Making the A9 between Perth and Inverness and the A96 from Nairn to Inverness dual carriageway are among new Scottish Government priorities.
Its transport plan for the next 20 years also includes improvements to the A82 road and faster rail services to and from the Highlands.
They are among 29 transport investment priorities.
Campaigners and business groups had high expectations of improvements to the A9 and A82.
Upgrades to the A82 include widening the road between Corran Ferry and Fort William and new climbing lanes.
The government said the Strategic Transport Projects Review was the "biggest and most ambitious" Scottish transport plan ever published.
Both the A82 and A9 have been the subject of public petitions that gathered thousands of signatures and there were growing calls ahead of the review's publication for the two trunk roads to feature prominently.
Sections of the two roads have been the scene of fatal accidents in recent years.
A father and son from Holland and a retired couple from Fife died in a crash on the A9 at the Slochd in July.
According to the A82 Partnership, there are three times the number of accidents resulting in injury per mile on the section of the road between Tarbet and Ardlui than on the average single carriageway road in Scotland.
It said just 19 miles out of the total of 147 met the required design standard of 7.3 metres width.
In August, research claiming the upgrading of a road in the central belt cut the number of fatal accidents to zero within a year was flagged up as a reason for improvements to the A9.
Surgeons Evan Crane and Gavin Tait looked at the effect of replacing 9.4 miles of A77 south of Glasgow with motorway on road casualty statistics.
Nationalist MSP Fergus Ewing said at the time he would use the clinicians' findings to reinforce calls for dualling the Highlands road.
But as well as addressing concerns over safety, economic benefits of upgrading the A9 and A82 have also been suggested.
Dualling the A9 road from Inverness to Perth could generate almost £1bn for the Highlands and Islands economy, according to a report commissioned by Highlands and Islands Enterprise (HIE) and transport campaign group Hitrans.
The A9 Perth to Inverness Economic Appraisal Study estimated journey times could be cut by 22 minutes and predicted that 724 jobs could be created in the short-term - rising to 4,500 over 30 years.