FAILURE MAP
← Case archive

FA-67396 / Elevator dispatch scheduling / Open access

Door dwell time calculation: first passenger allowance · case 01

Every stop is ten deciseconds longer than stipulated, or shorter when nobody moves.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The first passenger is charged transfer time too.

THE FAILURE

The first passenger is charged transfer time too.

Unsuccessful approach: Without the floor at zero an empty stop is shortened below the base.

Case contract

Dwell time in deciseconds: base 40 for a hall call stop (or a stop with both hall and car calls), 25 for a car-call-only stop. Accessible mode extends the base by half (integer). Every passenger beyond the first adds 10. The result is capped at 150. From the third reopen onward the door nudges with a fixed dwell of 20.

Why this case matters

Lift group controllers make these decisions many times per minute; a wrong answer strands passengers, wastes trips or overrides a safety rule.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    base = 40 if x['call_type'] in ('hall', 'both') else 25
    if x['accessible']:
        base = base * 3 // 2
    pax = x['boarding'] + x['alighting']
    dwell = base + 10 * pax
    dwell = min(dwell, 150)
    nudge = x['reopen_count'] >= 3
    if nudge:
        dwell = 20
    return {'dwell_ds': dwell, 'nudge': nudge}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: stop with hall and car calls', {'call_type': 'both', 'boarding': 1, 'alighting': 1, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 50, 'nudge': False}), ('boundary: nobody boards or alights', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 25, 'nudge': False}), ('regression: single passenger', {'call_type': 'hall', 'boarding': 1, 'alighting': 0, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 40, 'nudge': False}), ('control 69', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 1, 'accessible': True}, {'dwell_ds': 37, 'nudge': False}), ('regression: accessible car call stop', {'call_type': 'car', 'boarding': 1, 'alighting': 0, 'reopen_count': 0, 'accessible': True}, {'dwell_ds': 37, 'nudge': False}), ('control 1', {'call_type': 'both', 'boarding': 6, 'alighting': 3, 'reopen_count': 4, 'accessible': False}, {'dwell_ds': 20, 'nudge': True}), ('sampled regression 4', {'call_type': 'hall', 'boarding': 5, 'alighting': 0, 'reopen_count': 0, 'accessible': True}, {'dwell_ds': 100, 'nudge': False}), ('control 7', {'call_type': 'both', 'boarding': 5, 'alighting': 1, 'reopen_count': 4, 'accessible': True}, {'dwell_ds': 20, 'nudge': True})], [('regression: accessible car call stop', {'call_type': 'car', 'boarding': 1, 'alighting': 0, 'reopen_count': 0, 'accessible': True}, {'dwell_ds': 37, 'nudge': False}), ('boundary: nobody boards or alights', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 25, 'nudge': False}), ('sampled regression 11', {'call_type': 'car', 'boarding': 0, 'alighting': 3, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 45, 'nudge': False}), ('regression: accessible busy hall stop', {'call_type': 'hall', 'boarding': 5, 'alighting': 3, 'reopen_count': 0, 'accessible': True}, {'dwell_ds': 130, 'nudge': False}), ('boundary: crowd exceeds the cap', {'call_type': 'hall', 'boarding': 8, 'alighting': 8, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 150, 'nudge': False}), ('control 12', {'call_type': 'car', 'boarding': 0, 'alighting': 4, 'reopen_count': 3, 'accessible': False}, {'dwell_ds': 20, 'nudge': True}), ('sampled regression 15', {'call_type': 'hall', 'boarding': 2, 'alighting': 5, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 100, 'nudge': False}), ('control 18', {'call_type': 'car', 'boarding': 8, 'alighting': 7, 'reopen_count': 2, 'accessible': False}, {'dwell_ds': 150, 'nudge': False})], [('regression: accessible busy hall stop', {'call_type': 'hall', 'boarding': 5, 'alighting': 3, 'reopen_count': 0, 'accessible': True}, {'dwell_ds': 130, 'nudge': False}), ('boundary: nobody boards or alights', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 25, 'nudge': False}), ('sampled regression 23', {'call_type': 'hall', 'boarding': 7, 'alighting': 3, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 130, 'nudge': False}), ('control 69', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 1, 'accessible': True}, {'dwell_ds': 37, 'nudge': False}), ('boundary: crowd exceeds the cap', {'call_type': 'hall', 'boarding': 8, 'alighting': 8, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 150, 'nudge': False}), ('sampled regression 26', {'call_type': 'both', 'boarding': 3, 'alighting': 3, 'reopen_count': 0, 'accessible': True}, {'dwell_ds': 110, 'nudge': False}), ('control 29', {'call_type': 'both', 'boarding': 1, 'alighting': 0, 'reopen_count': 3, 'accessible': False}, {'dwell_ds': 20, 'nudge': True}), ('control 32', {'call_type': 'both', 'boarding': 8, 'alighting': 0, 'reopen_count': 4, 'accessible': False}, {'dwell_ds': 20, 'nudge': True})], [('regression: single passenger', {'call_type': 'hall', 'boarding': 1, 'alighting': 0, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 40, 'nudge': False}), ('boundary: nobody boards or alights', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 25, 'nudge': False}), ('sampled regression 41', {'call_type': 'hall', 'boarding': 0, 'alighting': 5, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 80, 'nudge': False}), ('boundary: third reopen with nobody moving', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 3, 'accessible': False}, {'dwell_ds': 20, 'nudge': True}), ('regression: stop with hall and car calls', {'call_type': 'both', 'boarding': 1, 'alighting': 1, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 50, 'nudge': False}), ('sampled regression 34', {'call_type': 'hall', 'boarding': 3, 'alighting': 5, 'reopen_count': 1, 'accessible': False}, {'dwell_ds': 110, 'nudge': False}), ('control 37', {'call_type': 'hall', 'boarding': 4, 'alighting': 0, 'reopen_count': 4, 'accessible': False}, {'dwell_ds': 20, 'nudge': True}), ('control 40', {'call_type': 'car', 'boarding': 1, 'alighting': 8, 'reopen_count': 4, 'accessible': False}, {'dwell_ds': 20, 'nudge': True})], [('regression: stop with hall and car calls', {'call_type': 'both', 'boarding': 1, 'alighting': 1, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 50, 'nudge': False}), ('boundary: nobody boards or alights', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 25, 'nudge': False}), ('sampled regression 58', {'call_type': 'both', 'boarding': 7, 'alighting': 1, 'reopen_count': 0, 'accessible': True}, {'dwell_ds': 130, 'nudge': False}), ('control 69', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 1, 'accessible': True}, {'dwell_ds': 37, 'nudge': False}), ('regression: accessible car call stop', {'call_type': 'car', 'boarding': 1, 'alighting': 0, 'reopen_count': 0, 'accessible': True}, {'dwell_ds': 37, 'nudge': False}), ('control 45', {'call_type': 'both', 'boarding': 6, 'alighting': 0, 'reopen_count': 4, 'accessible': False}, {'dwell_ds': 20, 'nudge': True}), ('sampled regression 48', {'call_type': 'hall', 'boarding': 3, 'alighting': 8, 'reopen_count': 2, 'accessible': False}, {'dwell_ds': 140, 'nudge': False}), ('sampled regression 51', {'call_type': 'hall', 'boarding': 2, 'alighting': 4, 'reopen_count': 1, 'accessible': False}, {'dwell_ds': 90, 'nudge': False})]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
regression: stop with hall and car calls{'dwell_ds': 60, 'nudge': False}{'dwell_ds': 50, 'nudge': False}Failed
boundary: nobody boards or alights{'dwell_ds': 25, 'nudge': False}{'dwell_ds': 25, 'nudge': False}Passed
regression: single passenger{'dwell_ds': 50, 'nudge': False}{'dwell_ds': 40, 'nudge': False}Failed
control 69{'dwell_ds': 37, 'nudge': False}{'dwell_ds': 37, 'nudge': False}Passed
regression: accessible car call stop{'dwell_ds': 47, 'nudge': False}{'dwell_ds': 37, 'nudge': False}Failed
control 1{'dwell_ds': 20, 'nudge': True}{'dwell_ds': 20, 'nudge': True}Passed
sampled regression 4{'dwell_ds': 110, 'nudge': False}{'dwell_ds': 100, 'nudge': False}Failed
control 7{'dwell_ds': 20, 'nudge': True}{'dwell_ds': 20, 'nudge': True}Passed

SHA-256 / 45d062a6efe2369e86f1da6ad19255ac398f7b6477419a6f37bccf864cc73ce2

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    base = 40 if x['call_type'] in ('hall', 'both') else 25
    if x['accessible']:
        base = base * 3 // 2
    pax = x['boarding'] + x['alighting']
    dwell = base + 10 * (pax - 1)
    dwell = min(dwell, 150)
    nudge = x['reopen_count'] >= 3
    if nudge:
        dwell = 20
    return {'dwell_ds': dwell, 'nudge': nudge}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: stop with hall and car calls', {'call_type': 'both', 'boarding': 1, 'alighting': 1, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 50, 'nudge': False}), ('boundary: nobody boards or alights', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 25, 'nudge': False}), ('regression: single passenger', {'call_type': 'hall', 'boarding': 1, 'alighting': 0, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 40, 'nudge': False}), ('control 69', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 1, 'accessible': True}, {'dwell_ds': 37, 'nudge': False}), ('regression: accessible car call stop', {'call_type': 'car', 'boarding': 1, 'alighting': 0, 'reopen_count': 0, 'accessible': True}, {'dwell_ds': 37, 'nudge': False}), ('control 1', {'call_type': 'both', 'boarding': 6, 'alighting': 3, 'reopen_count': 4, 'accessible': False}, {'dwell_ds': 20, 'nudge': True}), ('sampled regression 4', {'call_type': 'hall', 'boarding': 5, 'alighting': 0, 'reopen_count': 0, 'accessible': True}, {'dwell_ds': 100, 'nudge': False}), ('control 7', {'call_type': 'both', 'boarding': 5, 'alighting': 1, 'reopen_count': 4, 'accessible': True}, {'dwell_ds': 20, 'nudge': True})], [('regression: accessible car call stop', {'call_type': 'car', 'boarding': 1, 'alighting': 0, 'reopen_count': 0, 'accessible': True}, {'dwell_ds': 37, 'nudge': False}), ('boundary: nobody boards or alights', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 25, 'nudge': False}), ('sampled regression 11', {'call_type': 'car', 'boarding': 0, 'alighting': 3, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 45, 'nudge': False}), ('regression: accessible busy hall stop', {'call_type': 'hall', 'boarding': 5, 'alighting': 3, 'reopen_count': 0, 'accessible': True}, {'dwell_ds': 130, 'nudge': False}), ('boundary: crowd exceeds the cap', {'call_type': 'hall', 'boarding': 8, 'alighting': 8, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 150, 'nudge': False}), ('control 12', {'call_type': 'car', 'boarding': 0, 'alighting': 4, 'reopen_count': 3, 'accessible': False}, {'dwell_ds': 20, 'nudge': True}), ('sampled regression 15', {'call_type': 'hall', 'boarding': 2, 'alighting': 5, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 100, 'nudge': False}), ('control 18', {'call_type': 'car', 'boarding': 8, 'alighting': 7, 'reopen_count': 2, 'accessible': False}, {'dwell_ds': 150, 'nudge': False})], [('regression: accessible busy hall stop', {'call_type': 'hall', 'boarding': 5, 'alighting': 3, 'reopen_count': 0, 'accessible': True}, {'dwell_ds': 130, 'nudge': False}), ('boundary: nobody boards or alights', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 25, 'nudge': False}), ('sampled regression 23', {'call_type': 'hall', 'boarding': 7, 'alighting': 3, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 130, 'nudge': False}), ('control 69', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 1, 'accessible': True}, {'dwell_ds': 37, 'nudge': False}), ('boundary: crowd exceeds the cap', {'call_type': 'hall', 'boarding': 8, 'alighting': 8, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 150, 'nudge': False}), ('sampled regression 26', {'call_type': 'both', 'boarding': 3, 'alighting': 3, 'reopen_count': 0, 'accessible': True}, {'dwell_ds': 110, 'nudge': False}), ('control 29', {'call_type': 'both', 'boarding': 1, 'alighting': 0, 'reopen_count': 3, 'accessible': False}, {'dwell_ds': 20, 'nudge': True}), ('control 32', {'call_type': 'both', 'boarding': 8, 'alighting': 0, 'reopen_count': 4, 'accessible': False}, {'dwell_ds': 20, 'nudge': True})], [('regression: single passenger', {'call_type': 'hall', 'boarding': 1, 'alighting': 0, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 40, 'nudge': False}), ('boundary: nobody boards or alights', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 25, 'nudge': False}), ('sampled regression 41', {'call_type': 'hall', 'boarding': 0, 'alighting': 5, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 80, 'nudge': False}), ('boundary: third reopen with nobody moving', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 3, 'accessible': False}, {'dwell_ds': 20, 'nudge': True}), ('regression: stop with hall and car calls', {'call_type': 'both', 'boarding': 1, 'alighting': 1, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 50, 'nudge': False}), ('sampled regression 34', {'call_type': 'hall', 'boarding': 3, 'alighting': 5, 'reopen_count': 1, 'accessible': False}, {'dwell_ds': 110, 'nudge': False}), ('control 37', {'call_type': 'hall', 'boarding': 4, 'alighting': 0, 'reopen_count': 4, 'accessible': False}, {'dwell_ds': 20, 'nudge': True}), ('control 40', {'call_type': 'car', 'boarding': 1, 'alighting': 8, 'reopen_count': 4, 'accessible': False}, {'dwell_ds': 20, 'nudge': True})], [('regression: stop with hall and car calls', {'call_type': 'both', 'boarding': 1, 'alighting': 1, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 50, 'nudge': False}), ('boundary: nobody boards or alights', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 0, 'accessible': False}, {'dwell_ds': 25, 'nudge': False}), ('sampled regression 58', {'call_type': 'both', 'boarding': 7, 'alighting': 1, 'reopen_count': 0, 'accessible': True}, {'dwell_ds': 130, 'nudge': False}), ('control 69', {'call_type': 'car', 'boarding': 0, 'alighting': 0, 'reopen_count': 1, 'accessible': True}, {'dwell_ds': 37, 'nudge': False}), ('regression: accessible car call stop', {'call_type': 'car', 'boarding': 1, 'alighting': 0, 'reopen_count': 0, 'accessible': True}, {'dwell_ds': 37, 'nudge': False}), ('control 45', {'call_type': 'both', 'boarding': 6, 'alighting': 0, 'reopen_count': 4, 'accessible': False}, {'dwell_ds': 20, 'nudge': True}), ('sampled regression 48', {'call_type': 'hall', 'boarding': 3, 'alighting': 8, 'reopen_count': 2, 'accessible': False}, {'dwell_ds': 140, 'nudge': False}), ('sampled regression 51', {'call_type': 'hall', 'boarding': 2, 'alighting': 4, 'reopen_count': 1, 'accessible': False}, {'dwell_ds': 90, 'nudge': False})]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
regression: stop with hall and car calls{'dwell_ds': 50, 'nudge': False}{'dwell_ds': 50, 'nudge': False}Passed
boundary: nobody boards or alights{'dwell_ds': 15, 'nudge': False}{'dwell_ds': 25, 'nudge': False}Failed
regression: single passenger{'dwell_ds': 40, 'nudge': False}{'dwell_ds': 40, 'nudge': False}Passed
control 69{'dwell_ds': 27, 'nudge': False}{'dwell_ds': 37, 'nudge': False}Failed
regression: accessible car call stop{'dwell_ds': 37, 'nudge': False}{'dwell_ds': 37, 'nudge': False}Passed
control 1{'dwell_ds': 20, 'nudge': True}{'dwell_ds': 20, 'nudge': True}Passed
sampled regression 4{'dwell_ds': 100, 'nudge': False}{'dwell_ds': 100, 'nudge': False}Passed
control 7{'dwell_ds': 20, 'nudge': True}{'dwell_ds': 20, 'nudge': True}Passed

SHA-256 / c2443c743c342087b57ab47411ee834c3aa38f5581c1593a2a7e32974e885871

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 8 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

Sign in to the archive ↗

Verification & scope

Stipulated toy lift-control contract for a bounded teaching model; it makes no claim of conformance to any lift code or vendor dispatcher and omits real safety cases. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:47:52.501383+00:00.

Case digest / c40fda395b4516f3c3436f0a5857d415a790f9bb34c88cfae3768ecb201a8602