Vol 4 No 2 (2004)
2004-05-01
Vol 4 No 2 (2004)
2004-05-01
Articles
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Standard static traffic assignment models do not take into account the direct effects of capacities on network flows. Separable link performance functions cannot represent bottleneck and intersection delays, and thus might load links with traffic volumes, which far exceed their capacity. This work focuses on the side-constrained traffic assignment problem (SCTAP), which incorporates explicit capacity constraints into the traffic assignment framework to create a model that deals with capacities and queues. Assigned volumes are bounded by capacities, and queues are formed when capacity is reached. Delay values at these queues are closely related to Lagrange multipliers values, which are readily found in the solution. The equilibrium state is defined by total path travel times, which combine link travel times and delays at bottlenecks and intersections for which explicit capacity constraints have been introduced.
This paper presents a new solution procedure for the SCTAP based on the inner penalty function method combined with a path-based adaptation of the gradient projection algorithm. This procedure finds a solution at the path level as well as at the link level. All intermediate solutions produced by the algorithm are strictly feasible. The procedure used to ensure that side-constraints are not violated is efficient since it is only performed on constrained links that belong to the shortest path.
Standard static traffic assignment models do not take into account the direct effects of capacities on network flows. Separable link performance functions cannot represent bottleneck and intersection delays, and thus might load links with traffic volumes, which far exceed their capacity. This work focuses on the side-constrained traffic assignment problem (SCTAP), which incorporates explicit capacity constraints into the traffic assignment framework to create a model that deals with capacities and queues. Assigned volumes are bounded by capacities, and queues are formed when capacity is reached. Delay values at these queues are closely related to Lagrange multipliers values, which are readily found in the solution. The equilibrium state is defined by total path travel times, which combine link travel times and delays at bottlenecks and intersections for which explicit capacity constraints have been introduced.
This paper...
Standard static traffic assignment models do not take into account the direct effects of capacities on network flows. Separable link performance functions cannot represent bottleneck and intersection delays, and thus might load links with traffic volumes, which far exceed their...
Joseph N. Prashker, Tomer Toledo -
Multi-modal trips are a common travel phenomenon, which are expected to become more important in the future because of their expected contribution to sustainable urban transportation. However, multiple different types of travel choices, such as transport service types, travel modes, and transfer locations, are involved in a multi-modal trip, making it difficult to model multi-modal traveling. We present a method that generates choice sets of multi-modal routes using a supernetwork, which might be used for prediction purposes. This method considers stochasticity in the perception of the network attributes as well as in the preferences for the different trip components. The primary objective of the paper is to analyze the comparison of generated route sets and observed route sets. Three options for generating route sets have been studied, i.e.: variation in the network attributes only, variation in traveler preferences only, and the combination of both. The latter case proved to yield the best match with observed route sets. Furthermore, the analysis shows that variation in travelers’ preferences is more important than variation in network attributes. Recommendations for further improvement of the choice set generation method are included. The analysis revealed insights into the possibilities of generating realistic multi-modal route sets and it is proved that the randomization approach is feasible providing good coverage of the observed routes. By far the best results are obtained by randomizing both network attributes and variation in traveler preferences.
Multi-modal trips are a common travel phenomenon, which are expected to become more important in the future because of their expected contribution to sustainable urban transportation. However, multiple different types of travel choices, such as transport service types, travel modes, and transfer locations, are involved in a multi-modal trip, making it difficult to model multi-modal traveling. We present a method that generates choice sets of multi-modal routes using a supernetwork, which might be used for prediction purposes. This method considers stochasticity in the perception of the network attributes as well as in the preferences for the different trip components. The primary objective of the paper is to analyze the comparison of generated route sets and observed route sets. Three options for generating route sets have been studied, i.e.: variation in the network attributes only, variation in traveler preferences only, and the...
Multi-modal trips are a common travel phenomenon, which are expected to become more important in the future because of their expected contribution to sustainable urban transportation. However, multiple different types of travel choices, such as transport service types, travel...
Stella Fiorenzo-Catalano, Rob van Nes, Piet H.L. Bovy -
This paper contains a critical review of design standards for motorway diverges in the UK over the last 40 years. These standards have been progressively updated at regular intervals and their evolving nature has been assessed. Most changes have been minor as a result of changes to traffic flow, driver behaviour or vehicle performance. A brief comparison has also been made between standards for diverges in the UK and those in other selected EU countries. This paper particularly focuses on the diverging flow-region diagram contained in the latest Government Standard TD22/92 ‘The Layout of Grade-Separated Junctions’. This diagram is used by traffic engineers as a tool in order to select the most appropriate diverge layout for a particular site. The historical background leading to its derivation is reviewed along with a discussion of comments made by five practicing traffic engineers as to its effectiveness and usage. These comments have been used along with other analysis to make recommendations as to how the diagram should be interpreted and how it could be improved.
This paper contains a critical review of design standards for motorway diverges in the UK over the last 40 years. These standards have been progressively updated at regular intervals and their evolving nature has been assessed. Most changes have been minor as a result of changes to traffic flow, driver behaviour or vehicle performance. A brief comparison has also been made between standards for diverges in the UK and those in other selected EU countries. This paper particularly focuses on the diverging flow-region diagram contained in the latest Government Standard TD22/92 ‘The Layout of Grade-Separated Junctions’. This diagram is used by traffic engineers as a tool in order to select the most appropriate diverge layout for a particular site. The historical background leading to its derivation is reviewed along with a discussion of comments made by five practicing traffic engineers as to its effectiveness and usage. These...
This paper contains a critical review of design standards for motorway diverges in the UK over the last 40 years. These standards have been progressively updated at regular intervals and their evolving nature has been assessed. Most changes have been minor as a result of changes...
G.T. Wall, N.B. Hounsell -
Academic interest in transport economics waxes and wanes. It was initiated (at least in its modern form) in France in the 1840s and 1850s to handle issues of investment and pricing of transport infrastructure. The advent of the railways raised challenges of monopoly power, regulation and, in some countries, appropriate ownership. The internal combustion engine brought with it initially economic questions associated with traffic congestion and more recently concerns with environmental degradation. Regulation issues returned to the forefront from the 1980s as new approaches to economic regulation emerged and as there was increased interest in making fuller use of market instruments. Overlapping this, the globalization of trade and the formation of trade blocks such as the European Union has led to a more detailed look at the role transportation plays in the economic development process.
Academic interest in transport economics waxes and wanes. It was initiated (at least in its modern form) in France in the 1840s and 1850s to handle issues of investment and pricing of transport infrastructure. The advent of the railways raised challenges of monopoly power, regulation and, in some countries, appropriate ownership. The internal combustion engine brought with it initially economic questions associated with traffic congestion and more recently concerns with environmental degradation. Regulation issues returned to the forefront from the 1980s as new approaches to economic regulation emerged and as there was increased interest in making fuller use of market instruments. Overlapping this, the globalization of trade and the formation of trade blocks such as the European Union has led to a more detailed look at the role transportation plays in the economic development process.
Academic interest in transport economics waxes and wanes. It was initiated (at least in its modern form) in France in the 1840s and 1850s to handle issues of investment and pricing of transport infrastructure. The advent of the railways raised challenges of monopoly...
Kenneth Button -
This book was meant to disseminate the results of a national research project funded by the European Union. In this case, a standard structure could be expected containing the need for and the context of the research, the methodology used and the results obtained. But the book does a lot more than summarizing the research conducted. Each of the traditional items are of course reported throughout the different articles, but the emphasis is on original and provocative approaches. The evaluation of the latest trends in the sector, the impact of education and training on sector behaviour, the impact of culture, and the monitoring of reproductability and transferability of the evaluation procedure give an extra dimension to the analysis reporting. The main topic in itself too merits attention and praise since there is ample supply of training programmes, the quality of which, however, varies (a program useful in one situation may not apply to or even have a counterproductive effect in a different situation, and the need for training should be clearly evaluated before taking any action).
This book was meant to disseminate the results of a national research project funded by the European Union. In this case, a standard structure could be expected containing the need for and the context of the research, the methodology used and the results obtained. But the book does a lot more than summarizing the research conducted. Each of the traditional items are of course reported throughout the different articles, but the emphasis is on original and provocative approaches. The evaluation of the latest trends in the sector, the impact of education and training on sector behaviour, the impact of culture, and the monitoring of reproductability and transferability of the evaluation procedure give an extra dimension to the analysis reporting. The main topic in itself too merits attention and praise since there is ample supply of training programmes, the quality of which, however, varies (a program useful in one situation may not...
This book was meant to disseminate the results of a national research project funded by the European Union. In this case, a standard structure could be expected containing the need for and the context of the research, the methodology used and the results obtained. But the...
Thierry Vanelslander -
This book is a compilation of papers presented in a seminar on “Policy and project evaluation: context, theory and methods”, held in Brussels in 2000 and which was organized by the Interdisciplinary Center for Comparative Research in Social Sciences with support from the European Commission. In addition to the introductory chapter, written by two of the editors, the book contains 7 papers. These are roughly divided between 3 papers, which describe the “European scene”, and 4 papers, which review approaches and methods of transport evaluation. Needless to say, in a book of this nature some overlap between chapters is largely unavoidable. In general, however, I find the book to be well organized and the chapters quite informative and well written.
This book is a compilation of papers presented in a seminar on “Policy and project evaluation: context, theory and methods”, held in Brussels in 2000 and which was organized by the Interdisciplinary Center for Comparative Research in Social Sciences with support from the European Commission. In addition to the introductory chapter, written by two of the editors, the book contains 7 papers. These are roughly divided between 3 papers, which describe the “European scene”, and 4 papers, which review approaches and methods of transport evaluation. Needless to say, in a book of this nature some overlap between chapters is largely unavoidable. In general, however, I find the book to be well organized and the chapters quite informative and well written.
This book is a compilation of papers presented in a seminar on “Policy and project evaluation: context, theory and methods”, held in Brussels in 2000 and which was organized by the Interdisciplinary Center for Comparative Research in Social Sciences with support from the...
Joseph Berechman