Major maintenance on the Castle Mill Viaduct, which carries the A421 over the River Great Ouse between Renhold and Cardington, near Bedford, will see vital components replaced to ensure its safe and reliable operation for years to come.

Further work Highways England will be carrying out at the same time as the beam installation include gulley clearance, lane sweeping, and road resurfacing, while its partners will complete work including road inspections and lighting maintenance.

The beam being installed is an expansion joint, which protects the structure by allowing controlled movement between its different sections and allows them to expand and contract as the temperature changes. The Castle Mill viaduct is 400 metres long and is supported by 10 bridge piers. Built in 1996, the bridge can carry vehicles up to 40 tonnes.

This £400,000 work is part of £43.7million being invested in maintaining and improving the East of England’s trunk roads and motorways over the next year.

Kelly Millburn, project manager for Highways England, said: “Most people don’t give bridge joints a second thought, but they are vital components of a bridge and are designed to be replaced from time to time. We understand how important the A421 is to people’s journeys; it is a vital road, connecting the M1 to the East of England, so we are carrying the work out in a way that keeps disruption to an absolute minimum.”

The joint being replaced supports the westbound A421. A contraflow is being installed on the A421 between its Renhold and Cardington interchanges to keep one lane open in each direction while work is carried out. A 40mph speed limit will be in place throughout. There will be various closures while Highways England completes this essential work throughout June, usually overnight but with some weekend closures needed too.

Work on the project, which began Tuesday 28 May, is expected to be completed by the end of June.