Activity Network Diagram

An Activity Network Diagram is a diagram of project activities that shows the sequential relationships of activities using arrows and nodes. An activity network diagram is a tool that is used extensively in project management and is necessary for the identification of a project’s critical path.

Example: Suppose the team is assigned a task to improve the process of preparing Rajma for the evening meal. The team lists the major steps involved – everything from the boiling the Rajma to final preparation.

1.   Boil Rajma for 30 mins

2.   Cut Onion, green chili, tomato and Garlic

3.   Prepare a paste by frying Onion, Green chili, tomato and Garlic together

4.   Add Paste in the boiled Rajma along with salt and other spices

5.   Cook Rajma for further 10 mins

In the above activity network diagram, the boxes represent the 5 major steps involved in preparing Rajma. Arrows that connect the nodes shows the process flow.

Some of the process steps are in series like 4 and 5 and some of them are in parallel like 1 and (2,3).

Please note step 4 cannot start till the time step 1, 2 and 3 are finished, likewise step 3 can’t happen till step 2 is finished

Critical path: It is the maximum expected time for the entire end to process. Team must be careful of the fact that step 1 and (2, 3) are in parallel and they must see which one is talking more time. Step 2 and 3 combined are taking less time than step 1 so in the critical path step 1, step 4 and step 5 are included.

Critical path =

Total Expected maximum time is 45 + 5 + 10 = 60 mins

Hence critical path time is 60 mins