What is an Activity-on-Node (AON) network diagram, and why is it preferred for critical path analysis?

What is an Activity-on-Node (AON) network diagram, and why is it preferred for critical path analysis?

• A. In AON diagrams, edges represent dependencies and nodes are activities; it is preferred because it simplifies calculating early/late dates.
• B. In AON diagrams, nodes represent activities and edges show dependencies; it is preferred for easier calculation of early/late dates and the critical path.
• C. In AON diagrams, nodes represent milestones and edges show costs.
• D. In AON diagrams, activities are represented by edges and the nodes are events.

Answer: (B)

In an Activity-on-Node diagram, each node represents an activity and the arrows between nodes express the dependencies. This setup makes timing calculations straightforward: you perform a forward pass to compute earliest start and finish times by adding each node’s duration and taking the maximum of predecessors’ finish times for the start of each activity. Then you do a backward pass from the end to determine latest start and finish times by subtracting durations, which shows how much you can delay each activity without delaying the project. The critical path is the path through the network with zero total float, meaning those activities cannot slip without extending the project duration. This node-centered representation keeps the sequencing and timing logic clear, which is why it’s preferred for critical path analysis. The other descriptions mix up whether activities are on nodes or on edges, or confuse nodes with milestones, which is why they don’t fit the standard AON approach.

In an Activity-on-Node diagram, each node represents an activity and the arrows between nodes express the dependencies. This setup makes timing calculations straightforward: you perform a forward pass to compute earliest start and finish times by adding each node’s duration and taking the maximum of predecessors’ finish times for the start of each activity. Then you do a backward pass from the end to determine latest start and finish times by subtracting durations, which shows how much you can delay each activity without delaying the project. The critical path is the path through the network with zero total float, meaning those activities cannot slip without extending the project duration. This node-centered representation keeps the sequencing and timing logic clear, which is why it’s preferred for critical path analysis. The other descriptions mix up whether activities are on nodes or on edges, or confuse nodes with milestones, which is why they don’t fit the standard AON approach.