Traffic Signal Timing: adjustment_factor
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 typical (varies) |
|---|---|---|---|---|---|---|
| adjustment_factor | fa_cbd | fa for CBD area type | Accounts for higher pedestrian conflicts, congestion, and blockage in CBD | dimensionless | 0.9 | 0.9 |
| adjustment_factor | fa_non_cbd | fa for non-CBD area type | Reference condition for suburban and rural locations | dimensionless | 1 | 1 |
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