Design of Signal Timing Plan for Urban Signalized Networks including Left Turn Prohibition

Qinrui Tang,Bernhard Friedrich

doi:10.1155/2018/1645475

Qinrui Tang, Bernhard Friedrich

Open Access

https://doi.org/10.1155/2018/1645475

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Abstract

Urban road networks may benefit from left turn prohibition at signalized intersections regarding capacity, for particular traffic demand patterns. The objective of this paper is to propose a method for minimizing the total travel time by prohibiting left turns at intersections. With the flows obtained from the stochastic user equilibrium model, we were able to derive the stage generation, stage sequence, cycle length, and the green durations using a stage-based method which can handle the case that stages are sharing movements. The final output is a list of the prohibited left turns in the network and a new signal timing plan for every intersection. The optimal list of prohibited left turns was found using a genetic algorithm, and a combination of several algorithms was employed for the signal timing plan. The results show that left turn prohibition may lead to travel time reduction. Therefore, when designing a signal timing plan, left turn prohibition should be considered on a par with other left turn treatment options.

Highlights

Left turns at signalized intersections may cause efficiency problems, because they have comparatively high potential for conflicts with other movements
This paper presents a method for selecting left turns with a genetic algorithm for prohibition and designing a fixed signal timing plan including left turn prohibition (LTP) for a time in a day, by minimizing total travel times
We propose a method of designing signal timing plan including LTP by minimizing total travel time

Summary

Introduction

Left turns at signalized intersections may cause efficiency problems, because they have comparatively high potential for conflicts with other movements. Left turns can be avoided by constructing unconventional intersections such as U-turns in the middle of roads [7,8,9,10,11,12], mid-block left turns [13, 14], continuous flow intersections, jughandle intersections [15], exit lanes for left turn [16], special width intersection [17], and tandem intersection/presignals [18,19,20], due to space limitation in cities and high construction expense, these unconventional intersections may not be feasible in the urban area The impact of these unconventional intersections on networks is not clear because the intersections/locations are usually studied in isolation. It is necessary to design signal timing plan for the LTP problem

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