Traffic Signal Timing: adjustment factor
fp parking to fw lane width
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 | unit | value max (varies) | value typical (varies) |
|---|---|---|---|---|---|
| adjustment factor | fp parking | Parking lane adjustment factor fp | — | — | — |
| adjustment factor | frt exclusive | Right turn adjustment factor fRT exclusive | dimensionless | 0.85 | 0.85 |
| adjustment factor | fw 10ft | Lane width adjustment factor fw for 10-ft lane | dimensionless | 0.867 | 0.867 |
| adjustment factor | fw 11ft | Lane width adjustment factor fw for 11-ft lane | dimensionless | 0.933 | 0.933 |
| adjustment factor | fw 12ft | Lane width adjustment factor fw for 12-ft lane | dimensionless | 1 | 1 |
| adjustment factor | fw 13ft | Lane width adjustment factor fw for 13-ft lane | dimensionless | 1.044 | 1.044 |
| adjustment factor | fw 14ft | Lane width adjustment factor fw for 14-ft lane | dimensionless | 1.111 | 1.111 |
| adjustment factor | fw lane width | Lane width adjustment factor fw | dimensionless | — | — |
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