- Email: [email protected]
Urban Traffic Networks: Dynamic flow modeling and control
474
Book Reviews
detracted from an otherwise high quality book. There were also a few misspellings, including a prominent one in the table of contents. The Geography of Urban Transportation is a must for the bookshelves of urban transportation geographers, planners, and engineers. Within the confines of a single volume, the book’s collaborators have presented the diverse field of urban transportation from a geographic perspective. They are to be congratulated on the succinct, thoughtful and comprehensive treatments of their individual topics. The editor, in turn, deserves recognition for so skillfully blending and integrating these contributions. Ann K. Deakin Department of Political Science Special Studies Program in G.I.S. State University of New York College at Fredonia Fredonia, NY 14063 U.S.A.
Urban TrafIic Networks Dynamic Flow Modeling and Control. Nathan H. Gartner and Gennaro Improta, editors. Springer-Verlag, GmbH & Co. KG, Tiergartenstrasse 17, D-69 121, Heidelberg, Germany. 375 pp. + x. ISBN 3-54059073-O. $. Urban Trafic Networks is a collection of peerreviewed papers from the Second International Seminar on Urban Traffic Networks held in Capri, Italy, in July 1992. The papers are divided into two thematic sections. The first section emphasizes traffic information and control systems and traffic management strategies. The second section emphasizes dynamic network equilibrium models, solution algorithms, computational examples, and potential uses of these models in advanced transportation management/ advanced traveler information systems (ATMS/ ATIS). The two sections complement each other and are neatly joined. The primary goal of this volume is to present better ways of modeling the flow of traffic so that conditions can be improved for travelers on particular routes or within a transportation network. The main focus of these papers is on private vehicle travel, although transit use is also addressed. The book is a valuable reference, defining issues and presenting alternative approaches and solutions. Several papers model or discuss the differential impacts on travelers who are, or are not, provided with prior or in-vehicle route guidance information. Both simulation and optimization models are consid-
ered, with ample discussion of their comparative advantages. The entire field of advanced traffic management, modeling and control has greatly advanced since the seminar was convened. Many of the modeling approaches presented in this book have also advanced dramatically. A look at recent issues of the leading transportation research journals shows that many of the authors of papers in this volume have extended their work, developing more comprehensive approaches or demonstrating and implementing these approaches in a greater variety of settings. In light of recent advances, many authors would undoubtedly revise their statements about the properties of some models and the potential limitations of certain approaches. At the time of the conference, for example, one author noted that the ability to account for queue formation and dissipation had yet to be achieved in analytical modeling approaches. But recent papers have included this formulation in their solution algorithms. Affordable computer technology has also advanced more rapidly than many had expected, and concerns about computational burden and memory have been greatly reduced. Today, an approach that requires hundreds of megabytes of random access memory for large applications is quite acceptable. Several papers are quite rigorous and detailed in their discussion of mathematical properties of their formulation or solution approach. The papers contribute extensively to recent literature describing dynamic traffic systems and their model representations. Several papers also provide clear examples against which contemporary researchers can compare their own models. In fact, the broad range of concepts and issues discussed by the authors in this volume is perhaps of greater value than the details of any particular modeling approach or control strategy. The papers help the reader anticipate the implications of advanced traffic management approaches both in terms of feasible technology and user impacts. Several papers also provide extensive reviews of the literature prior to 1992. Others add references generated since the conference. For example, papers in the Proceedings of the 12th International Symposium on the Theory of Trajic Flow and Transportation are cited
frequently, although this symposium met a year later.2 A number of key issues were raised by papers in the first section. What type of information is most useful to travelers in making their deci21nternationalSymposium on the Theory of Traflc Flow and Transportation,12th. July 21-23, 1993. A Symposium in Honor of Gordon F. Newell, Amsterdam, New York: Elsevier, 1993.
475
Book Reviews
sions concerning destination, mode, departure time and route? How, and to what extent, will travelers with this information use it? Since travel information may be historical, current or predictive, what is the appropriate role for each type of information and how might it be used differently by travelers in travel decisions? Might over-reaction by a large percentage of travelers to advised routes or other travel choices become a problem when the market penetration of travel information reaches substantial levels? As one paper so clearly states, this depends on the joint probability that travelers have access to information and elect to access this information; and on how travelers will ultimately use the information. From a systemwide perspective, how will the advantage given to travelers with information disbenefit travelers without information, if at all? Given that travel information can be periodically updated, what is the effective update frequency for different parts of the network under different levels of traffic congestion and variation? Finally, what are the appropriate route guidance rules given the broad range of travelers’ route choice preferences, recognizing that rerouted traffic affects other users and nonusers along those routes? The second section of the book raises similar issues. Many different modeling approaches possess desirable properties for providing route guidance and other traveler information, predicting traveler choices, and designing and evaluating alternative traffic control schemes. It is important to understand the advantages and disadvantages of each approach for a given application to apply the appropriate tool for the level of detail and accuracy required. Certain model requirements, such as accounting for spillback queuing effects on link capacities, are important to properly represent and control highly congested network areas. Other modeling capabilities, such as maintaining FIFO trip ordering between all zone pairs, may be less critical to obtaining a very reliable and effective solution for traffic management purposes. There will always be a trade-off between theoretical correctness and the implementation needs of advanced traffic models and control systems. A common topic among the papers was the appropriate development of measures of effectiveness (MOEs) to evaluate the performance of models or to assess the effectiveness of traffic management and control strategies. Obviously, the degree of algorithmic convergence is not a meaningful MOE of the success of traffic management schemes. Measures of effectiveness suggested by some of the papers included systemwide travel times (or delay), individual
route travel times and travel time reliability. Only one paper specifically examines externalities such the impact of route guidance on vehicular emissions. Yet, as private vehicle ownership and use increases throughout the world, this will likely be a more critical topic for future conferences. A few of the papers provide a conceptual framework for the overall architecture of integrated traveler information and traffic control systems. Clearly, the success of advanced transportation management/ traveler information systems (ATMSATIS) depends on how well the component systems are implemented and integrated. These papers set the stage for future modeling enhancement, prototype applications and test demonstrations in selected urban areas. This volume is an important resource for researchers and practitioners involved in these efforts. Bruce N. Janson Department of Civil Engineering University of Colorado Denver, CO 80217-3364, U.S. A.
Road Pricing: Theory, Empirical Assesm ent and Policy. Borje Jonansson and Lars-Goran Mattsson, editors. (Transportation Research, Economics and Policy, Vol. 3). Kluwer Academic Publishers Group, P.O. Box 989, 3300 AZ Dordrecht, The Netherlands, 1994. 248 pp. ISBN o-7923-3134-6. $69.95. According to its preface, this volume is the outgrowth of a 1992 symposium sponsored by the Swedish National Road Administration and The Royal Institute of Technology. The editors’ goal was to produce an up-to-date and comprehensive book on road pricing that could be used both as a textbook on transportation and as a reference for planners and policy makers. The book satisfies none of these objectives. The papers do not cover congestion pricing - let alone transportation - comprehensively. They differ greatly in quality, originality, and level of technical detail. I enjoyed and learned appreciably from reading only two of them. One is “Road Pricing or Transport Planning?” by Phil B. Goodwin, a well-written defense of the proposition that it is unlikely that road pricing can be politically acceptable or technically successful unless the transport planning context in which it is implemented is itself satisfactory. The second is Peter M. Jones “Road Pricing: The Public Viewpoint,” a description of surveys from several countries dealing with public understanding
Book Reviews
detracted from an otherwise high quality book. There were also a few misspellings, including a prominent one in the table of contents. The Geography of Urban Transportation is a must for the bookshelves of urban transportation geographers, planners, and engineers. Within the confines of a single volume, the book’s collaborators have presented the diverse field of urban transportation from a geographic perspective. They are to be congratulated on the succinct, thoughtful and comprehensive treatments of their individual topics. The editor, in turn, deserves recognition for so skillfully blending and integrating these contributions. Ann K. Deakin Department of Political Science Special Studies Program in G.I.S. State University of New York College at Fredonia Fredonia, NY 14063 U.S.A.
Urban TrafIic Networks Dynamic Flow Modeling and Control. Nathan H. Gartner and Gennaro Improta, editors. Springer-Verlag, GmbH & Co. KG, Tiergartenstrasse 17, D-69 121, Heidelberg, Germany. 375 pp. + x. ISBN 3-54059073-O. $. Urban Trafic Networks is a collection of peerreviewed papers from the Second International Seminar on Urban Traffic Networks held in Capri, Italy, in July 1992. The papers are divided into two thematic sections. The first section emphasizes traffic information and control systems and traffic management strategies. The second section emphasizes dynamic network equilibrium models, solution algorithms, computational examples, and potential uses of these models in advanced transportation management/ advanced traveler information systems (ATMS/ ATIS). The two sections complement each other and are neatly joined. The primary goal of this volume is to present better ways of modeling the flow of traffic so that conditions can be improved for travelers on particular routes or within a transportation network. The main focus of these papers is on private vehicle travel, although transit use is also addressed. The book is a valuable reference, defining issues and presenting alternative approaches and solutions. Several papers model or discuss the differential impacts on travelers who are, or are not, provided with prior or in-vehicle route guidance information. Both simulation and optimization models are consid-
ered, with ample discussion of their comparative advantages. The entire field of advanced traffic management, modeling and control has greatly advanced since the seminar was convened. Many of the modeling approaches presented in this book have also advanced dramatically. A look at recent issues of the leading transportation research journals shows that many of the authors of papers in this volume have extended their work, developing more comprehensive approaches or demonstrating and implementing these approaches in a greater variety of settings. In light of recent advances, many authors would undoubtedly revise their statements about the properties of some models and the potential limitations of certain approaches. At the time of the conference, for example, one author noted that the ability to account for queue formation and dissipation had yet to be achieved in analytical modeling approaches. But recent papers have included this formulation in their solution algorithms. Affordable computer technology has also advanced more rapidly than many had expected, and concerns about computational burden and memory have been greatly reduced. Today, an approach that requires hundreds of megabytes of random access memory for large applications is quite acceptable. Several papers are quite rigorous and detailed in their discussion of mathematical properties of their formulation or solution approach. The papers contribute extensively to recent literature describing dynamic traffic systems and their model representations. Several papers also provide clear examples against which contemporary researchers can compare their own models. In fact, the broad range of concepts and issues discussed by the authors in this volume is perhaps of greater value than the details of any particular modeling approach or control strategy. The papers help the reader anticipate the implications of advanced traffic management approaches both in terms of feasible technology and user impacts. Several papers also provide extensive reviews of the literature prior to 1992. Others add references generated since the conference. For example, papers in the Proceedings of the 12th International Symposium on the Theory of Trajic Flow and Transportation are cited
frequently, although this symposium met a year later.2 A number of key issues were raised by papers in the first section. What type of information is most useful to travelers in making their deci21nternationalSymposium on the Theory of Traflc Flow and Transportation,12th. July 21-23, 1993. A Symposium in Honor of Gordon F. Newell, Amsterdam, New York: Elsevier, 1993.
475
Book Reviews
sions concerning destination, mode, departure time and route? How, and to what extent, will travelers with this information use it? Since travel information may be historical, current or predictive, what is the appropriate role for each type of information and how might it be used differently by travelers in travel decisions? Might over-reaction by a large percentage of travelers to advised routes or other travel choices become a problem when the market penetration of travel information reaches substantial levels? As one paper so clearly states, this depends on the joint probability that travelers have access to information and elect to access this information; and on how travelers will ultimately use the information. From a systemwide perspective, how will the advantage given to travelers with information disbenefit travelers without information, if at all? Given that travel information can be periodically updated, what is the effective update frequency for different parts of the network under different levels of traffic congestion and variation? Finally, what are the appropriate route guidance rules given the broad range of travelers’ route choice preferences, recognizing that rerouted traffic affects other users and nonusers along those routes? The second section of the book raises similar issues. Many different modeling approaches possess desirable properties for providing route guidance and other traveler information, predicting traveler choices, and designing and evaluating alternative traffic control schemes. It is important to understand the advantages and disadvantages of each approach for a given application to apply the appropriate tool for the level of detail and accuracy required. Certain model requirements, such as accounting for spillback queuing effects on link capacities, are important to properly represent and control highly congested network areas. Other modeling capabilities, such as maintaining FIFO trip ordering between all zone pairs, may be less critical to obtaining a very reliable and effective solution for traffic management purposes. There will always be a trade-off between theoretical correctness and the implementation needs of advanced traffic models and control systems. A common topic among the papers was the appropriate development of measures of effectiveness (MOEs) to evaluate the performance of models or to assess the effectiveness of traffic management and control strategies. Obviously, the degree of algorithmic convergence is not a meaningful MOE of the success of traffic management schemes. Measures of effectiveness suggested by some of the papers included systemwide travel times (or delay), individual
route travel times and travel time reliability. Only one paper specifically examines externalities such the impact of route guidance on vehicular emissions. Yet, as private vehicle ownership and use increases throughout the world, this will likely be a more critical topic for future conferences. A few of the papers provide a conceptual framework for the overall architecture of integrated traveler information and traffic control systems. Clearly, the success of advanced transportation management/ traveler information systems (ATMSATIS) depends on how well the component systems are implemented and integrated. These papers set the stage for future modeling enhancement, prototype applications and test demonstrations in selected urban areas. This volume is an important resource for researchers and practitioners involved in these efforts. Bruce N. Janson Department of Civil Engineering University of Colorado Denver, CO 80217-3364, U.S. A.
Road Pricing: Theory, Empirical Assesm ent and Policy. Borje Jonansson and Lars-Goran Mattsson, editors. (Transportation Research, Economics and Policy, Vol. 3). Kluwer Academic Publishers Group, P.O. Box 989, 3300 AZ Dordrecht, The Netherlands, 1994. 248 pp. ISBN o-7923-3134-6. $69.95. According to its preface, this volume is the outgrowth of a 1992 symposium sponsored by the Swedish National Road Administration and The Royal Institute of Technology. The editors’ goal was to produce an up-to-date and comprehensive book on road pricing that could be used both as a textbook on transportation and as a reference for planners and policy makers. The book satisfies none of these objectives. The papers do not cover congestion pricing - let alone transportation - comprehensively. They differ greatly in quality, originality, and level of technical detail. I enjoyed and learned appreciably from reading only two of them. One is “Road Pricing or Transport Planning?” by Phil B. Goodwin, a well-written defense of the proposition that it is unlikely that road pricing can be politically acceptable or technically successful unless the transport planning context in which it is implemented is itself satisfactory. The second is Peter M. Jones “Road Pricing: The Public Viewpoint,” a description of surveys from several countries dealing with public understanding