Critical Chain Analysis

Project Planning - Does it 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?

We pad tasks everywhere. Others in our team pad them as well. By how much? Time1t2t3t Probability of successful outcome 50%80% Individual Comfort Threshold?

We change the plan frequently. We restructure our expectations, downwards

We share resources between projects so they go back and forth, making all projects take longer! Project CProject BProject CProject B Project CProject B Project A Resource Multi-processing Duration

We take significant actions to reduce RISK ! We spend lots of money !

Typical Plan - shows resource + duration Plan 6Tech 3Engineer 5 Engineer 8Tech 5Cust Serv 3 Finish Critical Path Diagram shows normal method of planning with critical path method used. It can be seen 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 days can not be achieved. 19 days

Typical Plan - shows resource driven Plan 6Tech 3Engineer 5 Engineer 8Tech 5Cust Serv 3 Finish Critical 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 4Tech 2Engineer 3 Engineer 5Tech 3Cust Serv 2 Finish Critical 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 failure to achieve completion in 15 days is extensive. 15 days

Typical Plan - shows introduction of project buffer Plan 4Tech 2Engineer 3 Engineer 5Tech 3Cust Serv 2 Finish Critical 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 schedule and 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 4Tech 2Engineer 3 Engineer 5Tech 3Cust Serv 2 Finish Critical 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 float nearer the end. It is short and reasonably immune from disruptions. Project Buffer Package Buffer 15 days + buffer

Critical Chain - Strengths/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