01049285

Component

https://doi.org/10.3141/2035-16

http://scholar.google.com...hang&publication_year=2007

The basic concept and implementation of an active priority system of light rail transit (LRT) for highway–rail grade crossings are presented. The proposed priority system consists of four major components: train detectors, train travel and dwell time predictors, priority request generator (PRG), and traffic signal controllers. As the brain of the system, the PRG adopts a three-scheme conditional priority control strategy. Scheme I, which applies to late LRT trains, features a timing optimization model. The objective of this optimization model is to minimize intersection delays for late trains and meanwhile to minimize impacts on other traffic. Unlike existing signal priority studies, which typically focus on isolated intersections, the proposed model deals with signal timings at multiple intersections and provides an optimized green band for an incoming train. The optimized green band would start at the right time to cover the predicted train arrival time and would be wide enough to accommodate prediction errors. A case study, based on the San Diego Trolley system, in California, demonstrates enormous intersection delay savings of 89.5% and 25.3 s/train for late trains after application of the proposed Scheme I strategy. At the same time, the impact on other traffic in the priority cycle is only 4.1 s/veh. For Schemes II and III when no priority is needed, traffic delay savings are 32.5% and 52.0%, respectively. A simulation study confirms the system benefits and validates the practicality of the active priority system for future field testing.

01091263

English

pp 141-149

2007

Transportation Research Record: Journal of the Transportation Research Board

9780309104623

Print

Figures (6) ; References (9) ; Tables (4)

Light rail transit grade crossings; Optimization; Traffic delays; Traffic signal controllers; Traffic signal preemption; Traffic signal timing

San Diego Trolley

Highways; Operations and Traffic Management; Public Transportation; Terminals and Facilities; I73: Traffic Control

TRIS, TRB, ATRI

Feb 8 2007 6:37PM

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• Data-Driven Algorithms for Real-Time Adaptive Tuning of Offsets in Coordinated Traffic Signal Systems
• Effectiveness of Alternative Detector Configurations for Option Zone Protection on High-Speed Approaches to Traffic Signals
• Empirical Observations of Dynamic Dilemma Zones at Signalized Intersections
• Evaluating Effects of Toll Strategies on Route Diversion and Travel Times for Origin–Destination Pairs in a Regional Transportation Network
• Evaluation of Adaptive Maximum Feature in Actuated Traffic Controller: Hardware-in-the-Loop Simulation
• Event-Based Data Collection for Generating Actuated Controller Performance Measures
• Feasibility of Traffic Simulation for Decision Support in Real-Time Regional Traffic Management
• Foundation for Jointly Determining Passage Time and Detection Zone Length with Stop Bar Presence Detection
• Implementation of Lane-by-Lane Detection at Actuated Controlled Intersections
• Input–Output and Hybrid Techniques for Real-Time Prediction of Delay and Maximum Queue Length at Signalized Intersections
• Methodology to Assess Traffic Signal Transition Strategies for Exit Preemption Control
• Modeling Traffic Signal Operations with Precedence Graphs
• Models for Quantitative Assessment of Video Detection System Impacts on Signalized Intersection Operations
• Opening the New Woodrow Wilson Memorial Bridge: Planning and Implementing a Major Traffic Switch
• Performance Analysis of Coordinated Traffic Signals During Transition
• Recasting Dilemma Zone Design as a Marginal Cost-Benefit Problem
• Risk Analysis to Account for Uncertainty in Benefit–Cost Evaluations of Intelligent Transportation Systems
• Short or Long—Which Is Better? Probabilistic Approach to Cycle Length Optimization
• Traffic Operations for Hurricane Evacuation
• VisSim-Based Genetic Algorithm Optimization of Signal Timings