PERT Chart - Activity-On-Arrow (AOA)

PERT Chart Event Network · ACTIVITY-ON-ARROW (AOA)

A project management template implementing the classic 1958 PERT Activity-on-Arrow (AOA) methodology for visualizing project schedules, dependencies, and critical paths. This template helps teams map milestone sequences, identify schedule bottlenecks, and calculate project duration and float.

What It Is

A PERT Event Network using the Activity-on-Arrow convention where numbered circles represent milestone events and arrows represent time-consuming activities between those events. The logic is dependency-based: a downstream event cannot occur until all incoming activities are complete. This reads as "event 2 cannot happen until activity A is done."

Purpose and Use Cases

This template is designed for project management teams who need to:

• Map the sequence and dependencies of project activities

• Identify the critical path (the longest chain determining overall project duration)

• Calculate float/slack on non-critical paths

• Optimize schedules by understanding which activities drive project completion

Ideal for engineering projects, construction planning, product launches, software releases, or any work requiring milestone sequencing and schedule optimization.

How It Works

The network contains eight numbered milestone event nodes (1–8):

• Node 1 (cyan): Project start event

• Nodes 2, 3, 5, 6, 7 (yellow): Critical path milestones

• Node 4 (indigo): Off-critical-path event with slack

• Node 8 (pink): Final project event

Activities are represented by eight labeled arrows (A–H), each with a name and duration placeholder:

• Yellow/thick arrows (A, B, D, F, G, H): Critical path activities forming Path 1 (1→2→3→5→6→7→8)

• Purple/thin arrows (C, E): Activities with slack forming Path 2 (1→2→4→5→6→7→8)

The two parallel paths allow concurrent work streams while maintaining dependency logic.

Key Components

Milestone Event Nodes

• Eight numbered circles color-coded by path status

• Attached white rounded-rectangle labels for custom milestone names

Activity Arrows

• Directional arrows labeled A–H

• Duration placeholders (__d) for time estimates

• Visual weight indicates criticality (thick yellow vs thin purple)

Legend

• Distinguishes critical path activities from activities with slack

Path Tally Panel

• Calculation area to sum durations along each path

• Fields for identifying critical path, total project duration, and float on shorter paths

How to Use It

1. Number milestone events in the order they can logically occur

2. Label each arrow with its activity name and estimated duration

3. Add parallel arrows wherever work can proceed simultaneously

4. Highlight the longest chain in yellow—this is your critical path

5. Complete the Path Tally section by summing durations per path

6. Calculate float by comparing path lengths

Key principle: Events carry no duration themselves—all time lives on the arrows connecting them.

Cheers!

Khawaja Rizwan