All 11 fatalities so far this year between Perth and Inverness on the main route to and from the Highlands were on single carriageway sections, it is understood.
The total compares to just one death in each of the past three years, and is the highest since 13 deaths were recorded in 2010.
A total of 333 people have now been killed on that section of the road since 1979 in 250 collisions.
The Scottish Government pledged 11 years ago to complete the dualling by 2025, with that date still shown on the Transport Scotland website.
However, only around 11 miles have been added since then. Experts said finishing the remaining 70 miles of the estimated £3 billion project in little over three years was “incredibly unlikely”.
Upgrading the road to dual carriageway prevents head-on collisions and includes the creation of safer junctions.
This year’s surge in deaths has come despite average speed cameras being in operation over the single carriageway sections of the road for eight years.
In the latest incident, a man and a woman died when their car collided with a lorry about 5:45pm on Thursday near Birnam, south of Dunkeld.
All this year’s other deaths happened between July and September, including two crashes in which three people died in each.
The other was at Ralia, near Newtonmore, in August.
The remaining fatal crashes were near Carrbridge and Dunkeld in September.
Highlands and Islands Scottish Conservative MSP Jamie Halcro Johnston, who has campaigned for the dualling work to be completed, told The Scotsman: “This year alone, there have been 11 fatalities, yet the SNP Government has dodged fixing this death-trap of a road despite promising several years ago to address safety concerns and to dual the road between Perth and Inverness.
“This week’s fatal collision on the A9 has left more families devastated and mourning the loss of a loved one.
“SNP ministers must make good on their promise to dual the A9, and should come before Parliament at the earliest opportunity to advise of when that will be achieved.
"Any delay will mean these stark accident figures risk rising even further.”
The IAM RoadSmart motoring group said the SNP’s 2025 dualling pledge appeared hollow.
Neil Greig, its Scotland-based policy and research director, said: “Completing the A9 dualling project by 2025 is looking incredibly unlikely now and that failure will only be seen by road users as yet another Scottish Government transport promise broken.
“The average speed cameras may have reduced excessive speeding, but only full dualling will deliver safe junctions, safe overtaking and prevent crossover crashes.
"Progress is being made, but any delays to the original promises to dual the A9 by 2025 will clearly cost lives.”
Mr Greig said the “shocking” 2022 death toll might be due to a return to pre-Covid traffic and tourism levels, but he said crashes involved multiple factors, which must be investigated and acted upon.
He said: “Users of the A9 need to be confident that lessons are being learned by road engineers and remedial work put in place as soon as possible."
A Transport Scotland spokesperson said: “The recent accidents on the A9 are a tragedy for everyone involved.
"Our sympathies are with the families and friends of everyone affected by these events.
:“Road safety is of paramount importance and we are working with Police Scotland and our operating companies to understand the circumstances of the accidents that have happened.
“We will continue to invest in the safety of the A9 where it is appropriate and possible to do so, and the A9 Safety Group will continue to consider safety for the wider route.
“The Scottish Government remains firmly committed to completing the dualling of the A9 between Perth and Inverness.
"We have already invested over £400 million to date delivering the dualling programme.
“Work to determine the most suitable procurement options for the remaining sections is ongoing."
Chief Inspector Andy Barclay, road policing north area commander for Police Scotland, said: "Every loss of life on our roads is a tragedy.
"Police Scotland is committed to working with our partners to influence driver and road user behaviour, reduce casualties and improve road safety.
“Every incident presents a unique set of circumstances and specialist road policing officers carry out extensive investigations to establish the cause.
"This information directs our policing response, including education, enforcement, and where appropriate, engineering with our road safety partners.”