A £3.5m is being made to improve the Merseyrail network this autumn.

Network Rail will waterproof and strengthen four underground tunnels during a 26-day railway closure from Sunday 11 October to Friday 6 November.

The upgrades will improve journey reliability by preventing water from entering the tunnels and causing problems with the third-rail electricity supply. The scale and complexity of these projects mean the Northern line will be closed between Hunts Cross and Liverpool Central for just under four weeks.

Paul Owen, Network Rail Liverpool area director, said: “This is a significant £3.5m investment into the underground section of the Merseyrail network to maintain four Victorian-built tunnels for 21st century passengers.”

Stephen Dodd, chief operating officer at Merseyrail, said the upgrades will “help improve the long-term reliability of the Northern Line and reduce the risk of future disruption”.

To make the most of the closure, power control systems will also be modernised across both the Northern and Wirral lines.