Comparison of Delay Estimates at Under-Saturated and Over-Saturated Pre-Timed Signalized Intersections

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Abstract

This paper presents results of research comparing delays estimated by a number of fixed-time signal delay models for a range of conditions extending from undersaturated to highly saturated. The delay models compared are a deterministic queuing model, a model based on shock wave theory, the steady-state Webster model, the queue-based models defined in the 1981 Australian Capacity Guide (ARR No. 123), the 1995 Canadian Capacity Guide for Signalized Intersections, and the 1994 and 1997 versions of the Highway Capacity Manual (HCM) as well as the delays estimated from the INTEGRATION microscopic tra_c simulation software. The results of the comparisons indicate that all delay models produce similar results for signalized intersections with low tra_c demand, but that increasing di_erences occur as the tra_c demand approaches saturation. In particular, it is found that the delay estimates from the INTEGRATION microscopic simulation model generally follow the delay estimates from the time-dependent models defined in the 1997 HCM, 1995 Canadian Capacity Guide, and 1981 Australian Capacity Guide over the entire range of tra_c conditions considered.

Reference

DION, F., RAKHA, H., and KANG, Y-S (2004). Comparison of Delay Estimates at Under-Saturated and Over-Saturated Pre-Timed Signalized Intersections. Transportation Research, Part B: Methodological, Vol. 38(2), pp. 99-122.

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