Ever more complex computer models produced the statistical justification for more motorways

Ever more complex computer models produced the statistical justification for more motorways.The Royal Commission starts from a different point altogether, by asking what we are trying to achieve. What are our 'quality of life' objectives for transport? Once general goals have been set, targets for achieving them, together with a clear timetable, can be set out. It has set out a detailed and radical procedure for assessing the need and shape of new transport schemes.Thus, targets are set to remove existing damage, as in the Commission's Target F1: 'To reduce emissions of carbon dioxide from surface transport in 2020 to no more than 80 per cent of the 1990 level.' They can be positive, as in D1: 'To increase the proportion of passenger kilometres carried by public transport from 12 per cent in 1993 to 20 per cent by 2005 and 30 per cent by 2020.' There are 'constraints' not to cause damage, such as Recommendation 37a: '. This was the idea that everything could be given a monetary value, and then all the monetary values calculated for 20 or 30 years ahead and used to predict whether building roads was a good thing or not. This represents the most serious public challenge to the DoT's approach to date.Its approach is particularly interesting because it departs from a policy assumption that has held back transport planning since the Sixties. Without a massive road-building programme, the Government's traffic growth predictions cannot come true.

People may want to use their cars, but they also want their children to be able to breathe freely, to play and undertake social activity without the constant fear of traffic. 'Calming' the local street is not enough: despite the growth of pedestrian malls, shopping, education and leisure are still most usually concentrated in traditional high streets, which are also main roads.Thus, both in traffic and environmental terms, there is no coherent vision of the future which follows through the logic of a continued growth of car and lorry traffic.The Royal Commission's enormous report focuses on the environmental half of the equation, as it should, although it draws heavily on the new understanding that more roads mean more traffic. We cannot build our way out of congestion, and I know of no sane professional who believes we can. This was not so universally accepted 10 years ago.The second reason is that there is no technical fix which can make a transport system based on car and lorry use acceptable in environmental terms.

This is the opposite of predicting seemingly endless traffic growth and then building the roads to keep up. The change is from what is often described as 'predict and provide' to 'predict and prevent'.Why is this reversal happening so quickly and why is it accepted by such a broad spectrum of decision makers? There are two reasons: first, it is abundantly clear that there is no room for the Department of Transport's predicted increases in traffic to take place; even a road-building programme many times bigger than the current pounds 20bn would offer no guaranteed relief of existing congestion, while promising vast increases in pollution and damage to our social environment. Yesterday's achievement was to begin to set out a framework to put a sustainable transport policy in its place. Today, everyone at least talks sustainable: the desire to use cars must be 'managed' and 'restrained', the object of planning is to 'reduce the need to travel'. The report of the Royal Commission on Environmental Pollution, issued yesterday, marks a true watershed in transport policy.

Behind it is a 10-year history of accumulating awareness that the prevailing thrust of policy was literally unsustainable. What you won't have seen is any programme depicting a golden vision of a car-based future That sort hasn't been around for almost a decade. The second type will have set out an endlessly depressing list of how the car and the heavy lorry - and the roads they require - are destroying our health, poisoning our children, and ruining both our natural environment and our historic cities. The first will have shown pictures of sleek, glossy, Italianate road machines speeding along surprisingly uncongested roads, or sentimental tributes to icons of a misspent youth such as the Cortina, the Mini or even the Transit. If you've recently watched any television programmes involving cars they will have been one of two basic types. That, as Mr Major surely realises, would be a disaster: a buffers' inquiry would make his bad situation worse.For the truth is, there is precious little unearned or innate authority left in the system Mr Major could not find an answer because there isn't one.