Passengers in south-east London are being urged to plan ahead from Sunday 18 May to Sunday 27 July 2025 as the Blackheath tunnel, between Blackheath and Charlton, will close for 10 weeks when Network Rail begins £10 million of essential repairs to the 175-year-old Victorian-era structure.
The work follows a 10-week closure in 2024, during which engineers cleaned soot from the tunnel lining, carried out detailed surveys and replaced thousands of bricks to stop water leaking into the tunnel and damaging the railway.
The closure begins on the same day as Southeastern’s timetable change, and so customers are being reminded that some train times will change only for the period of the 10-week Blackheath tunnel closure.
Services that normally run through the tunnel will be diverted via other routes during the 10-week closure. Due to the diversion, fewer Cannon Street services will call at St Johns and New Cross.
The work is needed because the one-mile-long tunnel, which opened in 1849, is prone to leaks and water damage. The tunnel’s brickwork is affected by the freezing and thawing of rainwater which filters through the ground into the tunnel. While the tunnel is safe, the leaks and very wet conditions inside it damage track and electrical equipment, causing delays and speed restrictions.
Over the last year, faults in the tunnel have been the cause of around 1,000 minutes of delay to Southeastern passengers.
Speaking for the Southeastern-Network Rail Alliance, David Davidson, Network Rail’s Kent route director, said: “We know there’s never a good time to close the railway, and that changes to services for a 10-week period is a long time. These essential repairs will improve the safety and operation of the tunnel.
“We are carrying out the repairs over a series of 10-week closures because working in cramped and narrow tunnels is incredibly difficult. If traditional weekend working was used engineers would spend at least 50% of a weekend bringing materials and plant in and out of the tunnel, leaving limited time for actual work.
“I want to thank customers for bearing with us during the closure, during which there are a number of alternative travel options. We are running extra services on Woolwich line for connections to the Docklands Light Railway and the Elizabeth line, and there are also extra services on the Bexleyheath line. Rail tickets can also be used at no extra cost on some local bus routes, with full details available on the Southeastern website."
Over the course of the entire programme of works, Network Rail will replace thousands of bricks and install a new tunnel lining to stop water leaking into the tunnel, which will be crucial for the reliable running of the railway long into the future.
Drainage systems will be rebuilt and essential track work carried out, including the removal of ‘wet beds’ – in other words, dealing with waterlogged sections of track that cause bumpy train rides for customers. The additional work means less disruption for passengers in the long term.
When the tunnel is repaired and water damaged infrastructure replaced passengers will benefit from fewer delays, fewer speed restrictions and improved reliability.
