No more. It is ironic that almost as soon as this policy reached its apogee, the seeds of its doom were already being sown. The national roads programme, consisting of 330 schemes for trunk roads and motorways, was first set out in 1989 in a thin little White Paper called Roads to Prosperity. Written in the "boom, boom, Britain" style of the Lawson "economic miracle", it set in train a massive roadbuilding programme, promising that spending would double to reach £2bn per year. And it was predicated on the notion that traffic was forecast to increase by between 83 per cent and 142 per cent between 1988 and 2025.
Yet, almost as soon as this policy was being drawn up, the transport planners began to realise, studying these traffic growth forecasts, that building sufficient roads to cope with the congestion crisis was simply not viable. They calculated that even on the best estimates, with every planned road being built on time, the amount of congestion would still go up. All this money and effort was being put into a policy that might, at best, stop things from getting worse quicker.
Phil Goodwin, head of Oxford University's transport studies unit, says it has now become apparent that "no realistic trunk road programme can keep pace with forecast traffic growth, on current trends". This means that the supply of road space is not going to expand in line with demand and we have to examine other options.
For a while the Department of Transport - often called the ministry for roads by critics - turned a blind eye to the growing academic evidence and sought to plough on regardless. The idea for widening the M25 to 14 lanes was mooted almost as soon as the road was completed in 1986. It was disguised somewhat as the extra lanes were to be called "link roads" for use by local traffic, but the local protests were immediate and vociferous. What made it unpalatable for the residents was that they had been promised the M25 would solve all their traffic problems and now, within a couple of years of its completion, they were facing the prospect of yet more concrete.
By the time the scheme for the link roads had been published in preparation for the public inquiry, attacks on the roadbuilding programme were coming from many different directions. The "respectable" end of the environmentalist movement, such as Friends of the Earth and the Council for the Protection of Rural England, were finding that their lobbying efforts were being backed by a growing guerrilla wing. There were highly publicised protests at Twyford Down, east London (M11), Glasgow (M77) and Bath (A36). They comprised a dangerous cocktail of young activists and local residents, the latter, in many cases, representing a typical cross-section of Middle England. And once Middle England had turned against roads, it was inevitable that the Government's enthusiasm for the programme would wane.
But ranged against Middle England, there is the construction and roads lobby, a powerful paymaster of the Tories and a strong influence on their policy. That is why Dr Brian Mawhinney has tried to avoid making his decision look like a climbdown and has refused to acknowledge publicly the consequences of what he has announced. For not only will the 14-lane M25 never see the light of day, but the whole concept of widening motorways with link roads is sure to be scrapped. Britain will not get US-type multi- lane swathes of concrete covering vast areas of the countryside and similar schemes across the country will now be quietly dumped because they are equally politically unpalatable.
Despite Dr Mawhinney's caution, the importance of yesterday's decision cannot be overstated. In simple demand terms, the argument for the road was virtually irrefutable. The part of the M25 in question, between the M4 and the M3 in Surrey, is the busiest stretch of motorway in Britain, with up to 200,000 cars a day and traffic often at a standstill. If it is impossible to justify such a widening of the busiest motorway in the country because of the resulting environmental damage, how many other road schemes are now equally vulnerable? Dr Mawhinney had, in fact, being trying to announce the scrapping of the link roads for some time, but, according to a senior Conservative source, "He needed to find the right form of words that wouldn't scupper the whole roads programme."
The roads programme has also been steadily undermined by a shifting consensus among transport planners and economists. Increasingly, they have been questioning whether investment in roads helps the country's more remote regions. Last year, the department's own committee on measuring the benefits of roadbuilding, Sactra, reported that building new roads in itself generates further traffic, thereby undermining the case for building them in the first place.
The Treasury, needless to say, has been delighted by this reassessment. Its officials have even resorted to ringing up environmental groups to obtain arguments against the roads programme. It showed its teeth in the last Budget by chopping £200m per year off the programme for each of the next three years, to bring it well below the £2bn figure promised in the 1992 Conservative manifesto.
The pro-roads lobby is dismissive of alternative solutions to the congestion crisis. But evidence from the rest of Europe shows that they can work. Both German and French railways report increases in the amount of freight being carried on rail. In urban areas, comprehensive solutions such as those in Zurich, where there has been major investment in public transport, or in Copenhagen, where roadbuilding schemes were dropped in favour of measures to increase cycling, have been successful.
As Dr Mawhinney has now realised, it is no longer an option just to throw money at the roadbuilders and hope that they can solve the congestion crisis. In fact, roadbuilding in towns was effectively abandoned some years ago. Now, as the M25 decision indicates, it is becoming equally difficult to build roads around towns and yesterday's announcement essentially spells the end for suburban motorways.
Mr Goodwin suggests a number of ways by which to reduce road demand. Road tolling is an obvious example. Another is better engineering and design, perhaps cutting off some junctions on motorways to discourage local traffic. Legal restrictions could be introduced, such as forcing 40-ton lorries to stick to motorways which would be tolled, thereby reducing their effect on other roads.
We are in the midst of a widely welcomed transport debate which was launched by Dr Mawhinney last year. He has made a series of speeches asking a number of basic questions about transport priorities. He has raised issues such as setting targets for traffic levels which have previously been a taboo topic in transport circles. Labour has so far been relatively silent, content to snipe at whatever the Tories do. It has, for example, set its face against road tolling, which most transport experts suggest would be a vital component of any coherent transport strategy for the 21st century.
The partial scrapping of the M25 widening means we are entering the foothills of a new transport policy. Whether either the Tories or Labour have the imagination or courage to take us up the mountain is another matter.