TRAFFIC CONTROL THEORY AND INSTRUMENTATION

Transcription

1 TRAFFIC CONTROL THEORY AND INSTRUMENTATION

2 A publication of INSTRUMENT SOCIETY of AMERICA TRAFFIC CONTROL THEORY AND INSTRUMENTATION Based on papers presented at the Interdisciplinary Clinic on Instrumentation Requirements for Traffic Control Systems, sponsored by ISA/FIER and the Polytechnic Institute of Brooklyn, held December 16-17, 1963, at New York City. Edited by Thomas R. Horton IBM Corporation White Plains, New York Foreword by Henry A. Barnes, Commissioner New York City Department of Traffic PLENUM PRESS NEW YORK 1965

3 First Printing - November 1965 Second Printing - October 1968 Library of Congress Catalog Card Number ISBN-13: e-isbn-13: DOl: / Copyright C 1965 Softcover reprint of the hardcover 1st edition 1965 INSTRUMENT SOCIETY of AMERICA 530 William Penn Place Pittsburgh, Pa

4 Foreword At the close of the year 1900, motor vehicle registrations throughout the United States totaled These vehicles rode on unpaved and often dusty country roads. The only problem of traffic was an occasional pedestrian or a frightened horse or cow frenzied by the roar of this new creature. Today more than 82,000,000 registrations, representing 50% of the world's automobiles, are recorded in this country. In 1963 these vehicles traveled 798 billion miles over newly constructed modern highways, expressways, freeways, quickways, and thruways, as well as improved rural and urban roads and streets. Out of all this has sprung the traffic engineer. Today's modern roadway is an engineering structure which has been developed through sound principles of design with provisions for safety and efficiency. An example of this safety factor can be found by the exacting specifications for cross sections, grades, roadside control, medians, and other design features. For many years, the responsibility for controlling traffic fell naturally into the domain of the police. However, as traffic increased, many problems developed which were beyond the scope of normal police work. Since the highway system is an engineering structure which requires an engineering approach to appraise operating problems and engineering techniques to solve them, the traffic engineer came into being. New York City's vast network of highways and streets has challenged the minds of traffic engineers during the past ten years, and we not only have accepted this challenge, we are now at the doorstep of introducing a revolutionary new traffic control signal system into New York to help solve the congestion problem. But just as the network of roads within New York is vast, so too is the expense of installing our modern program; $100,000,000 during the next five years will be spent on electronic equipment designed to move traffic and ease congestion in New York City. This program is the result of experienced and highly qualified traffic engineers with the Department of Traffic in New York. But v

5 vi Foreword it is only an example of the thousands of traffic engineers around the country who are solving the everyday problems of traffic in every major city throughout the United States. In the following pages of this book, you will read of modem techniques employed by modem traffic engineers - men who have labored to bring to the cities of our nation greater safety and improved traffic engineering principles. I am honored to participate in this publication and share the pride of traffic engineers in their profession and achievements. We all look to the future for greater accomplishments as we move forward with our professional counterparts in education and enforcement toward greater safety for pedestrians and motorists in this great land of ours. HENRY A. BARNES, Commissioner New York City Department of Traffic

6 Preface The control of today's traffic calls for a fusion of time-honored means with the new - the practical with the theoretical. Paint, traffic signs, and fixed-time signal controllers are not likely to be supplanted overnight by vehicle sensors, digital control systems, and alternate traffic routings, electronically generated and displayed. Yet two ingredients necessary to any adequate traffic control system are applied knowledge of the "normal" vehicular stream, and the effective provision of a feedback mechanism which yields timely response to the stream's changing conditions. The physical tools to accomplish this exist today - instrumentation devices which detect the presence of vehicles or sense their speed; instrument configurations which assess lane occupancy or call attention to discontinuities in patterns of flow; and computing systems which perform simulations of arterial or network traffic, useful if not essential in system design. What is not available is a complete understanding of the phenomena of traffic flow. While vehicles must and therefore do obey the usual laws of physics, one must not ignore a fundamental link in this system-the human operator-whose behavior is somewhat less predictable than that of an inert fluid. Hence, the emerging science of traffic control is both physical and behavioral in nature, calling upon specialists from many fields. Yet the body of traffic theory is growing and much is available to apply today. The need to do so was never greater. The purpose of publishing this collection of papers and articles is to report on experience gained in several existing systems and to discuss the instrumentation employed in or required for these various approaches. About a year ago, an Interdisciplinary Clinic on Instrumentation Requirements for Traffic Control Systems was held at the United Engineering Center in New York City. This program was sponsored by the Polytechnic Institute of Brooklyn, the Foundation for Instrumentation Education and Research, the Instrument Society of America, and the Institute of Traffic Engineers. Agencies cooperatvii

7 viii Preface ing in this seminar were the New York City Department of Traffic and the Port Authority of New York. Most of the papers presented at that Clinic are contained herein. This book is comprised of three sections. Section I provides general background and contains a comprehensive survey article by Mr. Evan Herbert, associate editor of International Science and Technology. Section II introduces the basic elements ofthe control problem. Mr. John Barker describes recent advances in traffic instrumentation. Dr. Denos Gazis analyzes control problems of single intersections and networks in undersaturated and oversaturated states. The traffic engineer is introduced to the stored-program digital computer by Professor Matthew Huber of Yale University and to its use in simulating traffic control systems for evaluative purposes by Dr. Daniel Gerlough. Professor Louis Pignataro of the Polytechnic Institute of Brooklyn discusses several practical environmental considerations. Section III includes five case studies of operational or experimental traffic control systems installed in various metropolitan locations. Drs. Donald Drew and Charles Pinnell discuss freeway and at-grade arterial control in Houston and present models pertaining to peak hour traffic flow. The systems installed in the tunnels of the Port Authority of New York, mentioned in Mr. Herbert's introductory article, are described by Mr. Robert Foote. The Buffalo, New York, vehicle-detector-based system is depicted by Mr. J. H. Auer,Jr. Mr. Adolf May reports on the Chicago expressway surveillance project. Finally, the Toronto computer-controlled signal system is described by Mr. Neal A. Irwin. Clearly there are major costs attendant to the development of any large-scale, flexible traffic control system. These include costs of a computer system (or prorated costs if time-shared), costs of sensors, communications costs, and costs for systems work and programming. But, just as clearly, there are major benefits to be obtained. The number of highway accident deaths per vehicle mile is increasing year by year. The population is continuing its explosion. The movement toward increased urbanization has not abated. Effective urban planning cannot be done without seriously considering the future traffic pattern. The economic cost of traffic delays, if it could be accurately totaled, would be a staggering figure. Hence the need for improved systems is undeniable, and the traffic engineer has become an important figure indeed in our society. This need is not restricted to the United States, as anyone who has driven a car in Paris or taken a taxicab in Tokyo will attest. And if it is true that our need is the greatest, it is not at all obvious

8 Preface ix that we are substantially ahead of other countries in advanced experimentation, if one considers what is taking place, for example, in Germany, England, and Australia. Certainly the best ideas, wherever they turn up, need to be synthesized, harnessed, and focused on the expanding traffic problem. It is hoped that this collection of articles will help to stimulate interest in advancing the man-machine-system control of the flow of vehicular man-machine units which are ever more abundantly filling our highways and city streets. January, 1965 THOMAS R. HORTON

9 Contents I. INTRODUCTION Traffic.... by Evan Herbert 3 II. TRAFFIC CONTROL INSTRUMENTATION, THEORY AND PRACTICE Instrumentation for the Traffic Engineer by John L. Barker Traffic Control, Time-Space Diagrams, and Networks by Denos C. Gazis Computer Programming for Traffic Problems and Flow Characteristics by Matthew J. Huber Simulation as a Tool in Traffic Control System Evaluation. 71 by D. L. Gerlough Practicality in Traffic Control by L. J. Pignataro III. CASE STUDIES OF LARGE-SCALE INTEGRATED TRAFFIC CONTROL SYSTEMS Some Theoretical Considerations of Peak-Hour Control for Arterial Street Systems by Donald R. Drew and Charles Pinnell Installation of a Tunnel Traffic Surveillance and Control System by Robert S. Foote xi

10 xii Contents The Use of Vehicle Presence Detectors in Metropolitan Traffic-Control Systems by J. H. Auer, Jr. Experimentation with Manual and Automatic Ramp Control. 157 by Adolf D. May, Jr. The Toronto Computer-Controlled Traffic Signal System by Neal A. Irwin