Plan a project with dependencies: a practical guide to the critical path
Most project plans fail on dates, not on tasks. A date typed by hand is wrong the moment something before it slips. The fix is to stop typing dates and describe the work instead: how long each task takes, and what it waits for. The planner then calculates every date.
The four ingredients
- Tasks and durations. Count working days, not calendar days.
- Dependencies. Which task has to wait for which.
- A working calendar. Weekends, holidays and half days.
- People. Who does what, and how much of their time it takes.
The four kinds of link
- Finish to start (FS): B starts when A finishes. The most common.
- Start to start (SS): B starts when A starts. For work that can run side by side.
- Finish to finish (FF): B cannot finish before A finishes.
- Start to finish (SF): B cannot finish before A starts. Rare.
Add a delay or an overlap when needed, for example "starts 2 days after".
A small example
Task A takes 3 days. Task B takes 2 days and waits for A. Starting on a Monday, A runs Monday to Wednesday and B runs Thursday to Friday. Lengthen A to 5 days and A now ends on Friday, so B moves to the following Monday and Tuesday. You changed one number; the plan fixed the rest, weekend included.
The critical path
The critical path is the longest chain of dependent tasks: it decides the end date. A delay on any task of that chain delays the whole project. The other tasks have float: they can slip by a few days without moving the end date. Knowing which is which tells you where to spend your attention.
Measure against a baseline
Once the plan is agreed, save a baseline, a copy of the agreed dates and costs. Later you can see which tasks are late and how far the cost has drifted. Earned value adds one more view: it compares the work planned with the work actually done.
Try it
WyzePlan does the date arithmetic for you: enter durations and links, and it shows the Gantt chart, the critical path, the float of every task, the workload per person and the cost. For a lighter, card-based view of the same work, WyzeTasks gives you kanban boards.
