scope:

The contents of this Standard apply to the testing of all alterations to previously working and commissioned signalling systems, during maintenance, renewals and faulting, where the design remains unchanged. Alterations may take the form of like for like replacement of equipment, replacement of missing equipment and temporary diversion of circuits and normally apply to individual items of equipment. The Standard may be applied to multiple items as long as the principles are followed.

The Standard for testing alterations where the installation is new or the design has changed, except where allowed for as a specific operational equivalent in Appendix A, is published as Railway Group Standard GK/RT0221 Signalling Works Testing.

The Standard is based on the principle that the equipment was tested properly at commissioning and has been working correctly. The design may therefore be taken to be correct and the work shall not require a change to diagrams unless permitted in the Maintenance Test Plan or required as a result of correlation.

Appendices for this Standard are arranged sequentially within the particular Part of the standard to which they are most relevant. Guidance on the scope of Maintenance Testing and clarification of operational equivalence are included in Appendix A.

This Standard makes reference to Signalling Maintenance Specifications. It should be noted that these specifications are now the responsibility of Railtrack Line, not Railtrack Safety and Standards Directorate.

Purpose

The purpose of this Standard is to define the mandatory tests and procedures necessary to ensure that the replacement or renewal of previously working signalling equipment is tested with sufficient depth and independence to assure safe working when returned to service.