FA-67022 / Railway interlocking logic / Member archive

Overlap timed release: timer expiry boundary · case 02

The overlap stays locked at the exact moment the timer expires.

Member previewVariant 2 · 3 implementations · 8 checks per implementation

Case contract

The overlap beyond a signal is locked. The release timer starts at the first berth occupation; the overlap is released when an event time reaches start + timer_s while the train has not overrun into the overlap. A berth clear before release cancels the timer (a later occupation restarts it); after release it has no effect. Entering the overlap before release marks an overrun and blocks release. query appends locked or released.

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.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression: track circuit bob restarts nothing	`["locked"]`	`["released"]`	Failed

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