Parsons Tunnel Cable Diversions

The challenge

Part of Network Rail’s South West Rail Resilience Programme – and a reaction to the immense disruption caused by heavy storms in 2014 – Morgan Sindall were engaged to construct a 209m open-sided rockfall shelter at the mouth of Parson’s Tunnel.

Located on the South Devon coastal line between Dawlish and Halcombe, this route is a vital rail artery into the South West and beyond. Despite its great importance, however, it has long been constrained by its environment, with rock falls taking a significant toll upon rail users and the region’s economy.

With major piling works being required prior to construction, significant pre-construction works were needed in order to relocate and install critical S&T infrastructure.

The solution

Over a period of 7 months, an Amaro team of 2 were tasked with creating sufficient cable slack (via joining and re-routing) prior to also carrying out the following works…

• The installation of a number of line side telephones (LST) within the tunnel with all cabling run within a new trough route
• The re location of an axle counter dis box by 230m
• The installation of 2 no. 10-pair cables, jointed and run through the new trough route
• The installation of a FSP (Functional Supply Point) joint box, with all associated 650v cable run through the new trough route
• The jointing and installation of 2 no. 60-pair telecom cables through the new trough route
• The provision of 900m of 48-core signalling cable run out and installed into the new trough route through the tunnel and within the piling zone
• The recovery of several redundant cables from the route

The outcome

Delivered ahead of programme and with zero lost-time incidents, all works were completed in line with the client’s specification. This was achieved despite restricted access due to scrap rail, excess ballast and vegetation on the trough route.

Thanks in part to the role played by Amaro, piling was able to take place without damaging vital S&T infrastructure, facilitating the construction of a rock fall shelter which, in turn, significantly improved the resilience of the operational railway.