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Tri-County Metropolitan Transportation District of Oregon, Urban transportation -- Environmental aspects, Traffic signs and signals -- Control systems


Bus bunching takes place when headways between buses are irregular. Bus bunching is associated with longer waiting times for riders, overcrowding in some buses, and an overall decrease on the level of service and capacity. Understanding the temporal and spatial characteristics and the causes and effects of bus bunching incidents from archived bus data can greatly aid transit agencies to develop efficient mitigation strategies. This paper presents methods to identify and visualize specific time periods and segments where bus bunching incidents occur based on automatic vehicle location (AVL) and automatic passenger count (APC) data. The paper also proposes methods that help analyze the causes and effects of bus bunching based on AVL/APC data. Temporal and spatial distributions of bus bunching events indicate high concentration during high frequency service hours and segments, and increasing concentration toward downstream. Time point bus stops can help reduce bus headway variability but with limited capability. Results indicate that irregular departure headway at the initial stop is the key cause of bus bunching rather than downstream traffic conditions and passenger demand uncertainty. A bus departure headway control at the initial stop of high frequency service zone is highly recommended, and a switch from schedule-based control to headway-based control strategy at time point stops in high frequency service zone is suggested.


This is the author's version of the work. Submitted to the 94th Annual Meeting of Transportation Research Board, 40 January 11-15, 2015

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