Feasibility of Measuring the Induced Traffic Effects of the Completion of the Manchester Motorway Box
SKINNER A, COOMBE A, The MVA Consultaney, BATES J, John Bates Services, FOWKES T, University of Leeds and HYMAN G, Department of the Environment, Transport and the Regions, UK
The origins of the research into "induced traffic" can be traced back to the mid-1980s. A Review of Urban Roads Appraisal Methods was conducted for the UK Department of Transport in 1984-5 as an input to the Standing Advisory Committee on Trunk Road Appra
The origins of the research into "induced traffic" can be traced back to the mid-1980s. A Review of Urban Roads Appraisal Methods was conducted for the UK Department of Transport in 1984-5 as an input to the Standing Advisory Committee on Trunk Road Appraisal (SACTRA)'s deliberations on the same topic, reported in 1986. One of the recommendations of this Review was that a series of model tests should be undertaken to identify the scale of the different effects (generation, distribution, modal transfer, change in time of travel, and re-assignment) from a variety of road schemes and their contributions to the total economic benefits.
This recommendation was taken up in research conducted for the Department of Transport through the Transport and Road Research Laboratory (TRRL) in 1988 to 1989. In this research, entitled "A Modelling Exercise to Study Benefits from Urban Road Improvements", a four-stage transport model was used to investigate the effect of each model stage on the overall economic benefits of road schemes. This in turn led to a further investigation, undertaken for the TRRL by the Institute for Transport Studies, University of Leeds, into the Feasibility of Measuring Responses to Highway Improvements, resulting in the seminal Contractor Report 200.
SACTRA saw CR200 as central to its deliberations published in 1994 on Trunk Roads and the Generation of Traffic. Based on a very wide range of evidence submitted by the profession at large, SACTRA concluded that induced traffic can and does occur, probably quite extensively, though its size and significance is likely to vary widely in different circumstances. SACTRA was not, however, able to advise the Department, in general terms, about the composition of induced traffic, and therefore recommended that the Department's proposed programme of research, to investigate the responses of travellers to road network improvements, should be given high priority. The overall aim is to achieve greater understanding of induced traffic so that improved methods of forecasting traffic can be developed for road scheme appraisal.
The MVA Consultancy in Association with John Bates and ITS Leeds University were appointed in December 1996 to undertake a study of the feasibility of measuring the induced traffic effects of the completion of the Manchester Motorway Box. MVA have led the work, having responsibility for overall project planning and management, the creation of specialist software, and running of transport and analytical models. John Bates has been responsible for the overall technical approach, and ITS Leeds University provided major inputs with respect to the incorporation of measures of survey related variability into the analysis process.
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