Critical Path Activity

A Critical Path Activity is any activity on the critical path in a project schedule. These activities directly impact the project’s finish date because they have zero float (slack)—meaning any delay will extend the overall project duration.

Key Aspects of a Critical Path Activity

• Essential for Project Completion – Delays in these activities push back the entire project.
• Has Zero Float – No flexibility in scheduling.
• Forms the Longest Path in the Project – Determines the shortest possible project duration.
• Requires Close Monitoring – Must be tracked to prevent project overruns.

Example: Identifying Critical Path Activities

Activity	Duration (Days)	Predecessor	On Critical Path?
A	3	Start	✅ Yes
B	5	A	✅ Yes
C	2	A	❌ No
D	4	B	✅ Yes
E	6	C	❌ No
F	3	D, E	✅ Yes
G (End)	2	F	✅ Yes

• Critical Path: A → B → D → F → G (Total Duration: 17 days)
• Critical Path Activities: A, B, D, F, G

Mermaid Diagram: Critical Path Activities

graph LR;
    Start["Project Start"] --> A["Task A (3d)"]
    A --> B["Task B (5d)"]
    A --> C["Task C (2d)"]
    B --> D["Task D (4d)"]
    C --> E["Task E (6d)"]
    D --> F["Task F (3d)"]
    E --> F
    F --> G["Task G (2d)"]
    G --> End["Project Completion"]
    class A,B,D,F,G critical;

Why Critical Path Activities Matter

• Directly Impact the Project Deadline – Any delay in these tasks extends project completion.
• Require Priority Monitoring – High-risk tasks needing focused tracking.
• Help in Resource Allocation – Ensures critical tasks get necessary resources.
• Enable Proactive Risk Management – Identifies potential bottlenecks early.

See also: Critical Path, Critical Path Method (CPM), Schedule Network Diagram, Total Float.