South Devon railway resilience Programme - 109m-long Rockfall Shelter at Parsons Tunnel
The completion of the 109m-long rockfall shelter at Parsons Tunnel, near Holcombe, marks a major milestone in Network Rail’s Southwest Rail Resilience Programme. This programme was designed with the aim to protect the costal railways, running between Exeter and Newton Abbot, from extreme weather. On this route there was a particular focus on protecting the railway line from any potential rockfalls as steep cliffs cover that route.
This £48 million rockfall shelter is part of the wider Southwest Rail Resilience programme which was initiated following the 2014 storms that caused disruptions and cut of services to the peninsula for eight weeks. The programme has seen a total investment of £165 million, which includes the construction of a new sea wall at Dawlish and ongoing work to install additional protective measures between Dawlish and Holcombe. To ensure that there was as minimal disruptions to the train services and to maintain the safety of the workers and passengers, most of the construction work took place during the night.
Cornish Concrete Products LTD played a central role in the project, manufacturing a total of 185 precast concrete units. Each unit was specifically designed and coloured red to match the local sandstone, ensuring that the structure blended seamlessly with the natural surrounding whilst providing the necessary durability to withstand the extreme weather conditions. The structure itself is open on the seaward side, so that passengers are still able to continue to enjoy the costal views. All of the precast concrete units were then transported to site and installed to create the protective shelter.
To build the shelter, a gantry crane running along the rails was used to move the precast units into place. Due to the space constraints between the cliffs and the sea, the gantry crane proved to be invaluable to meet the unique challenges of working in such a confined space. The roof shelter was covered with 4,100 tonnes of red sand and 5,132m³ of foam concrete which was used to backfill between the shelter and the cliff edge. Stainless steel netting measuring 7000m² and secured with 1,400 soil nails was installed above the structure to add an additional layer of protection, to the bridge, against potential rockfall.
To ensure that there was as minimal as possible disruptions to the train services and to maintain the safety of the workers and passengers, most of the construction work took place during the night.
The completion of the Parsons Tunnel rockfall shelter is a vital step in ensuring the resilience of this crucial rail link, blending innovative engineering with thoughtful design. It not only enhances passenger safety but also preserves the natural beauty of the surrounding Cornish coastal landscape.
Images credit - Network Rail