Transport minister Jenny Gilruth told MSPs on Wednesday the improvements ahead of finishing the remaining sections of dual carriageway would be at Ballinluig, south of Pitlochry, Bruar, north of Blair Atholl, and Ralia, south of Newtonmore.
Three people died at Ralia in August, while there have been several fatal and serious crashes at Bruar over the last four years.
Further improvements will also be considered for implementation prior to dualling being completed.
Upgrading work at the three locations is due to be announced after a meeting of the A9 Safety Group in Pitlochry on Friday, which Gilruth will chair.
She said the Scottish Government remained “absolutely committed” to completing the estimated £3 billion dualling project. but did not refer to the 2025 finishing date pledged by ministers more than a decade ago which is now regarded as unachievable.
The minister also reaffirmed the Scottish Government’s commitment to completing the dualling of the A96 between Aberdeen and Inverness, at a similar estimated cost.
However, as part of a power-sharing agreement between the SNP and Greens last year, the two parties said they would maintain “distinct positions” on the project, which the Greens oppose.
They agreed to subject it to a "transparent, evidence-based review to include a climate compatibility assessment to assess direct and indirect impacts on the climate and the environment” to be completed by the end of this year.
Gilruth said: “In the coming weeks, I will announce additional short-term measures for the A9 between Perth and Inverness in advance of dualling works.
"We will be making investments to improve safety at Ballinluig, at Bruar and also at Ralia, but I accept that more will need to be done before full dualling is complete.”
She said £431 million had been spent on dualling to date – but that is less than one sixth of the estimated total cost.
Scottish Conservatives transport spokesperson Graham Simpson said only 12 miles of dual carriageway had been built since the SNP had pledged to complete the dualling work 11 years ago.
He said: “At that rate, it will be in 2086 by the time the other 70 miles is finished.
"None of us will be around to see this.”
Simpson said of both the A9 and A96: "It looks very much as if those historic commitments lie in the gutter.”
The Holyrood debate, led by by the Conservatives, comes weeks after The Scotsman revealed that more people have died on the A9 between Perth and Inverness in 2022 than any year since 2010.
The 12 deaths so far this year were all on single-carriageway sections of that stretch of the road and compare to just one in each of the last three years, with the latest on October 12 near Kingussie.
Inverness and Nairn SNP MSP Fergus Ewing said people wanted “real, rapid, solid, concrete, substantial progress”.
He called on ministers to publish a “revised plan of when the dualling commitments will be completed”.
However, Scottish Greens transport spokesperson Mark Ruskell accused some MSPs of attempting to use recent crashes “to bolster the case for dualling every single inch of the A9 and the A96 without any analysis about why recent accident rates have worsened or how they could have been prevented”.
Neil Greig, the Scotland-based policy and research director of motoring group IAM RoadSmart, told The Scotsman: “I would be looking for firm commitments on the dualling first and foremost.
"In the short term, they need to check that all the signs, road markings, lights and cats eyes work and are in good condition.
"High-profile police enforcement is also needed.
"Average speed cameras [which cover the single-carriageway sections between Perth and Inverness] stop high-end speeding but don’t deal with overtaking, junction and fatigue crashes.
"They should also review the bypassed community policy and allow some more high-quality roadside services.”