More than one million extra journeys have been made over the Queensferry Crossing in the past year despite ministers pledging that increased cross-Forth travel would be by public transport.
A record of nearly 28 million vehicles used the bridge in the 12 months to October, 3.9 per cent more than in the same period the previous year, Scotland on Sunday has learned.
The latest annual total of 27.73 million compares with 26.68 million a year before, and 26 million a year on the Forth Road Bridge in 2014, official figures show.
Most traffic switched with the opening in 2017 of the new bridge, first called the Forth Replacement Crossing (FRC).
The Scottish Government’s Transport Scotland agency said: “The FRC project was promoted on the basis that future demand for cross-Forth travel should be met by public transport rather than car.
“The use of the Forth Road Bridge as a public transport corridor enables more reliable journeys from Fife to Edinburgh, with journey time savings already being realised versus car travel at peak times.”
Sustainable transport campaigners Transform Scotland said the traffic figures suggested that strategy was not working, and claimed promised bus priority measures had still not been completed.
Director Colin Howden said: “Transport Scotland pledged that any new traffic growth across the Forth would be carried by public transport and not by new car journeys.
“It is hardly surprising they have failed in this task given the glacial progress in delivering the commitments in the FRC public transport strategy.
“Transport Scotland and the local councils need to urgently deliver the bus priority measures that were promised as part of that strategy, but which are yet to be implemented.”
A Scotland-based motoring expert also criticised the increased traffic figures.
IAM RoadSmart policy and research director Neil Greig said: “In many ways, these figures are indicative of a failure of Scottish Government transport policy to reduce car use, rather than a specific criticism of the Queensferry Crossing itself.
“Public transport measures that only assist those travelling into central Edinburgh were never going to provide alternatives that would have any impact on bridge traffic that is serving a huge swath of central and eastern Scotland and beyond.
“The case for further investment to increase capacity around the Queensferry Crossing is now clear. This could include extending smart motorways [with variable speed limits] to more roads around the bridge, and specific junction improvements to cope with the ever-increasing demand.”
Mid-Scotland and Fife Conservative MSP Liz Smith said: “These statistics emphasise how many vehicles use the Queensferry Crossing and how this has led to long periods of congestion, which are particularly bad for motorists on the southbound approach waiting to cross at peak-time traffic in the morning.
“I know from the number of complaints from constituents that this causes a great deal of frustration for motorists and the situation is often made worse by drivers ‘rat running’ – driving off the M90 at junctions and then driving straight back on to try to beat queues on the motorway.“
Transport Scotland said the current level of traffic growth might not continue, and the increase from 2014 “is not exceptional in terms of [trunk road] network-wide traffic growth”.
A spokesman said it would meet Fife Council in January to discuss congestion, but buses using the Forth Road Bridge along with improvements such as bus lanes on other roads had cut journey times between Fife and Edinburgh by up to 40 per cent.