Two South Cumbrian bridges at risk of damage or collapse will have physical width restrictions introduced after breaches of an existing weight limit.
Brigsteer and Underbarrow bridges, which run over the A591 near Kendal, were initially closed in 2024 as a precautionary measure due to structural concerns.
After detailed analysis, the bridges opened under a 7.5 tonne weight limit in February last year when they were classified as weak structures.
However, Westmorland and Furness Council said results of recent camera monitoring on the bridges showed there were over 30 breaches of the weight restriction over 13 days.
The authority said HGVs typically weighing up to 40 tonnes have been observed making return journeys over the bridges.
Westmorland and Furness Council’s cabinet member for Highways and ICT, Councillor Peter Thornton, said: “We know a number of these vehicles are travelling to local businesses or properties.
“These are not lost drivers from out of the area following a sat nav, these appear to be delivery vehicles serving the local area and breaching the weight restrictions, ignoring the signs and not using the designated alternative routes for larger vehicles.
“Unfortunately, the severity of the breaches presents an unacceptably high risk. Allowing this to continue could damage the bridge structures and, in a worst-case scenario, cause a collapse of the bridge deck onto the A591 below.
“We have therefore been left with no alternative but to introduce physical measures to prevent larger vehicles using the bridges.”
A 6ft 6in width restriction has been introduced with immediate effect.
Cllr Thorton added: “This will initially be through temporary traffic management, with permanent remodelling as soon as possible.”
A 20mph speed limit has also been introduced to make sure vehicles would approach new width restrictions at a safe speed.
Brigsteer and Underbarrow bridges are reinforced concrete half joint structures erected in the 1970s.
The council’s consultant engineers confirmed that no further refinements were possible, and the bridges must permanently remain at a 7.5 tonne limit.
As the bridges are now classified as weak structures, no exceptions to the weight limit could be permitted.
Cllr Thornton added: “Due to the scale and regularity of the blatant weight restriction breaches, even tougher enforcement, such as use of number plate recognition cameras to catch the culprits, wouldn’t be enough to prevent the unacceptable risk.
“The A591 runs below these bridges and we simply can’t risk a potentially catastrophic incident if part of the structure fell onto the carriageway below.
“Cameras may catch people after they’ve breached the restriction, but by then it could be too late. It’s vital we take action to stop the breach from happening in the first place if we are to fully protect road users.
“Unfortunately, the only way we can do this is by installing physical width restriction measures. These measures should ensure that vehicles will only be able to cross the bridges if they are both less than 7.5 tonnes gross weight and less than 6ft 6in wide.
“We recognise that some vehicles under 7.5 tonnes gross weight, previously able to use the bridges, will now be too wide to cross.
“Such vehicles could include supermarket delivery vehicles, agricultural tractors and emergency ambulances, although first-responder paramedic vehicles will still be able to cross.
“We have already contacted the relevant emergency services so they can adjust their response plans accordingly.
“This is a regrettable consequence of the new measures. It is unfortunate that the actions of the drivers who have been breaching the weight restrictions has led to this, but it is now the only safe way to keep the bridges open, retaining connectivity for local communities while maintaining the highest safety standards.”
