Schedule Risk Analysis

Presenter: Adrian Claridge

Lunch & Learn with LogiKal

Introduction

“They all finish on time & under budget”

• Air Warfare Destroyer Project – up to 3 years late

• Gorgon – potentially 1+ year late

• Perth Arena – more than 3 years

• NASA Orion EFT-1

• The list goes on ……..

Introduction

So the inaccuracies are either

1. In the project Schedule

Or

2. In the execution of the works

What is SRA ?

• When we estimate task durations there is inevitably some uncertainty about

whether the task will finish early, on time or late.

• When this is multiplied hundreds (or thousands) of times in a CPM network the

project finish is likely to be within a range of dates – not one specific finish

date.

• Schedule Risk Analysis is a technique which recognizes the uncertainty for task

durations by using a distribution representing the range of likely durations.

• Additionally discrete time risks (or opportunities) can be added into the model

to give a complete picture of likely project outcomes.

• SRA results are shown as a histogram and S-curve of all the potential project

finish dates, so an informed assessment of the schedule completion date can

be made

SRA Process

• SRA is a 4 step process1. Schedule Health Check (no open ends, minimise constraints etc.)

2. Define Inputs

1. Export base file from P6 (or MS Project)

2. Add Duration ranging (uncertainty) on activities (3 point - Min, ML, Max)

3. Add Discrete time risks from register & allocate to schedule activities

3. Run SRA model

4. Review Outputs

1. Management team select confidence level appropriate for project

2. Activities driving the schedule (most impact) can be reviewed/adjusted

Step 1 - Schedule Health Check

1. Project Calendars preferred to be ALL on same numbers of Hours per Day

2. Minimise Constraints

• Having dates ‘fixed’ in a schedule will not allow them to move

• This defeats the object of running an SRA and gives false results

• Some Start constraints are still OK – e.g. Client deliveries, Access Dates

3. Close open ends

• If activities have no successors they don’t affect project completion

4. Reduce Long Relationship Lags

• In OPRA we only look at duration uncertainty on activity durations

• If the LAG durations are overly long they may have a disproportionate

impact on the overall project duration

• OPRA does have the capability of converting the Lags to activities which

you then can add uncertainty to – time consuming & messy

Step 1 - Schedule Health Check

• Tools for Checking Schedule Integrity

1. Primavera

• Can generate text Log file when re-scheduling project. Basic

2. OPRA

• Generates same info as P6 – better format + interactive.

• Restricted to OPRA users

3. Acumen Fuse

• Commercial software. $$$$$. Not used in JH

4. XER Toolkit

• Free software used in JH – available from Internet

• Graphic Output – dashboards etc

Step 1 - Schedule Health Check

Step 2 – Define Inputs

• Inputs to OPRA1. Export base file (xer) from P6 – import into OPRA

2. Add Duration ranging (uncertainty) on activities (3 point - Min, ML, Max)

Note : Now recommend using codes in P6 before import – see below

3. Add Discrete time risks from register & allocate to schedule activities

4. Build the Risk model

Step 2 – Define Inputs

• Duration Ranging / Uncertainty – 3 options1. Consider each task individually – often impractical with large schedules

and tight timeframes

2. In OPRA use Duration Quick Risk (+/- nominated percentages) – for quick

exercise only

3. In OPRA use Templated Quick Risk

• Planners can nominate confidence level in P6

• Percentage ranges can be agreed with bid/project team

• Individual activities can still be adjusted as required

Step 2 – Define Inputs

• Appropriate percentages can be agreed with bid team

Step 2 – Define Inputs

Rating Guidance MinMost Likely Max

Vconservative Always finishes early 70% 100% 100%

Conservative Sometimes finishes early 80% 100% 105%

Realistic Realistic 90% 100% 115%

Aggressive Often delays 95% 100% 125%

SuperAggressive Historical poor performance 100% 100% 150%

• Note : 5 categories is not mandatory – more or less is OK, and each activity

can still be adjusted manually in OPRA

Step 2 – Define Inputs

• Discrete Risks1. Potential Risks / Opportunities collected at R&O Workshop

• Helpful if probability and impacts can also be captured at same time

2. Input Risks & Opportunities to OPRA

• Add probabilities and impacts

• Assign to relevant schedule activities

3. OPRA has

• Qualitative and Quantitative input fields – we use Quantitative

• Pre-mitigated and Post-mitigated scenarios

Step 2 – Define Inputs

• OPRA Risk Register - Quantitative

Step 2 – Define Inputs

PActivities fromP6 Schedule

Discrete Risks fromrisk register (in red)

Uncertainty in activity duration modeled as min : most likely : max

Uncertainty in the schedule duration (days) of each P6 activity

Probability of the discrete risk occurring

Step 3 – Run SRA Model

• Run the Model1. OPRA adds discrete risks into the schedule as additional activities with

%age probability

2. Model can be run with

• Duration Uncertainty Only

• Discrete Risks Only (set all uncertainty to zero)

• Combination of both – most realistic

3. Various options

• 1000 iterations generally adopted in JH.

• Step through etc.

Step 3 – Run SRA Model

• Cut to OPRA ……..

Step 4 – Review Outputs

• OPRA Outputs1. Distribution Graphs (histogram & cumulative S-curve)

2. Tornado Charts (Various)

3. Distribution Analyser (for comparing different scenarios)

4. Scatter Plots (if time and costs are considered – possible future use)

5. Risk Percentiles

6. Various Reports

Distribution Graphs

• Output available for all Schedule Activities

• Shows as standard• Deterministic Date

• P50 and P80 dates

• Other dates (as selected or set up in preferences)

• Graphs available for• Start Dates, Finish Dates,

• Duration, Float

• Cost, NPV

• Highlighters can be added to show overrun

Distribution GraphsSRA OutputCumulative distribution (S curve)

Planned completion date (Deterministic) has 86% Probability of being achieved

Probability distribution (Bell curve) – the gap represents no completion dates over Christmas

Mean completion date (P50) has a 50% chance of being achieved – in this example 20Nov2014

Distribution Analyser

• Used to show different scenarios• Pre-mitigated

• Post-mitigated

Tornado Charts

• Five Charts available

• These charts can be used to review & potentially de-risk activities which are driving the

schedule

1) CI CRITICALITY INDEX

Measures the probability that an activity is on the critical path.

Number of times activity is on the Project Critical Path

2) SI DURATION SENSITIVITY

Correlation between ACTIVITY and key task or summary duration. CAUTION CAN BE -ve

The duration sensitivity will show the correlation between two activity durations to determine if one is driving the other. This is often the best metric for isolating a specific milestone or activity and seeing what is driving its completion date. Equivalent of Significance Index.Can be used to look at individual activity drivers.

3) SSI SCHEDULE SENSITIVITY INDEX

Correlation between ACTIVITY and OVERALL PROJECT duration.

PMBOK: Schedule Sensitivity Index = SSI = (StDevActivityDuration * CI) / StDevProjectDuration. Top activities whose variation correlates with overall project duration (i.e., when these activities are extended, the project is also extended)

4) CRI DURATION CRUCIALITY

= 1) x 2) CAUTION CAN BE -ve PMBOK : Cruciality Index = CRI = |correlation(ActivityDuration, ProjectDuration)|

5) COST SENSITIVITY

Correlation between ACTIVITY and PROJECT cost.

Can be used to look at individual activity drivers.

Tornado Charts

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22%C-M-1010 - CV001 Module 64-72 Earthworks & Piling

C-M-1430 - Assemble, commission & launch Jetty Traveller 2 at Modules 73-76

PA-1050 - Screening Plant - Precommissioning/Punchlisting

C-M-1470 - CV001 Module 100-110 Piling, Headstocks & installation of roadway modules

C-M-1620 - Wharf Completion Works Module 41-20

C-M-1460 - CV001 Module 90-100 Piling, Headstocks & installation of roadway modules

C-3960 - CVR002 - Install Suspended Modules / Galleries

C-M-1450 - CV001 Module 80-90 Piling, Headstocks & installation of roadway modules

C-M-1560 - CV002 Module 20-30 Piling, Headstocks & installation of roadway modules

C-M-1500 - CV001 Module 73-76 Piling, headstocks & installation of roadway modules by cranes

C-M-1230 - Dolphin BD8 Piling, pile caps, steelwork framing, access walkways & braces

C-3370 - Screening Plant - Electrical & Instrumentation

COM-2 - Commissioning Train Unloading Station to Stockyard

C-M-1530 - Relocate commission & launch Jetty Traveller 2 on module 1-4

ED-1010 - PS - ECI Phase

C-M-1190 - Dolphin BD12 Piling, pile caps, steelwork framing, access walkways & braces

C-M-1050 - Wharf Bents W37-W34 Piling, pile caps, steelwork framing & braces

COM-1 - Commissioning Train Unloading Station

PA-1010 - Screening Plant - Pre-assembly Lump Bins Lower Hooper Section x3 (Modules 4,5,6)

C-4310 - CVR002 - Electrical & Instrumentation

F-1070 - Package 3 - Structural & Mechanical Steelwork

PA-1320 - CVR105 - Pre-assembly Suspended Modules / Galleries

C-1970 - TFS103A - Install Transfer Station Complete Structure

PA-1350 - CVR104 - Pre-assembly Pulleys Frame

PA-1490 - CVR105 - Pre-assembly Take-up Trolley Frame & Trolley

PA-1000 - Screening Plant - Pre-assembly Steel structure (Grids C - M) x3 (Modules 1,2,3)

PA-1220 - CVR104 - Pre-assembly Suspended Modules / Galleries

F-1230 - Package 4 - Conveyor Steelwork (LLM,Trusses)

C-3200 - Package 3 - Port Landside - Security

C-4630 - Screening Plant - Workshop Overhead Crane

RHIO - Package 3 and 4 SMP EI WorksDuration Sensitivity: "MS-1130 - PS- Practical Completion" - Logical predecessors

Criticality Index

584

Level Range Count Pct of Network

Very High 81% - 100% 67 11.5%

High 61% - 80% 8 1.4%

Medium 41% - 60% 29 5.0%

Low 11% - 40% 64 11.0%

Very Low 0% - 10% 80 13.7%

None 336 57.5%248 42.5%

Total Number of Activities in Network

Criticality Profile

Activities with Criticality0 100 200 300 400

Final Thoughts

Final Thoughts• NASA Orion EFT-1 – Launched 5th December 2014

1st March 2013

Final Thoughts• NASA Orion EFT-1 – Revised Schedule 2012

18 Sept 2104

Final Thoughts

Questions