scope:

The requirements of this Specification apply to electro-mechanical relays and electromechanical searchlight and banner signal mechanisms that perform safety critical or safety related functions and that form part of the infrastructure based railway signaling control system.

Relays internal to electronic systems (e.g. pcb mounted reed relays) are excluded from the scope as these are covered by system maintenance and associated tests. Relays within signalling equipment (e.g. token or block instruments) are included and may require the entire unit to be replaced.

Unless a relay is shown as exempt from routine replacement in this Specification or a Code of Practice, which relates to the type of interlocking concerned, or a risk assessment, authorised by the Territory Signal Engineer, has been completed, relays must be subject to routine replacement. A Code of Practice detailing a process for conducting specific application risk assessment is available.

Purpose

This Specification details the requirement to control the risks presented by failures of signalling relays and electro-mechanical searchlight and banner signal mechanisms, so as to satisfy the mandatory requirements of Railway Group Standard GK/RT0210, Asset Management for the Safety of Signalling and Operational Telecommunication Systems and Equipment.

The aim of life management, as it relates to signalling relays, searchlight and banner signals performing safety critical or safety related functions, is to ensure that equipment operates within its specified parameters.

In the case of this type of electro-mechanical equipment, this means that failure modes which may lead to the equipment not performing to the required specification shall be identified and managed and constraints relating to the maximum number of operations defined by the equipment specification must not be exceeded. Where there are also age related failuremodes, the number of years in service must be additionally restricted. The overall aim is to minimise the risk introduced into the signalling control system by this equipment.