The project is being jointly funded by the Department for Transport's Challenge Fund and Warwickshire County Council.
The aim of the project, which began in June and is due to be completed in the new year, is to repair the Baginton Mill bridge which carries Mill Hill Road over the River Sowe.
It is one of eight projects in the county council’s £6.3m programme to repair Warwickshire’s historic road bridges.
Baginton Mill bridge is formed of three brick arches with sandstone elevations. Routine inspections found the condition of the sandstone to be severely eroded after centuries of weathering.
The project has been delayed by two incidents of vehicles colliding into and damaging the bridge’s stone parapet walls.
The first of these occurred three weeks before the start of the project, while the second collision earlier this month, caused significant structural damage.
Repairing this additional damage has meant the project will take longer to complete than first planned. It is expected the bridge will be restored and the road fully reopened in early 2023.
Most of the work is being undertaken from below the road and the road is being kept open using temporary traffic signals and providing a temporary footbridge alongside the existing bridge.
Only the most severely eroded stonework is being replaced, so that much of the original fabric of the structure is retained and the bridge’s heritage value is protected.
Cllr Wallace Redford, Warwickshire County Council portfolio holder for transport and highways, said: “There’s a great deal of work to be done to repair this bridge which has been eroded through centuries of wear, with additional damage from recent road traffic collisions.
"The repairs need to be undertaken sensitively to retain the historic integrity of the structure, so it is taking a little more time than you might expect. Baginton Mill Bridge is a really important heritage asset for the local community, as well as the county as a whole. So please bear with us during the disruption and we’ll get the bridge fully open as soon as possible.”