The issues with the rollout of the bridge over the River Witham and the East Coast Main Line will also delay completion of the route by a year to 2026.

Cllr Richard Davies, executive member for highways, said: “This mistake related to the how the bridge was to be installed and us being told it couldn’t be pushed into place as intended due to concerns relating to specific wind conditions.

“Safety comes first, so the work was halted so our designers and contractors could address the problem.”

Galliford Try is main contractor on the current third phase and also built the second phase which was completed in 2022.

A Galliford Try spokesperson said: “Galliford Try continues to work in a collaborative manner with all the stakeholders on Grantham Southern Relief Road to ensure the safe and timely delivery of this vital piece of infrastructure.

“The challenges that have led to the reported delays relate to the design of the bridge across the River Witham and the East Coast Main Line and Galliford Try is contracted on a construct-only basis on the project.”

Cllr Davies added: “The complexities of designing and constructing this relief road, particularly this bridge, are far beyond what we as a council can do directly.

“That’s why top international engineering companies and experienced contractors were entrusted to handle the project. Although we oversee the scheme as a whole, we rely on our suppliers’ combined expertise.

“When undertaking a project of the magnitude, all design work also undergoes a mandatory, additional layer of independent checking. Unfortunately, despite all of this, a mistake was made along the way that’s led to this new delay.”

Once underway the bridge push over the 293-metre span will take several months as it crosses the rail line during overnight periods when trains have stopped running.

The rest of the structure will then be built on the east side of site, including lifting new steel beams into place.

Several more months will then be spent concreting the decks, installing safety barriers, and laying road surfacing.

Cllr Davies said: “The important thing is that the details of the solution are nearly finalised, meaning we can start pushing the bridge into place in the coming months.”