RISK-BASED MANAGEMENT OF GUARDRAILS: SITE SELECTION AND UPGRADING

transcript

Center for Risk Management of Engineering Systems University of Virginia, Charlottesville

RISK-BASED MANAGEMENT OF GUARDRAILS: SITE SELECTION

AND UPGRADINGPresented to

Project Steering Committee

The Center for Risk Management of Engineering Systems

February 9, 2000

Agenda

• Overview of risk assessment/management• Review of proposal and Comparison Tool• Literature review and survey• Risk assessment for guardrails• Corridor analysis for screening• Integration of electronic map and catalog• Budget optimization for evaluation• Webpage• Discussion

Overview of the Risk Assessment and Management Process

Technological AgeRisk Management Optimal Balance

Technology Management:

Man/Machine/Software Systems• Planning • Design• Operation

Management

UncertainBenefits

UncertainCosts

Risk assessment and management must be an integral part of the

decisionmaking process

A Measure of the Probability and Severity of Adverse Effects

RISK VS. SAFETY

Measuring risk is an empirical, quantitative, scientific activity (e.g., measuring the probability and severity of harm).

Judging safety is judging the acceptability of risks -- a normative, qualitative, political activity.

(After William W. Lowrance, 1976)

RISK ASSESSMENT AND MANAGEMENT

• What can go wrong?

• What is the likelihood that it will go wrong?

• What are the consequences?

• What can be done?

• What options are available and what are their associated trade-offs in terms of all costs, benefits, and risks?

• What are the impacts of current management decisions on future options?

Review of Goals/Tasks/Schedule

Problem Statement

• Public and transportation-agency values concerning the location of roadway guardrails are in need of clarification

• The concerns of Virginians for adequate guardrails are high relative to the national norms

• Current practice in some VDOT Districts for selecting locations for new guardrails is based on citizen complaints, a general knowledge of roadway needs from local engineers, and accident history

Problem Statement (cont.)

• Kentucky has developed a hazard-index point system (Kentucky Transportation Center Report KTC-89-39 "Warrants and Guidelines for Installation of Guardrail")

• There are hundreds of candidate locations on the thirteen-county secondary system of Richmond District

• Particular locations in New Kent and Charles City County have been the focus of a related preliminary study in Richmond District

Purpose and Scope

The effort will adopt quantitative and qualitative factors/endpoints and develop associated cost-

benefit-risk tradeoff methodology to support the preliminary screening and subsequent evaluation of guardrail site selection and upgrading with limited

available funding

Purpose and Scope (cont.)

• Four associated objectives:– Review and evaluation of what others have done

– Adoption of assessment methods and quantitative and qualitative factors/endpoints

– Development of a tradeoff methodology

– Specification and prototype development of databases

• Acknowledge that guardrails sometimes increase danger to vehicles

Methods

(1) Review of Literature

• Review and evaluation of past studies, theory and methodology, and databases

• Build on past surveys• Sample of resources:

– Bryden, J.E. and J.S. Fortuniewicz. “Traffic Barrier Performance Related to Vehicle Size and Type.” Transportation Research Record 1065, TRB, National Research Council, Washington D.C., 1986.

– Calcote, L.R. “Cost-Effectiveness Model for Guardrail Selection.” Transportation Research Record, 679, TRB, National Academy of Sciences 1978, pp. 8-12.

– Calcote, L.R. “Strategy for Selection and Placement of Highway Guardrails.” Transportation Research Record 736, TRB, National Academy of Sciences, 1979.

– Kentucky Transportation Center, Report KTC-89-39 "Warrants and Guidelines for Installation of Guardrail", 1989.– Mak, King K. “Cost-Effectiveness Evaluation of Roadside Safety Improvement.” Transportation Research Circular 416, TRB, National

Research Council, 1993.– Michie, Jarvis D. and Bronstad, Maurice E. “Highway Guardrails: Safety Feature or Roadside Hazard?” Transportation Research Record

1468, TRB, National Research Council, 1994.– Pigman, Jerry G. and Agent, Kenneth R. “Guidelines for Installation of Guardrail.” Transportation Research Record 1302, TRB, National

Research Council, 1991.– Stewart, Douglass. “Pedestrian Guardrails and Accidents.” Traffic Engineering and Control, September 1988, pp.450-455.– Tarko, Andrzej P., Sinha, Kumares C., Farooq, Omer. Methodology for Identifying Highway Safety Problem Areas. Transportation

Research Record 1542, TRB, National Research Council. 1196.

(2) Formation of Steering Committee and Communication

with Resident Engineers

• A project steering committee has been formed to guide the effort

• A sample of resident engineers representative of diverse VDOT districts will support:

– Identification of appropriate assessment factors/endpoints

– Refining the desired features of the developing methodology

(3) Adoption of Quantitative and Qualitative Factors/Endpoints

• Adopt models for the assessment of factors/endpoints from data and engineering judgment

• Where quantitative models are unavailable, qualitative scales will be defined, i.e., “highest” to “lowest” levels for a given attribute

• Ensure that an encompassing set of quantitative and qualitative factors/endpoints can be considered and balanced

(4) Characterization of Options

• The effort will distinguish options in two phases:

(1) Preliminary screening of candidate sites

(2) Evaluation of the smaller set of screened sites based on more detailed analysis

• The developing methodology will accommodate and distinguish different levels of the data available for assessment at the two phases

(5) Tradeoff Analysis for Guardrail Management

• Develop methodology for addressing the tradeoffs among costs, risks, and other factors/endpoints

• Develop an automated spreadsheet that facilitates the calculations and tradeoff comparison

(5) Tradeoff Analysis for Guardrail Management

• Graphical interfaces previously designed are only examples of the direction proposed in the current effort because of shortcomings in their application to guardrail management:– Inability to appreciate the merits of a large number of projects

– Complexity of interpretation and evaluation of imprecisely known quantities

– Tacit encouragement to ignore yet unquantified factors

C o n c e p t u a l P la n 1

S t a t u s Q u o

T r a v e l T i m e S a v e d( v e h i c l e h o u r s ) ( m a x = 1 2 0 0 )

C o n s t r u c t i o n C o s t S a v i n g s( m i l l i o n s o f d o l l a r s )

( m a x = 3 5 )

B r i d g e S p a n L e n g t h A v o i d e d( f e e t ) ( m a x = 2 2 0 )

F u e l S a v e d( g a l l o n s p e r d a y )

( m a x = 2 0 0 )

C r a s h e s A v o i d e d( c r a s h e s p e r y e a r ) ( m a x = 1 9 . 5 )

L a n d A r e a S a v e d( s q u a r e m i l e s ) ( m a x = 0 . 0 2 4 )

N u m b e r o f S i g n a l sA v o i d e d 1

( m a x = 8 )

E m i s s i o n s A v o i d e d( p o u n d s o f C O p e r d a y )

( m a x = 1 0 0 4 )

S t a t u s Q u o

Z e r o / O r i g i n o f a x e s

Intersection Design Evaluation

(6) Databases and Demonstrations

• Perform a case study with a sample of locations in the Richmond District

• Specify and apply databases necessary to quantify the factors/endpoints

• Interfaces of the developing software and VDOT’s electronic databases will be addressed through internet hyperlinks and automated access

• The effort will specify data requirements that are appropriate to the capabilities of the residencies

(7) Reports, Presentations, and Workshop

• Complete progress and final reports, presentations, and a training workshop; for example the Resident Engineer’s group and the District Traffic Engineer’s group

• Conform to the publication requirements of the Virginia Transportation Research Council

• Provide documentation and spreadsheets via a prototype internet web site at the University of Virginia

Expected Benefits

• Knowledge of what others have done

• Characterization of VDOT engineers’ experience with guardrail management

• Improved understanding of the balance among costs, average and catastrophic risk reduction, and other factors in the site selection and upgrading of guardrails

Expected Benefits (cont.)

• Informed, effective, and systematic allocation of limited funds for guardrails

• Databases of parameters related to guardrail performance, a basis for future research

• Education of VDOT professionals in the state of the art of cost-benefit-risk tradeoff analysis

RISK-BASED MANAGEMENT OF GUARDRAILS: SITE SELECTION AND UPGRADING

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