The Critical Path Analysis determines which activities are critical and which activities can be delayed without making the project longer. The Critical Path is sequence of project activities which add up to the longest overall project duration.


Critical Path Analysis (or time analysis) uses data on a Gantt chart to monitor progress and ensure that tasks are started and finished on time. The key features are presented in theirmost basic form below:

  1. Early dates – the earliest date a task can start or finish whilst obeying all theconstraints of its predecessors. Found by working forwards.
  2. Late dates – the latest date a task can start/finish whilst still obeying all theconstraints of its successors.  Found by working backwards.The difference between early and late finish dates is the ‘total float’ or ‘slack’.  
  3. If the plan results in negative float then the project cannot be completed on time.  If float is zero or negative for an activity or task it is said to be ‘critical’. Delaying thestart will delay the whole project. Those with positive float can be delayed.