HC Deb 26 June 1989 vol 155 c338W
Sir Barney Hayhoe

To ask the Secretary of State for Transport whether traffic studies, funded by public funds, in recent years have revealed evidence linking increased road capacities with increased traffic and worsening traffic congestion; and whether he will make a statement.

Mr. Peter Bottomley

The Department is currently undertaking a feasibility study into whether a before and after study of an urban trunk road scheme could detect the size of various changes in travel patterns, such as generation of new trips, changes in destination of journey time, and changes in mode of travel.

We are all asking the independent standing advisory committee on trunk road assessment to review the evidence on these effects. The Department has not recently carried out any traffic studies specifically addressed at identifying the effects of increased road capacity on the level of traffic.

For all new trunk road schemes, the Department monitors actual traffic flow a year after opening, for the purpose of making comparisons with the scheme forecasts. The evidence from this monitoring supports the Department's assumption in traffic forecasting that the general inter-urban road improvements do not generate significant additional traffic. The main effect is on choice of route.