Work to replace sections of the barrier around bridges will start next month on the A5 at Milton Keynes to Old Stratford Roundabout.
It will start on Monday, August 1 and involves a lower speed limit of 50mph and lane closures, which will mostly be overnight.
Work is expected to last about six months.
“We will be replacing parts of the existing verge barrier around the bridge supports on a 9.6 mile stretch of the A5. The barriers around the structures have reached the end of their life and need to be replaced to maintain safe and reliable journeys on this vital route,” said Highways England project manager Mindy Bhogal.
“The work has been carefully planned and will be carried out overnight, when traffic flows are lowest, to minimise disruption.
”There will be narrow lanes during the day and a temporary 50mph speed limit in place throughout the work for safety reasons.
“As part of this work we will also be clearing some of the vegetation around the bridges in the area,” Minday added.
The work will take place between the A508 and A416 in both directions between 10pm and 6am.