The £3 billion upgrade of the A9, which runs from central Scotland to the north coast, to full dual carriageway will cost more than the M74 completion, the new Forth road bridge and the Aberdeen bypass combined.
The first public displays setting out the logistical and environmental impact of the first £40 million section of the upgrade, from Kincraig to Dalraddy in the Highlands, will be unveiled this month.
Transport Minister Keith Brown said: "The A9 dualling programme is the most expensive transport project in Scotland's history - one that will exceed the cost of the M74 completion, Queensferry Crossing and AWPR combined.
"This is an ambitious and challenging programme, and we are doing everything possible to deliver improvements and bring forward work where we can."
The Kincraig to Dalraddy section is the first section of the programme to be dualled and work is expected to start there in 2015/16.
Mr Brown said the publication of the draft orders was an "important milestone" in the project.
He said: "We have been working closely with Sustrans and I can also confirm that the Kincraig section will include a new cycle facility as part of a strategy to improve connections for cyclists, equestrians and pedestrians between communities along the A9.
"This will include upgrades of existing routes and a new connection between Kingussie and Aviemore, of which this forms a part. I would encourage anyone with an interest to come along to one of the public exhibitions in mid-November to see our plans and take the opportunity to comment on them."
The Perth-Inverness route is expected to be dualled by 2025.
Mr Brown added: "On completion, the fully dualled route will bring benefits to road users, communities and businesses who live along or use this important road."