The £122,000 programme, which covers 41 miles and more than 100,000 square meters of the A9 from Perth to Dalnacardoch, is being carried out to improve safety and visibility for drivers.
Roads group BEAR Scotland is carrying out the work on behalf of Transport Scotland. The A9 carries as many as 21,500 vehicles each day at the busiest sections.
Stewart Leggett, Chair of the A9 Safety Group, 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 improve conditions on the A9."