The £122,000 scheme will involve removing more than 100,000 square metres of vegetation between Perth and Dalnacardoch, just north of House of Bruar.
The work, which will continue until early next month, will involve lower speed limits over sections of the road, which carries up to 21,500 vehicles a day.
‘See more of the road’
Much of the 113-mile section of the A9 between Perth and Inverness remains single carriageway, but upgrades since the 1970s have included long curves which were designed to provide a clear view of the road ahead to enable overtaking.
However, trees and bushes have grown on the insides of dozens of bends, preventing drivers from seeing oncoming traffic.
Experts have said this had made overtaking more dangerous and increased motorists’ frustration - making them more likely to risk potentially fatal manoeuvres to pass slower vehicles.
A9 Safety Group chair Stewart Leggett said: “This work is an important part of our safety plan for the A9.
“It will help drivers see more of the road ahead and this will give them a better understanding of what’s happening, improving safety as a result.
“We are focusing on engineering, education and enforcement as we look improve conditions on the A9.
“£137 million has been spent on safety and maintenance on the route in the last five years, including work to improve junctions as well as overtaking opportunities, and over the next two years we expect to spend an additional £18 million.”
Eddie Ross, north west unit representative for BEAR Scotland which maintains the road for the Scottish Government’s Transport Scotland agency, said: “This landscaping programme of roadside vegetation clearing will give further safety benefits to drivers by improving visibility. It will be particularly beneficial once the annual growing season starts.”