Next phase of Dawlish railway revealed

It's a tunnel that's like an Alpine avalanche shelter

The next phase of plans to protect the Dawlish railway line have been unveiled, with the extension of a tunnel that will look like "an avalanche shelter in the Alps."

Network Rail wants to install a 210 metre-long rock fall shelter at Parsons Tunnel North, as well as providing additional safety netting on the cliffs.

It's the third phase of the South West Rail Resilience Programme following the two Dawlish sea wall projects, and aims to protect the railway from falling rocks and cliff failures. The risk at this part of the coastline is from the cliff above and is not from the sea itself,

If approved, and subject to government funding, construction will start in August with the work expected to take around a year to complete. 

Rocks falling from the cliffs is not a new problem and was the reason for the construction of the original shelter a century ago. However, recent studies, including drone flights over the cliffs, show that there are active falls from the rear cliff. An accumulation of material on the slope could trigger larger debris slides and this stretch of railway is not currently protected against rock falls from this active area of cliffs above.

The construction of the rockfall shelter at this location poses engineering challenges, due to the limited access because the track is flanked by high cliffs on one side and the sea on the other. The design is open-sided to allow rail passengers to enjoy views of the coastline and it will be constructed from pre-made concrete wall panels and beams on the roof, covered by a cushioning material to absorb the impact of any rockfalls.

In a letter with the application, town planning manager for the Wales and Western routes Colin Field said: “The project will deliver a significant economic benefit to Teignbridge District Council and the wider south west peninsular by ensuring that the mainline railway remains operational and is not at risk from falling debris from the cliff.

“Parsons Tunnel has previously been extended a hundred years ago and this project proposes to extend that further providing a rock fall shelter in modern materials, but with open sides rather than the previous brick built enclosed tunnel extension.

“The works will involve a combination of additional safety netting on the cliff where it currently doesn’t exist and a Rockfall Shelter to extend the previously installed tunnel extension from 100 years ago, to protect the railway from falling rocks and cliff failures. The rockfall shelter will be similar in appearance to an avalanche shelter used in the Alps.”

The plans propose a 210 metre-long rockfall shelter directly in front of the 1920 tunnel extension to provide a continual 350 metre shelter in front of the original Parsons Tunnel.

The exact siting of the rock fall shelter is therefore very limited in that it has to be at the bottom of the cliff, over the top of the railway and in front of the previously built tunnel extension and could not be "reasonably be carried out elsewhere on the land," Mr Field said.

Ewen Morrison, senior programme manager for Network Rail’s South West Rail Resilience Programme, said: “The existing rockfall shelter has proven its effectiveness for a century and so this modern extended structure will protect the railway for generations to come alongside a section of cliff that is becoming increasingly hazardous from rock falls.”

Phase one, the Dawlish sea wall at Marine Parade, has already been completed, while phase two, to raise the sea wall at Dawlish station as well as station improvements are currently under way.

Once the rockfall shelter and cliff works at Parsons Tunnel, are underway, the fourth phase is the central tunnels section between Parsons Tunnel and Kennaway Tunnel. Network Rail is currently working up designs.

The fifth and largest phase is along the coastline between Teignmouth to Parsons Tunnel and will involve a new railway alignment with a new sea wall beyond the footprint of the existing one, together with stabilisation of the cliff once the railway has been moved.