scope:

This document covers RT type reed track circuits installed in double rail mode on d.c. electrified Railtrack controlled infrastructure. This also encompasses the older type 'R' equipment when installed in double rail mode where these are not fitted with step up transformers.

The methodology considers both intact and faulty infrastructure.

Purpose

The purpose of this document is to provide a methodology to demonstrate electrical compatibility with 'RT' type double rail reed track circuits on the d.c. electrified railway on Railtrack controlled infrastructure. This is achieved by:

• providing a characterisation of the reed track circuit receiver;

• providing a characterisation of the infrastructure;

• providing a methodology to define the susceptibility of a given reed track circuit.

Combining these elements will enable a full characterisation of reed track circuits applicable to Railtrack controlled infrastructure, for both worst case intact and faulty infrastructure conditions. This characterisation will take the form of a permissible train current which can then be compared to the emission footprint of an item of rolling stock. This methodology will facilitate the demonstration of compatibility of rolling stock with reed track circuits, as part of a Route Acceptance Safety Case.