scope:

This issue of the Specification includes the requirements for and positioning of TPWS Transmitter Loops at signals, speed restrictions and Buffer Stops, at which the provision of TPWS is necessary to meet the requirements of the Railway Safety Regulations 1999 ('the Regulations').

This Specification should be read in conjunction with Network Rail Company Standard RT/E/S/10178 for RETB Signalled areas.

In addition to the requirements of the Regulations contained within this Specification, the requirements for signal overrun risk assessments of existing and new signals shall also consider additional transmitter loop requirements based on an assessment of managing risk ALARP. In this context, this Specification includes the requirements for transmitter loop positioning for the application of TPWS+ to existing signals and to certain 'plain line' signals selected for retrospective application of TPWS.

Purpose

This Specification defines the criteria for the positioning of Train Protection and Warning System (TPWS) transmitter loops and determination of the need for Overspeed Sensor Systems (OSS).