Audio Frequency Track Circuit Inspection and Maintenance


This Standard offers requirements necessary to assure the safety and reliability of audio frequency track circuit systems.

Document History
Document Number Version Publication Date Publication Related Information
APTA RT-SC-S-009-03 Rev. 1 12/31/2014 Published Current


AF track circuit, audio frequency track circuit, HF track circuit, bond, impedance bond, signal, shunt, shunting device, track circuit


This standard provides Audio Frequency Track Circuit tests that verify train detection (shunting), and continued proper operation. These tests include recording the measured values for comparison over time to predict possible equipment deterioration. This standard also provides track circuit inspection requirements.

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