How to use it
- 1. Edit durationsUse the +/− steppers in the table; every earliest/latest time recalculates instantly.
- 2. Read the networkThe thick red route is critical - zero slack, so any delay there delays the whole project.
- 3. Watch it switchChange a duration enough and a banner announces the critical path has moved to a new route.
- 4. Crash itBuy weeks off critical activities and trace project duration against total crash cost.
Project network
Each node shows ES | EF on top and LS | LF below, with slack at the corner. Red nodes and arrows are on the critical path. Swipe the diagram sideways to see all of it.
Gantt & activity table
Solid bars run from ES to EF; hollow extensions show how far an activity could slip (its free/total slack) before the project is hit.
| Act | Pred | Dur | ES | EF | LS | LF | Slack |
|---|
Crash the project
| Act | Normal | Min | $/wk | Weeks cut |
|---|
Each point is a project state as you crash: cutting a week off a critical activity shortens the project; crashing a non-critical one just burns money.
Try these experiments
- Find the cheapest way to cut 3 weeks - only crashing critical activities helps, and the cheapest critical one first.
- Crash the critical path until a second path also becomes critical (two red routes) - from there you must crash both at once.
- Crash a critical activity and watch a case where the project stops shortening because the critical path has switched to another route.
About this tool
The concept
The Critical Path Method finds the longest chain of dependent tasks; its length is the shortest possible project duration.
How it works
A forward pass sets earliest start/finish; a backward pass sets latest start/finish. Slack = latest − earliest; zero-slack tasks are critical.
Crashing
Shortening a task costs money. Spend only on critical tasks, cheapest first, until another path becomes critical - then crash in parallel.