Project Schedule Network Diagram
Visualise project activities, sequence logic, and the critical path using deliverable swim-lanes to ensure accurate schedule development.
In this resource
§1 Purpose of the Network Diagram
The Schedule Network Diagram translates raw activity dependencies into a visual flow, proving that the project's logic is mathematically sound before a Gantt chart is generated.
While the Activity List defines the tasks and Activity Attributes define the dependencies (e.g., Task B cannot start until Task A finishes), it is nearly impossible for a human to verify the logic of a 40-step project by reading a table. The Network Diagram visualises these connections. By grouping activities into horizontal "swim-lanes" based on the Work Breakdown Structure (WBS), the Project Manager can instantly spot missing dependencies, dangling activities, and the all-important Critical Path.
§2 Blank Template Structure
A structural representation of how to layout a network diagram using WBS-aligned swim-lanes.
Note: In actual practice, project managers generate the interconnecting arrows dynamically using scheduling software (like MS Project) or diagramming tools (like Visio). The template below demonstrates the structural grouping required before drawing those lines.
PROJECT SCHEDULE NETWORK DIAGRAM
Activities are arranged sequentially in swim-lanes corresponding to their Major Deliverable category. Critical path activities are outlined prominently.
§3 Worked Example: Mary's Consulting
A completed structural mapping of a 40-activity digital implementation project, highlighting the critical sequence through the design, build, and test phases.
This layout groups the tasks generated in the Activity List into their respective phases. The items with bold plum borders (■) form the unbreakable chain of dependencies known as the Critical Path. A delay in any of these specific nodes will delay the final project delivery.
PROJECT SCHEDULE NETWORK DIAGRAM
The Power of Swim-lanes
By sorting activities horizontally into their WBS categories, the PM can clearly see hand-offs between functional groups. For example, Lane 1.2 (Design) must fully complete before Lane 1.4 (Build) can hit its critical stride.
Spotting Concurrency
Notice how Lane 1.3 (Content) has no critical path activities outlined. This entire lane runs concurrently with the design and build phases, utilizing its schedule float without delaying the project.
Validating Logic
If an activity box in this diagram has no arrows pointing to it (no predecessor) or no arrows pointing away from it (no successor, except the final closeout), the schedule logic is flawed and must be fixed.