sra training presentation
TRANSCRIPT
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