scope:

This document covers:

• Route Relay Interlocking (RRI) systems installed on a.c. and d.c. electrified Railtrack controlled infrastructure. This only includes relay room installations. External line circuits, TDM systems and vital Reed FDM systems which may form part of the interface between the RRI and trackside equipment are covered by other IDI documents [14, 15, 16].

• Solid State Interlocking (SSI) systems installed on a.c. and d.c. electrified Railtrack controlled infrastructure. This includes control centre equipment and Trackside Functional Modules (TFMs) which are manufactured by Westinghouse and ALSTOM in accordance with Railtrack specifications. Data Links (TDLs) and Long Line Links (LLL) which are used to send SSI data are covered by another IDI document [16].

Note: In the context of this document, "Solid State Interlocking" refers to the system developed by the British Railways Research Division in the 1970s and completed under a tripartite agreement between BR, GEC General Signal Ltd and Westinghouse Signal Ltd. This document does not cover other types of computer based interlockings.

Purpose

The purpose of this document is to provide a methodology to demonstrate compatibility with interlocking systems installed on the a.c. and d.c. electrified railway on Railtrack controlled infrastructure. This is achieved by specifying criteria/standards against which test results from new rolling stock should be compared to enable a safety case to be made.