FA-68966 / Tide and marine navigation tables / Open access

Bridge air draft clearance: Rising tide increases the bridge clearance · case 01

Clearance appears to grow as the tide rises, approving transits at high water.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The difference between MHWS and the current tide is taken as tide-mhws.

VERIFIED REPAIR

Add mhws-tide to the charted clearance.

Unsuccessful approach: Taking the absolute difference is right below MHWS but grows clearance during surges.

Case contract

Input [c, mhws, tide, air, safety]: charted vertical clearance c is measured above MHWS; mhws and tide are heights above chart datum; air is the vessel air draft. Available clearance = c+(mhws-tide) (it shrinks when the tide exceeds MHWS). Return [round(avail,2), round(avail-air,2), avail-air>=safety].

Why this case matters

Tide tables and passage plans turn published predictions into go/no-go decisions about depth, clearance and timing.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    c,mhws,tide,air,safety=x
    avail=c+(tide-mhws)
    margin=avail-air
    return [round(avail,2),round(margin,2),margin>=safety]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('bridge air draft clearance [18.0, 4.6, 1.2, 20.5, 1.0]', [18.0, 4.6, 1.2, 20.5, 1.0], [21.4, 0.9, False]), ('bridge air draft clearance [18.0, 4.6, 5.3, 17.0, 1.0]', [18.0, 4.6, 5.3, 17.0, 1.0], [17.3, 0.3, False]), ('bridge air draft clearance [18.0, 4.6, 4.6, 17.0, 1.0]', [18.0, 4.6, 4.6, 17.0, 1.0], [18.0, 1.0, True]), ('bridge air draft clearance [18.0, 4.6, 5.1, 16.9, 0.5]', [18.0, 4.6, 5.1, 16.9, 0.5], [17.5, 0.6, True]), ('bridge air draft clearance [12.5, 6.1, 0.4, 17.0, 0.5]', [12.5, 6.1, 0.4, 17.0, 0.5], [18.2, 1.2, True]), ('bridge air draft clearance [12.5, 6.1, 3.0, 14.9, 0.7]', [12.5, 6.1, 3.0, 14.9, 0.7], [15.6, 0.7, False]), ('bridge air draft clearance [30.0, 2.2, 2.9, 29.0, 0.2]', [30.0, 2.2, 2.9, 29.0, 0.2], [29.3, 0.3, True])], [('bridge air draft clearance [18.0, 4.6, 5.3, 17.0, 1.0]', [18.0, 4.6, 5.3, 17.0, 1.0], [17.3, 0.3, False]), ('bridge air draft clearance [18.0, 4.6, 5.1, 16.9, 0.5]', [18.0, 4.6, 5.1, 16.9, 0.5], [17.5, 0.6, True]), ('bridge air draft clearance [12.5, 6.1, 0.4, 17.0, 0.5]', [12.5, 6.1, 0.4, 17.0, 0.5], [18.2, 1.2, True]), ('bridge air draft clearance [12.5, 6.1, 3.0, 14.9, 0.7]', [12.5, 6.1, 3.0, 14.9, 0.7], [15.6, 0.7, False]), ('bridge air draft clearance [30.0, 2.2, 2.9, 29.0, 0.2]', [30.0, 2.2, 2.9, 29.0, 0.2], [29.3, 0.3, True]), ('bridge air draft clearance [9.0, 5.0, 5.0, 8.5, 0.5]', [9.0, 5.0, 5.0, 8.5, 0.5], [9.0, 0.5, True]), ('bridge air draft clearance [9.0, 5.0, 2.5, 11.0, 0.5]', [9.0, 5.0, 2.5, 11.0, 0.5], [11.5, 0.5, True])], [('bridge air draft clearance [18.0, 4.6, 5.1, 16.9, 0.5]', [18.0, 4.6, 5.1, 16.9, 0.5], [17.5, 0.6, True]), ('bridge air draft clearance [30.0, 2.2, 2.9, 29.0, 0.2]', [30.0, 2.2, 2.9, 29.0, 0.2], [29.3, 0.3, True]), ('bridge air draft clearance [9.0, 5.0, 5.0, 8.5, 0.5]', [9.0, 5.0, 5.0, 8.5, 0.5], [9.0, 0.5, True]), ('bridge air draft clearance [9.0, 5.0, 2.5, 11.0, 0.5]', [9.0, 5.0, 2.5, 11.0, 0.5], [11.5, 0.5, True]), ('bridge air draft clearance [9.0, 5.0, 6.0, 7.5, 0.4]', [9.0, 5.0, 6.0, 7.5, 0.4], [8.0, 0.5, True]), ('bridge air draft clearance [22.0, 3.5, 0.0, 25.0, 0.5]', [22.0, 3.5, 0.0, 25.0, 0.5], [25.5, 0.5, True]), ('bridge air draft clearance [15.0, 4.0, 4.4, 14.1, 0.5]', [15.0, 4.0, 4.4, 14.1, 0.5], [14.6, 0.5, True])], [('bridge air draft clearance [12.5, 6.1, 0.4, 17.0, 0.5]', [12.5, 6.1, 0.4, 17.0, 0.5], [18.2, 1.2, True]), ('bridge air draft clearance [9.0, 5.0, 6.0, 7.5, 0.4]', [9.0, 5.0, 6.0, 7.5, 0.4], [8.0, 0.5, True]), ('bridge air draft clearance [22.0, 3.5, 0.0, 25.0, 0.5]', [22.0, 3.5, 0.0, 25.0, 0.5], [25.5, 0.5, True]), ('bridge air draft clearance [15.0, 4.0, 4.4, 14.1, 0.5]', [15.0, 4.0, 4.4, 14.1, 0.5], [14.6, 0.5, True]), ('bridge air draft clearance [15.0, 4.0, 2.0, 16.46, 0.5]', [15.0, 4.0, 2.0, 16.46, 0.5], [17.0, 0.54, True]), ('bridge air draft clearance [15.0, 4.0, 4.8, 13.5, 0.2]', [15.0, 4.0, 4.8, 13.5, 0.2], [14.2, 0.7, True]), ('bridge air draft clearance [15.0, 4.0, 4.0, 14.42, 0.55]', [15.0, 4.0, 4.0, 14.42, 0.55], [15.0, 0.58, True])], [('bridge air draft clearance [12.5, 6.1, 3.0, 14.9, 0.7]', [12.5, 6.1, 3.0, 14.9, 0.7], [15.6, 0.7, False]), ('bridge air draft clearance [15.0, 4.0, 4.4, 14.1, 0.5]', [15.0, 4.0, 4.4, 14.1, 0.5], [14.6, 0.5, True]), ('bridge air draft clearance [15.0, 4.0, 2.0, 16.46, 0.5]', [15.0, 4.0, 2.0, 16.46, 0.5], [17.0, 0.54, True]), ('bridge air draft clearance [15.0, 4.0, 4.8, 13.5, 0.2]', [15.0, 4.0, 4.8, 13.5, 0.2], [14.2, 0.7, True]), ('bridge air draft clearance [15.0, 4.0, 4.0, 14.42, 0.55]', [15.0, 4.0, 4.0, 14.42, 0.55], [15.0, 0.58, True]), ('bridge air draft clearance [15.0, 4.0, 4.1, 14.35, 0.5]', [15.0, 4.0, 4.1, 14.35, 0.5], [14.9, 0.55, True]), ('bridge air draft clearance [18.0, 4.6, 1.2, 20.5, 1.0]', [18.0, 4.6, 1.2, 20.5, 1.0], [21.4, 0.9, 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 fixture	Actual	Expected	Outcome
bridge air draft clearance [18.0, 4.6, 1.2, 20.5, 1.0]	`[14.6, -5.9, False]`	`[21.4, 0.9, False]`	Failed
bridge air draft clearance [18.0, 4.6, 5.3, 17.0, 1.0]	`[18.7, 1.7, True]`	`[17.3, 0.3, False]`	Failed
bridge air draft clearance [18.0, 4.6, 4.6, 17.0, 1.0]	`[18.0, 1.0, True]`	`[18.0, 1.0, True]`	Passed
bridge air draft clearance [18.0, 4.6, 5.1, 16.9, 0.5]	`[18.5, 1.6, True]`	`[17.5, 0.6, True]`	Failed
bridge air draft clearance [12.5, 6.1, 0.4, 17.0, 0.5]	`[6.8, -10.2, False]`	`[18.2, 1.2, True]`	Failed
bridge air draft clearance [12.5, 6.1, 3.0, 14.9, 0.7]	`[9.4, -5.5, False]`	`[15.6, 0.7, False]`	Failed
bridge air draft clearance [30.0, 2.2, 2.9, 29.0, 0.2]	`[30.7, 1.7, True]`	`[29.3, 0.3, True]`	Failed

SHA-256 / 5de59a07f46a58bb5b89cb4b9eb311461b0e297b85d896e652a8d9ca7b4aee18

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    c,mhws,tide,air,safety=x
    avail=c+abs(mhws-tide)
    margin=avail-air
    return [round(avail,2),round(margin,2),margin>=safety]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('bridge air draft clearance [18.0, 4.6, 1.2, 20.5, 1.0]', [18.0, 4.6, 1.2, 20.5, 1.0], [21.4, 0.9, False]), ('bridge air draft clearance [18.0, 4.6, 5.3, 17.0, 1.0]', [18.0, 4.6, 5.3, 17.0, 1.0], [17.3, 0.3, False]), ('bridge air draft clearance [18.0, 4.6, 4.6, 17.0, 1.0]', [18.0, 4.6, 4.6, 17.0, 1.0], [18.0, 1.0, True]), ('bridge air draft clearance [18.0, 4.6, 5.1, 16.9, 0.5]', [18.0, 4.6, 5.1, 16.9, 0.5], [17.5, 0.6, True]), ('bridge air draft clearance [12.5, 6.1, 0.4, 17.0, 0.5]', [12.5, 6.1, 0.4, 17.0, 0.5], [18.2, 1.2, True]), ('bridge air draft clearance [12.5, 6.1, 3.0, 14.9, 0.7]', [12.5, 6.1, 3.0, 14.9, 0.7], [15.6, 0.7, False]), ('bridge air draft clearance [30.0, 2.2, 2.9, 29.0, 0.2]', [30.0, 2.2, 2.9, 29.0, 0.2], [29.3, 0.3, True])], [('bridge air draft clearance [18.0, 4.6, 5.3, 17.0, 1.0]', [18.0, 4.6, 5.3, 17.0, 1.0], [17.3, 0.3, False]), ('bridge air draft clearance [18.0, 4.6, 5.1, 16.9, 0.5]', [18.0, 4.6, 5.1, 16.9, 0.5], [17.5, 0.6, True]), ('bridge air draft clearance [12.5, 6.1, 0.4, 17.0, 0.5]', [12.5, 6.1, 0.4, 17.0, 0.5], [18.2, 1.2, True]), ('bridge air draft clearance [12.5, 6.1, 3.0, 14.9, 0.7]', [12.5, 6.1, 3.0, 14.9, 0.7], [15.6, 0.7, False]), ('bridge air draft clearance [30.0, 2.2, 2.9, 29.0, 0.2]', [30.0, 2.2, 2.9, 29.0, 0.2], [29.3, 0.3, True]), ('bridge air draft clearance [9.0, 5.0, 5.0, 8.5, 0.5]', [9.0, 5.0, 5.0, 8.5, 0.5], [9.0, 0.5, True]), ('bridge air draft clearance [9.0, 5.0, 2.5, 11.0, 0.5]', [9.0, 5.0, 2.5, 11.0, 0.5], [11.5, 0.5, True])], [('bridge air draft clearance [18.0, 4.6, 5.1, 16.9, 0.5]', [18.0, 4.6, 5.1, 16.9, 0.5], [17.5, 0.6, True]), ('bridge air draft clearance [30.0, 2.2, 2.9, 29.0, 0.2]', [30.0, 2.2, 2.9, 29.0, 0.2], [29.3, 0.3, True]), ('bridge air draft clearance [9.0, 5.0, 5.0, 8.5, 0.5]', [9.0, 5.0, 5.0, 8.5, 0.5], [9.0, 0.5, True]), ('bridge air draft clearance [9.0, 5.0, 2.5, 11.0, 0.5]', [9.0, 5.0, 2.5, 11.0, 0.5], [11.5, 0.5, True]), ('bridge air draft clearance [9.0, 5.0, 6.0, 7.5, 0.4]', [9.0, 5.0, 6.0, 7.5, 0.4], [8.0, 0.5, True]), ('bridge air draft clearance [22.0, 3.5, 0.0, 25.0, 0.5]', [22.0, 3.5, 0.0, 25.0, 0.5], [25.5, 0.5, True]), ('bridge air draft clearance [15.0, 4.0, 4.4, 14.1, 0.5]', [15.0, 4.0, 4.4, 14.1, 0.5], [14.6, 0.5, True])], [('bridge air draft clearance [12.5, 6.1, 0.4, 17.0, 0.5]', [12.5, 6.1, 0.4, 17.0, 0.5], [18.2, 1.2, True]), ('bridge air draft clearance [9.0, 5.0, 6.0, 7.5, 0.4]', [9.0, 5.0, 6.0, 7.5, 0.4], [8.0, 0.5, True]), ('bridge air draft clearance [22.0, 3.5, 0.0, 25.0, 0.5]', [22.0, 3.5, 0.0, 25.0, 0.5], [25.5, 0.5, True]), ('bridge air draft clearance [15.0, 4.0, 4.4, 14.1, 0.5]', [15.0, 4.0, 4.4, 14.1, 0.5], [14.6, 0.5, True]), ('bridge air draft clearance [15.0, 4.0, 2.0, 16.46, 0.5]', [15.0, 4.0, 2.0, 16.46, 0.5], [17.0, 0.54, True]), ('bridge air draft clearance [15.0, 4.0, 4.8, 13.5, 0.2]', [15.0, 4.0, 4.8, 13.5, 0.2], [14.2, 0.7, True]), ('bridge air draft clearance [15.0, 4.0, 4.0, 14.42, 0.55]', [15.0, 4.0, 4.0, 14.42, 0.55], [15.0, 0.58, True])], [('bridge air draft clearance [12.5, 6.1, 3.0, 14.9, 0.7]', [12.5, 6.1, 3.0, 14.9, 0.7], [15.6, 0.7, False]), ('bridge air draft clearance [15.0, 4.0, 4.4, 14.1, 0.5]', [15.0, 4.0, 4.4, 14.1, 0.5], [14.6, 0.5, True]), ('bridge air draft clearance [15.0, 4.0, 2.0, 16.46, 0.5]', [15.0, 4.0, 2.0, 16.46, 0.5], [17.0, 0.54, True]), ('bridge air draft clearance [15.0, 4.0, 4.8, 13.5, 0.2]', [15.0, 4.0, 4.8, 13.5, 0.2], [14.2, 0.7, True]), ('bridge air draft clearance [15.0, 4.0, 4.0, 14.42, 0.55]', [15.0, 4.0, 4.0, 14.42, 0.55], [15.0, 0.58, True]), ('bridge air draft clearance [15.0, 4.0, 4.1, 14.35, 0.5]', [15.0, 4.0, 4.1, 14.35, 0.5], [14.9, 0.55, True]), ('bridge air draft clearance [18.0, 4.6, 1.2, 20.5, 1.0]', [18.0, 4.6, 1.2, 20.5, 1.0], [21.4, 0.9, 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 fixture	Actual	Expected	Outcome
bridge air draft clearance [18.0, 4.6, 1.2, 20.5, 1.0]	`[21.4, 0.9, False]`	`[21.4, 0.9, False]`	Passed
bridge air draft clearance [18.0, 4.6, 5.3, 17.0, 1.0]	`[18.7, 1.7, True]`	`[17.3, 0.3, False]`	Failed
bridge air draft clearance [18.0, 4.6, 4.6, 17.0, 1.0]	`[18.0, 1.0, True]`	`[18.0, 1.0, True]`	Passed
bridge air draft clearance [18.0, 4.6, 5.1, 16.9, 0.5]	`[18.5, 1.6, True]`	`[17.5, 0.6, True]`	Failed
bridge air draft clearance [12.5, 6.1, 0.4, 17.0, 0.5]	`[18.2, 1.2, True]`	`[18.2, 1.2, True]`	Passed
bridge air draft clearance [12.5, 6.1, 3.0, 14.9, 0.7]	`[15.6, 0.7, False]`	`[15.6, 0.7, False]`	Passed
bridge air draft clearance [30.0, 2.2, 2.9, 29.0, 0.2]	`[30.7, 1.7, True]`	`[29.3, 0.3, True]`	Failed

SHA-256 / 505e6267defc28bc168a215348377cd2dc0d9d1ff06b32506088a662b45cae5d

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    c,mhws,tide,air,safety=x
    avail=c+(mhws-tide)
    margin=avail-air
    return [round(avail,2),round(margin,2),margin>=safety]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('bridge air draft clearance [18.0, 4.6, 1.2, 20.5, 1.0]', [18.0, 4.6, 1.2, 20.5, 1.0], [21.4, 0.9, False]), ('bridge air draft clearance [18.0, 4.6, 5.3, 17.0, 1.0]', [18.0, 4.6, 5.3, 17.0, 1.0], [17.3, 0.3, False]), ('bridge air draft clearance [18.0, 4.6, 4.6, 17.0, 1.0]', [18.0, 4.6, 4.6, 17.0, 1.0], [18.0, 1.0, True]), ('bridge air draft clearance [18.0, 4.6, 5.1, 16.9, 0.5]', [18.0, 4.6, 5.1, 16.9, 0.5], [17.5, 0.6, True]), ('bridge air draft clearance [12.5, 6.1, 0.4, 17.0, 0.5]', [12.5, 6.1, 0.4, 17.0, 0.5], [18.2, 1.2, True]), ('bridge air draft clearance [12.5, 6.1, 3.0, 14.9, 0.7]', [12.5, 6.1, 3.0, 14.9, 0.7], [15.6, 0.7, False]), ('bridge air draft clearance [30.0, 2.2, 2.9, 29.0, 0.2]', [30.0, 2.2, 2.9, 29.0, 0.2], [29.3, 0.3, True])], [('bridge air draft clearance [18.0, 4.6, 5.3, 17.0, 1.0]', [18.0, 4.6, 5.3, 17.0, 1.0], [17.3, 0.3, False]), ('bridge air draft clearance [18.0, 4.6, 5.1, 16.9, 0.5]', [18.0, 4.6, 5.1, 16.9, 0.5], [17.5, 0.6, True]), ('bridge air draft clearance [12.5, 6.1, 0.4, 17.0, 0.5]', [12.5, 6.1, 0.4, 17.0, 0.5], [18.2, 1.2, True]), ('bridge air draft clearance [12.5, 6.1, 3.0, 14.9, 0.7]', [12.5, 6.1, 3.0, 14.9, 0.7], [15.6, 0.7, False]), ('bridge air draft clearance [30.0, 2.2, 2.9, 29.0, 0.2]', [30.0, 2.2, 2.9, 29.0, 0.2], [29.3, 0.3, True]), ('bridge air draft clearance [9.0, 5.0, 5.0, 8.5, 0.5]', [9.0, 5.0, 5.0, 8.5, 0.5], [9.0, 0.5, True]), ('bridge air draft clearance [9.0, 5.0, 2.5, 11.0, 0.5]', [9.0, 5.0, 2.5, 11.0, 0.5], [11.5, 0.5, True])], [('bridge air draft clearance [18.0, 4.6, 5.1, 16.9, 0.5]', [18.0, 4.6, 5.1, 16.9, 0.5], [17.5, 0.6, True]), ('bridge air draft clearance [30.0, 2.2, 2.9, 29.0, 0.2]', [30.0, 2.2, 2.9, 29.0, 0.2], [29.3, 0.3, True]), ('bridge air draft clearance [9.0, 5.0, 5.0, 8.5, 0.5]', [9.0, 5.0, 5.0, 8.5, 0.5], [9.0, 0.5, True]), ('bridge air draft clearance [9.0, 5.0, 2.5, 11.0, 0.5]', [9.0, 5.0, 2.5, 11.0, 0.5], [11.5, 0.5, True]), ('bridge air draft clearance [9.0, 5.0, 6.0, 7.5, 0.4]', [9.0, 5.0, 6.0, 7.5, 0.4], [8.0, 0.5, True]), ('bridge air draft clearance [22.0, 3.5, 0.0, 25.0, 0.5]', [22.0, 3.5, 0.0, 25.0, 0.5], [25.5, 0.5, True]), ('bridge air draft clearance [15.0, 4.0, 4.4, 14.1, 0.5]', [15.0, 4.0, 4.4, 14.1, 0.5], [14.6, 0.5, True])], [('bridge air draft clearance [12.5, 6.1, 0.4, 17.0, 0.5]', [12.5, 6.1, 0.4, 17.0, 0.5], [18.2, 1.2, True]), ('bridge air draft clearance [9.0, 5.0, 6.0, 7.5, 0.4]', [9.0, 5.0, 6.0, 7.5, 0.4], [8.0, 0.5, True]), ('bridge air draft clearance [22.0, 3.5, 0.0, 25.0, 0.5]', [22.0, 3.5, 0.0, 25.0, 0.5], [25.5, 0.5, True]), ('bridge air draft clearance [15.0, 4.0, 4.4, 14.1, 0.5]', [15.0, 4.0, 4.4, 14.1, 0.5], [14.6, 0.5, True]), ('bridge air draft clearance [15.0, 4.0, 2.0, 16.46, 0.5]', [15.0, 4.0, 2.0, 16.46, 0.5], [17.0, 0.54, True]), ('bridge air draft clearance [15.0, 4.0, 4.8, 13.5, 0.2]', [15.0, 4.0, 4.8, 13.5, 0.2], [14.2, 0.7, True]), ('bridge air draft clearance [15.0, 4.0, 4.0, 14.42, 0.55]', [15.0, 4.0, 4.0, 14.42, 0.55], [15.0, 0.58, True])], [('bridge air draft clearance [12.5, 6.1, 3.0, 14.9, 0.7]', [12.5, 6.1, 3.0, 14.9, 0.7], [15.6, 0.7, False]), ('bridge air draft clearance [15.0, 4.0, 4.4, 14.1, 0.5]', [15.0, 4.0, 4.4, 14.1, 0.5], [14.6, 0.5, True]), ('bridge air draft clearance [15.0, 4.0, 2.0, 16.46, 0.5]', [15.0, 4.0, 2.0, 16.46, 0.5], [17.0, 0.54, True]), ('bridge air draft clearance [15.0, 4.0, 4.8, 13.5, 0.2]', [15.0, 4.0, 4.8, 13.5, 0.2], [14.2, 0.7, True]), ('bridge air draft clearance [15.0, 4.0, 4.0, 14.42, 0.55]', [15.0, 4.0, 4.0, 14.42, 0.55], [15.0, 0.58, True]), ('bridge air draft clearance [15.0, 4.0, 4.1, 14.35, 0.5]', [15.0, 4.0, 4.1, 14.35, 0.5], [14.9, 0.55, True]), ('bridge air draft clearance [18.0, 4.6, 1.2, 20.5, 1.0]', [18.0, 4.6, 1.2, 20.5, 1.0], [21.4, 0.9, 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 fixture	Actual	Expected	Outcome
bridge air draft clearance [18.0, 4.6, 1.2, 20.5, 1.0]	`[21.4, 0.9, False]`	`[21.4, 0.9, False]`	Passed
bridge air draft clearance [18.0, 4.6, 5.3, 17.0, 1.0]	`[17.3, 0.3, False]`	`[17.3, 0.3, False]`	Passed
bridge air draft clearance [18.0, 4.6, 4.6, 17.0, 1.0]	`[18.0, 1.0, True]`	`[18.0, 1.0, True]`	Passed
bridge air draft clearance [18.0, 4.6, 5.1, 16.9, 0.5]	`[17.5, 0.6, True]`	`[17.5, 0.6, True]`	Passed
bridge air draft clearance [12.5, 6.1, 0.4, 17.0, 0.5]	`[18.2, 1.2, True]`	`[18.2, 1.2, True]`	Passed
bridge air draft clearance [12.5, 6.1, 3.0, 14.9, 0.7]	`[15.6, 0.7, False]`	`[15.6, 0.7, False]`	Passed
bridge air draft clearance [30.0, 2.2, 2.9, 29.0, 0.2]	`[29.3, 0.3, True]`	`[29.3, 0.3, True]`	Passed

SHA-256 / 40115d8da626f2454bdfbe450d434a5e0bba102c109961f5e81f989233abea04

Verification & scope

A deterministic toy model with stipulated rules and constants; not certified hydrographic software or a substitute for official tide tables. 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 2026-09-29T14:48:07.106590+00:00.

Case digest / 4a1a793d9f6f0ff7ade5278ec122440ed4deee28f7bbb4a60c9d9b63bc199066