Theory 09/Fire Safety Engineering
Evacuation Is a Width Ratio
The claim
Evacuation time is set by the ratio of occupant load to exit width rather than by travel distance, so a compact building with narrow exits can be slower to clear than an extended one with wide exits.
01Mechanism
Flow through an exit is bounded by width; queues form when arrival rate exceeds discharge, and the queue, not the walk, sets the clearance time.
02Predictions
- P1Clearance time should track the load-to-width ratio.
- P2Distance alone should mispredict.
03Refutation
Clearance tracking distance would remove the flow limit.