Traffic Signal Timing: LOS_threshold
HCM 6th Edition (TRB 2016) traffic signal timing parameters — base saturation flow rates, adjustment factors (lane width fw, heavy vehicles fHV, grade fg, parking fp, bus blockage fbb, area type fa, turning fLT/fRT), LOS thresholds A–F by control delay, startup and clearance lost time, yellow/all-red interval design values, pedestrian WALK and FDW timing (MUTCD 2009), Webster optimal cycle length parameters, and v/c ratio thresholds.
| parameter type | record id | description | notes | unit | value max (varies) | value min (varies) | value typical (varies) |
|---|---|---|---|---|---|---|---|
| LOS_threshold | LOS_A | LOS A — average control delay per vehicle | LOS A: free flow, minimal delay; d ≤ 10 s/veh | s/veh | 10 | 0 | 5 |
| LOS_threshold | LOS_B | LOS B — average control delay per vehicle | LOS B: good operation, short delays; 10 < d ≤ 20 s/veh | s/veh | 20 | 10 | 15 |
| LOS_threshold | LOS_C | LOS C — average control delay per vehicle | LOS C: satisfactory, moderate delays; 20 < d ≤ 35 s/veh | s/veh | 35 | 20 | 27 |
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