Citation

Banks JH. Transp. Res. Rec. 1993; 1394: 17-25.

Copyright

(Copyright © 1993, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

Simulations of ramp meter responses were used to study the feasibility of replacing locally based moving-average estimates of mainline flow currently used in San Diego with estimates based on upstream data. The choice of estimation methodology made little practical difference in the performance of the system; instead, the major problem in providing precise control of meter outputs was the limited ability of the system to respond. The most important limitation is that the difference between the maximum and minimum metering rates tends to be small relative to normal random variation in mainline input flows at the minimum counting interval of 30 sec. Consequently, meters respond with their maximum or minimum rates most of the time, which leads to biases in average responses. Other response limitations include a comparatively large number of ramps at which demands are less than minimum metering rates and insufficient total metering capacity. For multiramp systems, the most promising way to prevent biases caused by the meters' limited response ranges is to set flow targets for upstream meters to cause the average response of the bottleneck meter to be about halfway between its maximum and minimum rates. This strategy may be employed only where there is sufficient total metering capacity and may conflict with other strategies for setting flow targets in multiramp systems, such as the so-called Wattleworth strategy.

Record URL:
http://onlinepubs.trb.org/Onlinepubs/trr/1993/1394/1394-003.pdf

Language: en

Keywords

Traffic control; Highway traffic control; Computer simulation; Street traffic control; Statistical methods; Instruments