The A9 road from Crubenmore to Kincraig is being upgraded to dual carriageway.
Ground investigation works are to start on Monday 22 October and expected to last about 12 weeks.
Drivers using the 10 mile (16.5km) road between Crubenmore and Kincraig may experience delays, as temporary traffic signals control traffic.
The work is part of a larger scheme to improve transport between Perth and Inverness, which is expected to be complete by 2025.
Additional measures will be implemented to allow the work beside the carriageway to be carried out safely, which could slow down traffic.
The contractor has said traffic levels will be monitored to keep delays and congestion to a minimum.
A Transport Scotland spokesperson said: “With the first scheme open to traffic and construction work to commence in the coming months on the second scheme, design work on the A9 dualling programme continues at pace with eight of the nine remaining dualling schemes being designed now at draft order stage.
“As part of the ongoing design work we need to carry out further ground investigations to get important information on the existing ground conditions on the sections to be dualled.
“We apologise for any inconvenience these works will cause and would thank road users and local communities in advance for their patience during the works.”
Although Transport Scotland do not expect any major disruption to traffic, they have advised drivers to plan their journeys in advance using the Traffic Scotland website, twitter feed or Traffic Scotland radio.
The works will stop for two-weeks over Christmas and the New Year.
The plan to upgrade 80 miles (129km) of single carriageway between Perth and Inverness will be one of Scotland’s largest transport infrastructure programmes. 30 miles (48km) of the 110 mile (117km) road is already a dual carriageway.
Transport Scotland’s programme plans to improve road safety and make journey times quicker and more reliable. The programme is designed to create stronger economic growth, with better links to public transport facilities, pedestrians and cycling.
Costing £3bn, the Scottish Government have committed to completing the project by 2025.