Sample drill scenarios
| Scenario | Occupants | Floors | Doors | Width (m) | Distance (m) | Flow (pp/min/m) | Target (min) |
|---|---|---|---|---|---|---|---|
| Office block | 220 | 5 | 3 | 1.1 | 65 | 50 | 8.0 |
| Workshop hall | 140 | 1 | 2 | 1.4 | 40 | 60 | 6.0 |
| Mixed-use building | 320 | 8 | 4 | 1.2 | 70 | 45 | 10.0 |
Formula used
- Travel_to_exit(s) = Distance_to_exit / Indoor_speed + Floors × Stair_sec_per_floor
- Door_capacity(pp/min) = Exit_doors × Door_width × Flow_rate
- Exit_queue_time(s) = (Occupants / Door_capacity) × 60
- Travel_to_assembly(s) = Assembly_distance / Outdoor_speed
- Total(s) = Alarm + Pre_movement + Travel_to_exit + Exit_queue + Travel_to_assembly + Roll_call + Briefing + Reset
How to use this calculator
- Enter occupants, floors, and realistic movement assumptions.
- Fill door count, door width, and flow rate for exit capacity.
- Set roll call and briefing times to reflect your process.
- Choose a target time that matches your internal benchmark.
- Press Submit to view results above the form.
- Export CSV for spreadsheets, and PDF for compliance evidence.
Assumptions and interpretation
- Flow rate is an engineering approximation; real conditions vary.
- Stair time per floor captures congestion and vertical travel effects.
- Use the same measurement method across drills for valid comparisons.
- If exit flow dominates, consider widening routes or adding doors.
Operational benchmarks for drill timing
A fire drill timeline is easiest to improve when each phase is measured and reported. This calculator separates alarm signaling, pre-movement, travel, exit flow, and assembly activities. For a 150-person drill, even a 15-second reduction in pre-movement can cut the total by 3–4%. Tracking mm:ss results across runs makes trends visible and supports consistent coaching. Store each run as a baseline, then compare phase percentages to spot drift during staffing changes. Document assumptions for audits.
Travel distance and stair descent effects
Movement time is driven by distance and vertical transitions. The model uses corridor distance divided by indoor speed, then adds stair time per evacuated floor. If distance is 55 m and speed is 1.1 m/s, horizontal travel is about 50 seconds. With 3 floors at 18 seconds per floor, stairs add 54 seconds, doubling the travel portion.
Exit throughput and queuing performance
Door flow is often the dominant bottleneck because it scales with both width and door count. Capacity is computed as doors × width × flow rate. Example: 3 doors × 1.2 m × 55 persons/min/m ≈ 198 persons/min. For 200 occupants, the estimated exit queue time is about 0.61 minutes (≈ 37 seconds). Use effective clear width, not nominal leaf width, and keep door areas free of bins and signs.
Accountability, briefing, and continuity steps
Roll call and briefing time determine how quickly operations can resume safely. A 120-second roll call plus a 90-second briefing adds 3.5 minutes to the timeline. If you include the all-clear and reset phase, record it consistently to avoid hiding delays. Capture the time to “last person accounted,” and note missed badges or late arrivals for corrective actions.
Improvement planning from phase shares
Use the largest phase share to select a single improvement focus per drill. If exit flow is highest, test additional doors, wider clear widths, or staggered release of zones. If pre-movement dominates, rehearse roles and reduce decision points. Aim for a target total time, then validate progress by exporting reports after each drill cycle. Over a quarter, a 10% reduction in the top phase typically delivers the most reliable overall gain.
FAQs
What value should I use for flow rate?
Start with a conservative value based on your doorway conditions, then calibrate using observed drill counts per minute and measured clear width.
How do I measure pre-movement delay?
Time from first alert perception to when the group begins moving. Use a stopwatch, record multiple points, and enter an average to reduce outlier effects.
Why do more doors change results so much?
Door capacity scales linearly with door count and width, so queuing time drops quickly. Speed changes help travel time but may not reduce queues.
Should I include all-clear and reset time?
Include it when your goal is full operational recovery timing. Exclude it when you want to benchmark evacuation and accountability performance only.
How can I compare two drill scenarios fairly?
Keep measurement rules consistent, change one input at a time, and compare the phase breakdown. Export CSV reports so the same metrics are tracked across runs.
What if the site has multiple assembly points?
Use a weighted average distance and outdoor speed, or run separate scenarios per assembly route. Pick the longest route for conservative planning.