Negative Short Circuit Devices


To reduce the inherent risks associated with taking electrical isolations for rail possessions, Negative Short Circuit Devices (NSCD’s) are being introduced to the rail infrastructure at substations in the Southern rail network.  NSCD’s provide a point of isolation for Direct Current Track (DC lines) when taking an isolation.  The NSCD’s are typically housed in a module or externally on concrete bases with various route works required.

Robert West were briefed to provide design delivery, Building Information Modelling (BIM) and programme management for the route works, foundations and Flood Risk Assessments for the NSCD’s across eight sites in the South East of England over a period of approximately five months. 


Robert West undertook the design whilst co-ordinating the requirements of both the electrical and civil disciplines.  In addition, topographical surveys and ground investigations were commissioned and findings integrated into the design solution.  Geotechnical and structural analysis of components such as concrete foundations and support frames was undertaken.

Attention to detail was critical as each site had its own conditions and complexities.  A number of constraints at different sites were identified and overcome with our solutions:

  • Access was poor at some sites for ground investigations to take place – the use of a demountable rig overcame this
  • the proposed solution in the outline design at one site had interfaces with a failing embankment slope – a new position was identified to locate the equipment to avoid this
  • limited space was available to extend the existing Track Paralleling (TP) hut to accommodate the NSCD – building a retaining wall and levelling the ground to house the equipment in a stable position resolved this.


Our team enjoyed providing a value-engineered solution and working with the client and end client, communicating intricacies quickly and clearly to all to enable the meeting of a tight programme.