This module: 

a) defines the safety requirements for the provision of flank protection;

NOTE: For circumstances requiring trapping protection, see Module D410.

b) provides guidance on a risk-based approach to the application of flank protection. 

Excluding ETCS without lineside signals, it applies to all signalling schemes and detailed design whenever:

a) the usage of lines is altered; or 

b) alterations are made to the layout. 

This Module and those directly associated with it equally apply to railway which is ETCS fitted unless there are no applicable lineside signals. 

NOTE: The principles appropriate to Modular Signalling are as specified within the functional requirements of NR/L2/SIG/30097/Appx C which references those standards extant in April 2014 and therefore is not affected by the publication of this module.

Wherever reasonable, other opportunities to review and optimise flank protection should also be taken. Such opportunities to update flank protection are likely when any of the following apply:

a) layouts are re-signalled or relocked;

b) additional routes are provided;

c) an overrun or timetable risk assessment (or similar) identifies the need to review protection.

This module does not apply to minor signalling alterations or alterations that are only a limited part of a wider junction layout.

Purpose

This module forms part of the Signalling Principles Handbook (NR/L2/SIG/30009) and is to be read in conjunction with the other modules of the handbook. See especially Module E060 and F060, and A200 which refers to legacy practices. 

The SPH details Network Rail’s requirements for the provision of interlocking between signals, movable infrastructure such as points and other parts of the signalling system to: 

a) control the risk of collision between a train on a set route and the possible exceedance of a movement authority on the flank of the protected route; 

b) formalise the use of (conditional) flank protection to harness the operational benefit afforded by split point controls coupled with the non-detection of facing points in the overlap; 

c) more completely defines how much flank protection should be provided. 

The SPH comprises mandatory sections and guidance. The guidance is to be followed unless an alternative can be demonstrated to be beneficial and no less safe. It satisfies the relevant parts of the IRSE Fundamental Requirements for Train Control Systems. 

NOTE: This approach is consistent with the Common Safety Method for Risk Assessment [CSM] regulations and meets Network Rail’s signalling policy. It also supports Network Rail’s ‘Safe by Design’ commitment that requires the taking of reasonable opportunities to make safety improvement.