Test 13: Relationship between flow rate, density and walking speeds in a corridor

1. Definition

A corridor of 60 m by 2 m is split into three zones of 20 m, with line A between zones 1 and 2 and line B between zones 2 and 3. Occupants with no pre-evacuation time and a speed of 1 m/s are spread uniformly over the whole corridor and walk to the exit on the right. The runs use 60, 120, 240, 360 and 480 occupants (initial densities 0.5, 1, 2, 3 and 4 persons per square metre). The last occupant in zone 2 is placed near line A, and the time it needs from A to B gives its walking speed. The flow at line B is averaged from the start until that occupant reaches B. The density in zone 2 is recorded when that occupant reaches the centre of the zone. The tester may vary the averaging intervals.

Source: ISO 20414:2020, Test 13, Table 14, pp. 23-24, Fig. 9. This is a paraphrase, not the text of the standard.

Reference: ISO (2020). ISO 20414:2020, Fire safety engineering - Verification and validation protocol for building fire evacuation models. First edition. International Organization for Standardization, Geneva. https://www.iso.org/standard/78348.html (Page numbers are the printed page numbers of ISO 20414:2020 (the copy read is a proof, so numbers can differ by a page in the published edition). ISO states that its tests are examples and that a tester may use different tests that verify the same component equivalently.)

2. Scenario

Scenario figure from the executed notebook.

3. What to expect

The speed against density and the flow against density in zone 2 are plotted and compared with the assumptions built into the model. ISO calls the test qualitative and sets no pass limit.

Our criterion: Zone-2 speed stays within the assigned free speed

4. Our result

Status: PASS

Test cases of this row

• test_zone2_speed_within_free_speed: bound: each measured <= 1.0 + 0.05; one value per run of [60, 120, 240] agents

Result figure from the executed notebook.

5. Our implementation

Deviations from the standard:

• The test runs 60, 120 and 240 occupants only. The 360 and 480 cases are not run.
• The pass rule is the suite’s own: the mean zone-2 speed over line A to line B must not exceed the assigned 1.0 m/s by more than 0.05 m/s. Only agents that start upstream of line A and cross both lines are timed. Agents that start inside zone 2 are left out, because timing them from their first frame would overstate their speed.
• ISO’s protocol for the last occupant in zone 2 is not implemented: the speed is the mean over all agents that cross both lines. Density and flow at line B are computed by the scenario builder and not asserted.
• Agents spawn inside a strip inset 0.3 m from the walls, so the initial density is about 1.4 times the nominal value. The scenario is built in code (standards/iso/scenario_builders/iso13_corridor_fd.py) rather than loaded from a scenario file. One seed (42) is run.

Model: CollisionFreeSpeedModel

• Test function: tests/vv/test_iso.py::test_zone2_speed_within_free_speed

6. Our notebook

• Executed notebook (HTML)
• Notebook source (.ipynb) on GitHub