In a lecture given in Oxford last night to launch a pounds 2m research programme on traffic growth, Phil Goodwin, the director of Oxford University's Transport Studies Unit, said that traffic growth cannot be allowed to continue on its projected path, and forms of transport which cause congestion or pollution will have to be made more expensive.
Currently in the UK, the average person spends just over an hour a day travelling 21 miles at an average of 20mph. Forty years ago, people travelled only eight miles per day but forecasts suggest this will increase to 50 miles per day by 2025.
Travel in cars and vans accounts for 86 per cent of all mileage and, in 1989, the Department of Transport produced figures which suggested that traffic would grow by '83 per cent to 142 per cent by 2025', a forecast Dr Goodwin calls 'a mantra of transport policy discussions'.
He argued that, in urban areas, it has become recognised that roadspace cannot be increased to meet such high forecast rises in traffic growth. Britain, however, has lagged behind the Continent in implementing policies to damp down traffic growth but he believes that 'we are poised for a very substantial catching-up exercise'.
Now, he suggested, there will have to be equal recognition of the fact that traffic growth in rural areas, predicted in parts to be between 300 per cent and 400 per cent, cannot be sustained.
The roads lobby may put forward a last-ditch argument suggesting that traffic forecasts are exaggerated, and therefore a bit of extra roadbuilding will be able to cope with new demand. Dr Goodwin rejected this, arguing that the extra traffic growth generated by new roads reduces the benefits of building them.
Dr Goodwin is a member of the Government's advisory committee on traffic growth forecasts, which produced an unpublished report last May saying that new roads generate traffic growth, a concept that undermines the calculations used for assessing the value of road schemes.
The publication of the report has been delayed while ministers consider their response. Yesterday, Frank Dobson, Labour's transport spokesman, called for its publication.
Dr Goodwin said that this induced traffic growth is one of several compelling arguments for actually reducing existing road capacity through 'a Beeching report on the road network'. In addition, as new roads are built, people desert public transport to use them, reducing its viability. The process could be reversed by improving public transport to attract people off the roads, therefore improving journey times.
Dr Goodwin also referred to 'a mathematical anomaly in the science of traffic flow called Braess's Paradox', which states that, in some circumstances, the provision of an extra road results in 'increased overall journey time'.
Moreover, where road capacity has been removed - through the creation of pedestrian areas in towns - they have proved to be successful both economically and environmentally.
Dr Goodwin added that the policy of removing roads needs be addressed carefully.