01126656

Component

Queues at controlled intersections play an important role in the performance of urban networks, as they are a main determinant of the delay experienced by the drivers. These queues have upper bounds, which, once exceeded, cause extra delays also to other links and other traffic streams. Often this effect is neglected in practice, or it is calculated as a deterministic phenomenon. In this paper the authors describe queue length probabilities at each moment in time for closely-spaced pre-timed traffic lights, using renewal theory. Special attention is given to the influence of the upstream signal settings on the downstream arrival pattern, and to the effects of downstream queues to the upstream signal, which can be blocked temporarily due to an excess of the available buffer space. Based on this model, a case study is used to illustrate the performance of uncoordinated signals. We show that if two signals are not well coordinated and if insufficient green is assigned to the downstream direction spillback will be likely to occur, causing extra delay in the system even when the signal is under saturated.

01120148

09-2856

English

18p

2009

Transportation Research Board 88th Annual Meeting

DVD

Figures (7) ; References (21)

Operations; Traffic delays; Traffic flow; Traffic oversaturation; Traffic queuing; Traffic signal control systems; Traffic signal timing; Urban highways

Downstream traffic; Spillback effects (Traffic); Upstream traffic

Highways; Operations and Traffic Management; I73: Traffic Control

Transportation Research Board Annual Meeting 2009 Paper #09-2856

TRIS, TRB

Jan 30 2009 7:13PM