scope:

This module applies to all changes to signalling where:

a) there are lineside signals; and

b) the changes appreciably alter the overrun risk associated with any of the signals within the scheme. Changes to overrun 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 is generally limited);

d) additional routes are provided;

e) a station is added;

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

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

It is not intended to be applied to minor signalling alterations where the scope of the scheme does not make any material impact to over-run risk on any of the signals within the scheme. For all changes, due cognisance should be taken of the principle of "Using Reasonable Opportunity" to include the provisions of this module

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. It details Network Rail's requirements for the provision of overlaps to control the risk of:

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

b) derailment when overrunning a signal at danger. This module comprises mandatory sections and guidance.

This module comprises mandatory sections and guidance. The guidance is to be followed unless an alternative can be demonstrated to be beneficial and no less safe.