Traffic Signal Timing: lost_time
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) |
|---|---|---|---|---|---|---|---|
| lost_time | clearance_lost_time | Clearance (end) lost time per phase | Time lost between end of green and start of conflicting movement; yellow + all-red minus time vehicles use; typically l2 = Y + AR - e where e ≈ 1.0–2.0 s extension | s/phase | 3 | 0.5 | 2 |
| lost_time | startup_lost_time | Start-up lost time per phase | Time vehicles take to react and accelerate at phase start; accounts for yellow start-up hesitation; default 2.0 s per HCM | s/phase | 2.5 | 1.5 | 2 |
| lost_time | total_lost_time | Total lost time per phase (l_t = l_1 + l_2) | l_t = l_1 + l_2; default 4.0 s/phase used in HCM analysis; effective green = g_e = g + Y - l_t | s/phase | 5 | 3 | 4 |
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