At regular intervals along a Kavach-fitted section of Indian Railways track, a small passive UHF RFID tag sits fixed to a sleeper between the rails. It has no battery, yet it is one of the reasons the locomotive above it knows, to within a few metres, exactly where it is. This post explains what a Kavach RFID tag does, what the 2026 rollout numbers say, and how it differs from the other big railway RFID programme in India — GS1-encoded tags on wagons and coaches.
What Kavach is and where RFID sits in it
Kavach is Indian Railways’ indigenous Automatic Train Protection (ATP) system, developed under the Research Designs and Standards Organisation (RDSO) with Indian manufacturers. It warns the loco pilot of a signal at danger or an overspeed, and applies the brakes automatically if the pilot does not respond. The current generation is Kavach 4.0, whose specification RDSO approved in July 2024.
The system has three broad parts, and RFID is one input among several:
- Loco Kavach — the on-board unit, with a UHF radio, GPS, driver display, brake interface and an RFID reader whose antenna is mounted under the locomotive.
- Station Kavach — the stationary unit at each station or interlocking, wired to the signalling system and talking to locos over UHF radio towers along the route.
- Trackside RFID tags — passive tags fixed on the track that give the loco an absolute position reference each time it passes over one.
Radio carries the movement authority; the tags tell the train precisely where on the line it is, so that authority is applied at the right place.
How trackside RFID tags work at line speed
On-board odometry tracks distance travelled, but it drifts through wheel slip, slide and wear. Each RFID tag carries encoded data — at minimum a unique tag identity — that Loco Kavach resolves against the section’s location data to a known chainage. When the antenna under the loco reads a tag, the position estimate resets to that fixed point. Between tags, odometry fills in; GPS assists but is not the primary reference in cuttings, tunnels or yards.
Two things make this an unusual RFID application. First, reads happen at full line speed — Kavach is designed for, and has reportedly been tested at, speeds up to 160 km/h — so the tag is in the antenna’s field for a very short window and must answer first time. Second, tags are typically installed in pairs or small groups, so a single damaged tag does not blind the system and the read sequence helps confirm direction of travel. The tag only reports what is encoded on it; the interpretation lives in the Kavach system, which is why the encoded data must never change unexpectedly.
Kavach 4.0 rollout in 2026: what the numbers say
The official figures have moved quickly this year, so the dates matter:
- 30 January 2026 (PIB): 472.3 route-km of Kavach 4.0 commissioned in a single day across three sections — Vadodara–Virar, Tughlakabad–Palwal and Manpur–Sarmatanr — taking the total to about 1,306 route-km across five zonal railways.
- 11 March 2026 (DD News, citing Railway Ministry data): 1,452 route-km commissioned on the Delhi–Mumbai and Delhi–Howrah corridors; Rs 2,763.9 crore spent on Kavach up to February 2026 and Rs 1,673 crore allocated for FY 2025-26.
- 31 July 2026 (Lok Sabha written reply, reported in early August 2026): 2,633 route-km commissioned — 1,423 on Delhi–Mumbai and 1,210 on Delhi–Howrah — with trackside work reported to be under way on roughly 21,800 route-km and several thousand locomotives fitted.
- 23 September 2026 (reported): Kavach Version 4.0 commissioned for the first time on South Central Railway — 108 route-km on the Malkajgiri–Kamareddi section of Hyderabad Division, following an inspection reported on 22 September, and replacing Version 3.2 on that stretch. SCR had previously run Version 3.2 across a reported 1,465 route-km. This is a version upgrade on an already-fitted section, not new route added to the national total — the two are easy to conflate.
Cost figures should be treated as reported rather than fixed. Railway Ministry statements carried by PIB and DD News have put trackside Kavach provisioning at roughly Rs 50 lakh per kilometre, with locomotive equipment reported at around Rs 80 lakh per loco. The per-km figure covers station units, radio towers, optical fibre and installation; the RFID tags are a small share of it, but one spread over every kilometre.
Two railway RFID programmes, not one
“Railway RFID tags” is often used for two separate programmes. Both use passive UHF in the same band, but that is where the similarity ends.
| Kavach trackside tags | Rolling-stock tags (CRIS / GS1 GIAI-202) | |
|---|---|---|
| What is tagged | Fixed points on sleepers | Wagons, coaches and locomotives |
| What reads them | An antenna under a moving loco | Fixed trackside readers at stations and yards; portable readers in depots |
| Purpose | Absolute location reference for train protection | Rolling-stock identification, movement tracking, maintenance records |
| Encoding | Data mapped to a chainage in the Kavach location database | GS1 Global Individual Asset Identifier (GIAI-202) per CRIS specification |
| Spec owner | RDSO (safety-critical) | Centre for Railway Information Systems (CRIS) with GS1 India |
| Supply route | RDSO-approved Kavach OEMs and developmental vendors | Zonal railway and CRIS tenders for GS1-compliant tags and readers |
The rolling-stock programme dates back roughly a decade and has, as of 2026, reportedly covered most of the wagon and coaching fleet, with tags typically fitted in pairs on the underframe. It is a logistics-and-maintenance system, not a safety system, so its procurement is more open.
What a Kavach tag must survive
A tag on a sleeper lives in one of the harshest passive-RFID environments there is:
- Vibration and shock from every passing axle, plus ballast movement and tamping machines working around it during track maintenance.
- Weather — monsoon standing water, summer sleeper temperatures that can exceed 50°C, dust and, on some routes, salt spray or frost.
- Mounting — fixed to a concrete sleeper or bracket with hardware that does not loosen, positioned for the loco antenna yet clear of dragging equipment.
- Encoding and locking — the data is written once and permanently locked; a re-encoded or cloned tag is a safety hazard, so write-protection and traceable programming matter.
- Lifetime and replacement — years of service without maintenance, with every installation recorded so a damaged tag can be replaced with an identically encoded one.
The exact mechanical, RF and encoding requirements sit in the RDSO specification for Kavach and its tag and reader annexures — obtain the current revision, as it has changed through the 3.2 and 4.0 generations. The general lesson travels well: outdoor tagging is decided by mounting, surface and read geometry far more than by the chip inside, which is why we always scope read range and environment before choosing hardware.
Who can supply, and what is live in August 2026
Kavach is safety-critical, so its supply path is narrow. Complete systems come from a short list of RDSO-approved OEMs — Medha Servo Drives, HBL Engineering (formerly HBL Power Systems) and Kernex Microsystems have been named in public reporting — and RDSO has been reported to be evaluating further developmental vendors. Trackside tags are supplied as part of, or type-tested against, those approved systems; a tag manufacturer generally enters through an approved OEM or the RDSO developmental-vendor route.
The rolling-stock and depot side is broader. When we checked TenderDetail’s live listing on 16 August 2026, 31 of the 86 open RFID tenders in India were from the Railways (counts change daily), including zonal tenders for RFID tags “as per GS1 standard and CRIS specification” for wagons, LHB coaches and WAG-9 locomotives, and for portable UHF readers — open to any manufacturer meeting the encoding standard, environmental ratings and reader integration requirements.
Identium’s place in this picture is straightforward and we will not overstate it: we do not claim RDSO Kavach vendor status. Where our products are relevant is the rolling-stock, depot and infrastructure side — rugged UHF tags and on-metal RFID tags for underframes, components and fixed assets, and Android portable UHF readers for yard and workshop verification, all on India’s delicensed 865-867 MHz band (Identium is BIS certified and our UHF readers are WPC-approved). Our Indian Railways asset-tracking case study describes that kind of deployment, and the same building blocks serve our wider RFID for infrastructure and transportation work.
Lessons for other infrastructure RFID
Kavach’s use of RFID as an absolute-position beacon is a pattern worth copying beyond mainline rail. Metro systems use similar tags for train positioning; ports fix tags to ground points and gantries so vehicles and cranes can localise themselves; mines tag haul-road markers; yards use ground-mounted tags so tractors log which bay they are in. The design questions are the same: read reliably at speed, survive the environment, lock the encoding, and keep the tag-to-location database authoritative.
FAQ
Are Kavach RFID tags UHF? Yes — passive UHF tags read by a loco-mounted reader in India’s delicensed 865-867 MHz band, per the current RDSO specification (obtain the latest revision for exact RF, protocol and mechanical requirements).
Can a handheld reader read a Kavach tag? Where the tag follows the EPC Gen2 / ISO 18000-63 air interface, a standard UHF handheld will typically detect it and return its encoded data, which is useful for installation checks. It cannot interpret that data without the Kavach location database, and must never be used to rewrite the tag.
How are Kavach tags encoded and replaced? Each tag is programmed and locked at installation and mapped to a chainage in the section’s location data. A failed tag is typically replaced with one encoded identically under the maintainer’s procedure and the RDSO specification, and the replacement is recorded.
Planning RFID for depots, rolling stock, yards or other outdoor infrastructure? Talk to our team for sample tags to trial on your actual mounting surfaces, or call or WhatsApp +91 70110 01472.