Tender documents were issued on Friday for a contract with an estimated value of £16 million.

The Kincardine Bridge is made up of multiple connected spans, including a piled viaduct at the southern end, which was assessed by civil engineers in 1984 as substandard in design. Since then, the viaduct has been closely monitored, and a steel propping system was installed in 1992 to provide interim structural support.

A tender competition is now under way to appoint a contractor to demolish the southern piled viaduct and replace it with a completely new reinforced concrete structure.

The contract will be let by Transport Scotland as the client, with operating company BEAR Scotland overseeing the project on their behalf. Detailed design has been carried out by Jacobs.

Construction is expected to take between 18 months and two years, following the conclusion of the tender process later this year.

Disruption to road users will be minimised during the project by diverting traffic along a temporary two-lane bridge, to be constructed alongside the old viaduct. This temporary bridge will also provide access for pedestrians.

Short-term lane closures and full bridge closures will still be required for specific construction activities, however these will be limited and timed to minimise disruption.

With the Kincardine Bridge designated as a Category A listed structure, the design team has been liaising closely with Historic Environment Scotland and Falkirk Council. The new viaduct will be similar in appearance to adjacent spans on the original bridge, with lamp posts and parapets from the demolished viaduct reinstated on the new structure.

Liaison has also been ongoing with the Scottish Environment Protection Agency, NatureScot and Marine Scotland, with the coastline of the Firth of Forth designated as a Special Protection Area, Ramsar Site and Site of Special Scientific Interest. An environmental impact assessment has been prepared to consider the potential cumulative effects of the proposed scheme and the most effective methods of mitigation.

Chris Tracey, BEAR Scotland’s south east unit bridges manager, said: “The replacement of the southern piled viaduct will help to ensure the Kincardine Bridge’s long-term availability for service as a key trunk route.

“Our priorities for the project are to maintain the structural integrity of the bridge, to ensure the new viaduct is in keeping with the rest of the structure, to keep the trunk road open during construction, and to mitigate the impact on the surrounding environment.

“Traffic modelling suggests that by maintaining two-way traffic during construction, no significant delays will occur at peak times under normal circumstances, although some lane closures and limited full closures will be required.

“The detail of the programme will be confirmed later this year after the contractor is appointed. We are committed to keeping road users and local communities fully informed as the project progresses.”