NR NR/L2/SIG/11201/MOD B7 ISSUE 8 [ Not for New Design ]

Signalling Systems (Types)

This module provides application guidance to the design of interlockings (including ground frames) to meet NR/L2/SIG/30009/(all modules) Interlocking Principles through the following:

a) mechanical signalling systems (see also NR/L2/SIG/11201, Module B8);

b) electro-mechanical signalling systems;

c) electro-pneumatic signalling systems;

d) all-electric non-route setting signalling systems;

e) free-wired route setting signalling systems (see also applications in NR/L2/SIG/11201, Module B9);

f) geographical route setting signalling systems (see also NR/L2/SIG/11201, Module B10);

g) electronic signalling systems [see also NR/L2/SIG/11201, Module B11 and for GB Solid State Interlockings NR/L2/SIG/17002 and SSI8003].

Hybrid combinations of the above systems are likely to require a ‘per site’ justification of the safety architecture.

NOTE Where appropriate, reference to “signals and routes” should be understood to apply to movement authorities within cab signalling systems whether or not lineside signals are also provided.

The use of interlocking circuits or systems that do not fall within the descriptions of this standard should be assessed against the design principles given in Section 2 and the signalling principles in NR/L2/SIG/30009. 

The examples shown in this Standard are based on the signalling layout and control table illustrations given in NR/L2/SIG/11201, Module A5-3. 

Presentation and Production Processes 

This module does not cover the presentation and production processes for design details. For the presentation and use of mechanical locking charts, interlocking circuit diagrams and central interlocking data listings within the design process, see NR/L2/SIG/11201, Module A4-1 to 4-8 and NR/L2/SIG/11201, Module A5-2. Documentary requirements for control tables are given in NR/L2/SIG/11201, Module A5-3. 

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.