Modelling Transport E-Book

Juan de Dios Ortúzar

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 1691

Veröffentlichungsjahr: 2024

Beschreibung

MODELLING TRANSPORT Comprehensive Textbook Resource for Understanding Transport Modelling Modelling Transport provides unrivalled depth and breadth of coverage on the topic of transport modelling. Each topic is approached as a modelling exercise with discussion of the roles of theory, data, model specification, estimation, validation, and application. The authors present the state of the art and its practical application in a pedagogic manner, easily understandable to both students and practitioners. An accompanying website hosts a solutions manual. Sample topics and learning resources included in the work are as follows: * State-of-the-art developments in the field of transport modelling, including new research and examples * Factors to consider for better modelling and forecasting * Information and analysis on dynamic assignment and micro-simulation and model design and specification * Agent and Activity Based Modelling * Modelling new modes and services Graduate students in transportation engineering and planning, transport economics, urban studies, and geography programs along with researchers and practitioners in the transportation and urban planning industry can use Modelling Transport as a comprehensive reference work for a wide array of topics pertaining to this field.

Leseprobe

Modelling Transport

Fifth Edition

Juan de Dios Ortúzar

Department of Transport Engineering and Logistics,Instituto Sistemas Complejos de Ingenieria (ISCI).Pontificia Universidad Catolica de Chile

Luis G. Willumsen

Nommon Solutions and Technologies

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Preface

This book results from over 50 years of collaboration, often at a distance and sometimes working together in Britain and Chile. During this half‐century, we have often discussed the more substantial and weaker aspects of transport modelling and planning. We have also speculated, researched, and tested some new and not‐so‐new ideas in practice. We have agreed and disagreed on topics such as the level of detail required for modelling or the value of disaggregate and activity‐based models in forecasting; some 33 years ago, we took advantage of a period when our views converged to put them in writing, but they have evolved and continue to do so.

At that time, we decided to present the most important (in our view) transport modelling techniques in a form accessible to students and practitioners alike. We attempted this giving particular emphasis to key topics in contemporary modelling and planning:

the practical importance of theoretical consistency in transport modelling;

the issues of data and specification errors in modelling, their relative importance and methods to handle them;

the key role played by the decision‐making context in the choice of the most appropriate modelling tool;

how uncertainty and risk influence the choice of the most appropriate modelling tool;

the advantages of variable resolution modelling; a simplified background model coupled with a much more detailed one addressing the decision questions in hand;

the need for a monitoring function relying on regular data collection and updating of forecasts and models so that courses of action can be adapted to a changing environment.

However, since we wrote that first edition, a lot has changed. The clear distinction between private and schedule‐based public transport has been disrupted by new forms of mobility: vehicle sharing, electric bikes, and, sometime in the future, autonomous vehicles. Also, transport planning objectives have evolved: today, the reduction of emissions and the provision of equitable access to all sections of the community are at the top of the agenda; they were secondary, if at all, in the twentieth century. More complex problems call for better tools to deal with them and develop a broader understanding and more considered judgment. Luckily, the profession has responded to this challenge, and this fifth edition of Modelling Transport attempts to bring these better tools and understanding to our audience.

In writing this book, we aimed to create both a text for a diploma or Master's course in transport and a reference volume for practitioners. However, we present the material in such a way as to be useful for undergraduate courses in civil engineering, geography, and town planning. We approached the subject from the point of view of a modelling exercise, discussing the role of theory, data, model specification in its broadest sense, model estimation, validation, and forecasting. Initially, we based the book on our lecture notes, prepared and improved over several years of teaching at undergraduate and graduate levels; we have also used them to teach practitioners through in‐house training programmes and short skills‐updating courses. We have extended and enhanced our lecture notes to cover additional material and to help the reader tackle the book without the support of a supervisor.

Chapters 2–9, 13, and 18 provide all the elements necessary to run a good 30 sessions course on transport demand modelling; in fact, such a course – with different emphases on certain subjects – has been taught by us at undergraduate level in Chile and at postgraduate level in Australia, Britain, China, Colombia, Germany, Italy, Mexico, Portugal, and Spain; the addition of material from Chapters 10–12 would make it a transport modelling course. Chapters 4–6, 10–12, and 14 provide the basic core for a course on network modelling and equilibrium in transport; a course on transport supply modelling would require more material, particularly relating to certain aspects of public transport supply which we do not discuss in enough detail. Chapters 15–17, 19, and 20 cover material which is getting more important as time goes by, in particular as the shift in interest in the profession is moving from passenger issues to freight and logistics and to the role that models play not only in social evaluation but also in the analysis of private projects. Chapter 1 provides an introduction to transport planning issues and outlines our view on the relationship between planning and modelling.

During our professional life, we have been fortunate to combine teaching with research and consultancy practice. We have learnt from the literature, our research and experimentation, and our mistakes. The latter has not been too expensive in terms of inaccurate advice. However, this is not just luck; a conscientious analyst pays for mistakes by working harder and longer to sort out alternative ways of dealing with a problematic modelling task. We have also learnt the importance of choosing appropriate techniques and technologies for each task; the ability to tailor modelling approaches to decision problems is an essential skill in our profession. Throughout the book, we examine the practical constraints to transport modelling for planning and policy-making in general, particularly given the limitations of current formal analytical techniques and the nature and quality of the data likely to be available.

We have avoided the intricate mathematical detail of every model to concentrate instead on their basic principles, identifying their strengths and limitations, and discussing their use. The level of theory supplied by this book is sufficient to select and use the models in practice. We have tried to bridge the gap between the more theoretical publications and a simplistic ‘how to' book offering a blueprint to each modelling problem. In this latest edition, we have also marked, with a shaded box, material which is more advanced or still under development but essential enough to be mentioned. There are no single solutions to transport modelling and planning issues. A recurring theme in the book is the dependence of modelling on context and theory. We aim to provide enough information and guidance so that readers can go and use each technique in the field; to this end, we have striven to look into practical questions about the application of each methodology. Wherever the subject area is still under development, we have striven to extensively reference more theoretical papers and books, which the interested reader can consult as necessary. Concerning other, more settled modelling approaches, we have kept the references to those essential for understanding the evolution of the topic or serving as entry points to further research.

Nobody can aspire to become a qualified practitioner in any area without working in a laboratory or field. Therefore, we have gone beyond the sole description of the techniques and have accompanied them with various application examples. These illustrate some of the theoretical or practical issues related to particular models. We provide a few exercises at the end of key chapters; these can be solved with the help of a scientific pocket (or better still, a spreadsheet) calculator and should assist in the understanding of the models discussed.

Although the book is ambitious in covering many themes, it must be made clear from the outset that we do not intend (nor believe it possible) to be up-to-the-minute on every topic. The book is a good reflection of the state-of-the-art, but for leading-edge research, the reader should use the references provided as signposts for further investigation.

We wrote most of the first edition during a sabbatical visit by the first of us to University College London in 1988–89. This was possible owing to the support provided by the UK Science and Engineering Research Council, The Royal Society, Fundación Andes (Chile), The British Council, and The Chartered Institute of Transport. We thank them for their support as we acknowledge the funding provided for our research by many institutions and agencies over the past 50 years. The third and fourth editions benefited greatly from further sabbatical stays at University College London in 1998–99 and 2009; these were possible owing to the support provided by the UK Engineering and Physical Sciences Research Council. We also wish to acknowledge the support for our research provided by several FONDECYT projects in Chile, by Instituto Sistemas Complejos de Ingeniería (ISCI), through grant ANID PIA/PUENTE AFB230002; the Centre for Sustainable Urban Development (CEDEUS), through grant CEDEUS/FONDAP/15110020; and the BRT+ Centre of Excellence funded by the Volvo Research and Educational Foundations.

We have managed to maintain a fairly even intellectual contribution to the contents of this book, but in writing and researching material for it, we have also benefited from numerous discussions with friends and colleagues. Richard Allsop taught us a good deal about methodology and rigour. Huw Williams’s ideas are behind many of the theoretical contributions in Chapter 7; Andrew Daly and Hugh Gunn helped to clarify many issues in Chapters 3, 7–9, and 18. Dirck Van Vliet’s emphasis in explaining assignment and equilibrium in simple but rigorous terms inspired Chapters 10–12. Tony Fowkes made valuable comments on car ownership forecasting and stated‐preference methods. Jim Steer provided a constant reference to practical issues and the need to develop improved approaches to address them.

Many parts of the first edition of the book also benefited from a free, and sometimes very enthusiastic, exchange of ideas with our colleagues J. Enrique Fernández and Joaquín de Cea at Pontificia Universidad Católica de Chile, Sergio Jara‐Díaz and Jaime Gibson at Universidad de Chile, Marc Gaudry then at Université de Montréal, Roger Mackett at University College London, and Dennis Gilbert and Mike Bell then at Imperial College. Many others also contributed, without knowing, to our thoughts.

Subsequent editions of the book have benefited from comments by a number of friends and readers, apart from those above, who have helped to identify errors and areas for improvement. Among them we should mention Francisco Bahamonde‐Birke at Tilburg University; Michel Bierlaire at Ecole Polytechnique Fédérale de Lausanne; Patrick Bonnel at the French Laboratoire d’Economie des Transports; David Boyce at University of Illinois; Victor Cantillo at Universidad del Norte, Barranquilla; Elisabetta Cherchi at Newcastle University; Michael Florian at Université de Montréal; Rodrigo Garrido, Ricardo Hurtubia, Luis I. Rizzi, and Francisca Yáñez from Pontificia Universidad Católica de Chile; David Hensher at ITLS, Sydney University; Ben Heydecker at University College London; Frank Koppelman at Northwestern University; Mariëtte Kraan at University of Twente; C. Angelo Guevara, Francisco J. Martínez, and Marcela Munizaga at Universidad de Chile; Piotr Olszewski at Warsaw University of Technology; Alejandro Tudela at Universidad de Concepción; Joan L. Walker at University of California at Berkeley; and Sofia Athanassiou, Neil Chadwick, Yaron Hollander, Gloria Hutt, Serbjeet Kohli, and John Swanson while they were at Steer. Special thanks are due to John M. Rose at ITLS, University of Sydney, for his contributions to Chapter 2; to Stephane Hess at Leeds University and Camila Balbontín at Pontificia Universidad Católica de Chile, for their contributions to Chapters 7 and 8; and to Jose Holguín‐Veras at Rensselaer Polytechnic Institute for his contribution to Chapter 15.

We have not taken on board all suggestions, as we felt some required changing the approach and style of the text; we are satisfied that future books will continue to clarify issues and provide greater rigour to many of the topics discussed here; transport is indeed a very dynamic subject.

We are grateful to the skilled editors at Wiley, whose efforts have helped us to express our ideas more clearly with their attention to detail and excellent work.

Our final thanks go to our graduate and undergraduate students in many countries; they are always sharp critics and provided the challenge to put our money (time) where our mouth was. We are also grateful to Tomás Ramírez for having carefully re‐drawn most of the figures in the book.

Despite all this generous assistance, we are, as usual, solely responsible for any errors remaining in this latest edition of the book. We genuinely value the opportunity to learn from our mistakes.

Juan de Dios Ortúzar and Luis G. Willumsen

About the Companion Website

This book is accompanied by a companion website. 

www.wiley.com/go/ortuzar5e 

This website includes:

Solution Manual

1Introduction

1.1 Background

We cannot predict the future with certainty, but we can prepare for it by designing policies and projects that we expect will improve the welfare and quality of life of a community. We can adopt an experimental approach to the design of some simple schemes, for example, changing the allocation of lanes to different types of users, using markers that can be removed later; we can then check whether the results from the experiment are positive and make them permanent, or return the roadway to its original use. We can test interventions like these in an emergency; for example, during the 2020 pandemic some of the road lanes were repurposed for cyclists, pedestrians, or pavement cafes on a temporary basis; as most people liked them, many have become permanent features. Nevertheless, this is not feasible for more significant interventions like a new road or tram link because the political, economic, and environmental costs would be too large. Moreover, most investments in transportation take several years to plan, implement, and mature, and, therefore, their impacts will happen mostly in the future and probably under different conditions, so no experiment would be truly valid; we need a different approach.

A good alternative is to develop a sufficiently realistic transport model where various interventions, policies, and projects can be tested for their performance against given objectives. This phrase hides two difficult issues: (i) how realistic the model should be, and (ii) what are the most relevant indicators of the performance of an intervention against objectives. This is the central topic of this introductory chapter. We look, first, at transport problems and the objectives to tackle them; indeed, they are two interconnected problems. Then, we discuss the nature of the transport models required to address these problems and use a simple example to illustrate their character and scope. Afterwards, we consider key issues in modelling and model design, concluding with comments on the apparent conflict between theory and practice.

The first part of the twenty‐first century has seen two powerful agents of change affecting most aspects of life and welfare, and of course, transport modelling. The first is technological progress, in particular cheap and fast telecommunications facilitating new forms of requesting, using, and paying for mobility. A consequence of this progress is the possibility of working and procuring goods and services remotely: telework and e‐commerce continuously change travel patterns. The second agent is the requirement that equity and fairness take a central role in designing transport interventions; this refers to both intra‐ and inter‐generational fairness. The former deals with the importance of a fair distribution of access to opportunities for the community rather than just the provision of time savings, for example. Inter‐generational equity, on the other hand, demands that protecting the environment for future generations be central to any policy and programme of investment. Notwithstanding, these two key agents of change, technology and equity, must be addressed in the context of a third important element, high uncertainty, which has a profound effect on modelling and decision‐making.

When we think about these issues, we cannot forget the role of transport infrastructure in enhancing the economic competitiveness of nations, the role of telecommunications in reducing the need to travel, the transformational impact of new technologies and the overarching objectives of reducing emissions and providing better access to opportunities to all sections of the community.

1.2 Models and Their Role

A model is a simplified representation of a part of the real world – the system of interest – which focuses on certain elements considered important from a particular point of view. Models are, therefore, problem‐ and viewpoint‐specific. Such a broad definition allows us to incorporate both physical and abstract models. In the first category, we find, for example, those used in architecture or fluid mechanics, which are basically aimed at design. In the latter, the range spans from the mental models all of us use in our daily interactions with the world to formal and abstract (typically analytical) representations of some theory about the system of interest and how it works. Mental models play an important role in understanding and interpreting the real world and our analytical models. They are enhanced through discussions, training, observation and, above all, experience. Mental models are, however, difficult to communicate and to discuss.

In this book, we are concerned mainly with an important class of abstract models: mathematical models. These models attempt to replicate the system of interest and its behaviour by means of mathematical equations based on certain theoretical statements about it. Although they are still simplified representations, these models may be very complex and often require large amounts of data to be used. However, they are invaluable in offering a ‘common ground’ for discussing policy and examining the inevitable compromises required in practice with a certain level of objectivity. Another important advantage of mathematical models is that during their formulation, calibration, and use, the planner can learn much, through experimentation, about the behaviour and internal workings of the system under scrutiny. In this way, we also enrich our mental models, thus permitting more intelligent management of the transport system.

A model is only realistic from a particular perspective or point of view. It may be reasonable to use a knife and fork on a table to model the position of cars before a collision, but not to represent their mechanical features or their route choice patterns. The same is true of analytical models: their value is limited to a range of problems under specific conditions. The appropriateness of a model is, as discussed in the rest of this chapter, dependent on the context where it will be used. The ability to choose and adapt models for particular contexts is one of the most important elements in the complete planner's toolkit.

This book is concerned with the contribution transport modelling can make to improved decision‐making and planning in the transport field. We argue that the use of models is inevitable and that formal models are highly desirable. However, transport modelling is only one element in transport planning: administrative practices, an institutional framework, skilled professionals, and good levels of communication with decision‐makers, the media, and stakeholders are some of the other requisites for an effective planning system. Moreover, transport modelling and decision making can be combined in different ways depending on local experience, traditions, and expertise.

Transport modelling has a long trajectory from the early beginnings in Detroit in the 1950s. Boyce and Williams (2015) provide us with an excellent non‐mathematical presentation of the evolution of theories, methods, and models underpinning transport forecasts and policy analysis. Their book is worth reading to gain an in‐depth understanding of the evolution and role of transport modelling and planning.

Before we discuss how to choose a modelling and planning approach, it is worth outlining some of the main characteristics of transport systems and their associated problems. We will also discuss some important modelling issues, which will find application in other chapters of this book.

1.3 Characteristics of Transport Problems

Our understanding of transport problems has evolved over time. Traditionally, we have seen a general increase in road traffic and transport demand that has resulted in congestion, delays, accidents, and environmental problems well beyond what has been considered acceptable so far. These problems have not been restricted to roads and car traffic alone. Economic growth seems to have generated levels of demand exceeding the capacity of many transport facilities. In this sense, transport problems have been perceived as a mismatch between demand expectations and the supply of transport services, including road space. This is consistent with conventional economic thinking.

1.3.1 Characteristics of Transport Demand

The demand for transport is derived; it is not an end in itself. With the possible exception of sight‐seeing, people travel in order to satisfy a need (work, leisure, or health) undertaking an activity at particular locations. This is equally significant for goods movements. In order to understand the demand for transport, we must understand the way in which these activities are distributed over space, in both urban and regional contexts. A good transport system should provide equitable opportunities to satisfy these needs; a heavily congested or poorly connected system restricts options and may restrain economic and social development.

The demand for transport services is highly qualitative and differentiated. There is a whole range of specific demands for transport that are differentiated by time of day, day of the week, journey purpose, type of cargo, importance of speed and frequency, and so on. A transport service without the attributes matching this differentiated demand may well be useless. This characteristic makes it more difficult to analyse and forecast the demand for transport services: tonne and passenger kilometres are extremely coarse units of performance hiding an immense range of requirements and services.

Transport demand takes place over space. This seems a trivial statement, but it is the distribution of activities over space, which creates transport demand. There are a few transport problems that may be treated, albeit at a very aggregate level, without explicitly considering space. However, in the vast majority of cases, the explicit treatment of space is unavoidable and highly desirable. The most common approach to treat space is to divide study areas into zones and code them, together with transport networks, in a form suitable for processing with the aid of computer programs. In some cases, study areas can be simplified by assuming that the zones of interest form a corridor, which can be collapsed into a linear form. However, different methods for treating distance and for allocating origins and destinations (and their attributes) over space are an essential element in transport analysis.

Finally, transport demand and supply have very strong dynamic elements. A good deal of the demand for transport is concentrated on a few hours of a day, in particular in urban areas where most of the congestion takes place during peak periods. In effect, the peak of demand usually happens at different times and in different locations in large cities. This time‐variable character of transport demand makes it more difficult – and interesting – to analyse and forecast. It may well be that a transport system could cope well with the average demand for travel in an area but that it breaks down during peak periods. A number of techniques exist to try to spread the peak and average the load on the system: flexible working hours, staggering working times, premium pricing, and so on. However, peak and off‐peak variations in demand remain a central, and fascinating, problem in transport modelling and planning.

1.3.2 Characteristics of Transport Supply

The first distinctive characteristic of transport supply is that it is a service and not a good. Therefore, it is not possible to stock it, for example, to use it in times of higher demand. A transport service must be consumed when and where it is produced; otherwise, its benefit is lost. For this reason, it is very important to estimate demand with as much accuracy as possible to save resources by tailoring the supply of transport services to it.

Many characteristics of transport systems derive from their nature as a service. In very broad terms, a transport system requires certain fixed assets, the infrastructure, and a number of mobile units, the vehicles. The combination of these, together with a set of rules for their operation, makes possible the movement of people and goods.

The infrastructure and vehicles are not often owned or operated by the same group or company. This is certainly the case for most transport modes, with the notable exception of some rail and ferry systems. This separation between supplier of infrastructure and provider of the final transport service generates a complex set of interactions between government authorities (central or local), stakeholders, construction companies, developers, transport operators, travellers and shippers, and the general public. The latter plays several roles in the supply of transport services: it represents the residents affected by a new scheme or the unemployed in an area seeking improved accessibility to foster economic growth; it may even be car owners wishing to travel unhindered through somebody else's residential area.

The provision of transport infrastructure is particularly important from a supply point of view. Transport infrastructure is ‘lumpy’ one cannot provide half a runway or one‐third of a railway station. In certain cases, there may be scope for providing a gradual build‐up of infrastructure to match growing demand. For example, one can start providing an unpaved road, upgrade it later to one or two lanes with surface treatment; at a later stage a well‐constructed single and dual carriageway road can be built, to culminate perhaps with motorway standards. In this way, the provision of infrastructure can be adjusted to demand and avoid unnecessary early investment in expensive facilities. This is more difficult in other areas such as airports, metro lines, and ports. Technology innovation is making the future increasingly fluid and difficult to predict; with greater uncertainty, the importance of building flexibility into the design of transport infrastructure will become even more critical.

Investments in transport infrastructure are not only lumpy but also take a long time to complete. These are usually large projects. The construction of a major facility may take from 5 to 15 years from planning to full implementation. This is even more critical in urban areas where a good deal of disruption is also required to build them. This disruption involves additional costs to users and non‐users alike.

Moreover, transport investment has an important political role. For example, politicians in developing countries often consider a road project a safe bet: it shows they care and is difficult to prove wrong or uneconomic by the popular press. In emerging and advanced nations, transport projects usually carry the risk of alienating large numbers of residents affected by them or travellers suffering from congestion and delay in overcrowded facilities. Political judgement as well as forethought and planning are essential in making choices of this kind.

The separation of providers of infrastructure and suppliers of services introduces economic complexities too. For a start, it is not always clear that all travellers and shippers perceive the total costs incurred in providing the services they use. These can be wide‐ranging. The resources used when travelling include much more than the direct vehicle operating costs or fares. Most roads are provided for free to most users. Charging for road space, for example, is seldom carried out directly, and when it happens, the price does not include congestion costs or other external effects; perhaps the nearest approximation to this is toll roads and modern road‐pricing schemes. The use of taxes on vehicles and fuels is only a poor approximation to charging for the provision of infrastructure.

Transport is an essential element in the welfare of nations and the well‐being of urban and rural dwellers. If those who make use of transport facilities do not perceive the resource implications of their choices, they are likely to generate a balance between supply and demand that is inherently inefficient. Under‐priced limited resources will be overused whilst other desirable but priced resources may be underused. Car owners probably see depreciation, insurance, and annual taxes as fixed, sunk, costs, which at most affect the decision to buy a car but not that of using it. The marginal perceived cost of using a car is quite low.

An additional element of distortion is provided by a number of external costs borne by non‐users – associated with the production of transport services: accidents, delays to others, pollution, and environmental degradation in general. These externalities are seldom internalised