Yesterday's publication of an obscure-sounding report from the Sactra committee on road-traffic growth forecasts is but the latest in a series of blows to the roads lobby which has seen both money and major schemes lost. The report seems certain to accelerate the debate over transport policy which Brian Mawhinney, Secretary of State for Transport, has initiated since taking office in July.
The Government's response to Sactra is essentially prevarication, but as each scheme is put under the microscope using the new criteria for traffic-growth forecasts, many more are likely to fall by the wayside.
The publication in 1989 of a White Paper, Roads to Prosperity, marked the roads lobby's finest hour. Roads were seen as the way to bring prosperity to disadvantaged regions and to ensure that the wheels of industry continued to roll. A manifesto commitment promised to spend £2bn per year on the national roads programme, in addition to the £1bn being spent locally by county and district councils districts.
But ministerial boasts about the biggest-ever road building programme became muted after the growth of widespread opposition to many key schemes such as Twyford Down in Hampshire, the M11 link roads in east London and the widening of the M25 to 14 lanes in Surrey.
The Treasury had also begun to suspect that the criteria used for road schemes were arbitrary and even asked senior officials to ring up environmental campaigners to find ways of reining back development. Last month's Budget promptly led to cuts of £200mfor each of the next two years in the roads programme.
The replacement of John MacGregor, an unimaginative pro-roads minister, by Mr Mawhinney in July also means the roads lobby can no longer rely on a favourable bias.
The most surprising aspect of this saga is that the pro-roads lobby has got away with it for so long. What the Sactra report says - that the construction of new roads leads to extra traffic - is not surprising. Although Sactra found it difficult to ascertain the precise mechanism for this, its truth is demonstrated. As the report says, if there had been no roadbuilding since 1950, there would be fewer cars on the roads today.
The Government's muted response to the report, the continued strength of the pro-roads lobby which is backed by major construction firms and the lack of any alternative coherent transport policy addressing real demands in the late 20th century will ensure continuing clashes over road schemes.
However, with the intellectual justification for new roads severely impaired, we are entering, what Dr Phil Goodwin, a member of the Sactra committee, calls a period of "new realism" in which ministers recognise that they cannot build sufficient roads totackle congestion.