Schedule Analysis Metrics: Crash Cost Per Unit Time

In recent posts, we discussed how scheduling analysis should not be limited by time optimisation and should also include cost and benefits optimisation.

For that, we can go back in history and uncover one well-forgotten metric that remains relevant today: Crash Cost Per Unit Time. This metric originates from the original Critical Path Method (1957), which focuses on balancing project time and cost.

💡 Crash Cost per Unit Time (CCpUT) is a project management metric used in schedule compression (specifically in the crashing technique) to evaluate the cost efficiency of accelerating a project activity.

💡 Crash Cost Per Unit Time = (Crash Cost – Normal Cost) / (Normal Time – Crash Time)

where,
🔹 Crash Cost: The total cost to complete an activity in its shortest possible time
🔹Normal Cost: The total cost to complete an activity in its normal, less expedited time
🔹Normal Time: The time it takes to complete the activity under normal conditions
🔹 Crash Time: The shortest possible time to complete the activity

The metric helps project managers:
📌 Determine which activities are most cost-effective to crash.
📌 Prioritise crashing activities on the critical path.
📌 Optimise project duration vs. cost trade-offs.
📌 Reduce project duration with minimum extra cost.

Combining CCpUT with ‘Activity Drag’ and ‘Activity Spread’ metrics gives an opportunity to understand where crashing or anti-crashing will have the maximum effect on project benefits.