Tamil Nadu Express - தங்களை அன்புடன் வரவேற்கிறது - Swaroop Kutti

How does Kavach work on Railway Systems?

The Traffic collision avoidance system (TCAS), with the help of equipment on board the locomotive and transmission towers at stations connected with Radio Frequency Identification (RFID) tags, helps in two-way communication between the station master and loco-pilot to convey any emergency message.
The instrument panel inside the cabin helps the loco-pilot know about the signal...
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in advance without visual sighting, and the permissible speeds to be maintained.
If a red signal is jumped and two trains come face to face on the same line, the technology automatically takes over and applies sudden brakes.
Additionally, the hooter activates by itself when approaching a level crossing which serves as a big boon to loco-pilots during fog conditions when visibility is low.

Source: The Hindu

It is a loco cabin and RFID based system. It can be applied in Frieghts also.