Main contractor Costain was due to oversee the lifting of a new bridge at Tolgroggan as part of its £330m A30 Chiverton to Carland Cross scheme.

Neil Winter, National Highways’ senior project manager for the scheme, told Cornwall Live: “Our contractors have detected unsuitable ground conditions for the crane deployment, and we have taken the decision to put back the bridge installation by a week to ensure everything is right for what will be a large-scale lifting operation.

“Adverse weather, a mixture of heavy rainfall and low temperatures, hasn’t helped recently. These circumstances are out of our control, and the safety and effectiveness of the operation are our primary concerns.

“Although we would have preferred to lift the bridge deck in place this coming week, we have allowed contingency in our programme, and decided to postpone to the following weekend to ensure that everything is in place ahead of the installation operation, and to give people as much notice as we can.

“The extra time will improve the ground in terms of firmer footings for the crane operation, and we’re confident a slight delay will help the teams with that, without impacting on our future road opening date.

“We apologise for any confusion caused by the postponement of this weekend’s closure but we understand that people need to plan their journeys and feel we need to show due diligence in making sure everything is 100 per cent.”

The work will now take place from the evening of Friday 10 February to the morning of Monday 13 February.