That is according to analysis by motoring research charity the RAC Foundation, which has revealed more than 3,100 council-owned bridges across Britain cannot carry the heaviest vehicles as of October.
In Falkirk, eight bridges were found to be below standard as of October – around 4% of the 224 managed by the council.
This means they were unable to support the heaviest loads, such as lorries of up to 44 tonnes.
The council said it would ideally return all of them to full capacity – but due to budget restrictions only expects to do so with one over the next five years.
There were 3,105 below-par bridges across Britain, according to the research – up from 3,055 a year earlier.
Many of the structures are subject to weight restrictions, while others are under programmes of increased monitoring or even managed decline.
RAC Foundation director Steve Gooding said: “There has been a worrying decline in the number of inspections carried out to examine just how much damage rivers, and the debris they carry, are doing to bridges below the waterline.
“This is storing up trouble for the future as our weather gets more extreme and traffic volumes rise again after the Covid-19 restrictions.”
Across Britain, local authorities said they would ideally get 2,256 bridges back to full carrying capacity, but only expect to bring 392 up to scratch over the next five years.
The research was carried out in partnership with Adept, a group representing local authority bosses responsible for transport and other sectors.