Examination of Core Highway Capacity Manual Concepts
Examination of Core Highway Capacity Manual Concepts

Author: Brian L. Smith

Publisher:

Published: 2002

Total Pages: 28

ISBN-13:

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The Highway Capacity Manual (HCM) is one of the most widely used traffic engineering guidance documents in the world. It was originally published in 1950, and has been under constant revision since. Unfortunately, due to past cost and time constraints associated with traffic data collection, much of information in the manual is based on research conducted using relatively small data sets. This calls into question the statistical significance of some of the manual's material. The Virginia Smart Travel Laboratory is a nationally unique research facility. The distinguishing feature of the laboratory is its direct connection to operational VDOT transportation management systems. This gives the laboratory access to unprecedented quantities of traffic data. The purpose of this research project is to use this data to investigate a key concept of the HCM: freeway traffic lane distribution. An important consideration of transportation management is the distribution of lane use by vehicles. This distribution plays a significant role in how traffic management devices, such as variable message signs, lane control signals, and ramp meters are utilized. Unfortunately, according to the HCM, "when two or more lanes are available for traffic in a single direction, the distribution in lane use varies widely ... there are not "typical" lane distributions." An investigation of this concept using a large set of data from freeways in the urbanized Hampton Roads region of Virginia led to the following conclusions: The distribution of vehicles along a specific link of a freeway system does tend to follow predictable trends by time-of-day. A missing data estimation procedure can be developed that exploits the consistency of lane distribution by time-of-day and location. This estimation methodology proved to accurately estimate missing detector data, generally producing results within the 6%-8% error range. Finally, the report presents the following recommendations to VDOT. VDOT should collect and archive traffic data at the lane level to support future applications, such as the missing data estimation methodology. VDOT should use the lane distribution-based missing data estimation methodology described in this report in Smart Traffic Centers and permanent count stations located on freeways. VDOT should formally transmit this report to TRB for committee consideration as the next version of the HCM is developed.

Introduction to Modern Traffic Flow Theory and Control
Introduction to Modern Traffic Flow Theory and Control

Author: Boris S. Kerner

Publisher: Springer Science & Business Media

Published: 2009-09-16

Total Pages: 271

ISBN-13: 3642026052

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The understanding of empirical traf?c congestion occurring on unsignalized mul- lane highways and freeways is a key for effective traf?c management, control, or- nization, and other applications of transportation engineering. However, the traf?c ?ow theories and models that dominate up to now in transportation research journals and teaching programs of most universities cannot explain either traf?c breakdown or most features of the resulting congested patterns. These theories are also the - sis of most dynamic traf?c assignment models and freeway traf?c control methods, which therefore are not consistent with features of real traf?c. For this reason, the author introduced an alternative traf?c ?ow theory called three-phase traf?c theory, which can predict and explain the empirical spatiot- poral features of traf?c breakdown and the resulting traf?c congestion. A previous book “The Physics of Traf?c” (Springer, Berlin, 2004) presented a discussion of the empirical spatiotemporal features of congested traf?c patterns and of three-phase traf?c theory as well as their engineering applications. Rather than a comprehensive analysis of empirical and theoretical results in the ?eld, the present book includes no more empirical and theoretical results than are necessary for the understanding of vehicular traf?c on unsignalized multi-lane roads. The main objectives of the book are to present an “elementary” traf?c ?ow theory and control methods as well as to show links between three-phase traf?c t- ory and earlier traf?c ?ow theories. The need for such a book follows from many commentsofcolleaguesmadeafterpublicationofthebook“ThePhysicsofTraf?c”.

Introduction to the Theory of Traffic Flow
Introduction to the Theory of Traffic Flow

Author: Wilhelm Leutzbach

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 210

ISBN-13: 3642613535

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This book describes a coherent approach to the explanation of the movement of individual vehicles or groups of vehicles. To avoid possible misunderstandings, some preliminary remarks are called for. 1. This is intended to be a textbook. It brings together methods and approaches that are widely distributed throughout the literature and that are therefore difficult to assess. Text citations of sources have been avoided; literature references are listed together at the end of the book. 2. The book is intended primarily for students of engineering. It describes the theoretical background necessary for an understanding of the methods by which links in a road network are designed and dimensioned or by which traffic is controlled; the methods themselves are not dealt with. It may also assist those actually working in such sectors to interpret the results of traffic flow measure ments more accurately than has hitherto been the case. 3. The book deals with traffic flow on links between nodes, and not at nodes themselves. Many readers will probably regret this, since nodes are usually the bottlenecks which limit the capacity of the road network. A book dedicated to the node would be the obvious follow-up. A separation of link and node is justified, however, partly because the quantity of material has to be kept within reasonable bounds and partly because the treatment of traffic flow at nodes requires additional mathematical techniques (in particular, those relating to queueing theory).