Title

Coordinated Pre-Preemption of Traffic Signals to Enhance Railroad Grade Crossing Safety in Urban Areas and Estimation of Train Impacts to Arterial Travel Time Delay

Document Type

Technical Report

Publication Date

1-2014

Keywords

Algorithms, Arterial highways, At grade intersections, Before and after studies, Implementation, Railroad grade crossings, Recommendations, Simulation, Software, Traffic safety, Traffic signal control systems, Traffic signal preemption, Travel time, Urban areas

Abstract

This research project investigated the potential for using advanced features of traffic signal system software platforms (ATMS.now), prevalent in Florida, to alleviate safety and mobility problems at highway-railroad at-grade crossings and adjacent arterials. Pre-preemption phasing was developed in this study to provide “extra” green time to the movements blocked by a train before the train’s arrival at the crossing in order to (1) mitigate congestion on the arterials near railways and (2) reduce the conflicts of train-vehicle and/or vehicle-vehicle adjacent to at-grade crossings. This study explored the technologies for implementing key functions of a pre-preemption system, including train detection, train arrival prediction, and pre-preemption control algorithms, and the capabilities of ATMS.now system. VISSIM-based simulation models were developed in this study based on three control sections along two railway corridors (FEC and CSX) in Broward County, Florida, to test the proposed pre-preemption strategies. A series of comparisons before-after implementing pre-preemption strategies was conducted to validate the effectiveness of pre-preemption strategies. The major findings and recommendations for implementation from this study are provided below. (1) Upstream preemption signals (activation or release) are suggested for triggering pre-preemptions at downstream intersections along the railroad corridor. The Estimated Time of Arrival (ETA) is predicted based on the logs of two or more preemptions at upstream crossings with ideal space less than 0.5 miles. (2) The coordinated pre-preemption strategy developed in this study aims to clear the through traffic at several intersections along an arterial as much as possible before train’s arrival. All pre-preemption phases are pre-timed; coordinated pre-preemption is easy to be implemented on existing traffic controllers. (3) Based on the simulation results, the coordinated pre-preemption strategy can effectively reduce average delay, average stops, and average queue length of the arterials near a railroad crossing. The performance pattern is sensitive to site features and strategy configurations. Considering its applicability and corridor-level effectiveness, coordinated pre-preemption is suggested when through traffic volume is higher than 500 vehicles per hour per lane (vphpl) and train block duration is longer than 100 seconds. (4) A generic pre-preemption plan was developed in this study to provide guidance on implementation of the pre-preemption strategy using the ATMS.now system in Florida.

Was this content written or created while at USF?

Yes

Citation / Publisher Attribution

Coordinated Pre-Preemption of Traffic Signals to Enhance Railroad Grade Crossing Safety in Urban Areas and Estimation of Train Impacts to Arterial Travel Time Delay, FDOT BDK85 977-44, National Center for Transit Research, 158 p.

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