scope:

This Company Standard supports relevant Railway Group Standards and Railway Industry Standards for all technologies of trackside equipment used to give, or restrict, visual movement authorities to train drivers. Associated train warning and protection systems are covered in other company standards.

Design Principles for positioning and controls are contained within the Signalling Principles Handbook NR/L2/SIG/30009, Railway Group Standards and Railway Industry Standards.

The application guidance in this module gives the minimum requirements that need to be addressed, even when a risk-based approach is used.The following guidelines and specifications implement the guidance of this standard:

a) the standard drawings for signal structures listed in NR/LS/CAT003 and NR/LS/CAT004;

b) mechanical design drawings for semaphore signals;

c) the typical circuits for signal operation and proving listed in NR/GN/SIG/CAT005, which are described in NR/L2/SIG/11201/Mod B19;

d) guidelines for SSI installations in SSI 8500; and

e) specific equipment specifications listed in NR/LS/CAT006.

PURPOSE AND INTRODUCTION

This module forms part of the Signalling Design handbook (SDH: NR/L2/SIG/11201) and is to be read in conjunction with the other modules of the handbook and reference documentation.

This Network Rail standard contains requirements and guidance on signalling engineering applications. The content supports the specific and general requirements described in Railway Group Standards and the Network Rail Signalling Principles Handbook [NR/L2/SIG/30009].

NOTE Where there is a conflict between this standard and a Railway Group Standard or the Network Rail Signalling Principles Handbook [NR/L2/SIG/30009] then this standard shall not take precedence

Decisions made by a competent person should be supported by appropriate evidence or documentation.

NOTE use of designer notes on drawings (see HSE CDM guidance) will generally suffice as may

Design Log entries. Any adoption of alternative solutions requires an assessment commensurate with the significance of the proposed change and which follows the guidance provided by the Common Safety Method for Risk Evaluation and Assessment [CSM-RA]; Network Rail's adopted method for the control of safety risks.