Motorists are being warned to expect seven weeks of disruption on the A9 as dualling preparation works get underway.
Investigation work on the Tomatin to Moy section on the Inverness to Perth road will get underway on Monday.
It is the most northerly section of the trunk road to be dualled in the current £3billion project.
The ground investigations will be carried out off the existing road, but traffic management will be in place because of workers close to the carriageway.
The arrangements will include short, alternate single-file sections controlled by temporary traffic lights.
The work will be carried out by Soil Engineering Geoservices Ltd, who were awarded a £1million contract last month.
A Transport Scotland spokesman said: “This ground investigation is needed to get vital information on the existing ground conditions in the vicinity of the A9 carriageway between Tomatin and Moy as we progress our plans to dual this section of the route.
“We apologise for any inconvenience this will cause and would thank road users and local communities in advance for their patience over the next few weeks.
“The contractor will closely monitor the operation of the traffic management measures to ensure that delays are kept to a minimum.
“When planning their journeys, we’d encourage drivers to visit the Traffic Scotland website – www.trafficscotland.org – for the latest travel updates.”
The section is more than five miles in length and will plug the gap between the existing dual carriageways from Inverness to Moy and Tomatin to the Slochd Summit.
The project is the first of several investigation works due to be carried out on the A9 over the rest of this year.
Initial assessments of the route suggest that it has relatively few constraints compared to other sections along the A9, although designers of the new route will have to contend with peat and a number of access junctions and crossing points.
Meanwhile investigation work on another section of the trunk road to be dualled has been honoured with an award.
Contractor Fugro was granted “ground investigation project of the year” at the Ground Engineering Awards.
They carried detailed examination of 28 miles of the road between the Pass of Birnam and Glen Garry in Perthshire.