Crashing
"Crashing" is a schedule-compression technique — a fancy way of saying "a method to finish the project faster." You crash a schedule by adding more resources (usually people, equipment, or overtime) to the tasks on the critical path, which is the chain of tasks that controls your finish date.
The logic is that more hands on a task can get it done sooner. But there's a catch you must always remember: crashing shortens time while it increases cost. Doubling the workers rarely halves the cost — you often pay overtime rates, extra coordination effort, and diminishing returns, so you spend more money to buy back time.
A project manager reads this as a trade-off decision. When you're behind schedule or facing a hard deadline, you look for the critical-path tasks where adding resources buys the most days for the least extra cost, and you crash those first. You only crash tasks on the critical path, because adding resources to tasks with float wouldn't move your finish date at all.
Think of it like hiring extra movers to empty a house before the truck leaves. Twice the movers can finish sooner, but you pay every one of them — so you get out faster, and your wallet feels it.
Suppose a "Testing" task on the critical path normally takes 10 days with 2 testers, costing $10,000. You need to finish sooner, so you add 2 more testers. With 4 testers the task now takes 6 days, but the cost rises to $16,000 because of the extra people and some overtime. You have crashed the task: you gained 4 days off the project's finish date, and it cost you an additional $6,000. You'd then compare that — $6,000 for 4 days, or $1,500 per day saved — against other tasks you could crash, and choose the cheapest way to buy the days you need.
Every PMP formula explained free — plus worked examples and practice in PMP Math, and full timed mocks in the simulator.