Medway Council is seeking government funding to upgrade England’s first immersed road tunnel.

The Kent local authority has submitted a £9.25m bid to the Department for Transport’s Structures Fund to complete a £10.5m upgrade of the Medway Tunnel. The works would include the renewal of the electrical, ventilation, pumping and life-safety systems.

The 720m-long tunnel, opened by Princess Anne in 1996, provided an additional crossing for the Medway River. As the first immersed tube road tunnel built in England, the £80m project was seen as a landmark engineering achievement. The three immersed concrete tunnel sections weigh approximately 90,000 tonnes.

More than 50,000 vehicles use the tunnel every day.

Many of the tunnel’s infrastructure and systems date back to 1996. While the structure itself remains sound, some system components have become obsolete, specialist parts are increasingly difficult to source, and what was once routine maintenance is now becoming increasingly complex and costly.

“As with many nationally important infrastructure assets from the 1990s – the challenge is now major lifecycle renewal rather than one of ongoing routine maintenance,” the council says.

Councillor Alex Paterson said the tunnel presented a unique set of challenges with complex systems required to keep it operational.

“Whilst our teams do an excellent job in maintaining the tunnel and keeping it running, the time has come where substantial investment is required. The proposed scheme will future-proof this vital asset, address the risks we face today, and ensure the Medway Tunnel continues to contribute to the economic growth and regeneration in the region tomorrow,” he said.

Councillor Simon Curry said the tunnel was a vital transport link.

“There are only a handful of specialist highway tunnel assets operated by a local authority across the whole of England – meaning the Medway Tunnel presents unique funding and asset pressures for the council. This investment is critical to ensure this essential transport route can continue to support communities, growth and businesses for decades to come,” he said.