TPWS is a train protection system designed to reduce the likelihood and consequences of signals passed at danger (SPADs). It automatically applies the emergency brakes on a train if it passes a red signal, or approaches a red signal or speed restriction too quickly. Thales Communications developed the system to a British Rail specification in 1996, fulfilling the need to realise significant early benefits through rapid implementation across the country. In accordance with the Rail Safety Regulations in 1999, Network Rail has to ensure that TPWS is fitted and operational on the entire British rail network by the end of 2003.

A key requirement for any kind of cable marker or insulation in TPWS is that the material is zero-halogen, so that on combustion, no toxic gases are released. Siegrist products fully meet the demanding specifications. Thales has been using the company for over 10 years, since it was first involved in a London Underground project and found that Siegrist was an approved supplier to London Underground. The limited fire hazard material used in the cable markers was originally developed by Siegrist-Orel for London Underground Limited in the wake of the Kings Cross fire in 1987. Following the incident, London Underground completely revised their materials specifications, by defining a level of required safety and requesting materials capable of meeting it. In response, Siegrist developed a low-toxic smoke silicone with a Temperature Index of above 340.