General observations on #Kavach/TCAS
• Kavach is the name given to the state-of-the-art train collision avoidance system (TCAS) developed by RDSO. It appears to be a complex communication system.
• Kavach costs ₹50 lakh/km & is claimed to be the cheapest TCAS
• Kavach is being installed in Rajdhani route main line, relief line & all passenger fit loop lines.
•...
more...

SIL-4 certification (communication between Stationary TCAS & Loco TCAS is SIL-4 certified, other communication are not failsafe) **please read official data for exact information & clarification on SIL-4 certification

Key components of TCAS:
• On-track Radio Frequency Identification tags (RFID tags) & Track Identification numbers (TIN)
• Stationary TCAS (StTCAS) present at block stations (with a radio tower & TCAS interfaced with station interlocking) , LC gates, IBP, etc
• Loco TCAS which has RFID readers, Driver Machine Interface (DMI), radio unit, brake interface unit (BMI) & a vital computer

RFID tags are always duplicated with identical information at most cases (photo provided). RFID tags are fitted on track in station section, point zones, near Signals & track in block section for giving Trackside information to Loco TCAS unit. RFID tag has IP 67 protection with 5 Ton impact
resistance tested.

RFID tags are categorised as:
• Normal tag : is placed anywhere (photo attached)
• Signal foot tag : placed at foot of signal (photo)
• Signal approach tag : placed 150-250m before signal
• TIN discrimination tag : placed on turnouts
• LC gate tag : placed at both ends of LC (photo)
• Kavach exit tag : placed at Kavach territory exit point
• Adjacent line tag
• Adjustment/junction tag

Major features of TCAS:
• Prevention of collision between Locos (?) with functional Kavach
• Prevention of SPAD by auto braking
• Display of approaching signal with aspect (cab signalling)
• Automatically reducing speed on turnouts (at 30kmph)
• Auto-whistle at LC gates
• Prediction & maintaining TSR/PSR, etc.