More than 80 businesses could compete for the highly lucrative next stage of the A9 dualling project.
Transport Scotland has announced details of a £70 million contract for the Luncarty to Pass of Birnam section.
The trunk roads authority is looking for contractors to design, construct and maintain the six-mile stretch, north of Perth.
And dozens of firms have already shown an interest in the work.
The job will represent the first stretch of new dual carriageway in Perthshire. A finalised route was decided following initial objections by landowners who claimed closing off access to the trunk road could cause them delays.
A deal for the upgrade, part of the overall £3 billion project, is likely to be struck next year.
A spokesman for Transport Scotland said: “We were pleased to welcome more than 80 prospective bidders to an industry day held recently to inform on plans to dual the A9 between Luncarty and Pass of Birnam.
“A contract notice was issued formally, inviting expressions of interest in the project with contract award expected in 2018.”
He added: “We continue to make good progress on the A9 Dualling Programme with work between Kincraig and Dalraddy expected to complete this summer and over 90 per cent of the programme now at preferred route status.
“We are making significant strides and remain on target to deliver the A9 Dualling Programme by 2025.”
Keith Brown, Cabinet secretary for economy, jobs and fair work, issued a rallying call to the construction industry during a recent event in Perth.
He said the infrastructure project – the largest in Scottish history – offered “huge potential” that must be harnessed.
In addition to the major construction works, small to medium sized businesses will also be invited to compete to undertake advance works in preparation for future heavy construction.
Over the next eight years, contracts will be available through Transport Scotland for tasks such as site clearance, property demolition, access track construction, signage and fencing.
Mr Brown said: “The presence here in Perth of representatives from the construction industry, including many from the local area, really drives home the importance of the A9 dualling to the north of Scotland.
“Transport infrastructure is a key area where improving connectivity between our cities, rural communities and centres of economic activity is vital to boosting productivity and competitiveness.”
At present, some 30 miles of the A9 between Perth and Inverness are already dual carriageway.
The £3 billion dualling project will upgrade 80 miles of single carriageway between the two cities.
