Bridge parapets at Fulsome and Fulsome South Bridges at Hook are to be replaced.
The bridges are located on the A30, west of Murrell Green near The Crooked Billet pub, over Whitewater River.
The repair work will cost £330,000 and be carried out on both bridges simultaneously by Dyer and Butler on behalf of the County Council and repairs are scheduled to start on Monday 7 April 2014 for 26 weeks.
Safe pedestrian passage will be maintained at all times for the duration of the work and local bus companies have been made aware.
Councillor Seán Woodward, Hampshire County Council's Executive Member for Economy, Transport and Environment, said: "This scheme is essential to maintain the safety of the road and that of road users. Temporary safety measures currently in place will be replaced with permanent ones and once it is complete the bridges will be safer, stronger and more durable. We will plan all works to minimise disruption, and information will be updated regularly so people can plan their journeys."
The Eastbound A30 runs over Fulsome Bridge while the westbound A30 runs over Fulsome South Bridge.
Temporary safety measures currently in place at both bridges will be replaced. They will have new metal parapets installed and will be waterproofed and resurfaced.
The A30 will be kept open during the day. However, each bridge will be closed for one night at the start of the operation to allow for the safe installation of temporary safety barriers and one night at the end to remove the barriers and resurface the carriage way.
There will be a temporary speed reduction during the works from 70 mph to 40 mph.
The Contractor will be responsible for notifying the public of the road closures and the available diversion routes.
The bridge repairs are taking place close to The Crooked Billet pub and the pub's parking areas, but safe access to and from the business will be kept open for the duration of the works.
Access in and out of Holt Lane will also be kept open.