The consortium tasked with delivering the £745 million project Aberdeen Roads Limited (ARL) said the impact of Storm Frank during winter 2015/16, recent extreme weather during early March and the collapse of Carillion have all had an impact on the opening date.

The Aberdeen bypass had previously been expected to open during Spring 2018 and last week an announcement by Balfour Beatty, one of the consortium partners, suggested that it expected the completion date to be Summer 2018.

Transport Scotland said it conducted “urgent discussions” with ARL to determine whether both partners shared this view.

“The outcome from the discussions with ARL is that we now expect to be able to open the project in Autumn 2018,” the transport body said.

Economy secretary Keith Brown said the £745m project cost “remains unchanged” as a result of the delay.

He added: “While this revision to the opening date is very disappointing to the people of the North East, we have to accept the expert advice of our contractors on the ground who are delivering this significant project.

“Clearly there has been a huge amount of work that has gone in to getting the project to where we are now. I would like to pay tribute to the effort of the people who are working hard to get this project over the finishing line.

“I understand how highly anticipated this project is for those living and working in the region and the patience local communities have shown during the construction process, I would like to thank them for their continued patience as we enter the final stages of the project. Transport Scotland will continue to work closely with ARL to open sections of the road at the earliest opportunity.

“The total scheme cost estimate is £745m and this remains unchanged as part of this announcement. Under the terms of the contract, ARL does not receive payment for the work until a section of road is open to traffic.

“During construction over 1,000 jobs have been created as a result of this project and it will generate over £6 billion for the local economy with an anticipated 14,000 new jobs to follow over the first 30 years after the scheme opens.

“Once open, the AWPR will cut congestion in and around Aberdeen city, with a positive impact on reducing emissions and improving active travel, it will also improve connectivity in the region, providing better journey time reliability, particularly for those travelling from the north of the city to the south side.”

The project, equivalent in length to building a new road between Edinburgh and Glasgow, is a key part of the Scottish Government’s £1 billion investment in transport in the region, which includes the AWPR, Aberdeen to Inverness rail improvements and the Haudagain roundabout improvement work.