While the Foreign Secretary, Mr Johnson, was going on about building a bridge to France this week, the RAC Foundation said that almost 3,500 bridges in Great Britain are substandard (2016/17 data).
"Substandard" relates to bridges which don't meet the 44 tonne classification for the maximum lorry weight (weight of fully laden vehicle) which comes from European legislation aimed at ensuring compatibility across the area. As usual, there are local variations in how this is implemented and it doesn't mean that 44 tonnes is the maximum allowed. In the UK, for example, there are rules about moving heavier vehicle/ load combinations, but that's another story.
There will be bridges which have weight restrictions (generally 3, 7.5 or 18 tonnes) which are perfectly adequate for their local situations (because larger vehicles are not wanted in the areas concerned) and there are plenty of bridges which have had some interim measures applied to them which means they still don't meet the 44 tonne classification, but they are safe enough.
For example, the photo below is of St Augustine Road in Leicester which is carried over the River Soar by the West Bridge. As far as I know, there is no weight limit on the bridge, but there will be an issue with the footway or parapet (the edge of the structure with the balustrade) because of the use of containment kerbs to keep vehicles off - it's a classic interim measure which can often stay in place for decades!
Given that most of the top ten of councils with the most substandard bridges have huge rural areas, it's not a huge surprise as this will include places which are off the beaten track where 44 tonne lorries either won't be going or where they are not welcome anyway!
The RAC Foundation estimates that the cost to bring the substandard bridges back up to standard is £934m and the wider maintenance backlog on our bridges is around £5bn. With my caveat about the need to bring everything up to 44 tonnes, this is another significant amount of money.
Taken with the £12bn backlog for carriageway maintenance (and that's just England & Wales), it is a timely story that when politicians start showboating about shiny new things, they always seem to ignore making the best of what we already have.