BCGBC4007A Plan building or construction work

Develop, track and revise project timeframes

Network systems or PERT charts
Activity - Path times
A diagram of a PERT chart showing the task sequence for building a brick fence is described as follows:
From node 1, the first task is 'Enquiries, orders' (takes two days). Node 2 has three branches, one to 'Wait bricks' (three days) which leads to node 3, 'Load bricks' (one day) then on to node 7. Also from node 2 is 'Clear site' (one day) then node 4, 'Dig trench' (two days) then node 5. The third task from node 2 is 'Order concrete' (one day) which also joins to node 5. The next task is 'Pour footings' (one day) then 
node 6, 'Footings curing' (three days) then node 7. The final section of the chart is 'Mix mortar and lay bricks' (one day) then node 8, 'Clean up' (one day) then the final node number 9. 

Question 1
What is the total time for this process if the path through nodes 2, 3 and 7 is taken?
A.     	8 days
B.     	10 days
C.     	11 days
D.     	Other
The correct answer is A - 8 days.

Question 2
What is the total time for this process if the path through nodes 2, 4 and 5 is taken?
A.     	8 days
B.     	10 days
C.     	11 days
D.     	Other
The correct answer is C - 11 days.

Question 3
What is the total time for this process if the path through nodes 2, 5 and 6 is taken?  
A.     	8 days
B.     	9 days
C.     	11 days
D.     	Other
The correct answer is B - 9 days.
Notice that the three different paths show three different times for this section of the project. We will return to this shortly after we look at the idea of 'float' in a network.

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