In the mid-18th century, General Wade built hundreds of sturdy stone bridges to help the Hanoverian army overcome the guerrilla resistance of the Highlanders. In the 19th century, Brunel, Telford, and their lesser known contemporaries erected countless viaducts, bridges and arches. Many of the structures, while functional, soared over the countryside as elegant additions to the landscape, and all of them were built to last.
What Brunel would have said of today's bridges, of which many are designed to be replaced after 30 years, will never be known.
He could not have imagined a world in which such scant regard is paid to the appearance of a bridge, as long as it carries its load. Or one in which the load of traffic is so great that, on one of the countries main routes, the M1, a slip road is closed at a few hours' notice because it has become unsafe. In fact, the M4/A4 into London has so many roadworks that the Highways Agency advises people to let the train take the strain.
But it is unfair to compare old with new when so few of our more venerable bridges have to suffer the indignity of carrying an endless stream of 38-ton lorries belching a fiery cocktail of chemicals, which, mixed with the salt laid down to de-ice roads, eats away at their structure.
Britain's roads are crumbling away from lack of maintenance, according to the motoring organisations. In a letter replying to a parliamentary question by Tory MP Nicholas Winterton, Lawrie Haynes, the chief executive of the Highways Agency, said that the current planned spending on maintenance for trunk roads is "not sufficient to avoid some deterioration of the network".
But in an attempt to be reassuring, he added: "However, by working hard and innovatively, the agency expects to be able to maintain safety and to minimise the effect on serviceability and value for money."
With the amount allocated to roads maintenance cut by pounds 100m over two years, according to the Royal Automobile Club, value for money will be a very real consideration. And next year only pounds 250m will be spent, compared with pounds 360m in 1994/5.
No such scrimping and saving bothered the Victorians; the immediate costs of construction did not figure as largely in our forefathers' assessment of projects as they do today. Structures had to be built very solidly because the Victorians were not so knowledgeable about the loading criteria - they had to play safe, even if that increased expenditure.
Nowadays, according to John Whitwell, deputy secretary of the Institution of Civil Engineers, "we would use half the bricks that they did".
But lack of bricks, or of maintenance, was not the reason for closing the two slip roads linking the A1 and M1 in north London, the Highways Agency said. Its spokesman, Alastair Frew, explained that the story of the A1-M1 overpass was "a one-off. It had been scheduled for strengthening next year to take lorries of 40 tons rather than 38 tons and it was found that it needed extra support". Part of the roadway was coned to ensure traffic went down the middle, but lorries kept ploughing through the cones, so it was decided to close the bridge.
Edmund King, campaigns manager of the RAC, was sceptical about the closure. "They have known about this for months and should have done something about it. If you don't look after these structures, they start to fall apart," he said.
Similar problems have already emerged on the elevated section of the M4 in west London, which could take 10 years to repair. In February, one of the 131 sections of the overhead part will be removed to assess how badly it has been damaged by corrosion. The motorway will be closed for several weekends, with the possibility ofmore serious closures.
Already, there have been jams caused by closing the A4 as it leads into the M4 and the Highways Agency has issued a leaflet saying: "Great Western Trains provide fast, frequent comfortable services over routes which parallel much of the M4/A4 from London Paddington to stations in Avon, South Wales and the West."
The British Road Federation said, in another letter to an MP, that Mr Haynes pointed to 34 other bridges on the motorway network that will need strengthening in the next few years. A BRF spokesman said: "The seriousness of this maintenance crisis has been predicted for some time."
The RAC said roads were surfaced every 42 years on average, as against the recommended 20 years, and 5 per cent of calls to its legal department - a total of 7,000 per year - related to damage caused by potholes and poor conditions.
Brunel would not have been amused.
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