HADRIAN’S WALL has survived barbarian invaders, smugglers and the 2,000-year march of history. Now its very survival has come under threat — from an army of walkers.

The erosion of the World Heritage Site is becoming so severe that the Roman wall could be placed on the World Heritage “in danger” list, experts told The Times yesterday.

Some 400,000 people have marched across the Hadrian’s Wall Path Trail since it was opened 18 months ago. They are banned from walking on the wall itself, yet many do so. One day last winter 800 Dutch bankers walked across the wall.

Although only a small fraction of the wall and its forts has been excavated, the fragile site is being eroded by heavy boots, archaeologists say. They note that only 20,000 visitors had been expected when the plans were made in the early 1990s.

Hadrian’s Wall is among 600 locations designated as World Heritage cultural sites by Unesco. Governments recognise an obligation, under the 1972 World Heritage Convention, to care for their countries’ heritage, and so only 29 of the 600 sites are considered at risk.

Peter Fowler, an adviser to the UN cultural body, said that adding a location to the list was something the World Heritage Committee took extremely seriously. “It is a very deep insult to a nation when this happens,” he said. “Were something not done to stop the erosion, Hadrian’s Wall could be added to the list. I’m surprised that this should happen in an advanced country which apparently takes the world’s heritage seriously.” Only one other developed nation has suffered such an indignity: Cologne Cathedral was included last year.

Professor Fowler was among the archaeologists who opposed the trail’s creation. They were told that the structure and earthworks would be protected, and that there would be effective management of the route. “That hasn’t happened,” he said. “There is one person responsible for the whole 73 miles. It’s unacceptable. This is not the way for Britain to meet the obligations.”

Most visitors, he said, were simply “out for a good walk”. “That’s fine, but walk somewhere else,” he said. “A fragile archaeological site should not be used. This needs more close management of the trail on the ground so that people can be moved a few yards one way or the other and to encourage people not to walk along the wall.

“The wall was never built to take 400,000 people. It was meant for economic and military purposes. Small numbers of people walked along the top, just the sentry guards.”