Evacuation Strategies

Strategy	How it works	Suits
Simultaneous	Everyone evacuates on the alarm	Most single and low-rise buildings, industrial sites
Phased	The affected floor and the one above evacuate first, then others in sequence	Tall buildings where simultaneous movement would overwhelm stairs
Progressive horizontal	Occupants move to an adjoining fire compartment on the same level	Hospitals and care settings where full evacuation is impracticable
Defend in place	Occupants stay put unless directly affected, relying on compartmentation	Certain residential buildings with robust compartmentation

The strategy must be stated in the fire risk assessment, reflected in the alarm system design, and known by everyone. It also depends on the construction being in the condition assumed — defend in place depends entirely on compartmentation that has not been breached.

How people actually behave

• People do not move immediately. They seek confirmation, finish tasks, gather belongings and look for colleagues. This pre-movement delay is often longer than the travel time itself.
• People use the route they came in by, not the nearest exit, unless directed.
• People follow others. One person moving decisively starts everyone else.
• People underestimate the danger, particularly when alarms have previously been false.

These behaviours are why marshals, clear voice messaging and a credible alarm history matter more than route capacity in most buildings.