scope:

This module primarily reflects multiple aspect signalling to which Track Circuit Block Regulations apply, controlled from a route setting panel or VDU system. The concepts also apply to other interlocking and block systems. Any significantly different / additional considerations to other forms of signalling are specifically identified.

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.

This module applies to all command and control equipments (see the typical listing in NR/L2/SIG/30009/A060) for new provision and, subject to consideration of "using reasonable opportunity" and practicability, all alterations to signalling where the changes appreciably alter the risk associated with the layout and with any of the signals within the scheme.

Changes to layout risk are likely when any of the following apply:

a) alterations are made to a layout;

b) lines become designated as passenger;

c) layouts are re-signalled or relocked (or re-controlled, though it is recognised that the opportunity to mitigate existing risk is generally limited);

d) additional routes are provided;

e) platforms are added;

f) permissible or attainable speeds are changed, whether raised or lowered;

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

This module defines the requirements to:

a) maintain the safety of an approaching train after the withdrawal of an authority to proceed at a signal;

b) automatically cancel the route after the train has passed the signal;

c) release the locking imposed when the route was set, once it is safe to do so.

Where the content of application standards (such as NR/L2/SIG/11201, SSI8003, NR/GN/SIG/ CAT0005) are different to the requirements described in this standard this standard takes precedence.

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.

The SPH details Network Rail's requirements for the provision of functional logic between signals, movable infrastructure such as points and other parts of the signalling system to control the risk of:

a) failure of moving infrastructure to establish a wheeled path;

b) collision between a train and another train legitimately present;

c) the issuing of a movement authority to the train driver and its subsequent removal.

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, see Appendix C for extract.