The completion of dualling the A9 will be more than a century late if the current pace of progress continues, analysis by the Scottish Conservatives suggests.
Graham Simpson, the party’s transport spokesman, said research which estimates it will take decades for the programme of work to be finished is “shameful”.
The estimated time-frame for the work on the trunk road linking Perth and Inverness was calculated on the basis that Transport Scotland’s annual expenditure rate of £37.9 million since 2012 continues annually until the initially promised completion date of 2025.
First Minister Humza Yousaf admitted earlier this year that the dualling project will not be completed before the next Holyrood election in May 2026.
According to the Tory research, the A9 will now not be fully dualled until 2134, based on the rate of investment seen between 2012 and 2023.
The Scottish Government has spent more than £455 million on the dualling programme in 12 years, meaning there is £4.2 billion still to be spent on the programme, the Tories said.
The party said there has been an average investment of £37,956,707 each year, according to its analysis of estimates received under freedom of information requests.
But the Government dismissed the estimated time-frame.
Mr Simpson said: “These figures demonstrate the appalling betrayal by the SNP of those who reply on the A9.
“Every day that these essential upgrades are delayed, more lives are put at risk on this deadly road.
“The nationalists originally pledged to have the A9 fully dualled by 2025, yet at the current rate of progress it would be well over a century late.
“That’s beyond embarrassing – it’s shameful. SNP ministers were already making pitiful, snail-paced progress on this, but the addition of the anti-car Greens to Government has made things worse.
“Despite the mounting death toll and the understandable fury of campaigners, they continue to drag their heels by delaying a promised statement to Parliament.
“The rural communities who depend on the A9 want to see the talking stop and work to finally start on the huge stretches that remain single carriageways.”
The Tories said they will “always stand up for rural Scotland”, by putting the dualling programme as their first general election manifesto pledge.
A Scottish Government spokesperson said: “This is simply not the case. Ministers are committed to dualling the A9 between Perth and Inverness and work is continuing across the route.
“Parliament will be updated on the programme for completing the remaining sections in the coming weeks.
“As the then minister for transport confirmed to Parliament in February this year, the decision-making includes consideration of different contractual approaches, such as design and build contracts and public-private partnership contracts, to determine the most suitable procurement options for the remaining sections of the A9 dualling.”