Dualling of the A9 will take more than a century to complete at the current rate of progress, analysis by the Scottish Conservatives suggests. 

It will take until 2134 for the road to be fully dualled, according to Tory research based on the rate of investment from 2012 to 2023. 

Graham Simpson, the party's transport spokesman, said it was "shameful" and "embarrassing" that the research estimates it will take 109 years past the original deadline for the programme of work to be finished.

Read more: Humza Yousaf: A9 dualling will not be finished before 2026 election

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 the dualling project will not be completed before the next Holyrood election in May 2026.

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.

The Herald: The Scottish Government committed to dualling the A9 in 2011The Scottish Government committed to dualling the A9 in 2011 (Image: PA)

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."

Read more: Alex Neil criticises Nicola Sturgeon over failure to dual A9

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."

Transport Scotland previously said it hoped to award a contract for the Tomatin to Moy stretch of the road in early summer 2024, with the work expected to take around three years to complete.

The Herald: Humza Yousaf has admitted the A9 dualling won't be complete in 2026Humza Yousaf has admitted the A9 dualling won't be complete in 2026 (Image: PA)

Meanwhile, after admitting the delay of the project in September, Mr Yousaf said there should be no doubt the Scottish Government is "absolutely committed" to getting the job done. 

He promised to come back to parliament later this year to give an update on the timetable of the scheme. 

The Scottish Government committed to widening around 80 miles of single-carriageway in 11 sections of the A9 in 2011. 

However, only 11 miles in two sections have been dualled in the last 12 years. Last year, 12 people died on the A9, of those 12 were on single-carriageway section. 

Read more: Humza Yousaf urged to rule out using bonds to fund dualling of A9

In February, then transport minister Jenny Gilruth told parliament the ambition to dual the road between Perth and Inverness by 2025 had become "simply unachievable". 

While former SNP MSP Alex Neil, who served as infrastructure secretary when the proposals were created, has described the delay to the road as a "betrayal" to the Highlands and Scotland. 

Speaking during a Holyrood committee as part of an inquiry into the A9 dualling, the former Scottish minister said he suspected "the foot was well and truly taken off the accelerator".