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FA-67336 / Railway interlocking logic / Open access

Temporary speed restriction over train length: sighting distance reference · case 01

A restriction exactly at the sighting distance is not announced, or sighting is measured from the wrong end.

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

ROOT CAUSE

The sighting comparison is exclusive.

VERIFIED REPAIR

Announce restrictions starting within sight_m of the front, inclusive.

Unsuccessful approach: Measuring from the rear shortens the effective sighting distance.

Case contract

A restriction [from_m, to_m) applies while any part of the train (rear = front - length) is inside it: from <= front and to > rear. The limit is the minimum of the line speed and applicable restrictions. next_m is the start of the nearest restriction ahead of the front (from > front) within sight_m of the front whose speed is below the current limit, else None.

Why this case matters

Interlocking logic decides whether trains may be given authority; a wrong decision at this point either grants unsafe movements or strands traffic.

1 / The failure

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

N = 1
observations = []
def solve(x):
    front = x['front_m']
    rear = front - x['length_m']
    limit = x['line_kmh']
    for s in x['tsr']:
        if s['from_m'] <= front and s['to_m'] > rear:
            limit = min(limit, s['kmh'])
    ahead = [s for s in x['tsr'] if s['from_m'] > front and s['from_m'] - front < x['sight_m'] and s['kmh'] < limit]
    nxt = min(ahead, key=lambda s: s['from_m'])['from_m'] if ahead else None
    return {'limit': limit, 'next_m': nxt}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: restriction exactly at sighting distance', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 600, 'to_m': 700, 'kmh': 40}]}, {'limit': 100, 'next_m': 600}), ('sampled regression 34', {'front_m': 700, 'length_m': 200, 'line_kmh': 100, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1300, 'kmh': 80}, {'from_m': 0, 'to_m': 300, 'kmh': 20}, {'from_m': 1000, 'to_m': 1600, 'kmh': 80}, {'from_m': 1000, 'to_m': 1300, 'kmh': 60}]}, {'limit': 100, 'next_m': 1000}), ('sampled regression 5', {'front_m': 500, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 800, 'to_m': 1100, 'kmh': 20}]}, {'limit': 120, 'next_m': 800}), ('boundary: rear still inside the restriction', {'front_m': 700, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}]}, {'limit': 40, 'next_m': None}), ('boundary: rear exactly at the restriction end', {'front_m': 800, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}]}, {'limit': 100, 'next_m': None}), ('control 1', {'front_m': 1100, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 1500, 'to_m': 2100, 'kmh': 40}, {'from_m': 800, 'to_m': 1100, 'kmh': 40}]}, {'limit': 40, 'next_m': None}), ('control 4', {'front_m': 700, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1100, 'kmh': 40}, {'from_m': 1000, 'to_m': 1600, 'kmh': 20}, {'from_m': 800, 'to_m': 900, 'kmh': 20}, {'from_m': 500, 'to_m': 600, 'kmh': 20}]}, {'limit': 20, 'next_m': None}), ('control 7', {'front_m': 1100, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 800, 'kmh': 40}, {'from_m': 1000, 'to_m': 1300, 'kmh': 60}]}, {'limit': 60, 'next_m': None})], [('regression: restriction exactly at sighting distance', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 600, 'to_m': 700, 'kmh': 40}]}, {'limit': 100, 'next_m': 600}), ('control 57', {'front_m': 250, 'length_m': 200, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1600, 'kmh': 40}, {'from_m': 800, 'to_m': 1100, 'kmh': 60}, {'from_m': 500, 'to_m': 800, 'kmh': 40}, {'from_m': 500, 'to_m': 600, 'kmh': 40}]}, {'limit': 120, 'next_m': 500}), ('boundary: restriction ahead faster than current limit', {'front_m': 500, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}, {'from_m': 800, 'to_m': 900, 'kmh': 60}]}, {'limit': 40, 'next_m': None}), ('boundary: restriction ahead slower than line speed only', {'front_m': 500, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 450, 'to_m': 700, 'kmh': 30}, {'from_m': 800, 'to_m': 900, 'kmh': 60}]}, {'limit': 30, 'next_m': None}), ('boundary: two restrictions ahead listed far first', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 600, 'kmh': 40}, {'from_m': 300, 'to_m': 400, 'kmh': 60}]}, {'limit': 100, 'next_m': 300}), ('control 12', {'front_m': 1300, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 500, 'to_m': 1100, 'kmh': 20}, {'from_m': 1500, 'to_m': 1600, 'kmh': 20}, {'from_m': 200, 'to_m': 300, 'kmh': 40}]}, {'limit': 20, 'next_m': None}), ('control 15', {'front_m': 100, 'length_m': 400, 'line_kmh': 120, 'sight_m': 500, 'tsr': [{'from_m': 1500, 'to_m': 2100, 'kmh': 60}, {'from_m': 800, 'to_m': 900, 'kmh': 20}, {'from_m': 200, 'to_m': 300, 'kmh': 40}]}, {'limit': 120, 'next_m': 200}), ('control 18', {'front_m': 700, 'length_m': 400, 'line_kmh': 120, 'sight_m': 500, 'tsr': [{'from_m': 1000, 'to_m': 1300, 'kmh': 60}]}, {'limit': 120, 'next_m': 1000})], [('regression: restriction exactly at sighting distance', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 600, 'to_m': 700, 'kmh': 40}]}, {'limit': 100, 'next_m': 600}), ('sampled regression 26', {'front_m': 500, 'length_m': 100, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 800, 'to_m': 1100, 'kmh': 40}]}, {'limit': 120, 'next_m': 800}), ('sampled regression 5', {'front_m': 500, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 800, 'to_m': 1100, 'kmh': 20}]}, {'limit': 120, 'next_m': 800}), ('boundary: two restrictions ahead listed far first', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 600, 'kmh': 40}, {'from_m': 300, 'to_m': 400, 'kmh': 60}]}, {'limit': 100, 'next_m': 300}), ('boundary: restriction just behind the rear', {'front_m': 1000, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 900, 'kmh': 20}]}, {'limit': 100, 'next_m': None}), ('control 23', {'front_m': 700, 'length_m': 100, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 200, 'to_m': 300, 'kmh': 40}, {'from_m': 800, 'to_m': 900, 'kmh': 80}]}, {'limit': 120, 'next_m': 800}), ('control 29', {'front_m': 100, 'length_m': 200, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 0, 'to_m': 300, 'kmh': 20}, {'from_m': 200, 'to_m': 800, 'kmh': 80}, {'from_m': 0, 'to_m': 100, 'kmh': 20}]}, {'limit': 20, 'next_m': None}), ('control 32', {'front_m': 1100, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1100, 'kmh': 20}]}, {'limit': 20, 'next_m': None})], [('regression: restriction exactly at sighting distance', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 600, 'to_m': 700, 'kmh': 40}]}, {'limit': 100, 'next_m': 600}), ('sampled regression 62', {'front_m': 500, 'length_m': 400, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 1500, 'to_m': 2100, 'kmh': 40}, {'from_m': 1000, 'to_m': 1600, 'kmh': 20}]}, {'limit': 100, 'next_m': 1000}), ('control 57', {'front_m': 250, 'length_m': 200, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1600, 'kmh': 40}, {'from_m': 800, 'to_m': 1100, 'kmh': 60}, {'from_m': 500, 'to_m': 800, 'kmh': 40}, {'from_m': 500, 'to_m': 600, 'kmh': 40}]}, {'limit': 120, 'next_m': 500}), ('boundary: restriction just behind the rear', {'front_m': 1000, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 900, 'kmh': 20}]}, {'limit': 100, 'next_m': None}), ('boundary: rear still inside the restriction', {'front_m': 700, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}]}, {'limit': 40, 'next_m': None}), ('sampled regression 34', {'front_m': 700, 'length_m': 200, 'line_kmh': 100, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1300, 'kmh': 80}, {'from_m': 0, 'to_m': 300, 'kmh': 20}, {'from_m': 1000, 'to_m': 1600, 'kmh': 80}, {'from_m': 1000, 'to_m': 1300, 'kmh': 60}]}, {'limit': 100, 'next_m': 1000}), ('control 37', {'front_m': 500, 'length_m': 400, 'line_kmh': 100, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1600, 'kmh': 60}, {'from_m': 200, 'to_m': 800, 'kmh': 40}, {'from_m': 0, 'to_m': 100, 'kmh': 20}, {'from_m': 1500, 'to_m': 1800, 'kmh': 20}]}, {'limit': 40, 'next_m': None}), ('control 40', {'front_m': 1300, 'length_m': 200, 'line_kmh': 120, 'sight_m': 500, 'tsr': [{'from_m': 1000, 'to_m': 1100, 'kmh': 60}, {'from_m': 1500, 'to_m': 2100, 'kmh': 20}]}, {'limit': 120, 'next_m': 1500})], [('regression: restriction exactly at sighting distance', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 600, 'to_m': 700, 'kmh': 40}]}, {'limit': 100, 'next_m': 600}), ('sampled regression 5', {'front_m': 500, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 800, 'to_m': 1100, 'kmh': 20}]}, {'limit': 120, 'next_m': 800}), ('boundary: rear exactly at the restriction end', {'front_m': 800, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}]}, {'limit': 100, 'next_m': None}), ('boundary: restriction ahead faster than current limit', {'front_m': 500, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}, {'from_m': 800, 'to_m': 900, 'kmh': 60}]}, {'limit': 40, 'next_m': None}), ('boundary: restriction ahead slower than line speed only', {'front_m': 500, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 450, 'to_m': 700, 'kmh': 30}, {'from_m': 800, 'to_m': 900, 'kmh': 60}]}, {'limit': 30, 'next_m': None}), ('control 45', {'front_m': 700, 'length_m': 200, 'line_kmh': 100, 'sight_m': 300, 'tsr': [{'from_m': 0, 'to_m': 300, 'kmh': 60}, {'from_m': 200, 'to_m': 800, 'kmh': 80}, {'from_m': 800, 'to_m': 1100, 'kmh': 40}, {'from_m': 200, 'to_m': 500, 'kmh': 60}]}, {'limit': 80, 'next_m': 800}), ('control 48', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 200, 'to_m': 800, 'kmh': 80}, {'from_m': 800, 'to_m': 1400, 'kmh': 80}, {'from_m': 1000, 'to_m': 1100, 'kmh': 40}, {'from_m': 0, 'to_m': 100, 'kmh': 20}]}, {'limit': 20, 'next_m': None}), ('control 51', {'front_m': 900, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 600, 'kmh': 40}]}, {'limit': 100, 'next_m': None})]]
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: restriction exactly at sighting distance{'limit': 100, 'next_m': None}{'limit': 100, 'next_m': 600}Failed
sampled regression 34{'limit': 100, 'next_m': None}{'limit': 100, 'next_m': 1000}Failed
sampled regression 5{'limit': 120, 'next_m': None}{'limit': 120, 'next_m': 800}Failed
boundary: rear still inside the restriction{'limit': 40, 'next_m': None}{'limit': 40, 'next_m': None}Passed
boundary: rear exactly at the restriction end{'limit': 100, 'next_m': None}{'limit': 100, 'next_m': None}Passed
control 1{'limit': 40, 'next_m': None}{'limit': 40, 'next_m': None}Passed
control 4{'limit': 20, 'next_m': None}{'limit': 20, 'next_m': None}Passed
control 7{'limit': 60, 'next_m': None}{'limit': 60, 'next_m': None}Passed

SHA-256 / c2d8842555a1b8b99cdaf8abe30bf85d25d476bb5486f03d0578f34b756053c4

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(x):
    front = x['front_m']
    rear = front - x['length_m']
    limit = x['line_kmh']
    for s in x['tsr']:
        if s['from_m'] <= front and s['to_m'] > rear:
            limit = min(limit, s['kmh'])
    ahead = [s for s in x['tsr'] if s['from_m'] > front and s['from_m'] - rear <= x['sight_m'] and s['kmh'] < limit]
    nxt = min(ahead, key=lambda s: s['from_m'])['from_m'] if ahead else None
    return {'limit': limit, 'next_m': nxt}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: restriction exactly at sighting distance', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 600, 'to_m': 700, 'kmh': 40}]}, {'limit': 100, 'next_m': 600}), ('sampled regression 34', {'front_m': 700, 'length_m': 200, 'line_kmh': 100, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1300, 'kmh': 80}, {'from_m': 0, 'to_m': 300, 'kmh': 20}, {'from_m': 1000, 'to_m': 1600, 'kmh': 80}, {'from_m': 1000, 'to_m': 1300, 'kmh': 60}]}, {'limit': 100, 'next_m': 1000}), ('sampled regression 5', {'front_m': 500, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 800, 'to_m': 1100, 'kmh': 20}]}, {'limit': 120, 'next_m': 800}), ('boundary: rear still inside the restriction', {'front_m': 700, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}]}, {'limit': 40, 'next_m': None}), ('boundary: rear exactly at the restriction end', {'front_m': 800, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}]}, {'limit': 100, 'next_m': None}), ('control 1', {'front_m': 1100, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 1500, 'to_m': 2100, 'kmh': 40}, {'from_m': 800, 'to_m': 1100, 'kmh': 40}]}, {'limit': 40, 'next_m': None}), ('control 4', {'front_m': 700, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1100, 'kmh': 40}, {'from_m': 1000, 'to_m': 1600, 'kmh': 20}, {'from_m': 800, 'to_m': 900, 'kmh': 20}, {'from_m': 500, 'to_m': 600, 'kmh': 20}]}, {'limit': 20, 'next_m': None}), ('control 7', {'front_m': 1100, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 800, 'kmh': 40}, {'from_m': 1000, 'to_m': 1300, 'kmh': 60}]}, {'limit': 60, 'next_m': None})], [('regression: restriction exactly at sighting distance', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 600, 'to_m': 700, 'kmh': 40}]}, {'limit': 100, 'next_m': 600}), ('control 57', {'front_m': 250, 'length_m': 200, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1600, 'kmh': 40}, {'from_m': 800, 'to_m': 1100, 'kmh': 60}, {'from_m': 500, 'to_m': 800, 'kmh': 40}, {'from_m': 500, 'to_m': 600, 'kmh': 40}]}, {'limit': 120, 'next_m': 500}), ('boundary: restriction ahead faster than current limit', {'front_m': 500, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}, {'from_m': 800, 'to_m': 900, 'kmh': 60}]}, {'limit': 40, 'next_m': None}), ('boundary: restriction ahead slower than line speed only', {'front_m': 500, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 450, 'to_m': 700, 'kmh': 30}, {'from_m': 800, 'to_m': 900, 'kmh': 60}]}, {'limit': 30, 'next_m': None}), ('boundary: two restrictions ahead listed far first', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 600, 'kmh': 40}, {'from_m': 300, 'to_m': 400, 'kmh': 60}]}, {'limit': 100, 'next_m': 300}), ('control 12', {'front_m': 1300, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 500, 'to_m': 1100, 'kmh': 20}, {'from_m': 1500, 'to_m': 1600, 'kmh': 20}, {'from_m': 200, 'to_m': 300, 'kmh': 40}]}, {'limit': 20, 'next_m': None}), ('control 15', {'front_m': 100, 'length_m': 400, 'line_kmh': 120, 'sight_m': 500, 'tsr': [{'from_m': 1500, 'to_m': 2100, 'kmh': 60}, {'from_m': 800, 'to_m': 900, 'kmh': 20}, {'from_m': 200, 'to_m': 300, 'kmh': 40}]}, {'limit': 120, 'next_m': 200}), ('control 18', {'front_m': 700, 'length_m': 400, 'line_kmh': 120, 'sight_m': 500, 'tsr': [{'from_m': 1000, 'to_m': 1300, 'kmh': 60}]}, {'limit': 120, 'next_m': 1000})], [('regression: restriction exactly at sighting distance', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 600, 'to_m': 700, 'kmh': 40}]}, {'limit': 100, 'next_m': 600}), ('sampled regression 26', {'front_m': 500, 'length_m': 100, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 800, 'to_m': 1100, 'kmh': 40}]}, {'limit': 120, 'next_m': 800}), ('sampled regression 5', {'front_m': 500, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 800, 'to_m': 1100, 'kmh': 20}]}, {'limit': 120, 'next_m': 800}), ('boundary: two restrictions ahead listed far first', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 600, 'kmh': 40}, {'from_m': 300, 'to_m': 400, 'kmh': 60}]}, {'limit': 100, 'next_m': 300}), ('boundary: restriction just behind the rear', {'front_m': 1000, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 900, 'kmh': 20}]}, {'limit': 100, 'next_m': None}), ('control 23', {'front_m': 700, 'length_m': 100, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 200, 'to_m': 300, 'kmh': 40}, {'from_m': 800, 'to_m': 900, 'kmh': 80}]}, {'limit': 120, 'next_m': 800}), ('control 29', {'front_m': 100, 'length_m': 200, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 0, 'to_m': 300, 'kmh': 20}, {'from_m': 200, 'to_m': 800, 'kmh': 80}, {'from_m': 0, 'to_m': 100, 'kmh': 20}]}, {'limit': 20, 'next_m': None}), ('control 32', {'front_m': 1100, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1100, 'kmh': 20}]}, {'limit': 20, 'next_m': None})], [('regression: restriction exactly at sighting distance', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 600, 'to_m': 700, 'kmh': 40}]}, {'limit': 100, 'next_m': 600}), ('sampled regression 62', {'front_m': 500, 'length_m': 400, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 1500, 'to_m': 2100, 'kmh': 40}, {'from_m': 1000, 'to_m': 1600, 'kmh': 20}]}, {'limit': 100, 'next_m': 1000}), ('control 57', {'front_m': 250, 'length_m': 200, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1600, 'kmh': 40}, {'from_m': 800, 'to_m': 1100, 'kmh': 60}, {'from_m': 500, 'to_m': 800, 'kmh': 40}, {'from_m': 500, 'to_m': 600, 'kmh': 40}]}, {'limit': 120, 'next_m': 500}), ('boundary: restriction just behind the rear', {'front_m': 1000, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 900, 'kmh': 20}]}, {'limit': 100, 'next_m': None}), ('boundary: rear still inside the restriction', {'front_m': 700, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}]}, {'limit': 40, 'next_m': None}), ('sampled regression 34', {'front_m': 700, 'length_m': 200, 'line_kmh': 100, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1300, 'kmh': 80}, {'from_m': 0, 'to_m': 300, 'kmh': 20}, {'from_m': 1000, 'to_m': 1600, 'kmh': 80}, {'from_m': 1000, 'to_m': 1300, 'kmh': 60}]}, {'limit': 100, 'next_m': 1000}), ('control 37', {'front_m': 500, 'length_m': 400, 'line_kmh': 100, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1600, 'kmh': 60}, {'from_m': 200, 'to_m': 800, 'kmh': 40}, {'from_m': 0, 'to_m': 100, 'kmh': 20}, {'from_m': 1500, 'to_m': 1800, 'kmh': 20}]}, {'limit': 40, 'next_m': None}), ('control 40', {'front_m': 1300, 'length_m': 200, 'line_kmh': 120, 'sight_m': 500, 'tsr': [{'from_m': 1000, 'to_m': 1100, 'kmh': 60}, {'from_m': 1500, 'to_m': 2100, 'kmh': 20}]}, {'limit': 120, 'next_m': 1500})], [('regression: restriction exactly at sighting distance', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 600, 'to_m': 700, 'kmh': 40}]}, {'limit': 100, 'next_m': 600}), ('sampled regression 5', {'front_m': 500, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 800, 'to_m': 1100, 'kmh': 20}]}, {'limit': 120, 'next_m': 800}), ('boundary: rear exactly at the restriction end', {'front_m': 800, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}]}, {'limit': 100, 'next_m': None}), ('boundary: restriction ahead faster than current limit', {'front_m': 500, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}, {'from_m': 800, 'to_m': 900, 'kmh': 60}]}, {'limit': 40, 'next_m': None}), ('boundary: restriction ahead slower than line speed only', {'front_m': 500, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 450, 'to_m': 700, 'kmh': 30}, {'from_m': 800, 'to_m': 900, 'kmh': 60}]}, {'limit': 30, 'next_m': None}), ('control 45', {'front_m': 700, 'length_m': 200, 'line_kmh': 100, 'sight_m': 300, 'tsr': [{'from_m': 0, 'to_m': 300, 'kmh': 60}, {'from_m': 200, 'to_m': 800, 'kmh': 80}, {'from_m': 800, 'to_m': 1100, 'kmh': 40}, {'from_m': 200, 'to_m': 500, 'kmh': 60}]}, {'limit': 80, 'next_m': 800}), ('control 48', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 200, 'to_m': 800, 'kmh': 80}, {'from_m': 800, 'to_m': 1400, 'kmh': 80}, {'from_m': 1000, 'to_m': 1100, 'kmh': 40}, {'from_m': 0, 'to_m': 100, 'kmh': 20}]}, {'limit': 20, 'next_m': None}), ('control 51', {'front_m': 900, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 600, 'kmh': 40}]}, {'limit': 100, 'next_m': None})]]
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: restriction exactly at sighting distance{'limit': 100, 'next_m': None}{'limit': 100, 'next_m': 600}Failed
sampled regression 34{'limit': 100, 'next_m': None}{'limit': 100, 'next_m': 1000}Failed
sampled regression 5{'limit': 120, 'next_m': None}{'limit': 120, 'next_m': 800}Failed
boundary: rear still inside the restriction{'limit': 40, 'next_m': None}{'limit': 40, 'next_m': None}Passed
boundary: rear exactly at the restriction end{'limit': 100, 'next_m': None}{'limit': 100, 'next_m': None}Passed
control 1{'limit': 40, 'next_m': None}{'limit': 40, 'next_m': None}Passed
control 4{'limit': 20, 'next_m': None}{'limit': 20, 'next_m': None}Passed
control 7{'limit': 60, 'next_m': None}{'limit': 60, 'next_m': None}Passed

SHA-256 / 1a589044bbad198e3a9977a6c061cc9b5ba1a7a0b1890be44b5b299d958ec407

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    front = x['front_m']
    rear = front - x['length_m']
    limit = x['line_kmh']
    for s in x['tsr']:
        if s['from_m'] <= front and s['to_m'] > rear:
            limit = min(limit, s['kmh'])
    ahead = [s for s in x['tsr'] if s['from_m'] > front and s['from_m'] - front <= x['sight_m'] and s['kmh'] < limit]
    nxt = min(ahead, key=lambda s: s['from_m'])['from_m'] if ahead else None
    return {'limit': limit, 'next_m': nxt}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: restriction exactly at sighting distance', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 600, 'to_m': 700, 'kmh': 40}]}, {'limit': 100, 'next_m': 600}), ('sampled regression 34', {'front_m': 700, 'length_m': 200, 'line_kmh': 100, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1300, 'kmh': 80}, {'from_m': 0, 'to_m': 300, 'kmh': 20}, {'from_m': 1000, 'to_m': 1600, 'kmh': 80}, {'from_m': 1000, 'to_m': 1300, 'kmh': 60}]}, {'limit': 100, 'next_m': 1000}), ('sampled regression 5', {'front_m': 500, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 800, 'to_m': 1100, 'kmh': 20}]}, {'limit': 120, 'next_m': 800}), ('boundary: rear still inside the restriction', {'front_m': 700, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}]}, {'limit': 40, 'next_m': None}), ('boundary: rear exactly at the restriction end', {'front_m': 800, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}]}, {'limit': 100, 'next_m': None}), ('control 1', {'front_m': 1100, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 1500, 'to_m': 2100, 'kmh': 40}, {'from_m': 800, 'to_m': 1100, 'kmh': 40}]}, {'limit': 40, 'next_m': None}), ('control 4', {'front_m': 700, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1100, 'kmh': 40}, {'from_m': 1000, 'to_m': 1600, 'kmh': 20}, {'from_m': 800, 'to_m': 900, 'kmh': 20}, {'from_m': 500, 'to_m': 600, 'kmh': 20}]}, {'limit': 20, 'next_m': None}), ('control 7', {'front_m': 1100, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 800, 'kmh': 40}, {'from_m': 1000, 'to_m': 1300, 'kmh': 60}]}, {'limit': 60, 'next_m': None})], [('regression: restriction exactly at sighting distance', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 600, 'to_m': 700, 'kmh': 40}]}, {'limit': 100, 'next_m': 600}), ('control 57', {'front_m': 250, 'length_m': 200, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1600, 'kmh': 40}, {'from_m': 800, 'to_m': 1100, 'kmh': 60}, {'from_m': 500, 'to_m': 800, 'kmh': 40}, {'from_m': 500, 'to_m': 600, 'kmh': 40}]}, {'limit': 120, 'next_m': 500}), ('boundary: restriction ahead faster than current limit', {'front_m': 500, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}, {'from_m': 800, 'to_m': 900, 'kmh': 60}]}, {'limit': 40, 'next_m': None}), ('boundary: restriction ahead slower than line speed only', {'front_m': 500, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 450, 'to_m': 700, 'kmh': 30}, {'from_m': 800, 'to_m': 900, 'kmh': 60}]}, {'limit': 30, 'next_m': None}), ('boundary: two restrictions ahead listed far first', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 600, 'kmh': 40}, {'from_m': 300, 'to_m': 400, 'kmh': 60}]}, {'limit': 100, 'next_m': 300}), ('control 12', {'front_m': 1300, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 500, 'to_m': 1100, 'kmh': 20}, {'from_m': 1500, 'to_m': 1600, 'kmh': 20}, {'from_m': 200, 'to_m': 300, 'kmh': 40}]}, {'limit': 20, 'next_m': None}), ('control 15', {'front_m': 100, 'length_m': 400, 'line_kmh': 120, 'sight_m': 500, 'tsr': [{'from_m': 1500, 'to_m': 2100, 'kmh': 60}, {'from_m': 800, 'to_m': 900, 'kmh': 20}, {'from_m': 200, 'to_m': 300, 'kmh': 40}]}, {'limit': 120, 'next_m': 200}), ('control 18', {'front_m': 700, 'length_m': 400, 'line_kmh': 120, 'sight_m': 500, 'tsr': [{'from_m': 1000, 'to_m': 1300, 'kmh': 60}]}, {'limit': 120, 'next_m': 1000})], [('regression: restriction exactly at sighting distance', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 600, 'to_m': 700, 'kmh': 40}]}, {'limit': 100, 'next_m': 600}), ('sampled regression 26', {'front_m': 500, 'length_m': 100, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 800, 'to_m': 1100, 'kmh': 40}]}, {'limit': 120, 'next_m': 800}), ('sampled regression 5', {'front_m': 500, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 800, 'to_m': 1100, 'kmh': 20}]}, {'limit': 120, 'next_m': 800}), ('boundary: two restrictions ahead listed far first', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 600, 'kmh': 40}, {'from_m': 300, 'to_m': 400, 'kmh': 60}]}, {'limit': 100, 'next_m': 300}), ('boundary: restriction just behind the rear', {'front_m': 1000, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 900, 'kmh': 20}]}, {'limit': 100, 'next_m': None}), ('control 23', {'front_m': 700, 'length_m': 100, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 200, 'to_m': 300, 'kmh': 40}, {'from_m': 800, 'to_m': 900, 'kmh': 80}]}, {'limit': 120, 'next_m': 800}), ('control 29', {'front_m': 100, 'length_m': 200, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 0, 'to_m': 300, 'kmh': 20}, {'from_m': 200, 'to_m': 800, 'kmh': 80}, {'from_m': 0, 'to_m': 100, 'kmh': 20}]}, {'limit': 20, 'next_m': None}), ('control 32', {'front_m': 1100, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1100, 'kmh': 20}]}, {'limit': 20, 'next_m': None})], [('regression: restriction exactly at sighting distance', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 600, 'to_m': 700, 'kmh': 40}]}, {'limit': 100, 'next_m': 600}), ('sampled regression 62', {'front_m': 500, 'length_m': 400, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 1500, 'to_m': 2100, 'kmh': 40}, {'from_m': 1000, 'to_m': 1600, 'kmh': 20}]}, {'limit': 100, 'next_m': 1000}), ('control 57', {'front_m': 250, 'length_m': 200, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1600, 'kmh': 40}, {'from_m': 800, 'to_m': 1100, 'kmh': 60}, {'from_m': 500, 'to_m': 800, 'kmh': 40}, {'from_m': 500, 'to_m': 600, 'kmh': 40}]}, {'limit': 120, 'next_m': 500}), ('boundary: restriction just behind the rear', {'front_m': 1000, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 900, 'kmh': 20}]}, {'limit': 100, 'next_m': None}), ('boundary: rear still inside the restriction', {'front_m': 700, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}]}, {'limit': 40, 'next_m': None}), ('sampled regression 34', {'front_m': 700, 'length_m': 200, 'line_kmh': 100, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1300, 'kmh': 80}, {'from_m': 0, 'to_m': 300, 'kmh': 20}, {'from_m': 1000, 'to_m': 1600, 'kmh': 80}, {'from_m': 1000, 'to_m': 1300, 'kmh': 60}]}, {'limit': 100, 'next_m': 1000}), ('control 37', {'front_m': 500, 'length_m': 400, 'line_kmh': 100, 'sight_m': 300, 'tsr': [{'from_m': 1000, 'to_m': 1600, 'kmh': 60}, {'from_m': 200, 'to_m': 800, 'kmh': 40}, {'from_m': 0, 'to_m': 100, 'kmh': 20}, {'from_m': 1500, 'to_m': 1800, 'kmh': 20}]}, {'limit': 40, 'next_m': None}), ('control 40', {'front_m': 1300, 'length_m': 200, 'line_kmh': 120, 'sight_m': 500, 'tsr': [{'from_m': 1000, 'to_m': 1100, 'kmh': 60}, {'from_m': 1500, 'to_m': 2100, 'kmh': 20}]}, {'limit': 120, 'next_m': 1500})], [('regression: restriction exactly at sighting distance', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 600, 'to_m': 700, 'kmh': 40}]}, {'limit': 100, 'next_m': 600}), ('sampled regression 5', {'front_m': 500, 'length_m': 400, 'line_kmh': 120, 'sight_m': 300, 'tsr': [{'from_m': 800, 'to_m': 1100, 'kmh': 20}]}, {'limit': 120, 'next_m': 800}), ('boundary: rear exactly at the restriction end', {'front_m': 800, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}]}, {'limit': 100, 'next_m': None}), ('boundary: restriction ahead faster than current limit', {'front_m': 500, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 400, 'to_m': 600, 'kmh': 40}, {'from_m': 800, 'to_m': 900, 'kmh': 60}]}, {'limit': 40, 'next_m': None}), ('boundary: restriction ahead slower than line speed only', {'front_m': 500, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 450, 'to_m': 700, 'kmh': 30}, {'from_m': 800, 'to_m': 900, 'kmh': 60}]}, {'limit': 30, 'next_m': None}), ('control 45', {'front_m': 700, 'length_m': 200, 'line_kmh': 100, 'sight_m': 300, 'tsr': [{'from_m': 0, 'to_m': 300, 'kmh': 60}, {'from_m': 200, 'to_m': 800, 'kmh': 80}, {'from_m': 800, 'to_m': 1100, 'kmh': 40}, {'from_m': 200, 'to_m': 500, 'kmh': 60}]}, {'limit': 80, 'next_m': 800}), ('control 48', {'front_m': 100, 'length_m': 100, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 200, 'to_m': 800, 'kmh': 80}, {'from_m': 800, 'to_m': 1400, 'kmh': 80}, {'from_m': 1000, 'to_m': 1100, 'kmh': 40}, {'from_m': 0, 'to_m': 100, 'kmh': 20}]}, {'limit': 20, 'next_m': None}), ('control 51', {'front_m': 900, 'length_m': 200, 'line_kmh': 100, 'sight_m': 500, 'tsr': [{'from_m': 500, 'to_m': 600, 'kmh': 40}]}, {'limit': 100, 'next_m': None})]]
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: restriction exactly at sighting distance{'limit': 100, 'next_m': 600}{'limit': 100, 'next_m': 600}Passed
sampled regression 34{'limit': 100, 'next_m': 1000}{'limit': 100, 'next_m': 1000}Passed
sampled regression 5{'limit': 120, 'next_m': 800}{'limit': 120, 'next_m': 800}Passed
boundary: rear still inside the restriction{'limit': 40, 'next_m': None}{'limit': 40, 'next_m': None}Passed
boundary: rear exactly at the restriction end{'limit': 100, 'next_m': None}{'limit': 100, 'next_m': None}Passed
control 1{'limit': 40, 'next_m': None}{'limit': 40, 'next_m': None}Passed
control 4{'limit': 20, 'next_m': None}{'limit': 20, 'next_m': None}Passed
control 7{'limit': 60, 'next_m': None}{'limit': 60, 'next_m': None}Passed

SHA-256 / a167d7445c56ef53c7b7cbbd4a6aed3285ebdb6b76db3c065826788d2df3ab73

Verification & scope

Stipulated toy interlocking contract for a bounded teaching model; it makes no claim of conformance to any railway signalling standard 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 2026-09-29T14:47:51.982542+00:00.

Case digest / 8fb19a7c3a62d9754065788bd47950293904e4105c9b7af252731028428447f3