Critical Chain AnalysisCritical Chain Analysis

Project Planning - Does it Project Planning - Does it work?work?

Generally Yes, but things don’t generally go as we planned, unexpected things happen: What is needed keeps changing (goalposts

move) Our resources are stolen (operations or other

projects become higher priority) Risks happen Deliverables slip Costs escalate Benefits disappear

So what do we do?So what do we do?

We pad tasks everywhere. Others We pad tasks everywhere. Others in our team pad them as well. By in our team pad them as well. By how much?how much?

Time 1t 2t 3t

Probability ofsuccessful outcome 50% 80%

Individual Comfort Threshold?

We change the plan frequently. We change the plan frequently.

We restructure our expectations, We restructure our expectations,

downwardsdownwards

We share resources between We share resources between projects so they go back and forth, projects so they go back and forth, making all projects take longer!making all projects take longer!

Project CProject BProject CProject B

Project CProject B

Project AProject A

Project A

Resource Multi-processing

Duration 5 10 15 20 25 30

We take significant actions to We take significant actions to reduce RISK !reduce RISK !

We spend lots of money !We spend lots of money !

Typical Plan Typical Plan - shows resource + duration- shows resource + duration

Plan 6 Tech 3 Engineer 5

Engineer 8Tech 5Cust Serv 3 Cust Serv 3Finish

Critical Path

Diagram shows normal method of planning with critical path method used. It can beseen that the resource conflict for the Engineer and the Technician will introduce significant problems and if no other duplicate resource is available the duration of 19 dayscan not be achieved.

19 days

Typical Plan - shows resource driven

Plan 6 Tech 3 Engineer 5

Engineer 8Tech 5Cust Serv 3 Cust Serv 3

FinishCritical Chain

Diagram shows the critical chain through the project to resolve resource conflict.The project is now very sensitive to resources being available exactly when needed but it can be achieved within the 24 days predicted with the limited resources.

24 days

Typical Plan - safety removed

Plan 4 Tech 2 Engineer 3

Engineer 5Tech 3Cust Serv 2 Cust Serv 2

FinishCritical Chain

The padding has now been removed from the schedule so the safety has been removed.The project is now very sensitive to variation in task completion and the risk of failureto achieve completion in 15 days is extensive.

15 days

Typical Plan - shows introduction of project buffer

Plan 4 Tech 2 Engineer 3

Engineer 5Tech 3Cust Serv 2 Cust Serv 2

FinishCritical Chain

Diagram shows the introduction of a project buffer which protects the project against statistical fluctuations. This buffer has protected the RFS but tension still exists in the scheduleand the Critical Chain is too dependant on non-critical activities. Package buffers are put into the planning where non-critical tasks meet the Critical Chain activities.

Project Buffer

15 days + buffer?

Typical Plan - shows introduction of package buffer

Plan 4 Tech 2 Engineer 3

Engineer 5Tech 3Cust Serv 2 Cust Serv 2

FinishCritical Chain

Diagram shows the introduction of a package buffer which protects the Critical Chain.This is now becoming a realistic schedule which has moved risk nearer the start and floatnearer the end. It is short and reasonably immune from disruptions.

Project Buffer

Package Buffer

15 days + buffer

Critical Chain - Critical Chain - Strengths/WeaknessesStrengths/Weaknesses

Reduces overall project durations

Better manages the scarce resource pools

Reduces project schedule risk Increases Project Manager

control of schedule using buffer management techniques

Individuals unwilling to change what they have always done

Senior managers and sponsors “steal” the buffer making the method unworkable

Measurements of progress needs to be taken and reported

Strength Weakness