Network Rail passes halfway on £3.5m Merseyrail tunnel waterproofing

Network Rail has passed the halfway point of its £3.5m programme to strengthen and waterproof four Victorian-built tunnels on Merseyrail's Northern Line in Liverpool, 17 days into a closure that began on Sunday 11 October.

The infrastructure owner said on Tuesday 27 October that a team of more than 50 workers had removed 92m² of old concrete ahead of new concrete being applied, drilled 6,400 holes in the tunnel walls for waterproofing injections and drilled a further 197 weep holes to direct water into drainage.

By the same point the team had waterproofed 1,672m² of tunnel wall, Network Rail said.

Paul Owen, Liverpool area director for Network Rail, 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."

The engineering

Network Rail said the waterproofing is applied by drilling holes and injecting a liquid resin into the tunnel walls. Once set, the resin forms a barrier that stops water coming through the brickwork and instead directs it through weep holes down into drainage on the track bed.

According to Network Rail's project page, the tunnels carry services from the south of the city into the city centre, and water entering them can cause problems with the third rail electricity supply to trains.

Merseyrail said the work is designed to stop water reaching the 750V electrified third rail, which it said should reduce the risk of power failures, emergency speed restrictions and unplanned closures across the network.

Alongside the tunnel strengthening and waterproofing, Network Rail said power control systems are being modernised across both Merseyrail lines during extended Sunday closures. Its project page said the aim is to make it quicker and easier to turn the electrified rail on and off in future, whether for planned maintenance or unexpected faults.

Merseyrail said new track feeder switches will allow engineers to remotely isolate smaller sections of the railway for faster repairs.

Network Rail said carrying out the work in a planned closure avoids the risk of emergency or unplanned closures that would cause greater disruption at short notice.

Services

The Northern Line is closed between Hunts Cross and Liverpool Central during the work, with rail replacement buses running across the city region. Merseyrail said tickets bought as usual at stations are accepted on the replacement buses.

Network Rail first announced the works on 10 August as a 26-day closure from Sunday 11 October to Friday 6 November. Its 27 October release said normal train services would return on the morning of Saturday 7 November once all the work has been completed.

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

Network Rail said Liverpool Central recorded more than 14 million entries and exits in 2024/25. The Office of Rail and Road's annual station usage estimates for April 2024 to March 2025, published on 4 December 2025, put the figure at 14.8m, making it the ninth busiest station in Great Britain outside London.

Background

Network Rail said the programme follows similar improvements made in 2022 to High Neck Tunnel, another tunnel on the Northern Line's southern approach to Liverpool Central, between Liverpool Central and Brunswick stations.

That earlier job was also a £3.5m investment, and is separate from this autumn's four-tunnel programme. Network Rail described High Neck Tunnel at the time as a 130-year-old structure with leaks and loose Victorian brickwork. Engineers installed a steel 'ram-arch' tension system to the tunnel roof, sprayed with concrete, working from a temporary platform while trains passed underneath as normal.

This year's works, by contrast, require the line to be closed.

Ahead of the closure, Network Rail launched a passenger awareness campaign on 14 September warning people not to 'get spooked this autumn' during the work.

On Sunday 8 November, the day after Northern Line services are due to resume, separate track upgrades at Mossley Hill will affect services in and out of Liverpool Lime Street, Network Rail said.