IMO 4: Exit flow rate

PASS

1. Definition

100 persons stand in a room of 8 m by 5 m. A 1 m wide exit sits at the centre of one of the 5 m walls. The flow rate measured over the whole evacuation must not exceed 1.33 p/s. Section 3.2.6 states the same limit as a specific flow of 1.33 p/m/s for any exit.

Source: IMO MSC.1/Circ.1533, Annex 3, Appendix 2, Test 4, para. 6, p. 9; see also Section 3.2.6, p. 6. This is a paraphrase, not the text of the standard.

Reference: International Maritime Organization (2016). Revised guidelines on evacuation analysis for new and existing passenger ships. MSC.1/Circ.1533, 6 June 2016. https://edocs.imo.org/Final%20Documents/English/MSC.1-CIRC.1533%20(E).docx (Page numbers are the printed page numbers of Annex 3 (“Annex 3, page n”). Tests are cited by test number and paragraph of Appendix 2.)

2. Scenario

Scenario picture not available.

3. What to expect

The flow does not exceed 1.33 p/s. The text does not define the averaging period beyond “the entire period”.

Our criterion: Flow (N-1)/(t_last-t_first) through a 1 m exit <= 1.33 p/s with the exit throughput limiter enabled

Limiter enabled at 1.33 p/s (maintainer decision D12); measured 1.31 p/s on seed 42, tolerance 1%. The emergent flow with the limiter off (~5.8 p/s) is printed by the test, not asserted. The exit is a 1 x 1 m absorbing square inside the room, not a wall opening (known, unchanged).

4. Our result

Status: PASS

Test cases of this row

Case	Status	Result	Run
`test_all_evacuate`	PASS	agents_remaining = 0 count accepted 0 – 0 count	n = 100 · seed 42
`test_emergent_flow_without_limiter_is_reported`	PASS	specific_exit_flow_limiter_off = 5.789 p/m/s	n = 100 · seed 42
`test_flow_within_cap_with_limiter`	PASS	specific_exit_flow_limiter_on = 1.316 p/m/s accepted ≤ 1.3433 p/m/s	n = 100 · seed 42

test_all_evacuate: bound: total_agents = 100; 0 <= measured <= 0
test_emergent_flow_without_limiter_is_reported: information only: emergent flow, not asserted
test_flow_within_cap_with_limiter: bound: measured <= 1.33 * (1 + 0.01); exit limiter on, 1 m exit

5. Our implementation

Deviations from the standard:

The exit throughput limiter is switched on at 1.33 p/s (decision D12). The test therefore checks that the limiter holds the flow at the cap. The flow the model produces without the limiter is printed by a second test and is not asserted.
The flow is (N - 1) / (t_last - t_first) over the exit times of the 100 agents, divided by the exit width of 1 m. The standard does not name this window.
The pass rule is the suite’s own: measured flow is at most 1.33 p/s plus a 1 % tolerance.
The exit is a 1 m by 1 m absorbing square inside the room, against the right-hand 5 m wall, not an opening in the wall. Agents are removed when they touch it.
The 100 agents start in the left 6 m of the room (x = 0 m to 6 m), not spread over the whole room.
Agents have a constant desired speed of 1.2 m/s and the suite’s default body radius of 0.15 m; one seed (42). The scenario is built in code (tests/vv/test_imo.py).

Model: CollisionFreeSpeedModel

Test function: tests/vv/test_imo.py::test_all_evacuate

6. Our notebook

No notebook for this test yet.

IMO 3: Maintaining a set walking speed down a staircase IMO 5: Response duration