NR TPWS/TI/046 ISSUE 1 PDF

This issue of Technical Instruction No. 46 details the selection requirements for TPWS fitment at those TSRs meeting the criteria set out in the Regulations, where there is a risk of derailment leading to catastrophic consequences, but only where the TSR is planned to be in place for greater than 12 months (Long Term TSR). Later issues of this Technical Instruction will cover TPWS fitment at TSRs of planned duration greater than 3 months but no longer than 12 months (Short Term TSR).

This Technical Instruction:

shall be read in conjunction with the requirements of GO/RT3000, GK/RT0007, GK/RT0038, GC/RT5060, RT/E/S/10133, RT/E/S/10138 and RT/E/P/10175. This instruction supplements/amends the requirements of these standards, and will be incorporated into the relevant standards in due course.

requires TPWS (for Long Term TSRs only) to be considered only for the following categories of TSR that meet the requirements of the Regulations, including ‘cascaded' PSRs/TSRs meeting the criteria:

plain line curve-related TSRs.

TSRs controlling speed through diverging junctions without speed control through signalling arrangements, i.e. without Approach Released signalling controls or similar signalling arrangements.

TSRs controlling speed through converging junctions.

TSRs controlling the speed of approach to vehicular level crossings.

TSRs in place for the condition of asset where there is a significant risk of derailment through a single overspeeding event.

Refer to Appendix C for the TAMAR database TSR categories (although it will apply only to Long Term TSRs). Appendix A supplements the text within this Technical Instruction with a flowchart for initial TSR selection and Appendix D provides guidance on the selection criteria. Because of their transient nature, Short Term TSRs shall not be recorded in TAMAR.

defines the general requirements and design rules to enable the Overspeed Sensor System (OSS) loops to be positioned appropriately, and the OSS Set Speed to be determined. Appendix B supplements the text with a flowchart.

This Technical Instruction does NOT apply to:

Emergency Speed Restrictions which are not required to be protected by TPWS by the RSR 1999 as they will not, by definition, be in place for longer than 3 months.

Short Term TSRs, i.e. those in place for up to and including 12 months duration. Specific portable equipment is being developed for such TSRs and this Technical Instruction will be re-issued to include the requirements for these in due course

Long Term TSRs with complex approaches where the conditioning controls are required to be implemented as an SSI data change. In this case, further advice shall be sought from the TPWS NPT