The traffic signal controller is one of the most ubiquitous and important components of our nation’s transportation system. About two-thirds of all miles driven each year by U.S. motorists are on roadways controlled by traffic signals. In some urban areas, signals at busy intersections control the movement of more than 100,000 vehicles per day [Paulson, 2002]. However, most transportation engineers receive little if any education on traffic controllers, how they work, and how one designs a signal timing plan that takes advantage of all of the intricacies of the traffic controller-detector system. And despite the importance of the signal timing plan to the successful operation of urban arterials, the design, implementation, and maintenance of most signal timing plans are the responsibility of a technician reporting to an engineer. The latter often does not understand or appreciate the subtleties of traffic controller operations, while the former does not usually have the system perspective that is so fundamental to the education of an engineer. This project takes a first step in helping to alleviate this problem. My primary objective was to develop materials on traffic signal operations and timing that could be used to educate university students and practicing traffic engineers about the major components of the traffic control system. This report summarizes the work I have completed to achieve this objective. This work is divided into four parts.
Section 2 of the report describes the role of experts in identifying and documenting knowledge. The section also describes a set of interviews that I conducted with seven experts, each with significant field experience in traffic signal operations. This knowledge base sets the stage for the case studies that are described later in this report.
Section 3 describes an assessment of the problems with current transportation engineering textbooks and describes the need for case studies as part of the engineering education process. Next, a summary of what should be included in traffic signal timing case studies is presented. Finally, the section presents a summary of the case studies that I gathered that can be used for classroom purposes.
Section 4 describes the need for materials that present the basic elements of traffic signal operations. The section also presents the text and web site that I have assembled and designed to meet this need.
Section 5 presents a summary and conclusions from this study. The section also describes a new study recently funded by the Federal Highway Administration that will develop a set of laboratory exercises designed to educate practicing engineers and engineering students on traffic signal timing.