Hugh Gunn

National and International Freight Transport Models: An Overview and Ideas for Future Development

This paper contains a review of the literature on freight transport models, focusing on the types of models that have been developed since the 1990s for forecasting, policy simulation and project evaluation at the national and international levels. Models for production, attraction, distribution, modal split and assignment are discussed. Furthermore, a number of ideas for future development, especially for the regional and urban components within national freight transport models, are included.

AN ON-LINE DYNAMIC TRAFFIC PREDICTION MODEL FOR AN INTER-URBAN MOTORWAY NETWORK

This paper specifies the overall structure of an on-line Dynamic Traffic Model System for an inter-urban motorway network. The model predicts traffic conditions on a motorway network in real time, and can be used to provide information on (expected) congestion to a motorway traffic control centre. The model receives traffic data such as traffic flow, average speed and average detector occupancy in real-time from a motorway monitoring system. Additionally, a database of historic traffic information will be used.

THE OPENING OF THE AMSTERDAM RING ROAD. A CASE STUDY ON SHORT-TERM EFFECTS OF REMOVING A BOTTLENECK

This paper presents the results of a major before-and-after study carried out to establish the short term effects of the removal of a severe bottleneck in the road network around Amsterdam. An important focus in the study was on measuring changes in the timing of travel, as well as changes in route choice, mode choice, destination choice and frequency of travel. The results of the study indicated that, in the short run, there was little or no change in mode choice, nor was there significant emergence of new “induced” trips. On the other hand, large shifts in time of travel as well as route choice were reported, emphasising the importance of alterations to the timing and routes of existing trips when congestion is relieved, and the need to consider the benefits these bring in evaluating the impact of any road investment.

An Overview of European National Models

The aim of this chapter is to provide something of a historical perspective from which to view recent advances in National Travel Demand Models, as an introduction to the discussion in other chapters of this book.

The strengths and weakness of travel demand model systems for assessing emission reduction policies

Abstract Systems of models which predict various aspects of travel behaviour—frequency of travel, choice of destination, choice of mode, choice of route, etc.—are now often applied to predict the influence of transport policies. The forecasting horizon for such studies is often as long as 15–25 years into the future. In recent years, the environmental and energy impacts of private travel have become vital issues in transport policy assessment. The main question addressed in the paper is thus what travel demand model systems can and cannot yet tell us about long-term changes in emissions from private transportation. The paper first outlines the typical structure, inputs and outputs of travel demandmodel systems. Then, two European case studies are described—one in the Netherlands and the other in Norway. In both cases, predictions of future emissions levels were key results. These studies illustrate both the strength of such models in providing a detailed and realistic treatment of the demand for travel, but also some current weaknesses with respect to predicting fuel use and emission rates. The final section discusses two particular areas of modelling which can address these weaknesses. The first area is that of vehicle purchase behaviour. Further progress in this area will allow better forecasts of the makeup of the car park in terms of the fuel use and emissions characteristics of the vehicles. A second area is that of driving behaviour, as might be influenced by, for instance, lower speed limits, in-vehicle information systems or greater environmental awareness.