There are three main types of left-turn control at signalized intersections: permitted, protected, and protected–permitted. Determining left-turn signal control types is one of the major elements in traffic signal design and operations, and it is a systematic approach involving complex decision rules. Existing guidelines for determining left-turn signal control have been primarily based on traffic volume, delay, geometry, crash experience, and other related factors. Such guidelines are generally presented in a flowchart format. One of the major shortcomings of the existing guidelines is that a single variable could dominate the decision process and thereby prevent a balanced consideration of all other important variables. A new guideline for determining left-turn control types mostly applicable to conventional left-turn displays is presented. The current format is designed for a four-leg intersection configuration; however, it can be easily adapted to the other formats. The guideline is based on the principles of multicriterion decision analysis and provides an index-based recommendation: a numerical scale is used to compare each type of left-turn control with the others instead of an absolute left-turn control type. With the data collected from the field, it is shown that the proposed guideline can be calibrated and tailored to specific left-turn control policies. Therefore, the guideline can be easily adapted by any jurisdiction.
Guidelines for Multicriterion Decision-Based Left-Turn Signal Control
Transportation Research Record
Transportation Research Record: Journal of the Transportation Research Board ; 2128 , 1 ; 96-104
2009-01-01
Article (Journal)
Electronic Resource
English
Guidelines for Multicriterion Decision-Based Left-Turn Signal Control
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