scope:

This document applies to all projects deemed to be Modular Signalling Schemes and being implemented on Network Rail infrastructure.

The handbook contains principles and derogations which may only be used in the context of a Modular Signalling Scheme and use in any other context or project type is not supported by this handbook

Purpose

The purpose of this document is to guide the Signalling Design Engineer through the Modular Signalling SORA process which has been designed to be efficient yet mitigate the risks to a level that is ALARP.

The simplicity and low traffic densities of the routes Modular Signalling will be applied to make it possible to design a layout which is as safe as it is reasonably practicable to achieve. This avoids the need for extensive overrun risk assessment on every signal. However, it remains necessary to provide a SAT score for certain signals to allow ongoing understanding of the layout risks for future changes to the rolling stock used on the route, the timetable, etc.

All the signals will be low risk and so following the current overrun risk assessment process provides little benefit.

The process spans 2 GRIP Stages - GS3 for the design of the scheme (scheme plans to AiP level) and GS4 for review of the overrun risks (scheme plans finalised) and generation of any necessary SAT scores.

The methods detailed in this document are an interim solution until the full deployment of the SORAT tool. SORAT is designed to mechanise the risk assessment process hence providing the labour savings achieved by the method set out in this document.