Britain's environmentalists have won every argument against expanding the roads network - but still the government keeps pouring billions of pounds into new highways.
Studies show that new roads do not solve congestion - they just generate more traffic. They add to pollution and, of course, they raise Britain's greenhouse gas emissions. Road transport already generates 142m tonnes of CO2 a year - about 25 per cent of Britain's total. As the European emissions trading scheme puts an ever-higher price on carbon, those emissions could cost the taxpayer increasingly dearly.
The Treasury and Department for Transport know this, so why do their economists give their blessing to Labour's £13bn roads programme?
The answer lies far away from public scrutiny in the arcane and biased rules under which proposed roads are assessed. These New Approach to Appraisal (Nata) rules were introduced by La bour in 1998 under the integrated transport policy designed by John Prescott, then overseeing environment and transport. Most of Prescott's plans were chucked out by Blair and Brown as being far too green, but the Department for Transport (DfT) loved Nata and now the reasons are becoming clear.
Under Nata, road builders such as the Highways Agency and local authorities must submit detailed assessments of proposed transport projects to the government. These are meant to be balance sheets showing the costs, benefits and environmental impacts. In theory this is a good thing, but in reality the rules are designed to make road schemes look better than any greener alternative, every time.
Take section 3.5.1 of the Nata rules. This awards extra points to schemes that generate more traffic because more cars and lorries on the road mean more fuel sales - and hence more tax revenue for the government. By contrast, public transport schemes, which take motor vehicles off the road and so reduce fuel sales and tax revenue, have points deducted.
Then there's the rule on journey times, where planners can claim that a road will bring economic benefits if they can show it will cut the average journey time of each user. Every minute saved for a car driver is valued at 44p - which can be offset against the cost of building the road.
Forty-four pence may not sound much, but multiply it by the number of minutes saved per trip, then again by the millions of drivers using the road each year - and then yet again by 60 years, the notional lifetime of most road schemes. The result, invariably, is a huge positive value for every proposed road.
How does this work in practice? Look, for example, at the scheme to widen a 56km stretch of the M1 between junctions 30 and 42. The cost to the taxpayer is £1.5bn, which sounds like a lot, but the Highways Agency has used the Nata system to claim that, over the next 60 years, the widening is worth no less than £4.5bn because of the time it will save travellers. Since this supposed "benefit" to the economy far exceeds the cost, the scheme has been approved.
Just how biased this system can be is set out in the Nata rules that assign lower values to other types of traveller. A minute saved on a cyclist's travel time, for example, isn't worth 44p but just 28p. A bus-user's time is valued at 33p a minute. The implicit assumption is that cyclists and bus-users make less contribution to the economy than car drivers.
Roads can be made to look even better. Manipulating the accident figures is a typical device. If a proposed road can be predicted to reduce accidents, then each life saved and injury prevented can be given a notional value. The Highways Agency predicts that another £2.5bn M1 widening scheme (junctions 21-30) would prevent 2,081 accidents over 60 years, of which four would be fatal. This, it claims, adds £105m to the value of the scheme. (It would also, it calculates, generate another £41.3m in taxes from the extra fuel sold.) Critics point out that such calculations, based on accidents that have not yet happened on a road that is not even built, are dubious in the extreme.
Nata assessments have also always avoided costing the most damaging aspects of new roads, such as the impact on landscapes, noise and pollution and, of course, carbon emissions. This means that, even though a road might be an environmental disaster, there are no estimated cash costs to be set against the claimed economic benefits. Instead the planners give a qualitative assessment, using terms such as "moderate", "severe" or, worst of all, "very large adverse".
These qualitative judgements have in the past been enough to frustrate the road builders. Alistair Darling rejected "improvements" to the A303 that would have carved a new road through the Blackdown Hills, an area of outstanding natural beauty on the Devon-Somerset borders, after seeing in the Nata assessment that it would have a "seriously adverse" impact. He apparently did not want to be the minister who overruled such a negative assessment.
It should be no surprise that ever since that decision was taken, Treasury and DfT officials have been working to get rid of such "emotional" analyses by designing a system to assign monetary values to landscapes, tranquillity and biodiversity. The ostensible aim is to make the system more "objective" and number-based - but the crucial issue is what values are assigned to qualities that are inherently priceless. How much might the last dormouse in Wiltshire be worth? Soon Labour's minions may be able to tell you.
Appearance of objectivity
A hint of what lies in store came in the Eddington report, published last December. Sir Rod Ed dington, former chief executive of British Airways, was commissioned by the Treasury and DfT to examine the long-term links between transport and the UK's economic productivity and he found that building lots more roads would bring huge benefits to the economy for a relatively low environmental cost. "Even after accounting for environmental effects, there appears to be a good case for adding strategic road infrastructure over and above the schemes in the current roads programme," said his report, suggesting that Britain's trunk roads and motorways needed 3,350km of new lanes by 2025, at a cost of up to £33bn.
But how did Eddington account for environmental costs? His report does not explain, but a footnote directs the reader to an obscure research annexe, "Transport Demand to 2025 and the Economic Case for Road Pricing and Investment", written by Treasury officials. This document doesn't explain how Eddington priced the environment either, but it refers the reader to yet another set of reports commissioned by the Office of the Deputy Prime Minister in 2002, for a purpose entirely different from road-building.
Based on these outdated reports, the Eddington study assigned a one-off value to the damage done by roads to the landscape of between £900,000 and £1.25m for each kilometre of new lane that is built - a remarkably small sum compared to both the claimed economic benefits and the £40m cost of building the average kilometre of trunk road.
(If this approach seems to lack rigour then the Treasury report's forecasts for fuel costs are even less rooted in reality. "Fuel costs are forecast to fall by 26 per cent up to 2025," they said. "This comprises a 3 per cent increase in fuel prices and a 28 per cent increase in fuel efficiency. An oil price of $35 a barrel is assumed in 2025." Oil prices, of course, had already hit $50 a barrel when this report was published last year. They have stayed that way ever since and analysts predict the long-term trend is upwards, meaning roads will become ever less economical.)
What Eddington and the Treasury have done is to give the road builders a way of putting an apparent monetary value on landscape and tranquillity, so creating the appearance of objectivity when assessing the costs and benefits of any new road. In reality, however, the values assigned to landscape and tranquillity are so low that they will always be far outweighed by the apparent economic benefits.
"The upshot of all these assessment systems is that, however bad a road might look to the people living near its route, and however damaging it is likely to be to the environment, the economic 'benefits' will, on paper, always look much greater," says Rebecca Lush of Transport 2000, who has analysed the reports.
The great factor that is missing from these calculations is the cost of carbon emissions. In their appraisals, the road builders have to say how much extra CO2 their scheme will generate. The M1 widening scheme above, for example, will generate more than 186,000 tonnes a year extra CO2. But no financial cost was assigned to these emissions when this scheme was approved.
It wasn't until January this year that the DfT told road builders to begin adding a cost of £70 for each tonne of carbon emitted in project calculations. This is still too low to shift the equations away from favouring road building - and it will apply only to new projects. Moreover, £70 is an arbitrary sum because no one can agree how to price the the cost of future carbon emissions. Some experts have said the real value should be around £1,000 a tonne. Once again, therefore, factors that should count against new road projects are undervalued while those that support them are overvalued.
The £13bn-worth of new roads approved under the Nata system makes Labour's roads programme even larger than the one they inherited from the Conservatives in 1997. Back then, the new Labour government cancelled that programme with promises of an integrated transport system.
Among schemes that have recently been approved is the widening of the M25, which will turn most of London's orbital motorway into an eight-lane highway under a private finance initiative that will cost taxpayers more than £5bn. Around Leeds, the M62 motorway is approved for a £336m widening. This year the government will decide whether to approve a £3bn project to widen the M6 between Birmingham and Manchester.
The Highways Agency is also seeking approval for the Mottram-Tintwistle bypass, a short-cut for lorries through the Peak District National Park. The main economic justification is the notional value, under Nata criteria, of the time the road would save for drivers - put at £159m over 60 years. Opponents of the scheme say the national park is worth a lot more than that.
Also on the table are some highly controversial local road schemes such as the Dorset County Council's Weymouth relief road, which would slice through the Dorset Downs area of outstanding natural beauty, a site of special scientific interest, as well as ancient woodlands. Again, the main economic justification is the notional time saved for drivers, put at £275m over 30 years.
A secondary effect of the Nata rules is to undermine the economic case for investing in public transport. The light rail schemes variously proposed for Liverpool, Sheffield, Portsmouth, Leeds and other cities were all turned down for funding under the Nata formula, as the government declared they were "poor value for money" and recommended bus schemes instead. Another bias in the system is that the government requires light rail planners to contribute 25 per cent of the funding, whereas road builders have to contribute only 10 per cent.
There is strong evidence that assessment systems such as Nata offer no real guide to a road's future performance. Last year the former Countryside Agency and the Campaign for the Protection of Rural England published an investigation into three completed road projects, comparing the predictions made before they were built with what happened afterwards.
It looked at the A34 Newbury bypass, the A27 Polegate bypass and the M65 Blackburn southern bypass, and in each case found that the preliminary assessments had underestimated the scale of traffic growth and the impact on the landscape. They had also made little allowance for the way new roads increase development pressure, often leading to a rash of buildings along their length.
The report concluded: "Issues of induced traffic growth, landscape impact and development pressures are rarely addressed adequately in the evaluations. It is easy to gain the impression that evaluations are carried out in consultancy back offices for the interests of Highways Agency officers only."
Recently the DfT said it planned to "refresh" the Nata rules to take account of the Stern review on the economics of climate change, the Eddington report and other developments. What this is likely to mean, say insiders, is the disappearance of "emotive" descriptions of a new road's impact on the landscape and wildlife and their replacement with indices - numbers - that will have far less obvious meaning. The low price placed on carbon emissions of £70 per tonne is unlikely to change.
This will open the way for Eddington's vision to prevail. Carbon emissions, damaged landscapes, lost tranquillity and vanishing biodiversity will all be given such tiny numerical values that they will inevitably be wiped out by the economic "benefits". The economists will be satisfied, the politicians will be absolved - and the road builders will be delighted.
Jonathan Leake is the Sunday Times science and environment editor