Guidelines for Multicriterion Decision-Based Left-Turn Signal Control

left-turn lanes; that is, protected left-turn control is recommended if the number of left-turn lanes exceeds 1. Such a decision process lacks a balanced consideration of other factors such as opposing traffic volume, which may be very low; therefore, the decision may not be rational at all locations or under all conditions. In many cases, an alternative left-turn control type might provide equal performance, especially when jurisdictions have clear policies and preferences toward a specific type of left-turn control. Because many factors cannot always be quantitatively evaluated, engineering judgment often plays a critical role in the selection of a left-turn control type. The primary objectives of this study are (a) to develop a new guideline for selecting left-turn signal control based on the principles of multicriterion decision-making analyses and (b) to test the feasibility and validity of the guideline for practical applications.