The tunnel over the railway line between Dawlish and Holcombe is to be extended for more than 200 metres with an open-sided shelter to protect the track from rock falls.

Network Rail has submitted plans for the extension north of Parsons Tunnel to Teignbridge District Council.

The rock fall shelter will be built with modern materials and with gaps along the sea-facing side so that train passengers can see the view.

The proposals are subject to planning approval and funding from the Government, but construction work is expected to begin in August.

However, Network Rail is due to start preparatory work on March 22. Engineers will begin cutting back some of the vegetation at the top of the cliffs and installing safety netting to secure shrubbery on the cliffs and prevent falling debris.

The company says this work will be closely monitored to minimise disruption to wildlife habitats and biodiversity - as will the main building project. Following early feedback from the district council, Network Rail has carried out studies and submitted reports setting out its approach to ecological protection and 'the management of potential impacts on wildlife habitats'.

Why is this extension needed?

The problem of rocks falling from the cliffs on to the railway is not a new one, and was the reason for the construction of the original tunnel 100 years ago. But 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 will pose a number of engineering challenges. Access is limited, with high cliffs on one side of the track and the sea on the other. Network Rail will also have to make sure the work doesn't result in lengthy closures of the vital rail link.

The open-sided rockfall shelter will be constructed out of pre-made concrete wall panels and beams on the roof, covered by a cushioning material to absorb the impact of any rockfalls.

Network Rail has submitted the plans for 'prior approval' under Network Rail's permitted development rights. Under this, Teignbridge District Council will consider only the design, materials, or siting of the project to ensure that development 'would not injure the amenities of the neighbourhood' and be satisfied that it could not be 'reasonably carried out elsewhere'.

Teignbridge District Council will now be able to formally consult the local community on the proposed designs.

Ewen Morrison, senior programme manager for Network Rail's South West Rail Resilience Programme, said: "The coastal location of the railway in south Devon is truly stunning but it also presents its biggest challenge with the sea on one side and steep cliffs on the other.

"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."

Councillor Andrea Davis, Chair of Peninsula Rail Task Force, said: "The PRTF welcomes the planning submission for the extension of the rockfall shelter north of Parsons Tunnel.

"The line at Dawlish is a vital link between the peninsula and the rest of the UK and the rockfall shelter is an important element in future proofing and improving the resilience of our main line.

"We congratulate Network Rail on developing a modern, ecologically conscious, solution to the ongoing rock fall issue. The PRTF look forward to continuing our work with government to build upon efforts to level up the region, focussing on the next stage of the project which will deliver a resilient rail infrastructure, fit for the future."

The full details of the project can be viewed on the planning portal of the council's website.