FA-68142 / Traffic signal timing plans / Member archive

Uniform delay level of service: the delay is truncated to tenths · case 02

Uniform delay level of service returns a wrong result when the delay is truncated to tenths.

Member previewVariant 2 · 3 implementations · 8 checks per implementation

Case contract

Input {cycle, green, volume, sat_per_lane, lanes}. lam = green/cycle, capacity = sat*lanes*lam, X = volume/capacity, uniform delay d = 0.5*C*(1-lam)^2/(1 - min(1,X)*lam) rounded half up to tenths. LOS thresholds on tenths: <=100 A, <=200 B, <=350 C, <=550 D, <=800 E, else F; any X > 1 is F. Return {vc_milli: floor(1000X), delay_tenths, los}.

Why this case matters

Signal timing arithmetic is exact and integer or rational; a wrong rule silently produces unsafe or inefficient timing plans.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
timing oracle 4	`{"delay_tenths": 59, "los": "A", "vc_milli": 393}`	`{"delay_tenths": 60, "los": "A", "vc_milli": 393}`	Failed

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