Project time–cost trade-off terminology What is the essential condition for “decompression” of an activity (i.e., relaxing a previously crashed activity) in time–cost analysis?

Introduction / Context:
Time–cost trade-off (crashing) shortens project duration by increasing activity direct costs. When schedule pressure eases, managers may “decompress” activities—reversing some crashing to reduce costs. Understanding the boundary conditions prevents invalid changes to baseline logic and durations.

Given Data / Assumptions:

• Each activity has a normal time and a crash time with corresponding costs.
• Crashing reduces duration toward crash time at higher cost; decompression is the reverse movement toward normal time.
• Network logic and precedence are unchanged.

Concept / Approach:
Normal time is the standard (uncrashed) duration. Decompression can only restore duration back toward this normal point; it cannot increase duration beyond normal without redefining scope or logic. Thus, the essential condition is that decompression is bounded by the normal time of the activity. Project duration may or may not change depending on whether the decompressed activity lies on the current critical path.

Step-by-Step Solution:
Identify crashed activities and their current durations.Move duration back toward normal to reduce direct cost.Ensure duration after decompression ≤ normal time limit (i.e., not exceeding normal time).Recalculate floats and critical path to see if project duration changes.

Verification / Alternative check:
Cost–slope tables show valid duration range: crash time ≤ allowed ≤ normal time. Any value beyond normal time is outside the defined envelope.

Why Other Options Are Wrong:
Project duration need not change (option a). Exceeding normal time (option b) contradicts the defined range. Option e suggests going below crash time, which is not allowed.

Common Pitfalls:
Forgetting that decompression on a noncritical activity will not affect project duration, but may improve resource leveling and reduce direct costs.

Final Answer:
An activity can be decompressed only up to its normal (unchanged) time, not beyond