British Waterways (BW) has called on motorists to be more responsible when driving across hump-back canal bridges after revealing that drivers cause up to £2.5m worth of damage each year.

According to the company, which is responsible for the maintenance of 2,000 miles of canals and rivers, the cost of repairing damaged hump-back bridges is diverting much-needed funds away from more important schemes. BW revealed at least two of the 1,800 historic bridges in its care, which were originally designed in the 18th and 19th centuries for horse-drawn carts, are struck by modern vehicles each week.

Concerns are being raised that the increasing number of incidents involving hump-back bridges will have a severe impact on the maintenance of inland waters when there is limited funding available. BW is also unhappy that it cannot claim the cost of the damage from a driver's insurance company because offenders have already left the accident scene without reporting it.

Nigel Crowe, BW's head of heritage, said: "Whenever you go over a hump-back bridge in Britain you are likely to be going over a canal. Often officially listed as being of special architectural or historical significance, these bridges have to be painstakingly repaired at considerable cost. "Frankly, if motorists just slowed down a bit and took more care and attention then we'd not be defacing our heritage in this way on a day-to-day basis."