to prevent the likelihood of a 'Fatality'. If the
hazard is identified as 'Extreme' and, as seen from the table, immediate action is
required, the appropriate Health and Safety Authority should be notified.
Table 2.4: A Typical Risks Assessment Matrix
Exposure
of Risk
High Exposure Medium Exposure Low Exposure
Likelihood (Probability of Event)
Consequences
of Event
Very Likely Likely Unlikely Highly unlikely
High Fatality Extreme Extreme High Medium
Medium Major injuries Extreme High Medium Medium
Minor injuries High Medium Medium Low
Low Negligible injuries Medium Medium Low Low
E (Extreme risk) - immediate action required; notify supervisor or appropriate Health and Safety
Authority as required;
H (High risk) - notify supervisor or Health and Safety rep immediately;
M (Moderate risk) - immediate action to minimise injury e.g. signs; supervisor remedial action
required with 5 working days; and
L (Low risk) - remedial action within 1 month, supervisor attention required.
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Risk assessment enables employers to plan, introduce and monitor measures for
ensuring that risks are adequately controlled. Events or situations that are assessed as
very likely with fatal consequences are the most serious (high risk). Those assessed
as highly unlikely with negligible injuries are the least serious (low risk). When risk-
control strategies are developed, employers should tackle anything with a high rating
first. Table 2.4 provides a typical risk matrix to assess the risk in accordance with the
level of risk exposure of an event, likelihood and consequence of the event.
2.3.3.3 Recording Results of Risk Assessment
It is most important that the conclusions reached about risks are documented and that
any supporting information on how these conclusions were made is included in
associated records. This is not only a legal requirement of the Occupational Health
and Safety Act 2004 but is also important for corporate knowledge and demonstrates
how a decision was achieved with regard to investigating a hazard.
Risk assessment records: Once the risk assessment process has been completed, the
results need to be recorded in a systematic manner. This means itemising the:
• Work sector, division or department involved;
• Name of the person heading up the risk assessment;
• Date on which the assessment was completed;
• Work zone or location of the hazard involved;
• Task, activity or work process involved;
• Hazard involved;
• People who may be exposed to risks from the hazard;
• Likelihood ranking of the risk (such as 'very likely');
• Severity ranking of the risk (such as 'fatality); and
• Risk rating assigned (the numerical value about priority such as 'extreme').
Acting on the risk assessment results: The risk ratings determined during risk
assessment enable decisions to be taken on the amount of effort to be expended in
controlling risks associated with particular hazards. However, any hazard that is
'highly likely' or 'certain/imminent' to cause harm needs to be attended to and the risk
reduced even if the severity is low. Those hazards identified as not adequately
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controlled can now be itemised in a prioritised list for action using the risk rating as a
guide to those which will require urgent attention (and possibly suspension of
operations), and those which can be listed for action sometime in the future.
2.3.3.4 Considering Current Controls
It is important that the effectiveness of any control measures already provided is
maintained and considered for further improvements. At the same time, it is
necessary to consider the possibility of current control measures not being used due
to issues such as:
• Lack of training or supervision;
• Failure to replace controls following cleaning, maintenance or repair work;
• Difficulty or awkwardness in using or working with controls; and
• Complexity of controls.
Once the likelihood and consequences of the potential hazard have been rated, it is
now possible to prioritise the risks based on these two criteria. Prioritising risk is the
final step in the risk assessment process.
2.3.3.5 Setting Times Limits for Action
Among many methods of dealing with actions to control risks, setting time limit
bands against the risk rating score is a common one. Time limit bands commonly
used include:
• L (Low) - must be attended to preferably within 1 month but issues such as
funding may make it more appropriate to rectify the hazard within up to
12 months.
• M (Moderate) - should be attended to within five working days and interim
controls put in place immediately.
• H (High) - risks should be attended to within one working day and interim
controls put in place immediately.
• E (Extreme) - risks must be attended to immediately. It is preferable that
activities are suspended until controls are in place.
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In setting these time scales (time limit bands), it should be remembered that the
control measures for risks associated with individual hazards vary enormously as far
as time, cost and other resources are concerned. It is essential for realistic time limits
to be set for the various items to be dealt with in the same way that other
management objectives are given deadlines. Once the risks associated with all of the
hazards identified have been assessed and control measures have been introduced,
the risk assessment exercise can be repeated to decide if the residual risk has been
reduced to trivial or adequately controlled levels. Continual assessment forms part of
the monitoring and review phase of risk management.
2.3.4 Risk Control or Elimination
Risk control is the process by which the risks associated with each of the hazards
present in the workplace are controlled. The process is executed using the priorities
(and any related time scales) determined during the risk assessment phase. The
primary aim of risk control is to eliminate the hazards leading to the risks, thereby
eliminating the risks. In situations where this is not possible, risk control seeks to
minimise risks by modifying or controlling the hazard and/or the associated work
systems (Australian/New Zealand Standard 4360, 2004).
2.3.4.1 Risk Control Involvement
Risk control provides a means by which risks can be systematically evaluated against
a set of control options (the hierarchy of controls) to determine the most effective
control method(s) for the risk(s) associated with each hazard. This process involves
analysing the data collected during the hazard identification and risk assessment
processes, and developing a strategic plan to control the risks identified. A form
called ‘Risk control schedule form’ assists in the allocation of tasks to relevant
people and the prioritisation of controls. The risk control process starts by
considering the highest ranked risks and working down to the least significant. Each
risk needs to be examined having regard to the 'hierarchy of controls'. This provides
a method of systematically evaluating each risk in order to determine firstly if the
causal hazard can be eliminated and otherwise, to find the most effective control
method for each risk.
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2.3.4.2 Hierarchy of Controls
In the event that an unacceptable risk to health and safety has been identified, control
needs to be introduced to reduce the risk to an acceptable level. There are a number
of ways of controlling risks in the workplace. These are known as the “Hierarchy of
Controls”. Placed in order of effectiveness they are as follows.
Eliminate the hazard: For example, remove trip hazards in a crowded corridor.
Dispose of unwanted chemicals.
Substitute with something of a lesser risk: For example, in manual handling, use
smaller packages. Use a less toxic chemical.
Isolate the hazard: For example, store chemicals in a locked enclosure. Use trolleys
to move heavy loads.
Personal protective equipment: For example, hearing and eye protection, hard hats,
gloves to be provided and worn.
Use administrative controls: For example, provide training and adequate
instruction on work practices. Provide adequate supervision. Ensure regular
maintenance of plant and equipment. Limit exposure time by implementing staff
rotation.
Back-up controls: Controls should be selected from as high up the list as is practical
for maximum effectiveness. In many cases, a combination of the above will be
necessary to reduce the level of risk. Back-up controls (such as personal protective
equipment and administrative controls) should only be used as a last resort or as a
support to other control measures. Worker involvement is essential to the decision-
making process for implementing risk control.
Control worst first: While the risk control process concentrates on controlling the
highest ranked risks first, this does not mean that lower priority risks, which can be
controlled quickly and easily, should not be controlled simultaneously. The best
available control measures should be put in place as soon as possible. In some cases
it may be necessary to put temporary controls in place until such time as the proper
controls can be instituted. Wherever there is a high risk and the control measures are
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not immediately available, temporary controls which reduce the risk(s) must be put
in place or the activity must cease until adequate controls are implemented.
Using the hierarchy of controls: The hierarchy of controls are developed by safety
regulators to assist employers in finding the most effective control measures for
hazards in their workplaces (NT WorkSafe 2003). When examined in greater detail,
the controls hierarchy may be divided into three levels, the second two levels
involving several elements:
• Level 1: Eliminate the hazard.
• Level 2: Minimise the risk.
o Substitute with a lesser hazard.
o Modify the work system or process.
o Isolate the hazard.
o Introduce engineering controls.
• Level 3: Institute back-up controls.
o Implement administrative controls and safe work practices.
o Require personal protective equipment to be used.
2.3.4.3 Sequence of Risk Control
A schedule should then be drawn up outlining the deadlines by which each control
must be implemented, and the people responsible. During the process of determining
appropriate control measures, and scheduling and implementing these controls,
records need to be kept.
Deciding on controls: The best control measure is determined by considering each
of the 'hierarchy of control' options starting at the top and working down. The higher
on the list the control we choose, the better the results should be. Unless we
completely eliminate the hazard, which is the first control option, we may need to
consider using more than one control simultaneously. Both elimination and
substitution control the hazard itself. They are, therefore, more effective in reducing
risk than controls which reduce exposure and which therefore do not reduce the
hazard itself (such as modification or isolation).
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Controlling exposure does not generally reduce the consequence, or severity (factor
of the risk), although it can reduce the likelihood of harm occurring. Another
limitation is that controls on exposure can be more easily removed or defeated.
Therefore, there will be a need to set up higher standards of supervision,
maintenance, checking, training and other administrative measures. Engineering
controls consider the question: 'Is it possible to use engineering controls such as
lockout procedures, process changes, presence-sensing systems, ventilation or
machine guarding to reduce the risk?' Back-up controls may take the form of
administrative controls or provision of personal protective equipment. Administrative
controls involve the use of management systems to minimise risks and promote
workplace safety. At any workplace, the primary administrative control, which
should be in place at all times, is the use of safe work practices. This should include
the use of written procedures to indicate:
• How tasks are to be undertaken;
• Who is permitted in the work area;
• What the requirements for operating different types of equipment are;
• Operator competencies; and
• Any training and supervision needed.
Other examples of administrative controls, which may be used, include the
following:
• Providing worker rotation so that the same workers are not exposed all the
time;
• Rescheduling operations to times when there are fewer workers around;
• Providing one-way traffic flow to minimise traffic hazards;
• Instituting purchasing controls where a hazard has been eliminated to ensure
that, for example, a solvent-based adhesive is not purchased by someone in
the organisation who is unaware of the decision to use only the water-based
alternative; and
• Providing adequate information, instruction, training and supervision to
ensure that employees undertake their work safely.
Personal protective equipment (PPE): This involves some form of equipment
being worn by workers who may be exposed to hazards, to shield their bodies from
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harm. For the most part, PPE shall not be used as a primary means of protection, but
only as a back-up to support other control measures.
Documenting risk control: The risk control process needs to be fully documented
and these records kept with other relevant risk management records. Controls can be
documented on the Risk Management Matrix, as part of a Risk Control Record Form.
2.3.4.4 Undertaking Monitoring and Review
Monitoring and review is the final stage of the process. This stage of the process
keeps risk management current and effective, as new hazards and those overlooked
in the original process are identified and controlled. Monitoring and review involves:
• The systematic re-implementation of the original steps of:
o Hazard identification
o Risk assessment
o Risk control
This is to ensure that the process was undertaken properly and that, in
hindsight, the conclusions were correct.
• Ongoing monitoring of existing risk control measures to assess their
effectiveness in light of changes and fluctuations in the workplace
• Collection of data on any new hazards which may have arisen and the
formulation of new control measures
• Review of the risk management process to ensure that all new hazards
identified are controlled.
Aids to monitoring and review: In repeating the original elements of our safety
program, other related activities need to be undertaken periodically as part of the
monitoring and review system. These include:
• Scheduled inspections;
• Ongoing measurement and testing;
• Workplace monitoring where necessary (for hazards such as noise and air
contaminants); and
• Periodic incident analysis.
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In overall, the aims of a risk assessment determine the types of output required and
the approach taken. A range of methodologies are available from qualitative to semi-
quantitative to quantitative approaches. Risk assessments can be used for corporate
overviews, to prioritise risks and screen options to define management focus, or
applied to specific events or planned tasks. The context description and aims of the
risk assessment also help determine what structure is required for the risk
assessment, and the nature and levels of expertise required to identify and to describe
key risk events.
2.4 Safety Risk Potentials in Railways
Safety is one of the critical aspects in railways, given that it deals with the safety of
large volumes of people across a huge transportation infrastructure, compared to
safety at workplaces which deals mainly with employees. The Transport sector is
expected to deliver services to their customers at a high level of safety. Although the
Rail sector has been reasonably good at doing this for a long time, many thousands
of people (the public, passengers and employees) are injured globally in railway
accidents each year (United Nations 2000). The following consequences result in
these railway accidents:
• Several billions of dollars are paid in medical costs and disability payments;
• Medical insurance premiums are increased to meet the rising costs;
• Capacity of productivity is decreased;
• Loss of lives and human suffering;
• Inconvenience caused to injured people, to others and to the environment.
Railway occurrences (accidents and incidents) don’t just happen, nor are occurrences
completely accidental. There may be many hidden factors, including the failure of
one or more safety components of the railway system, which contribute to railway
occurrences. Identifying, prioritising and targeting the hazard potentials which cause
railway occurrences, and developing mitigation initiatives and controls on these
hazard potentials can prevent such occurrences. Nevertheless, we find ourselves now
in a world where the opening up of the commercial availability of railways and the
search for an optimum level of safety, taking economic and organisational
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constraints into account, is a priority target at the very heart of development strategy
on all continents.
Safety of passengers, customers, the public, contractors and staff is an absolute pre-
requisite for safety management development in railways. Emphasis has been placed
on complying with statutory and Railway Inspectorate requirements, promulgating
Rules and Procedures, the training of staff, and enforcing discipline and compliance.
This approach has been appropriate and successful in establishing a good safety
performance from the beginning of railway operations. There is doubt as to whether
continuation of this management approach is adequate in coping with the increasing
complexity of railway operations, since the following issues were noted:
• The tendency for safety performance to depend on the expertise of key senior
operations and management personnel;
• Lack of understanding on the part lower level staff have to play in ensuring
the safe operation of the railway;
• The concept of safety is not sufficiently integrated into daily work practices;
• Inquiries into serious railway accidents worldwide highlighted the following
desired features in modern safety management:
o Adopting a formal and systematic approach to managing safety; and
o Conducting safety audits to provide assurance in safety management
performance
• A comprehensive program of risk management is crucial to safety
management.
The Railway Safety Act (RSA, 1989) and the amendments which came into force
later (RSA, 1999) redefined roles by implicitly placing crossing safety
responsibilities on the railways and the road authorities (Railway Safety Transport
Canada 2000, p.1). This policy reflects the objectives of Section 3 of the RSA, which
includes:
• Promote and provide for the safety of the public and personnel, and the
protection of property and the environment in the operation of railways;
• Encourage the collaboration and participation of interested parties in
improving railway safety;
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• Recognise the responsibility of railway companies in ensuring the safety of
their operations; and
• Facilitate a modern, flexible and efficient regulatory scheme that will ensure
the continuing enhancement of railway safety.
2.4.1 Priority Issues Id entified in Rail Safety
This section describes most of the priority areas identified in rail safety issues. They
are not placed in order of priority. They are divided into two major groups (Fig 2.7)
as follows (ETSC 1999):
• System based safety issues; and
• People based safety issues.
1. System Based Safety Issues
• Signal Passed at Danger (SPAD) • Automatic Train Protection (ATP) • Lack of Co-operation at Global Level • Comprehensive Rail Safety Information • Safe Team Work in Various Railway
Operations • Privatisation of Railways • Formal Safety Operational Recognition • Independent Bodies for Accident
Investigations
2. People Based Safety Issues
• Driver Alertness • Drugs and Alcohol • Job Training • Effective Communication • Train Boarding and Alighting • Employees Working on or about the
Railway Employees • Health & safety • Security • Safety culture • Training
• Railway Safety Policy Statement • Safety Organisation • Authorities, Responsibilities and Accountabilities • Employee and Representative
involvement • Safety Plan and Objectives • Compliance with legal requirements • Document and data control • Safety Change Management • Safety Performance Monitoring • Safety Audits • Safety Management System Review
• Human
Safety Standards • Safety
Critical Work
• Station
operations • Depot
operations • Signalling
operations
Figure 2.8: Rail Safety Management System as a Central System to All Rail Operations
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2.5.2 Development and Management of Rail Safety
Safety rules and standards, such as operating rules, signalling rules, requirements on
staff and technical requirements applicable to rolling stock, have been devised both
nationally and internationally. Under the regulations currently in force, a variety of
bodies deal with safety. These national safety rules, which are often based on
national technical standards, should gradually be replaced by rules based on common
international standards, established by technical specifications for interoperability.
The new national rules should be in line with current legislations and facilitate
migration towards a common approach to railway safety. In this connection, the Rail
sector ensures that:
• Railway safety is generally maintained and continuously improved, taking
into consideration the development of current legislations;
• Safety rules are laid down, applied and enforced in an open and non-
discriminatory manner;
• Responsibility for the safe operation of the railway system and the control of
risks associated with it is borne by the infrastructure managers and railway
undertakings;
• Information is collected on common safety indicators through annual reports
in order to assess the achievement of the common safety targets and monitor
the general development of railway safety.
In order to coordinate the different rules, a distinction needs to be drawn between:
• Infrastructure managers, who are bodies or companies responsible in
particular for establishing, building and maintaining infrastructure and safety;
• Railway undertakings, which are private sector service providers and
government agencies engaged in the supply of goods and/or passenger
transport services by rail.
2.5.3 Key Components of SMS Managed by Rail Sectors
The railway is committed to maintaining a high degree of safety awareness and
continuously employing management systems to strive for continuous improvement
in safety performance. A risk-based approach is generally adopted for managing
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safety internally by Rail sectors. The SMS provides a workable framework for
managing safety in a systematic, proactive and consistent manner, so that the Safety
Policy can be effectively implemented. It allows the railway to manage safety
systematically, similar to how other critical aspects of the business are managed, and
reduces the need for “safety experts” as safety management then becomes line
management’s responsibility. Most importantly, all staff involved can discuss safety
using the same language. Wu (2006, p.3) stated that the Rail SMS comprises the
following nine key components:
• Safety Policy
• Safety Tasks
• Safety Management Process
• Safety Responsibility Statements
• Safety Audit System
• Risk Control System
• Safety Critical Items
• Safety Committees
• Staff Consultation.
Safety Policy: The Safety Policy sets out the high level requirement for managing
safety and health risks. It declares that the safety of railway customers, the public,
contractors and employees is an absolute pre-requisite. The organisation is
committed to maintaining a climate of safety awareness and employing management
systems to assure corporate safety goals for continuous improvement in safety
performance in all aspects of the business. The policy also stipulates that safety
demands active involvement by all. Safety management is the line responsibility of
senior management staff. To maintain the climate of safety awareness, senior
management is committed to the following missions (Leung 2002, p.1):
• Setting high standards which consistently meet legal requirements;
• Giving specific safety responsibilities to individual;
• Training up staff and manage contractors to ensure safety in their activities;
• Maintaining safety communication channels at all levels;
• Employing management systems that will reduce risks to as low as
reasonably practicable;
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• Measuring safety performance by identifying appropriate indicators;
• Using internationally recognised modern practices and processes; and
• Providing necessary funding and resources.
Safety Tasks: Fifteen Safety Tasks have been identified as most important and
relevant for managing safety in the Rail sector in order to clearly define the scope of
rail safety management (Yiu 2004). Each Safety Task has an objective to be
achieved, supported by a number of Safety Modules that provide the standards to
meet. The fifteen Safety Tasks identified are as follows:
Task 1: Safety Information
Task 2: Safe Systems of Work
Task 3: Asset, Design and Project Management
Task 4: Protective Equipment
Task 5: Fire
Task 6: Human Resources
Task 7: Communication on Safety Matters
Task 8: Contractors and Visitors
Task 9: Emergency Preparedness and Response
Task 10: Accident Reporting and Investigation
Task 11: Safety Inspections
Task 12: Safety Performance Monitoring
Task 13: Funding for Safety
Task 14: Review and Audit
Task 15: Security
Safety Management Process: Having identified the Safety Tasks to be performed
and the standards to be met, middle managers need to manage the safety tasks using
a familiar management process similar to managing any other important aspects of
the business. This Safety Management Process need to be in alignment with the
guidance outlined in current national Health and Safety Acts and Regulations.
Successful safety management system comprises the following functions (Wu 2006):
• Policy: Within the context of a department or section, this includes a structure
of guidelines, procedures, and standards on safety. It should meet legal
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requirements and provide a framework for controlling risks to as low as
reasonably practicable.
• Organising: This involves distinguishing the roles of line management and
support staff, and establishing individual safety responsibilities.
• Planning: This includes setting performance targets, allocating priorities for
implementing safety initiatives, and allocating funds for safety items.
• Implementing: This comprises leading staff to implement safety initiatives,
communicating the requirements to staff, obtaining feedback, providing
training, generating safety awareness, etc.
• Monitoring: This includes safety inspections, performance monitoring, and
investigations of undesired events.
• Review: This involves a broader review of the SMS of a department, section,
or operation. Formal, independent safety reviews are also conducted.
• Audit: This involves assessment and evaluation of the adequacy,
effectiveness and conformance to a set of laid down procedures and standards
in a SMS.
Safety Responsibility Statements: The SMS also includes a system of Safety
Responsibility Statements (SRS), which sets out in writing the safety responsibilities
and accountabilities of each post, for supervisory grades and above. Individual staff
members are required to understand and discharge the responsibilities stated in their
own SRS. These SRSs are being used in human resource functions such as
recruitment, appraisal, and promotion. Staff members who are not provided with
SRS will be provided with a Safety Responsibility Card, which gives simplified
guidelines on their safety responsibilities.
Safety Audit System: The purposes of safety audits are to provide assurance on the
compliance and effectiveness of safety management, assist middle management in
identifying opportunities for improving safety performance, identifying new hazards
and raising safety awareness (Wu 2006). In general, there are four types of
independent safety audits conducted in the railway, including:
• System audit
• Activity audit
• Contractor audit and
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• Safety technical audit.
Risk Control System: The Rail sector is required to operate on prudent commercial
principles. To support this, a risk-based approach to managing safety has been
established which includes a systematic and proactive process for identifying
hazards, registering them, estimating the associated risks, establishing standards of
acceptability and tolerability, evaluating the risks, identifying and prioritising
mitigation measures, and tracking the hazards and mitigation measures. A formal risk
control process and organisation have been set up. Hazards are ranked according to a
Risk Matrix based on their expected frequency and severity. An interactive database,
(such as “Risk Register System” or "Hazard Register System"), will be in place to
facilitate risk control and management.
Safety Critical Items: These are items requiring a high level of integrity because of
their criticality for the safe operation of the railways. Therefore, all aspects of the
management of these items, from design through to operation and maintenance, are
subject to stringent controls. In addition to requirements of the Safety Modules,
comprehensive standards are prescribed for the design, operation, and maintenance
of these items.
Safety Committees: A Corporate Safety Committee will be established to oversee
safety governance at corporate level. Reporting to the Corporate Safety Committee,
divisional safety committees are established to support line management in
discharging their safety management responsibilities. The Safety Committee for the
railway is supported by a number of sub-committees, each with their respective
functions, e.g. reviewing, developing and proposing safety.
Staff Consultation: Safety is a standing agenda item in line management meetings
at all levels of the organisation and safety topics are discussed regularly at divisional
level communications. Regular safety briefings and pre-work safety talks are held for
different work teams. Furthermore, Staff Consultative Committees will be formed
and they are mechanisms for consultation with staff to provide a means for
management and staff to freely exchange views on safety and health matters. In
addition, large-scale educational and promotional programs may be held periodically
to enhance staff’s safety awareness and knowledge. For example, the programs
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include an annual corporate event enhancing staff’s and contractors’ safety
awareness through safety seminars and exhibitions. A Safety and Quality Quiz and a
First Aid Competition are organised to enhance staff’s safety, health and first aid
knowledge and skills, which is useful to deliver an even higher quality service at
work. In order to update safety awareness of passengers on a regular basis, some
annual events are held, e.g. the safety awareness of passengers travelling on the
railway. Moreover, a few programs are targeted for special passengers groups which
address to their concerns on safety particularly. For example, Youngster Kit and
Elderly Kit have been produced for school children and elderly, on-line interactive
safety games and regular visits to schools and elderly / community centres enhance
their understanding on the proper and safe ways of travelling on the railway.
2.5.4 External Bodies Assisting in Rail Safety
Serious rail accidents, such as derailments and collisions which resulted in fatal
consequences, occur rarely but when they occur they attract the interest of the public
and safety professionals all over world. In order to avoid such accidents or to
minimise the consequences in the event of accidents occurring, a group of external
bodies (who are safety authorities and independent from railways) assist in various
ways to enhance the safety environment in railways. Following are some of the
external bodies and their responsibilities regarding the assistance of safety
improvement.
Accident and Incident Investigating Bodies: Criteria governing the independence
of the investigating body are strictly defined so that this body has no link with the
various areas of the sector. This body decides whether or not an investigation of such
an accident or incident should be undertaken, and determines the extent of
investigations depending on consequences and the necessary procedures to be
followed. The investigations need to be carried out with as much openness as
possible, so that all parties can be heard and can share the results. The relevant
infrastructure manager and railway undertakings, the safety authority, victims and
their relatives, owners of damaged property, manufacturers, emergency services
involved and representatives of staff and users should be regularly informed of the
investigation and its progress. Each investigation of an accident or incident will be
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the subject of reports in a form appropriate to the type and seriousness of the accident
or incident and the importance of the investigation findings. Each country should
ensure that investigations of accidents and incidents are conducted by a permanent
body, which comprises at least one investigator able to perform the function of
investigator-in-charge in the event of an accident or incident.
Rail Safety Certification: It is a requirement that a railway undertaking (governing
bodies and other stakeholders) holds a safety certificate before it is granted access to
the railway infrastructure. This safety certificate may cover the whole railway
network or only a defined part thereof. The fact that national safety certificates differ
is an obstacle to the development of the international railway system. The ultimate
objective is to introduce a single community certificate. In other words, if a railway
undertaking obtains a safety certificate in a country, that certificate should be the
subject of mutual recognition anywhere in the world. The safety certificate should
give evidence that the railway undertaking has established its SMS and is able to
comply with the relevant safety standards and rules. For international transport
services it should be enough to approve the SMS in a country. Adherence to national
laws on the other hand should be subject to additional certification in each country.
The safety certificate must be renewed upon application by the railway undertaking
at regular intervals. It must be wholly or partly updated whenever the type or extent
of the railway operation is substantially altered. A railway undertaking applying for
authorisation to place rolling stock in service will submit a technical file concerning
the rolling stock or type of rolling stock to the relevant safety authority, indicating its
intended use on the network. In addition to the safety requirements laid down in the
certificate, licensed railway undertakings must comply with national requirements,
compatible with international law and applied in a non-discriminatory manner,
relating to health, safety and social conditions, and the rights of workers and
consumers. An essential aspect of safety is the training and certification of staff,
particularly of train drivers. The training covers operating rules, the signalling
system, the knowledge of routes and emergency procedures.
National Safety Authority: Each state within a country will establish a safety
authority (for example, WorkCover Authority (WCA); Independent Transport Safety
and Reliability Regulator (ITSRR) in New South Wales, Australia), which is
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independent from railway undertakings, infrastructure managers, applicants for
certificates and procurement entities. It will respond promptly to requests for
applications, communicate its requests for information without delay and adopt its
decisions after all requested information has been provided. The safety authority will
carry out all inspections and investigations that are needed for the accomplishment of
its tasks and be granted access to all relevant documents and to premises,
installations and equipment of infrastructure managers and railway undertakings.
Each year the safety authority should publish a report concerning its activities in the
preceding year.
2.5.5 Need for Measuring Rail Safety
As societies become more affluent their levels of mobility also increase. While
greater mobility is to be encouraged, there are risks associated with travel. Safety
measures need to be taken to decrease the propensity to incur accidents. This is a
common practice in nations that have been motorised for many decades and
transportation-related accidents and fatalities have been studied and modelled for
decades (Soot, Metaxatos & Sen 2004). The need for measuring safety arises to
assess the level of Safety on a railway network, to help management decide resources
allocation by providing “what if” data, and to identify weak links in the SMS. As
quoted by Lord Kelvin “When you can measure what you are speaking about and
express it in numbers you know something about it; but when you cannot measure it,
when you cannot express it in numbers, your knowledge is of a unsatisfactory kind.”
Statistical analysis is one of the key methods to monitor safety performance levels
and to benchmark trends within the industry. Shall we consider accident statistics as
safety performance indicator? They provide a cost effective measure of performance
in terms of the cost associated with data collection, but they suffer from several
limitation, which should be taken into account while assessing an organisation’s
safety performance. Statistics conceal a lot more than what they reveal, which are the
most charitable remarks about statistics. It is further argued that accident statistics
measure only failures. These are ‘trailing indicators’ and not ‘leading indicators’.
Thus the utility of accident statistics as a measure of safety in a railway network is
extremely limited. So how do we measure safety performance better? It is stated that
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for the purpose of measuring Safety, ‘leading indicators’ will provide a better
system. The Rail SMS of measuring Safety should meet the following two criteria:
• Validity – the extent to which the measurement reflects the true ground
conditions; and
• Reliability - the extent to which the system of measurement gives the same
results on successive occasions of use.
Safety in the Rail SMS, a railway network or otherwise, has to be an integral part of
processes, methods, equipment, materials, people, etc. Logically measuring safety
should be concerned with the quantity and quality of the activity in these areas as
well as measuring events such as accidents, averted accidents, other incidents,
equipment failure, etc. Safety is not a directly measurable entity in the same manner
as, for example, profit or loss of an organisation. It is more constructed, and reflects a
sphere of activity concerned with the reduction of risk and the reduction of the
consequences of the unwanted events.
2.5.6 Risk Assessment in Rail SMS
The Rail sector will provide both strategic and operational management services that
underpin the risk management process.
• Development of management systems and assurance processes in close
conjunction with client requirements
• Due diligence studies to identify risk exposures and develop plans for
ongoing management control and implementation of process improvements
• Validation of organizational change and development of SMS, procedures
and risk management arrangements
• Management reviews and use of Pharos system to manage workplace
hazards.
Assessment of risk is an important process in SMS. The Rail sector's core objective
is assessing and prioritising these risks to passengers, the public and railway
employees and to put in place recommendations and actions to help eliminate their
underlying causes and effects. It should bring together engineering and management
skills to assess risk and develop cost-beneficial risk reduction strategies.
83
• Hazard identification using techniques such as task analysis, audit, etc.
• Human factors assessments
• Reliability, availability, maintainability and safety studies
• Quantitative evaluation of risk using tools such as fault and event trees
• Qualitative risk assessment
• Risk ranking.
Change Management: The sector should provide interpretation of client objectives,
development of close partnerships with clients and risk based change solutions. It
may also provide support from senior managers with industry experience to assist
with implementation of the change.
Safety Case Support: The sector will provide an unrivalled service for the co-
ordination, planning, preparation and ongoing support for all aspects of the Railway
Safety Case.
• Safety Case program management
• Risk assessments of changed operations, methods and management structures
for inclusion in the Safety Case
• Audit against the provisions of the Safety Case
• Safety Case peer review, understanding of issues, and recommendations for
improvement implementation
• Training of staff at all levels in the concepts and applications of Safety Case
• Development of emergency plans
Specialised Engineering Analysis & Risk-based Inspection: The railway’s multi-
disciplined engineers should have extensive experience in the practical application of
advanced analysis techniques to solve real engineering problems and provide real
engineering answers.
Safety Information Database: In order to improve rail SMS, it is necessary to
maintain an effective safety information database and to have access to continuously
updated information on each and every area of rail operations. For example,
information in the area of grade crossing operations such as detailed grade crossing
inventories, details of accident circumstances, accidental causes, casualties, details of
84
the growth in the highway and rail traffic passing through should be maintained and
updated in the safety information database. In general, the main purpose of
maintaining the safety information database is to provide search capabilities for
information and compile various statistics related to events on railway accidents /
incidents. The information stored in the database may be used to:
• Provide feedback and exchange information promptly
• Draw up statistics to conduct analysis
• Conduct risk assessments and
• Enhance proactive safety management.
2.6 Major Safety Issues at Railway-Highw ay Interfaces
Railroad transportation became one of the major factors in accelerating the expansion
of a country’s economy by providing a reliable, economical and rapid method of
transportation. Today, railroad transportation facilitates the establishment and growth
of towns in a country by providing a relatively rapid means of transportation of
passengers. Additionally, they are major movers of fuel, coal, ores, minerals, grains
and farm products, chemicals and allied products, food and kindred products, lumber
and other forest products, motor vehicles, heavy equipment and bulk materials. New
towns are generally developed along the railway line as they heavily depend on
transport services. In the east, railroads were built to serve the existing towns and
cities. Many communities wanted a railroad and certain concessions were made to
obtain one. Railroads were allowed to build their tracks across existing roads and
highways at-grade, primarily to avoid the high capital costs of grade separations. As
people followed the railroads to the west there was a need for new roads and
highways, most of which crossed the railroads at-grade.
In earlier days, safety at railway-highway grade crossings was not considered a
problem. Trains were very few and relatively slow, as were highway travellers who
were usually on foot, horseback, horse-drawn vehicles, or cycles. By the end of the
century, as crossing accidents were gradually increasing, communities became more
concerned about safety and operations at grade crossings. In some countries, a very
large number of railroad accidents and heavy accidental consequences are now
85
associated with railway-highway crossings. For example, grade crossing accidents on
Indian Railways accounting for 22% of the total rail accidents were responsible for
49% of total fatalities during the last decade (Verma 2007, p.1). Level crossings are
responsible for more than 23% of the train accident risk factors present on the British
Rail Network (Rail Safety & Standards Board 2004). A set of statistics on accidents
at level crossings and consequences from some selected countries are provided
below. These statistics suggest that efforts are needed to develop effective
countermeasures to reduce crossing accidents. Many countries adopted laws,
ordinances and regulations to provide safety improvements on operations at the
crossings. In fact, the railway-highway interface is unique in that it constitutes the
intersection of two individual transportation modes which differ both in the physical
characteristics of their travelled ways and their operations. Accidents at railway-
highway crossings cause huge damages and losses including passengers, members of
the public, rail workers and properties such as rolling stocks, road vehicles, rail
infrastructures, etc. Safety levels at railway-highway interfaces continue to be of
major concern despite improved design and application practices.
2.6.1 Statistical Overview of Gl obal Level Crossing Collisions and
Consequences
This section presents an overview of global highway - railway grade crossing
accidents and their consequences in the past few years, from both qualitative and
quantitative perspectives. It assists in comparing the risks at level crossings in
various countries around the world. For the purpose of overview, level crossing
collisions and consequences over fifteen selected countries are considered. Statistical
details of “highway-railway” grade crossings accidents and consequences resulted
from those accidents are reported as given below.
United States: There are 241,817 railway-highway grade crossings (including
146,103 public, 93,689 private and 2,025 pedestrian) in the USA. Each year, about
368 people lose their lives and 1,057 people are injured as a direct result of grade-
crossing collisions occurring at the annual rate of 3,081 approximately (USDOT
FRA accidents database, 2006).
86
Canada: Within 10,381 unique crossings in Canada, a total of 1,724 collisions were
reported over a nine-year period (1993-2001). These collisions resulted in
242 fatalities and 347 serious injuries (Department of Civil Engineering, University
of Waterloo, 2003).
Japan: In Japan, there are currently about 37,326 level crossings of all types. Over a
nine-year period (1990-1998), 5,352 level crossing accidents were reported which
resulted in 1,387 fatalities and 2,171 injuries (Transportation Ministry, Japan, 2001).
New Zealand: There are 1,398 level crossings over the New Zealand railway
network. Between 2001 and 2003 there was an average of 30 collisions. There were
six fatal, five serious injury and four minor injury crashes per year at these level
crossings (Patterson 2004).
Australia: There are approximately 9,400 public railway level crossings in Australia
(Australian Transport Council, 2003). Over a seven-year period (2001-2007), a total
of 551 level crossing accidents were reported which resulted in 259 fatalities
(Australian Transport Safety Bureau, 2008). In the state of New South Wales, there
were 267 level crossing crashes reported over the period of 12 years (1990-2001)
which resulted in 50 fatalities.
Selected Ten European Countries: Figures for the number of level crossings,
annual average number of collisions and fatalities for a selection of ten European
countries are given in Table 2.5 (Rail Safety & Standards Board, 2004).
87
Table 2.5: Level Crossing Accident Statistics in Selected European Countries
Country Number of Level
Crossings
Annual Average
Collisions
Annual Average
Fatalities
Belgium 2,409 62.86 14.29
Finland 5,283 48.57 9.86
France 19,831 178.29 49.71
Great Britain 8,323 30.29 8.57
Germany 26,980 451.80 91.20
Ireland 1,976 4.14 0.57
Luxembourg 149 2.00 0.57
Netherlands 3,006 74.43 27.43
Portugal 2,972 117.20 24.00
Sweden 10,000 30.00 8.57
It can be noted from above overview that many countries show different statistics on
the rates of annual accidents and consequences at railway-highway grade crossings.
However, the USA has exceptionally highest figures compared to other countries.
2.6.2 Global Comparison of Level Crossing Accidents
Railway level crossing accidents are one of the major contributing factors of railway
related fatality problems in many countries (Zaharah 2007, p.1). Even though railway
level crossing accidents can be considered as a rare event, the impact is often severe.
The aim of this section is to compare the number of collisions and fatalities that
occurred at level crossings in fifteen different countries around the world. However,
it should be remembered that there may be major differences between the various rail
networks worldwide and how many incidents may be recorded.
2.6.2.1 Level Crossing Collisions
Figures 2.9 and 2.10 show the data ordered in decreasing safety risk rates per
selected countries for collision and fatality respectively. The safety risk rate for
collision (Annual Collision Rate) for a country is calculated as the number of average
annual collisions per the number of level crossings in the country. In the similar way,
the safety risk rate for fatality (Annual Fatality Rate) for a country is computed as the
number of average annual fatalities per the number of level crossings in the country.
* Unwanted event expected to happen 1 in 10 times the circumstances occur.
Table 3.2: Group Selection for Measuring Consequences of an Event
Identifier Descripto r
Fatality Catastrophic or fatal event
Major injury Critical serious injury yields permanent disability
Minor injury Moderate or average lost time injury occurs
First aid only First aid given to minor injury
Negligible No injury at all
It is noted that there are many variations on design of qualitative analysis approaches
(Joy & Griffith 2005). However, the description or numerical ranges are required to
be carefully defined to meet objectives as well as to provide discrete and suitable
choices. Qualitative analysis is useful when reliable data for more quantitative
approaches is not available. Some techniques outlined below are suitable for
categorising risks on the basis of individual or team opinion. Further, differences
between categories (high, medium, low, etc.) are difficult to define and quantify as
they simply describe using qualitative terms. Therefore it remains for the individual
who uses this method to decide those differences. As such, it generally can be
considered a rough method of risk analysis that simply divides the identified risks
into four categories:
• Extreme;
• High;
• Medium or Moderate; and
• Low.
Once the probability and consequences of an event are chosen, a comparative risk
rank matrix can be developed as shown in Table 3.3 (Joy & Griffith 2005). The
details of each element of the matrix are given in below the table.
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Table 3.3: A Typical Qualitative Risks Ranking Matrix
Likelihood (Probability)
Consequences (Severity)
Negligible First aid only
Minor injury
Major injury Fatality
Very likely M H H E E
Likely M M H H E
Possible L M M H H
Unlikely L L M M H
Highly unlikely L L L M M
Identifier Risk Level Risk Control Measures
E Extreme risk
• Activity must not start or if started, must be stopped; • Immediate action required; • Notify supervisor or appropriate Health and Safety Authority as required; • Highest level corporate management needs to be involved; • Identify hazards and implement controls to reduce risk to low before starting or recommencing activity.
H High risk • Activity must not start or if started, must be stopped; • Immediate action required; • Notify supervisor as required; • Senior site management needs to be involved; • Identify hazards and implement controls to reduce risk to low before starting or recommencing activity.
M Moderate risk
• Immediate action to minimise injury e.g. signs; • Supervisor remedial action required within 5 working days; • Complete risk assessment needed; • Identify hazards and implement controls to reduce risks; • Management responsibility must be defined. L Low risk • Remedial action within 1 month, supervisor attention required; • Identify hazards and implement controls as required; • Manage by routine processes.
3.1.4.2 Quantitative Risk Analysis
Numerical values are assigned to both impact and likelihood in quantitative analysis
(Joy & Griffith 2005). In general, these values are derived from a variety of sources.
Further, the quality of the entire analysis depends on the accuracy of the assigned
values and the validity of the statistical models used. Impact can be determined by
evaluating and processing the various results of an event or by extrapolation from
experimental studies or past data. Consequences can be expressed based on various
terms of following impact criteria.
• Monetary;
• Technical;
• Operational; and
• Human.
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Quantitative risk analysis, based on (reference to the above) involves the calculation
of probability of unwanted events and subsequently the probability of consequences
from those events, using numerical data where the numbers are real numbers (i.e. 1,
2, 3, 4, etc. where 4 is twice 2 and half of 8) but rather are not in ranking order (i.e.
1st, 2nd, 3rd etc.). As such, accurate quantification of risk offers the opportunity to
be more objective and analytical than the qualitative approach. Most commonly,
quantification of risk involves generating a number that represents the probability of
a selected consequence of an event, such as a fatality. For example, Table 3.4 shows
a range of causes and corresponding probability of death in the UK over one year
period. British Nuclear Industry research reports the following probability of death,
based on historical data from various causes in the UK (Joy & Griffith 2007).
Another example, the risk of a total petroleum storage tank structural failure might
be .003 per year. If there are multiple events that must happen before a major loss
can occur, then assigning probabilities to multiple events allows for estimations /
calculations of risks that are normally not possible with qualitative or semi-
quantitative data.
Table 3.4: Probability of Deaths by Causes
Causes Probability of Death in the UK
Smoking 0.05 or 1 in 200
Mining Accidents 0.001 or 1 in 1000
Road Traffic Accidents 0.0001 or 1 in 10000
Industrial Accidents 0.00001 or 1 in 100000
Flying in Commercial Aircraft 0.00001 or 1 in 100000
Fire / Explosion at Home 0.000001 or 1 in 1 million
Lightning 0.0000001 or 1 in 10 million
Individual safety cases rely heavily on the selected risk assessment techniques and
some people see this as unsatisfactory (Hopkins & Wilkinson 2005, p.7). Complex
risk assessment methodologies, particular where quantification is involved, can be
difficult to understand for everyone. Not surprisingly therefore they may not be
trusted. Furthermore it is often suggested that quantitative risks assessments have
been massaged so as to reduce the risk to an acceptable level. Such misuse of risk
103
assessment almost certainly occurs. However, this is a criticism of how risk
assessment is applied and not the concept itself. For example, in a complex plant
with complicated processes there is no alternative to the use of systematic hazard and
risk assessment methodologies. It is therefore expected that any kind of
methodologies, which are being developed to evaluate risks, need to be very simple
and easily understandable to people with different levels of knowledge on safety.
3.1.4.3 Semi-Quantitative Risk Analysis
The objective of semi-quantitative risk analysis is to provide an analysis using some
indicator values, which are assigned to the scales used in the qualitative assessment.
These values are usually indicative and are prerequisite of the quantitative approach.
Since the indicator value allocated to each scale is not an accurate representation of
the actual magnitude of impact or likelihood, the numbers need to be combined using
a formula that recognises the limitations or assumptions made in the description of
the scales used. It also needs to be mentioned that the use of semi-quantitative
analysis may lead to various inconsistencies due to the fact that the numbers chosen
may not properly reflect analogies between risks, particularly when either
consequences or likelihood are extreme. As noted in the above discussion on
qualitative and quantitative risk analyses, the specification of the risk level is not
unique. Impact and likelihood of an event can be expressed or combined differently,
depending on the type of risk, the scope and objective of risk management practices,
processes and systems.
3.2 Developing Theoretical Framework on Safety Risk
Evaluation at Rail Grade Crossings
There has been increased emphasis on rail safety management in recent years due to
the application of new legislations globally and the establishment of various SMS
standards. It has been determined from reported work that the risk assessment within
the broader area of risk management is a key process within a rail SMS. Further,
based on the facts and reasons outlined earlier in Chapter 2 on why level crossings
104
now have the potential to become the largest single cause of potentially catastrophic
train accidents on the railway globally, this research aims to develop a theoretical
framework on safety risk evaluation at rail grade crossings. This is further endorsed
by the significance on safety improvement at level crossings identified earlier and the
need for developing an improved method to assess the risk at rail grade crossings.
This study therefore focuses on developing a framework to assess the residual risks
at railway-highway grade crossings and to prioritise these crossings in ranking order
using quantitative methods / models. In order to assess and to prioritise the risks at
grade crossings, three risk assessment models are developed and tested for their
validity using a comprehensive statistical analysis. The three risk assessment models
include (i) accident prediction, (ii) consequences estimation, and (iii) a combination
of the two models. The first two models are outlined with associated processes of
developing these models explained in Chapter 5. The final model, labelled “Safety
Risk Index (SRI)” is presented in Chapter 6.
3.2.1 Development of a Quantitati ve Risk Assessment Model for
Safety Evaluation at Rail Crossi ngs - Safety Risk Index (SRI)
As discussed earlier in the Chapter 2, there are two central principles in rail safety
evaluation: risk-based proactive and reactive approaches (Elms 2001, p.296). The
risk-based proactive safety approach is based on the implementation of modern
safety procedures and practices in rail operations. The risk-based reactive safety
approach is performed by analysing the past safety integration of data and
information for the different aspects of a rail safety system. For a reactive approach
in safety evaluation, rail accidents and their consequences are the direct measures of
rail safety. Since those accidents are random events, statistical models such as
Poisson or Negative Binomial can be utilised to generate mathematical models for
predicting accidents and consequences. The details of mathematical models,
including a brief introduction and background of models, objectives of the risk index,
the methodology for the development of the index, and some comparative results to
test on validity of the index are presented here.
105
In general, it is common to discover facts about a real world phenomenon that
actually exists. The phenomenon is explained by collecting data from the real world
and then analysing this data to draw conclusions about the subject being studied. One
of a researcher’s tasks is to take available real world data and to use it in a
meaningful way. The nature of the tasks often involves building statistical models
under certain conditions and using them to make predictions about the real world
phenomenon of interest. The model may differ from reality in several ways. If we
want our inferences to be accurate, then our model needs to represent the data
collected as closely as possible. The degree to which the model represents the
observed data is known as the “goodness-of-fit” of the model (Wood 2002, p.419).
This section aims to provide a brief overview of some important statistical concepts
such as how statistical models can be developed, built and used.
3.2.1.1 Basic Concepts Used in Developing SRI
In order to provide rail safety evaluation from a quantitative perspective, the
fundamental elements associated with risk measurement need to be initially
identified. Based on research activities conducted by various researchers (such as
Estimation of Accident Frequency ( )(ˆ YE ) obtained from Chapter 5
Estimation of Consequences per Accident ( )|(ˆ YCE ) obtained from Chapter 5
Computation ofSafety Risk Index [ ℜ = )(ˆ YE * )|(ˆ YCE ]
Figure 6.1: Flow Diagram of Developing Safety Risk Index (SRI) Model
6.1.2 Identifying Safety Status of a Crossing using Graphical
Method
Based on the recognition of graphical methods being developed and widely used in
the past for assessing the risk at grade crossings with identification of Black-Spots,
this research adapts and extends Saccomanno et al. (2003)’s work by allowing
different values for accident frequency and accidental consequences, as opposed to
equal importance in the original model. Thus, an improved quantitative risk
assessment approach was developed where the two key indicators (accidents
frequency and accidental consequences) are combined together to provide a single
risk measure. A two-dimensional graphical representation is adopted, in order to
assess the safety risks at grade crossings. This approach locates grade crossings in a
two-dimensional graph with their safety risks status (including estimated accidents
and estimated consequences). For example, Figure 6.2 shows a typical two-
dimensional graph for identifying the safety status of grade crossings. Estimated
accidents over five years (X) and estimated consequences (Y) are displayed on the
x-axis and y-axis of the graph respectively. Each point plotted on the graph
279
represents the safety risk status of an individual crossing. By plotting points for each
crossing on the graph for all four types of protection separately, the safety risk status
of each crossing can be depicted. From the graph, the black-spots can then be
conveniently identified in the relevant crossings protection type. By definition, a
Safety Risk Index is defined as:
Y*X)(IndexRisk Safety =ℜ
Identifying Safety Risk Status of a Crossing by Severity Risk Index Graph
Number of Predicted Accidents per Year (X)
Pre
dict
ed C
onse
quen
ces
(Y)
(Equ
ival
ent F
atal
ities
per
Acc
iden
t)
Severity Risk Status Position of a Crossing Concerned Severity Risk Index Curve (X*Y = R)
Figure 6.2: Identifying Safety Status of Grade Crossings using Safety Risk Index Curve
Consider the equation of X*Y = ℜ which represents a typical set of power decay
curves, where the values of X and Y can vary while “ℜ ” remains a constant value
which will depends on the safety risk status of a crossing concerned. This curve is
known as the “Safety Risk Index Curve” and can be illustrated by point ‘A’ being on
the Safety Risk Index Curve (C) as shown in Figure 6.2 which represents the safety
status of a particular or concerned grade crossing. The risk value of the crossing (ℜ )
is given by ℜ = X*Y. It is therefore obvious that all crossings having the same safety
risk index values should fall on the same curve (C). This approach logically
demonstrates that dangerous crossings will have higher values of “ℜ ” and moderate
or safer crossings will have values lower than ℜ . The sensitivity of this curve is
explained in the following section.
A
At Point ‘A’ on Safety Risk Index Curve,
Safety Risk Index value of a crossing (ℜ ) is given by ℜ = X*Y
X
Y
Safety Risk Index Curve ‘C’
280
6.2 Identifying Black-Spots (C rossings with Unacceptable
Higher Safety Risk Index Values)
As stated earlier, the group of grade crossings which have higher (unacceptable)
safety risk values are known as “black-spot” crossings. The safety risk index values
play a vital role in identifying these black-spots.
6.2.1 Introducing Threshold Curves of Safety Risk Index
Consider three safety risk index curves shown in Figure 6.3 with different SRI values
1ℜ , 2ℜ and 3ℜ (provided 1ℜ < 2ℜ < 3ℜ ). The crossings having safety risk index
values of 1ℜ fall on the curve ‘C1’. In a similar manner, the crossings having safety
risk index values of 2ℜ and 3ℜ will fall on the curves ‘C2’ and ‘C3’ respectively.
Because of 1ℜ < 2ℜ < 3ℜ , by definition it can be considered that the crossings
represented by the curve ‘C3’ are more dangerous than others represented by either
the curve ‘C1’ or ‘C2’.
Safety Risk Index Curves with Different SRI Values
Number of Predicted Accidents per Year (X)
Pre
dict
ed C
onse
quen
ces
(Y)
(Equ
ival
ent F
atal
ities
per
Acc
iden
t)
Safety Risk Index Curve C1 Safety Risk Index Curve C2 Safety Risk Index Curve C3
Figure 6.3: Safety Risk Index Curves with Different SRI Values
SRI value (ℜ ) increases upwards
X*Y=3ℜ
X*Y=2ℜ
X*Y=1ℜ
SRI value (ℜ ) decreases downwards
1ℜ <
2ℜ < 3ℜ
281
However, the crossings represented by the curve ‘C1’ are safer. The crossings falling
on the curve ‘C2’ will be moderate in safety. In fact, the safety of a crossing depends
on the value of ℜ . As the value of ℜ increases, the safety status of the crossings
becomes more dangerous. When “ℜ ” takes its optimal value or minimum
unacceptable value (0ℜ ), the Safety Risk curve becomes a “Safety Risk Index
Threshold” curve (X*Y = 0ℜ ). In other words, the threshold curve is a reference
curve which retains the minimum unacceptable risk index value of a crossing. It is
therefore noted that dangerous crossings (black-spots) should fall on or above the
threshold curve (X*Y = 0ℜ ) in the safety risk index graph. The crossings falling
below the threshold curve are assumed to be reasonably safer than others.
6.2.2 Selecting Safety Ri sk Index Threshold Value
To determine the optimal value for threshold curves requires clear and considerable
explanations. Basically, this critical value relates to the number of crossings
suggested to enhance safety at minimal cost of intervention. Of course, the number of
crossings depends on budgetary constraints set by the relevant authorities. Therefore
a great deal of study on cost benefit analysis while considering several
countermeasures for intervention will be needed to determine the critical value of the
threshold for each protection type of crossing. See example in Figure 6.4 for
estimating the threshold value for black-spots identification.
In general, the relationship between the safety risk levels and the percentage of
crossings which experienced accidents is expressed in the form of an exponential
decay curve as shown in the Figure. Meanwhile, it can be assumed that the
intervention cost to enhance safety at crossings linearly depends on the number of
crossings concerned. For example, consider if funds 0F are currently available and
allocated by the authorities for safety enhancement at grade crossings. Point “A”
indicates the value of 0F on the axis of intervention cost. Construct the horizontal
line “BA” through the point “A”, which meets the line of ‘Intervention cost to
enhance safety’ (BF) at the point “B” as shown on the figure. Draw the vertical line
“BC”, which meets the X-axis of ‘Percentage of crossings experienced with
accidents’ at the point “C”. The maximum number of crossings (0N ) for safety
282
intervention can then be decided at point “C”. Similarly, construct the vertical line
“CD” which meets the curve of ‘Safety risk level of crossings’ at the point “D”.
Finally, draw the horizontal line “DE” which meets the Y-axis of ‘Safety risk level’
at the point “E”. The optimum value for Safety Risk Index Threshold (0ℜ ) is to be
determined at point “E”.
Estimating Threshold Value for Black-spots Identification
Percentage of Crossings Experienced w ith Accidents
Saf
ety
Ris
k Le
vel
Inte
rven
tion
Cos
t ($)
Intervention Cost ($) to Enhance Safety Safety Risk Level of Crossings
Cut-off Line
Optimum Safety Risk Index Value (
oℜ ) Achievable
Number of Crossings (oN )
need to be Enhanced in Safety at Available Fund
Available Fund for Safety Intervention (
oF )
E D
A
B
C
F
Figure 6.4: Estimating Threshold Value for Black-Spots Identification
However, as this type of cost benefit analysis (as shown in the above demonstration
in Figure 6.4) is not feasibly available at this stage in the study, an alternative method
is introduced to choose the critical value in this study. The Safety Risk Index values
of crossings within a protection type are initially calculated. The standardised scores
for all Safety Risk Indexes are then computed. Finally, the number of high risk
crossings are identified at various standardised score levels (such as 2, 3, 4 and so
on). This procedure is repeated for all types of protection. The relationship between
the standardised scores and the number of black-spot crossings is individually
identified and summarised in all types of protections (Figure 6.5).
283
2 3 4 5 6
Protection Type 1 5 3 3 2 2
Protection Type 2 401 193 136 78 54
Protection Type 3 178 77 76 39 36
Protection Type 4 426 242 148 91 61
Grand Total 1010 515 363 210 153
0
200
400
600
800
1000
1200
Num
ber o
f Bla
ck-s
pots
Iden
tifie
d
Standardized Score of Severity Risk Index
Number of Black-spots by Protection Types Vs Standardized Score of SRI
Figure 6.5: Number of Black-Spots by Protection Types Vs Standardised Score of SRI
Table 6.1: Summary of Proposed Threshold Critical Values by Protection Types
Protection Type
of Grade
Crossings
Mean of Safety
Risk Index
Standard Deviance
of Safety Risk
Index
Reference
Standardized
Score
Threshold Critical
Value
1 0.0053 0.0367 4 0.15
2 0.0079 0.0326 4 0.14
3 0.0070 0.0380 4 0.16
4 0.0120 0.0376 4 0.16
It is therefore clearly noted that the number of black-spots identified entirely depends
on the standardised scores associated with the Safety Risk Index. For example, if the
score of 2 is selected, a total of 1,010 crossings are identified as black-spots within
all four protection types. The number of black-spots drops to 515 for the score of 3
and to 363 for score of 4 and so on. A further investigation and analysis is needed to
improve this relationship using budgetary constraints information, in order to
enhance the safety at grade crossings. In the absence of this information at this stage
of analysis, and for the purpose of demonstration, the value of the Safety Risk Index
that relates to the standardised score of 4 has been adopted as a threshold value in
this study. The proposed threshold values for each type of protections are
284
summarised in the Table 6.1. Following is an illustration showing how the critical
threshold values are obtained. Consider Protection Type 1 crossings. The threshold
value for this type is calculated by the equation of:
deviance Standard
)Mean value - valueCritical (Threshold 4 of valueat the score edStandardis =
Mean valuedeviance Standardx4 valueCritical Threshold +=
15.0
0367.0*40053.0 valueCritical Threshold
=+=
6.2.3 Identifying Bl ack-Spots in Each Protection Type
Table 6.1 shows that for the common reference standardised score of 4, Protection
types 1, 2, 3 and 4 yielded the threshold critical values of 0.15, 0.14, 0.16 and 0.16
respectively. Using the average of these critical values, the common threshold can
assign the value of 0.15 approximately. In this study black-spots are therefore
identified with respect to a common threshold critical value of 0.15 in all types of
protection. This means that grade crossings with the estimated risk value of 0.15
equivalent fatalities or more over one year period are considered as black-spots. The
accidental grade crossings from each protection types are plotted separately in order
to compare them and to determine the black-spots in each group. Details of these
black-spots are listed and summarised in Table 6.6.
6.2.3.1 Crossing Protection Type 1 (No Signs or No signals)
From the data analysis it is noted that only 3 crossings (1.37% of all accidental
crossings in Protection Type 1) are estimated with a Safety Risk Index value more
than 0.15 as shown in Figure 6.6.
285
SRI Vs Percentage of Crossings Experienced w ith Accidents - Prote ction Type 1
98.63
0.91
0.46
0.00 25.00 50.00 75.00 100.00
Less than 0.15
Betw een 0.15 and 0.30
More than 0.30
Saf
ety
Ris
k In
dex
(Equ
ival
ent F
atal
ities
per
Yea
r)
Percentage of Grade Crossings Experienced w ith Accidents
Figure 6.6: Safety Risk Index Vs Percentage of Protection Type 1 Accidental Crossings
Identifying Black-Spots Using SRI Threshold Curve - Protection Type 1
Severity Risk Threshold CurveX*Y = 0.15
0.00
0.50
1.00
1.50
2.00
0.00 0.10 0.20 0.30 0.40 0.50
Predicted Accidents per Year (X)
Pre
dict
ed E
quiv
alen
t Fat
aliti
es p
er A
ccid
ent (
Y)
3 Crossings (with Severity Risk Value over 0.15) which fall above the Threshold Curve are considered as Black-Spots in this Group
Grade Crossing (ID No.: 632469J) at Highest Riskwith Severity Risk Value of 0.43
Figure 6.7: Black-Spots Identification in Protection Type 1 Grade Crossings
In Figure 6.7, the safety status of individual crossings is plotted by estimated
accidents (X) and estimated consequences (Y) of the relevant crossings. In the same
graph, using the suggested critical value of 0.15, the threshold curve is also plotted.
The same plotting procedure will apply later to the other protection types. By looking
at the crossings in this group which fall on or above the threshold curve, only
286
3 crossings are identified as black-spots and the details are summarised in Table 6.2.
In the same manner, the black-spots in other types of protection are identified and
their details are summarised.
Table 6.2: List of 3 Black-Spots Identified in Protection Type 1
Crossing ID Number
Number of Collisions Predicted per Year (X)
Consequences Predicted per an Accident (Y)
Severity Risk Index
632469J 0.28 1.51 0.43
022694S 0.36 0.72 0.26
361331H 0.25 0.72 0.18
6.2.3.2 Crossing Protection Type 2 (Stop Signs or Cross-bucks)
The analysis shows that 129 crossings (1.39 % of all accidental crossings in
Protection Type 2) are calculated with a Safety Risk Index value more than 0.15
(Figure 6.8).
SRI Vs Percentage of Crossings Experienced w ith Accidents - Protection Type 2
98.61
1.14
0.25
0.00 25.00 50.00 75.00 100.00
Less than 0.15
Betw een 0.15 and 0.30
More than 0.30
Saf
ety
Ris
k In
dex
(Equ
ival
ent F
atal
ities
per
Yea
r)
Percentage of Grade Crossings Experienced w ith Accidents
Figure 6.8: Safety Risk Index Vs Percentage of Protection Type 2 Accidental Crossings
287
Identifying Black-Spots Using SRI Threshold Curve - Protection Type 2
Severity Risk Threshold CurveX*Y = 0.15
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
0.00 0.25 0.50 0.75 1.00
Predicted Accidents per Year (X)
Pre
dict
ed E
quiv
alen
t Fat
aliti
es p
er A
ccid
ent (
Y)
129 Crossings (with Severity Risk Value over 0.15) which fall above the Threshold Curve are considered as Black-Spots in this
Grade Crossing (ID No.: 300182S) at Highest Riskwith Severity Risk Value of 0.77
Figure 6.9: Black-Spots Identification in Protection Type 2 Grade Crossings Figure 6.9 shows the safety status of grade crossings plotted. A total of 129 crossings
are identified as black-spots and details of the top five are summarised in Table 6.3.
Table 6.3: List of Top Five within 129 Black-Spots Identified in Protection Type 2
Crossing ID Number
Number of Collisions Predicted per Year (X)
Consequences Predicted per an Accident (Y)
Severity Risk Index
300182S 0.57 1.35 0.77
731968X 0.28 1.91 0.53
329012H 0.25 1.90 0.48
622318S 0.34 1.35 0.46
014877P 0.24 1.90 0.45
6.2.3.3 Crossing Protection Type 3 (Signals, Bells or Warning Devices)
The analysis shows that 76 crossings (1.35 % of all accidental crossings in Protection
Type 3) are calculated with a Safety Risk Index value more than 0.15 (Figure 6.10).
288
SRI Vs Percentage of Crossings Experienced w ith Accidents - Protection Type 3
98.65
0.94
0.41
0.00 25.00 50.00 75.00 100.00
Less than 0.15
Betw een 0.15 and 0.30
More than 0.30
Saf
ety
Ris
k In
dex
(Equ
ival
ent F
atal
ities
per
Yea
r)
Percentage of Grade Crossings Experienced w ith Accidents
Figure 6.10: Safety Risk Index Vs Percentage of Protection Type 3 Accidental Crossings Figure 6.11 shows the safety status of grade crossings plotted. A total of 76 crossings
are identified as black-spots and details of the top five are summarised in Table 6.4.
Identifying Black-Spots Using SRI Threshold Curve - Protection Type 3
Severity Risk Threshold CurveX*Y = 0.15
0.00
1.00
2.00
3.00
4.00
5.00
0.00 0.50 1.00 1.50
Predicted Accidents per Year (X)
Pre
dict
ed E
quiv
alen
t Fat
aliti
es p
er A
ccid
ent (
Y)
76 Crossings (with Severity Risk Value over 0.15) which fall above the Threshold Curve are considered as Black-Spots in this Group
Grade Crossing (ID No.: 028394Y) at Highest Riskwith Severity Risk Value of 1.20
Figure 6.11: Black-Spots Identification in Protection Type 3 Grade Crossings
289
Table 6.4: List of Top Five within 76 Black-Spots Identified in Protection Type 3
Crossing ID Number
Number of Collisions Predicted per Year (X)
Consequences Predicted per an Accident (Y)
Severity Risk Index
028394Y 0.26 4.72 1.20
794960S 0.48 1.36 0.65
640124J 0.85 0.69 0.59
352066W 0.38 1.37 0.52
478051H 0.76 0.67 0.52
6.2.3.4 Crossing Protection Type 4 (Gates or Full Barrier)
The analysis shows that 239 crossings (2.16 % of all accidental crossings in
Protection Type 4) are calculated with a Safety Risk Index value more than 0.15
(Figure 6.12).
SRI Vs Percentage of Crossings Experienced w ith Accidents - Protection Type 4
97.84
1.83
0.32
0.00 25.00 50.00 75.00 100.00
Less than 0.15
Betw een 0.15 and 0.30
More than 0.30
Saf
ety
Ris
k In
dex
(Equ
ival
ent F
atal
ities
per
Yea
r)
Percentage of Grade Crossings Experienced w ith Accidents
Figure 6.12: Safety Risk Index Vs Percentage of Protection Type 4 Accidental Crossing
290
Identifying Black-Spots Using SRI Threshold Curve - Protection Type 4
Severity Risk Threshold CurveX*Y = 0.15
0.00
0.50
1.00
1.50
2.00
2.50
3.00
0.00 0.25 0.50 0.75 1.00
Predicted Accidents per Year (X)
Pre
dict
ed E
quiv
alen
t Fat
aliti
es p
er A
ccid
ent (
Y)
239 Crossings (with Severity Risk Value over 0.15) which fall above the Threshold Curve are considered as Black-Spots in this Group
Grade Crossing (ID No.: 628171P) at Highest Riskwith Severity Risk Value of 0.88
Figure 6.13: Black-Spots Identification in Protection Type 4 Grade Crossings Figure 6.13 shows the safety status of grade crossings plotted. A total of
239 crossings are identified as black-spots and details of the top five are summarised
in Table 6.5.
Table 6.5: List of Top Five within 239 Black-Spots Identified in Protection Type 4
Crossing ID Number
Number of Collisions Predicted per Year (X)
Consequences Predicted per an Accident (Y)
Severity Risk Index
628171P 0.50 1.75 0.88
512363H 0.73 1.18 0.86
426309E 0.36 1.78 0.64
755624C 0.84 0.67 0.56
673655X 0.83 0.62 0.51
291
6.2.4 List of All Black-Spot s Identified in the Study
As stated in the earlier section, budgetary constraints play a major role in selecting
the safety risk index threshold critical values to decide on the number of crossings
which are the worst ones (black-spots). However, in this study the safety risk index
threshold critical values were set up at 0.15 and with respect to this value a total of
447 black-spots were identified in all four types of protections. They are shown in
Figure 6.14 and summarised in Table 6.6. This total comprises of the numbers of 3,
129, 76 and 239 grade crossings from the Protection Types 1, 2, 3 and 4 respectively.
Identifying Black-Spots Using SRI Threshold Curve - All Protection Types
Severity Risk Threshold CurveX*Y = 0.15
0.00
1.00
2.00
3.00
4.00
5.00
0.00 0.50 1.00 1.50 2.00
Predicted Accidents per Year (X)
Pre
dict
ed E
quiv
alen
t Fat
aliti
es p
er A
ccid
ent (
Y)
447 Crossings (with Severity Risk Value over 0.15) which fall above the Threshold Curve are considered as Black-Spots in All Groups
Grade Crossing (ID No.: 028394Y) at Highest Riskwith Severity Risk Value of 1.20
Figure 6.14: All 447 Black-Spots Identified in Four Protection Types of Grade Crossings
292
Table 6.6: List of 447 Black-Spots Identified from the Study and Their Locations
