Plan an evacuation as three legs: out of the building, along a route that stays clear of the fire, and to an assembly point where everyone is counted. In the best case two outward-opening 1.2 m doors empty a hall of 150 people in about 48 seconds, a single door takes about 96 seconds when the other is blocked by fire, and a 100 m walk to the assembly point adds 100 to 143 seconds at the speed of a mixed group.
Part of Fire Prevention in Settlements
Evacuation routes and assembly are the exits, paths and gathering places that let everyone leave a burning building or area quickly and be accounted for.
Every Building Needs Two Ways Out, And Every Way Out Needs Somewhere To Go
An evacuation has three legs: out of the building, along the route, and into the count at the assembly point.
The fire guide’s response ends at an assembly point with a head count, and the assembly-area guide sizes that point (75-105 m² for 150 standing people) and asks for a second point on the other side of the settlement (Emergency Assembly Areas). The workshop guide and the gathering-hall guide both ask for at least two exits, the hall’s with a clear opening of at least 120 cm (Community Gathering Hall). The part left open is the route in between: how fast the doors empty a room, and whether the path from the door to the point is passable when the fire is where fires are.
Worked Example: Doors And Walking
Inputs: 150 people; two doors 1.2 m clear width; a specific flow of 1.3 persons per second per metre of door width (a figure recalled from fire-engineering references for free-flowing crowds, not read from this corpus; check it); walking speed 1.0 m/s for a mixed group in the dark, and 0.7 m/s for slow members (both assumed); assembly point 100 m away.
- Two doors: width 2 × 1.2 = 2.4 m; flow 2.4 × 1.3 = 3.1 persons/s; time 150 ÷ 3.1 = 48 s.
- One door only (the other blocked): 1.2 × 1.3 = 1.56 persons/s; time 150 ÷ 1.56 = 96 s.
- Walk to the assembly point at 1.0 m/s: 100 ÷ 1.0 = 100 s; at 0.7 m/s: 100 ÷ 0.7 = 143 s.
- Best-case total with two doors and the fast walk: 48 + 100 = 148 s; worst of these cases, one door and the slow walk: 96 + 143 = 239 s.
These are times after people are moving. The flow figure is for an orderly crowd; a crowd pressing a door that opens inward, or a door held shut by a bar, moves far slower and can crush people. That is why the defensive-architecture guide requires that any room holding more than a handful of people exits outward by pushing, with nothing to work first (Defensive Architecture).
What You Need
- Two exits from every building, on different walls, opening outward, with nothing to lift or unlock
- Two routes from each cluster to two assembly points, diverging
- Clear, firm paths at least wide enough for two people side by side
- Marks you can find in smoke and dark: a rope handrail, a painted post, a change of texture underfoot
- An emergency opening in every hedge, fence or ditch line on the route
Method: Lay Out And Test The Routes
Step 1: Draw each building’s two doors and the path from each to the nearest assembly point.
Step 2: Check that no route runs along the wall of a building that could burn. The spacing article gives about 23 kW/m² at 5 m from a burning wall 5 m long and 3 m high, and 12.5 kW/m² at about 7 m (Fire Breaks & Building Spacing); keep routes beyond that distance.
Step 3: Put the assembly points upwind of the likely fires where possible, and not on dry grass.
Step 4: Build in the openings. A thorn hedge or a ditch on the route needs a gap that opens in one movement, since a living hedge cannot be cut quickly in a fire (Controlled Access Points).
Step 5: Walk the routes in the dark with the slowest members and time them.
Step 6: Keep the routes clear: no carts, woodpiles or tools left on them.
Common Mistakes
- Doors that open inward. A crowd cannot pull them against its own weight.
- A route that passes the workshop. The forge is the likeliest fire.
- A single assembly point beside the hall. A hall fire exposes it.
- Routes blocked by stored goods. The commonest blocked exit is the one used as a store.
Safety
The exit must open by pushing
In a fire a crowd presses toward the door. An exit with a bar, hook, latch or key to work first fails at exactly that moment, which is the case the defensive-architecture guide warns about. Secure a building from outside when it is empty, never from inside when it is full, and rehearse the exit in the dark with the real doors.
What’s Next
- Learn next: Response Protocols & Training — drilling the legs
- Combine with: Detection & Response — what starts the evacuation