This report contains the results of the NC Department of Transportation research project Placement of Detection Loops on High Speed Approaches to Traffic Signals (HWY 2007-13). The goal of this project was to determine the best places to locate detectors on the approaches to high-speed signalized intersections and the best signal control strategy to employ in conjunction with those sensor placement ideas to minimize dilemma zone occurrences.
The primary objective of this research was to validate the new TxDOT procedures for loop detector placement on high-speed approaches to signalized intersections. The study approach involved conducting a field study at selected sites to compare the proposed new loop configuration to the existing configuration. The data analysis included investigating approach speeds to the intersection, driver actions in response to a yellow indication, and vehicle location at the onset of yellow. The Results from the field study revealed that the new loop configuration is as good as, and in some cases better than the old loop configuration. Because the new loop configuration can detect vehicles further upstream from the intersection (at the beginning of the dilemma zone), it results in fewer vehicles being caught in the dilemma zone at the onset of yellow. Also, because the new loop configuration typically resulted in more vehicles running the yellow light instead of stopping, fewer rear-end accidents may result. In addition, the new loop configuration resulted in fewer vehicles running the red light, also a major cause of accidents.
This handbook, which was developed in recognition of the need for the compilation and dissemination of information on advanced traffic control systems, presents the basic principles for the planning, design, and implementation of such systems for urban streets and freeways. The presentation concept and organization of this handbook is developed from the viewpoint of systems engineering. Traffic control studies are described, and traffic control and surveillance concepts are reviewed. Hardware components are outlined, and computer concepts, and communication concepts are stated. Local and central controllers are described, as well as display, television and driver information systems. Available systems technology and candidate system definition, evaluation and implementation are also covered. The management of traffic control systems is discussed.
The study was undertaken to improve understanding of how to place vehicle detectors at high-speed (at least 35 mph), isolated, traffic-actuated intersections, and how to test and evaluate alternative detector/controller configurations for intersection traffic safety and efficiency.
This report serves as a comprehensive guide to traffic signal timing and documents the tasks completed in association with its development. The focus of this document is on traffic signal control principles, practices, and procedures. It describes the relationship between traffic signal timing and transportation policy and addresses maintenance and operations of traffic signals. It represents a synthesis of traffic signal timing concepts and their application and focuses on the use of detection, related timing parameters, and resulting effects to users at the intersection. It discusses advanced topics briefly to raise awareness related to their use and application. The purpose of the Signal Timing Manual is to provide direction and guidance to managers, supervisors, and practitioners based on sound practice to proactively and comprehensively improve signal timing. The outcome of properly training staff and proactively operating and maintaining traffic signals is signal timing that reduces congestion and fuel consumption ultimately improving our quality of life and the air we breathe. This manual provides an easy-to-use concise, practical and modular guide on signal timing. The elements of signal timing from policy and funding considerations to timing plan development, assessment, and maintenance are covered in the manual. The manual is the culmination of research into practices across North America and serves as a reference for a range of practitioners, from those involved in the day to day management, operation and maintenance of traffic signals to those that plan, design, operate and maintain these systems.
