Nine weeks of work is set to begin at the Longman junction in Inverness.
The work, scheduled to start on Monday 30 September, forms part of the A9/A82 Longman junction improvement scheme.
The majority of work will take place off the line of the existing junction.
A Transport Scotland spokesperson said: "Following the public consultation on the preferred option for the scheme earlier in June, this ground investigation will help inform the ongoing design and assessment of the improvements to this strategic junction in the Highland capital.
“Although the majority of the work is located away from the existing road network, some investigative work is required on and in close proximity to the live carriageway. Such work on or in the vicinity of the live carriageway will necessitate traffic management, including some night-time and off-peak lane closures, lay-by closures and verge protection measures.
“We would thank road users and local communities in advance for their patience during any traffic management operations which may be required to ensure safety of the public and workforce.
"The contractor will closely monitor the operation of any traffic management measures to ensure that any delays are kept to an absolute minimum. We would ask drivers to plan their journeys in advance using the Traffic Scotland website, twitter or radio.”