SFPE & ISO/TR 16738 EGRESS MODEL

Building Evacuation Time Calculator

Calculate Required Safe Egress Time (RSET) based on building geometry, stairwell effective width, human pre-movement behavior, and crowd bottleneck dynamics.

Building & Safety Parameters

1 Architecture & Egress Geometry

Above ground level
Separate enclosed exits
Room door to stairwell entry

2 Human Behavior & Pre-Movement (ISO/TR 16738)

3 Evacuation Strategy

REQUIRED SAFE EGRESS TIME (RSET)

Simulation Results

Optimal
Estimated Total Time to Full Building Clearance:
--
Best-Case (fast reaction):
--
Conservative / Safety Plan:
--
Evacuation Timeline Breakdown Stage Proportions
Detection & Alarm Pre-movement Delay Corridor Walk Stair Descent Queuing Chokepoint

Phase-by-Phase Timeline Table

  • Phase 1 Detection & Alarm Trigger:
    --
  • Phase 2 Pre-Movement (Recognition + Response):
    Recognition: -- | Preparation: --
    --
  • Phase 3 Horizontal Corridor Walk:
    --
  • Phase 4 Stairway Descent (unimpeded):
    --
  • Goulot Queuing / Bottleneck Delay:
    0 s
-- Discharge Rate (p/min)
-- Total Effective Width
-- Stair Flow Index Écoulement fluide

Phased Evacuation Fast Clearance

Evacuating only the immediate danger zone (-- occupants: fire floor + 1 above + 1 below) takes:

--

Engineering Fire Safety Recommendations

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Scientific Methodology & Leading Studies

SFPE Handbook of Fire Protection Engineering (5th Edition) Nelson & Mowrer (Ch. 60 "Emergency Movement") et Pauls (1980, 1995). Modèle hydraulique d'écoulement de foule, vitesses de déplacement selon la pente des marches, et déduction de couche limite (0,15 m par côté).
ISO/TR 16738:2009 International Organization for Standardization. Évaluation technique du comportement humain et des distributions de temps de réaction lors d'évacuations de bâtiments.
British Standard PD 7974-6:2019 Human factors: Life safety strategies. Temps de pré-mouvement empiriques catégorisés selon le type d'alarme (W1 vocal, W2 sonnerie, W3 local) et l'éveil (M1 jour, M2 nuit).
NFPA 101: Life Safety Code & Fruin (1971) Facteurs de capacité d'évacuation (0,3 po/personne pour escaliers, 0,2 po/personne pour paliers) et niveaux de service piétons (LOS).

Frequently Asked Questions

Required Safe Egress Time (RSET) combines four successive phases: fire detection time, alarm notification delay, pre-movement time (occupant recognition and response behaviors per ISO/TR 16738 / PD 7974-6), and physical travel time (corridor walk and stairway descent governed by SFPE hydraulic crowd flow and Pauls effective width model).

Fire safety human behavior research (Purser, Gwynne, ISO/TR 16738) reveals occupants do not immediately flee when an alarm sounds. They investigate cues, seek family members or pets, gather valuables, and dress (especially at night). In residential buildings with standard alarm bells, nighttime pre-movement hesitation typically spans 5 to 8 minutes.

Developed by Jake Pauls and codified in the SFPE Handbook, the effective width model subtracts a 15 cm (6 inch) boundary layer from each side of stairways and handrails where body sway prevents shoulder-to-shoulder movement. A nominal 1.12 m (44 in) stairway provides 0.82 m of effective width, capping maximum crowd flow at approximately 57 persons per minute per stair.

In high-rise buildings (typically 6+ storeys), simultaneous evacuation quickly overwhelms exit stairs, resulting in severe crowd crush at landings. Phased evacuation directs the immediate evacuation of the fire floor plus the floors directly above and below first, clearing the life-critical zone in under 3 to 5 minutes before subsequent floors discharge.