A huge pontoon the size of two tennis courts has been placed over a river while engineers carry out essential repairs to a motorway bridge.

Teams from National Highways are using the temporary structure on the Great Stour River underpass below the M20 in Ashford.

The route - which links Ashford Rugby Club in Kennington with the Heathfield Road estate – closed at the beginning of the month and is set to remain shut until the end of the year.

Engineers are in the process of carrying out maintenance to the concrete and steel that helps reinforce the bridge, to keep the structure secure.

Covering an area of roughly 550 sq m - around the same as two tennis courts - the pontoon allows the team to get under the bridge and make repairs while traffic on the motorway continues to flow above.

Nikki Thorp, National Highways project manager for the scheme, said: “As we’ve not found the secret of how to walk on water yet, floating work platforms and walkways are ideal for bridge maintenance, allowing contractors to access structures underside from the water.

“They are modular and lightweight, so they can be mobilised quickly.

“This allows us to be flexible and responsive, meaning we can be busy making repairs out of sight without disrupting traffic flows.”

An 88-mile diversion was put in place in April when National Highways closed the motorway between Junctions 9 and 10a to allow for initial repairs to the bridge.

While the M20 itself will remain open during the latest stage of works, National Highways says the diversion will add approximately seven minutes to pedestrians' journeys.

The alternative route is via Heathfield Road, Canterbury Road and Kinney's Lane.

Bosses say the works to Great Stour Bridge are "critical for safety reasons" and include replacing expansion joints at the site, which regularly floods.

The work which is expected to take three months was due to begin in August, but was pushed back.