Meanwhile, Transport Secretary Fiona Hyslop has told MSPs the dualling of the A9 between Perth and Inverness was an “absolute priority” for the Scottish government.
She said the project was on course to be completed by the end of 2035, with half of the road to be done by the end of 2030.
The original target date for the whole project had been 2025.
Hyslop said remaining sections would now be paid for from the Scottish government’s capital budget – rather than using public and private investment.
Ministers announced a further £200m for the work in Tuesday’s Budget.
Opposition MSPs said the money was a “drop in the ocean”, and questioned when future funding would be delivered given shortfalls in the capital budget.