01049605

Component

Several recent studies have concluded that the saturation flow rates from the Highway Capacity Manual (HCM) need revision. Some studies have shown that the base saturation flow rate is too low and needs to be increased. Others have shown that the rate is not constant, but decreases after 40 or 50 seconds of green time. Some field data have shown that the base saturation flow rate is not a constant value after the first three to five vehicles are discharged, but continues to grow indefinitely. Some studies have concluded that another handful of adjustment factors are needed for modifying the HCM values. A driver-response model shows that the base saturation flow rate is not a constant but varies with downstream cruising speed and green-phase length. This paper presents the application of the driver-response model with several sets of field observations to find some common values to use to investigate some of the conflicts. It was found that differences in driver aggressiveness might underlie several of the conflicting recommendations from other studies.

01042056

07-2689

English

22p

2007

Transportation Research Board 86th Annual Meeting

CD-ROM

Figures (7) ; References (16) ; Tables (1)

Aggression; Green interval (Traffic signal cycle); Highway capacity; Saturation flow; Traffic congestion; Traffic flow; Traffic signal control systems; Traffic signal cycle

Highway Capacity Manual

Variability index

Highways; Operations and Traffic Management; Planning and Forecasting; I72: Traffic and Transport Planning

Transportation Research Board Annual Meeting 2007 Paper #07-2689

TRIS, TRB

Feb 8 2007 7:24PM