PMP lesson · Schedule · Schedule · lesson 3 of 4 · about 8 minutes
Schedule compression: crashing and fast tracking
Predictive · also used for hardware in hybrid projectsFree preview
Goal: After this lesson you can choose between crashing and fast tracking, pick the cheapest activity to crash, and recognise when compression stops working.
1The situation
“Can you finish 2 days earlier?”
The robot cell plan from the last lesson takes 12 days. Critical path: A mount base (3) → B wiring (5) → D commissioning (4). The other paths: E → D (10 days) and A → C → D (9 days).
The customer calls: “Our production start moved. We need commissioning done in 10 days, not 12.”
You have two tools: spend money to make critical work faster (crashing), or overlap work that was planned in sequence (fast tracking). Each has a price.
2Two ways to shorten a schedule
Both techniques are called schedule compression. Both work only on the critical path; shortening activities that have float does not move the end date.
Crashing
Add resources
Make critical activities shorter by adding people, overtime or money.
Price: extra cost
Fast tracking
Overlap activities
Do critical activities in parallel instead of in sequence.
Price: extra risk and rework
Exam shortcut: “no extra budget” → fast tracking.“dependencies are mandatory” or “cannot accept more risk” → crashing.
3See it in one picture
Crashing
Add resources to critical-path activities: overtime, more people, faster equipment, express delivery.
✔ Keeps the original sequence ✘ Costs money ✘ Has a limit: some work cannot go faster
Choose the activity with the lowest cost slope first.
Fast tracking
Overlap activities that were planned one after another, e.g. start wiring the cabinet before the base is fully mounted.
✔ Usually no extra cost ✘ Adds risk: rework if the earlier work changes ✘ Only possible for discretionary dependencies
Never overlap mandatory (physical or legal) dependencies.
Crashing buys time with money; fast tracking buys time with risk.
4How it looks on the exam
Exam-style question 1. A project must finish three weeks earlier to meet a revised market launch. The sponsor will not approve any additional funding. Several dependencies on the critical path are discretionary. What should the project manager do?
A. Crash the critical path using overtime
B. Fast-track the discretionary dependencies on the critical path and manage the added rework risk
C. Reduce the quality of deliverables to save time
D. Crash the non-critical activities, since they are cheaper
Show the answer and the decode
Answer: B.
In simple English
The project must be shorter, but there is no extra money.
What is the question really asking?
The right compression technique.
Key words / trigger
“will not approve any additional funding … discretionary”
PMP logic
No funding → not crashing. Discretionary dependencies → fast tracking is possible, but its risk must be managed.
Why the wrong answer looks attractive
Overtime feels like the normal way to recover time, but it costs money, which the sponsor refused.