Work will start on Monday 26 July to improve safety on the Cliff Road bridge between Leadenham and Welbourn on the A607.
Currently, there are existing safety barriers on three approaches to the former rail bridge to prevent vehicles from leaving the road and falling down the steep banks.
New barriers are set to be installed on the unprotected fourth side, and collision damage to the existing brick parapet will be repaired.
The A607 will remain open throughout the works with temporary, two-way traffic lights.
Work is expected to take around four weeks, from 26 July to 20 August 2021, weather depending.
Karen Cassar, assistant director for highways at Lincolnshire County Council, said:
"We have planned for these important safety works to take place during the school summer holidays to avoid impacting on daily school traffic to the nearby Sir William Robertson Academy.
"I'd like to thank local residents for bearing with us whilst we make these improvements."
You can keep up to date with other roadworks, closures and events across the county by visiting www.lincolnshire.gov.uk/roadworks.