Module 7 : Traffic Signal Design

Lecture 37 : Capacity and Los Analysis of a Signalized I/S

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	Methodology Scope This chapter contains a methodology for analyzing the capacity and level of service (LOS) of signalized intersections. The analysis must consider a wide variety of prevailing conditions, including the amount and distribution of traffic movements, traffic composition, geometric characteristics, and details of intersection signalization. The methodology focuses on the determination of LOS for known or projected conditions. The capacity analysis methodology for signalized intersections is based on known or projected signalization plans. Limitation The methodology does not take into account the potential impact of downstream congestion on intersection operation. Nor does the methodology detect and adjust for the impacts of turn-pocket overflows on through traffic and intersection operation. Objective This method uses wide range of operational configuration along with various phase plans, lane utilization, and left-turn treatment alternatives. Geometric condition Traffic condition Signalization condition The primary output of the method is level of service (LOS). This methodology covers a wide range of operational configurations, including combinations of phase plans, lane utilization, and left-turn treatment alternatives. The below figure shows the signalized intersection methodology. Figure 1: signalized intersection methodology