South West Rail Resilience Programme: Plans for an extended rockfall shelter to protect the railway between Dawlish and Holcombe in south Devon
Work is progressing well on the construction of the new rockfall shelter at the northern end of Parson’s Tunnel, between Dawlish and Holcombe.
The shelter, along with soil nails and netting on the cliff face, will help protect trains from falling rocks along this section of railway,
We were granted permission to build a 209m open-sided shelter but, always keen to reduce the community and environmental impacts, we refined the design to ensure we have the right balance of resilience measures.
Further analysis showed that we could deliver the same linear extent of railway resilience by installing soil nails and netting along 104m, which will keep the cliff material in place rather than allowing it to degrade. This means that the rockfall shelter has been halved in length, saving money and cutting the project’s carbon footprint.
Our contractor Morgan Sindall Infrastructure started work on site in autumn 2021. Much of the work is having to be done at night, while trains aren’t running.
By Spring 2023, most of the 185 pre-cast concrete sections that make up the shelter were in place, lifted in using a rail-mounted gantry crane. The bulk of the construction work is expected to be finished later this year.
Given the challenging coastal location, site compounds have been built on the top of the cliffs in fields near Windward Lane in Holcombe. There is a main compound, which includes office cabins, welfare units, toilet facilities and areas for parking and storage. In addition to the main compound, there is also a smaller site at the top of the cliffs above the worksite which will store machinery and materials for the worksite and a ‘haul road’, which is like a long driveway designed for large and heavy vehicles to travel to and from the main road to the site.
When our work is complete, the fields will be returned to their original state. Full details of the layout of the compounds can be seen in the map below:
The railway is a vital artery, which connects communities, businesses and visitors in 50 towns and cities in the South West with the rest of the UK. Since the damage caused by heavy storms which resulted in an eight-week closure of the railway in 2014, Network Rail has been developing plans to improve the resilience of the railway between Exeter and Newton Abbot.
The South West Rail Resilience Programme was established to identify and implement the best options to improve rail resilience between Dawlish and Teignmouth, helping to avoid a repetition of the events of 2014.
The cliffs between Kennaway and Parsons Tunnel (including the northern entrance/exit at Parsons Tunnel) were identified as one of three priority sites requiring works in order to deliver a more resilient railway.
Parsons Tunnel was previously extended a hundred years ago and Network Rail proposes to extend that further by providing a rockfall shelter in modern materials, but with open sides rather than the previous brick built enclosed tunnel extension.
Our studies, including drone flights over the cliffs, show that there are active falls from the rear cliff above the railway. 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 a number of engineering challenges, due to the limited access with the track sandwiched between high cliffs on one side and the sea on the other, as well as ensuring this work doesn’t result in lengthy closures of this critical rail artery to the south west.
The design has been carefully developed to ensure that it provides the protection the railway needs but is buildable in this hard-to-access location and that the appearance of the new structure is appropriate to its setting.
The structure needs to be robust enough to protect the railway line from falling rocks and other cliff material as well as be resistant to the harsh coastal environment, so this new section of the rockfall shelter is being built out of pre-cast reinforced concrete sections.
The design of the new rockfall shelter is open-sided to allow rail passengers to enjoy the views of the beautiful south west coastline. It will be covered by a cushioning material to absorb the impact of any rockfalls as well as promoting vegetation growth.
Environmental protection is a key focus for the project and, following early feedback from Teignbridge District Council, Network Rail has carried out additional studies and submitted reports that set out its approach to ecological protection and management of potential impacts on wildlife habitats. These include:
- Habitat surveys
- Cirl Bunting migration report
- Preliminary ecological appraisal of main compound
- Habitat creation plan
In addition, a Marine Environmental Impact Assessment (EIA) Screening application was submitted to the MMO in January 2020 and the MMO has concluded that the works are not EIA development.
What are the benefits?
The project will:
- Protect this vital section of railway line, whilst still maintaining the scenic views of the south Devon coast
- Improve resilience of the railway which connects communities in 50 towns and cities in the south west to the rest of the UK
- The project will leave a lasting legacy for the communities and economy in south Devon, with the impact of the scheme aiming to create £10m in long-term opportunities for the local area, This investment builds upon the £10m that is expected to be spent with local businesses during Network Rail’s construction of the second section of new sea wall at Dawlish which started in November 2020, and follows the £5m spent on local labour, suppliers and accommodation during the first section of the new sea wall which was completed in July 2020.
The planning process
The local planning authority, Teignbridge District Council, granted ‘prior approval’ in April 2021.
The plans for prior approval were submitted under Network Rail’s permitted development rights, enabling the council to formally consult the local community on the proposed designs.
If you have any questions about the plans, you can send us an email at: SouthWestRRP@networkrail.co.uk