Modelling Long-Distance Travel in Great Britain

Trips longer than 50 mi account for less than one-fortieth of all trips but nearly one-third of all distance traveled within Great Britain. Because of the small proportion of all travel that they form, long-distance trips may not be adequately represented in national databases and models. However, because they account for a substantial proportion of total distance traveled, particularly on motorways and rail, these trips are important for transport policy and have a substantial impact on congestion. Moreover, study of existing data indicates that travelers' behavior in long-distance journeys differs substantially from that in routine journeys. Not only is the set of available modes different, but the profile of travelers is also substantially different, with income playing an important role in both travel frequency and mode choice. In addition, model responsiveness and values of time vary significantly with journey length. For these reasons, treatment of the specific properties of long-distance travel is essential for appraising the impact of transport policy aimed at this market, such as high-speed rail, highway construction and management policies, and policies directed toward domestic air travel. This paper describes the development of a model to address these policy issues. The specific aim of the modeling work is to provide empirical evidence on the relative importance of mode, destination, and frequency responses for long-distance travel models. The models that have been developed form the basis for a forecasting model that can be used for the appraisal of a wide range of transport policy aimed at long-distance journeys.