A Rail Freight Forecasting Model for the Strategic Rail Authority
J Hawthorne and I Brooker, Sinclair Knight Merz, UK;
In May 2001, the British Strategic Rail Authority set out its strategy for delivery of the 80% growth in freight by rail over the period of the Government?s 10 Year Plan. In order to inform this strategy, and tounderstand the potential for the growth of freight, a demand forecasting model has been developed by Sinclair Knight Merz (Europe), for the SRA.
This paper describes the development of the model, from the initial version which produces national forecasts, to the current version which can be used for regional and corridor studies.
A particular feature is the development of a detailed database of road and rail freight movements across Great Britain to enable the synthesis of input datasets for specific regions and corridors.
The model brings together a series of techniques developed by SKM, and drawing on work by AEA Technology and Leeds ITS, into an integrated package.
The total freight market is segmented by size of road vehicle, rail connectivity and load size. A series of filters are applied to the freight market to exclude traffic which consists of small loads or cannot use required sections of the network. These filters can be adjusted to reflect different scenarios.
A separate module is used to calculate break-even distances for each commodity and segment using a very detailed cost model. Mode share is determined by a logit function based on distance relative to the break-even distance.
An important factor in the development of the model has been to maximise practical useability by the client, with particular emphasis on the development of a simple user interface. This enables the SRA to model the effects of possible legislative and regulatory changes, such as permitted lorry weights and track access charges, also factors such as enhancement to the rail loading gauge on specific routes.
SKM has considerable hands-on freight experience, and the modular approach to development of the model has enabled the outputs from each module to be benchmarked against identifiable features and trends in the freight market, enabling a good representation of how the freight market actually works.
The paper concludes with a review of some of the problem areas encountered by SKM in developing models of this type, including the particular issues arising from emerging changes in the UK freight marketplace.
Association for European Transport