CONSTRUCTION MANAGER: Critical Path Calculation

How to determine “Critical Path” in a project ?
To determine “critical Path” in a project required:-

Knowledge in the sequence of every task until completion of the project.
“Start” and “ Finish” date need to be pre-determine base on current available resources or planned resources for the project.
Calculation on the Numbers of float days for individual task and also Numbers of Total float days for each of single path or series of task which formed a path.

Calculation on Individual Float and Total float need us to do the following steps :-

Forward Pass Method ( Begin from the Start date to completion date of a project ).
Backward Pass Method ( Begin with the completion date to Start date).
Individual Float Calculation required the Information on the Early finish date and Late finish date Which can be obtain from the step 1 and Step 2.
Total float required us to add all of the individual float that resemble series of task to form a Path.

Individual Float calculation for a Task.

Formula : Individual Float = Late finish date – Early finish date

Example 1.

Individual Float = 28.04.2014 – 28.03.2014

= 30 days

Example 2.

Individual Float = 28.03.2014 – 28.03.2014

= 0 days

Total Float calculation for a Path.

Formula : Total Float = Activity 1+Activity2+Activity3+Activity4

Path1 Total Float = Individual Activity 1 + Individual Activity 2 + Individual Activity 3 + Individual Activity 5

= 0 + 0 + 0 + 0 = 0 days

Path 2 Total Float = Individual Activity 1 + Individual Activity 4 + Individual Activity 5

= 0 + (27.04.2014 – 18.04.2014) + 0

= 0 + 9 days + 0 days = 9 days float

Critical path is the path that consist of activities with “0 days” of float.

Normally critical path when show in a chart or work program it is colored in “RED”

Further reading reference:

CONSTRUCTION MANAGER