The safety of Scotland’s road bridges is being threatened by council cuts, experts have warned.
The concerns came as Transport Scotland’s chief bridge engineer called for a major funding increase for trunk road crossings “to prevent issues becoming critical”.
A motoring group said a list of bridges most in need of repairs was a priority.
The concerns follow the collapse of a bridge in Genoa in August, killing 43 people.
Six people also died when a footbridge in Florida collapsed in March.
The Forth Road Bridge was closed for three weeks in 2015 because of a structural fault.
Transport Scotland’s bridge spending increased from £39.1 million in 2015, when it took over the crossing, to £65.2m in 2017.
However, it fell back to £64m this year and the Scottish Government agency’s top bridge engineer wants it to reach £100m.
Richard Fish, an independent consultant and technical secretary of the Bridge Owners Forum, told a conference last week: “Could the 2018 collapses be the wake-up call we need? Yes – but that doesn’t mean we won’t sleep through it.
“It’s not just about budget cuts but the gradual erosion of capacity and capability among – especially local authority – bridge engineers.
“Even if politicians are made aware of the ‘risk’, with other immediate pressures the view is usually ‘will it last another year?’.
“If there is a highway concern, it’s generally about potholes. There aren’t many votes in bridge maintenance... until something happens like the Forth Road Bridge closure (or worse).”
Transport Scotland chief bridge engineer Hazel McDonald, who was also speaking at the Bridges Scotland event in Edinburgh, agreed: “Maintenance doesn’t win votes. It is very much the poor relation of new build.
“We are trying to sell [the importance of] maintenance – we need to spend money now to prevent issues becoming critical.”
However, McDonald said spending was at the “safety critical defects” rather than the “do everything” end of the scale.
She said: “We have a backlog of work which needs to be addressed.
“I would like to see the budget get towards £100m over a period of time – about five years. That would certainly make a difference.”
The RAC Foundation reported in January that there were 412 “substandard” bridges in Scotland, with only 53 planned to be returned to full load capacity by 2023.
The Society of Chief Officers of Transportation in Scotland (SCOTS), which represents council roads chiefs, said numerous bridges across the country have been closed or had weight restrictions imposed “as the funds have not been available to strengthen or replace them”.
Its spokesman said: “The ongoing cuts to road maintenance budgets are substantial. Bridges are clearly a key component of our road networks but often fail to attract the same attention as potholes.
“They are often expensive to maintain and replace, and in the current financial climate few councils are in a position to dedicate the levels of funding which professional advice considers necessary.”
He said priorities should include strengthening older bridges not designed for heavy lorries, and replacing worn-out ones.
Steel bridges also needed repainting to avoid premature corrosion failure.
Derek Halden, civil engineering consultant at Loop Connections, said: “The average age of the bridge stock has been growing in Scotland and key preventative maintenance tasks are simply not being undertaken as they should.”
Neil Greig, the Scotland-based policy and research director of the IAM RoadSmart motoring group, said: “Allowing bridges to deteriorate due to lack of funding is unacceptable when drivers pay so much in tax. The first urgent step is for all road authorities to work together to produce a table showing those structures most in need of attention. Local and central government should then ring fence a fund to fix them.
“This must supplement other budgets to allow action to be taken as a precursor to a longer-term plan.
“Providing diversions is never easy across Scotland’s diverse road network, so investing now can help avoid delays and minimise the economic impact.”
A Transport Scotland spokesman said: “The safety of drivers using our roads is our top priority and that is why the budget for maintenance of the trunk road network, including bridge maintenance, has increased by around £65m to £433m in this financial year.
“Our road asset management plan sets out what we do to deliver the best possible service with the resources available. We have developed maintenance strategies for our major asset types, including bridges, in order to make best use of available funds and ensure that they remain safe and fit for purpose.”