More than £100 million is needed to restore substandard bridges in Lancashire and Blackburn with Darwen to good condition, new figures show.

Figures from the RAC Foundation show that of the 1,481 bridges in Lancashire, 78 were substandard last year, and out of the 148 bridges in Blackburn with Darwen, seven were substandard.

Substandard means bridges are either too weak to carry 40-tonne vehicles or there is a weight restriction for environmental reasons such as a narrow bridge or narrow approach roads.

Lancashire County Council estimated it would cost £122.6 million to bring the road bridges back to good condition, while Blackburn with Darwen Council estimated it would cost £5.6 million to bring the road bridges back to good condition.

The RAC Foundation said there is only so long councils can continue to "patch things up before bigger cracks literally start to appear" in road infrastructure.

Across Great Britain, councils said 3,090 bridges were substandard – accounting for 4.3 per cent of the total 71,925 bridges.

It was down slightly from 3,211 substandard bridges reported the year before (4.5 per cent).

The estimated one-time cost to clear the maintenance backlog on bridges across the nations was £5.9 billion.

Steve Gooding, director of the RAC Foundation, said the figures reveal the challenge local authorities are wrestling with to protect critical road infrastructure.

"The numbers illustrate how important it is for significant sums of money to be spent tackling at least the higher priority work," Mr Gooding added.

"Whether it is potholes or bridges there is only so long that councils can continue to patch things up before bigger cracks literally start to appear in the road network."

Areas with the highest number of substandard bridges were Devon with 224, Cheshire East with 194 and Essex with 151.

No collapsed bridges were reported across Great Britain last year, however there were 14 partial collapses including one in Lancashire.

David Renard, transport spokesperson for the Local Government Association said bridges are a vital part of the UK's transport infrastructure.

Mr Renard added: “Not all bridges are the responsibility of councils, but for those that are, they are doing their best to ensure they are well maintained and withstand extreme weather, the like of which communities have been experiencing for much of the last few months.

"However, this is becoming increasingly challenging in the face of a backlog of nearly £12 billion to bring our local roads up to scratch.

Lancashire County Council said it would ideally restore 78 bridges to full capacity.

Blackburn with Darwen Borough Council said it would ideally restore five bridges to full capacity, but only foresees one returning to good condition in the next five years.

A spokesperson for the Department for Transport said: “The Government is providing more than £5 billion of investment over this Parliament to local authorities across England to support the maintenance of their local highway infrastructure, including the repair of bridges and the resurfacing of roads up and down the country.”

Exact data for the location of the substandard bridges in Lancashire and Blackburn with Darwen has not been provided by the RAC. 

Last year a bridge collapsed in Roeburndale leaving one man dead and two others seriously injured.

Then in December a section of a bridge wall collapsed in Gisburn.