Network Rail gives historic deep shaft a new lease of life24 September 2021
Network Rail has completed the rehabilitation of a 241m-deep ventilation shaft serving the Cowburn Tunnel, located in a remote moorland area of the Peak District National Park and also one of the UK’s deepest railway tunnels.
The US$1.1m rehabilitation of the shaft was needed after extensive water ingress had occurred over more than a century. In effect, the shaft had acted like a water funnel: rain falling on to the land would seep through the shaft’s brickwork, cascading ‘like a massive shower’ into the tunnel and on to the rail tracks. The result: degrading infrastructure and delays to rail services.
Network Rail (NR) engineers’ solution to the problem was to install a sophisticated system of drainage pipes to collect the water and divert it into drains located in the tunnel. But what would be the best way to allow maintenance crews to access such a remotely located tunnel at the bottom of a shaft that is deeper than Canary Wharf tower is high?
The solution was to build a temporary lift platform from which crews could be lowered down the shaft in a custom-built cradle using winches and pulleys. Materials and components had to be flown-in by helicopter. The result was that no disruption was caused to passenger or freight services during the working period. However, drainage improvements at track level could only take place on Saturday nights when trains were not running. The work began in August 2021 and finished this week.
“We work on a lot of structures in remote locations but working in a tunnel this deep and using helicopters to get materials to site is rare,” said Dennis McGonnell, Network Rail works delivery manager. “It makes you realise what an amazing feat of engineering building this tunnel and ventilation shaft was all that time ago without the modern machinery we have today. It’s amazing to see up close the quality of the Victorians’ workmanship.”
The shaft was completed in 1896 over a two-year period. NR said that to excavate, mason and brick the original shaft required 102 men working eight-hour shifts day and night. At its lower end, the shaft terminates into a large 10m-high stone chamber (‘the cathedral’) that is offset from the tunnel’s twin track lines. NR says it is uncertain why pristine stonework was used for the pitch-dark chamber that would rarely be seen by anyone.
The Cowburn Tunnel lies on the Hope Valley Line between Edale and Chinley, and runs beneath key peaks near Kinder Scout and Mam Tor in the Peak District National Park.