Works to upgrade the A9 north of Perth to dual carriageway have been put on hold by Transport Scotland.
The Scottish Government body have ceased work on the 9.5km stretch between Luncarty and Birnam to adhere to social distancing guidance.
Bosses say they will be continually reviewing when they can restart work on the project, which started early last year.
The upgrade had been scheduled for completion next spring, and road safety measures will be enforced throughout lockdown.
A Transport Scotland letter stated: “The safety of operatives working on our sites is of paramount importance and following the measures announced by the Scottish Government, we can confirm the construction of the A9 Dualling: Luncarty to Pass of Birnam project has temporarily ceased until further notice, due to the Covid-19 pandemic.
“Our contractor for the site, Balfour Beatty, has implemented a managed shutdown of the site in line with current health and safety guidelines including the government’s recommendations on social distancing .
“The safe and secure shutdown of the site ensures that partially built structures and current operations are made safe, associated equipment and plant is properly stored and security measures are in place at site compounds for the duration of the closure.
“The current traffic management arrangement on the A9 which consists of narrow lanes, safety barriers, the temporary roundabout south of Bankfoot and 40mph speed restrictions enforced by speed cameras, will remain in place during this time.
“Balfour Beatty will continue to undertake essential services such as monitoring traffic management arrangements.”