NR RT/SIN/050 ISSUE 1A PDF

All Aster U Type and SF15 track circuits (both end fed and centre fed) of any frequency shall be tested where the receiver end of the track circuit is adjacent to insulated block joints.

Track circuits with the receiver at a jointless termination need not be tested.

Purpose

A mode of failure of Aster U Type and SF15 track circuits has been discovered where, under certain conditions, a poor drop shunt is obtained near the transmitter. Investigations are still continuing to determine the precise cause of the failure. Track circuits affected are those which have their receiver adjacent to a pair of insulated block joints.

As an immediate precaution, all track circuits which might be affected by this mode of failure are to be tested to determine whether this failure mode is present.

Where the test reveals an actual or potential wrong side failure, remedial action is to be taken to ensure the safety of the railway.

Records of the test results will be made to aid further investigation of the problem.