More than 100 million pounds needed to restore substandard bridges in Monmouthshire to good condition, new figures show.
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.
Figures from the RAC Foundation show that of the 400 bridges in Monmouthshire, 22 were substandard last year.
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.
The council estimated it would cost £20.4 million to bring the road bridges back to good condition.
Across Great Britain, councils said 3,090 bridges were substandard – accounting for 4.3% of the total 71,925 bridges. It was down slightly from 3,211 substandard bridges reported the year before (4.5%).
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," 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.
David Renard, transport spokesperson for the Local Government Association said bridges are a vital part of the UK's transport infrastructure.
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.”
Monmouthshire Council said it would ideally restore four bridges to full capacity, but only foresees three 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.”