Indian Railways has implemented GPS-enabled anti-fog devices (such as the Loco Pilot Assistance System and FOG PASS) in thousands of trains to alert drivers about signals and track conditions during dense fog, significantly reducing delays and accidents. While scientists at the Indian Institute of Technology (IIT) developed a device named Trinetra, its widespread adoption in railways was hindered by high costs and the lack of a global solution for visibility in fog.
Airports in the National Capital Region rely on Runway Visual Range (RVR) devices installed by the Indian Meteorological Department (IMD) to provide real-time visibility data, allowing Air Traffic Control to manage flight intervals and diversions safely during winter fog. Additionally, Indian Railways is deploying the indigenous Kavach automatic train protection system to further enhance safety by automatically stopping trains if signals are missed or obstacles are detected.
Here's the cost comparison based on available data:
| System | Cost | Notes |
| Trinetra (IIT-BHU) | ₹25,000 (prototype) | Proof-of-concept model built at IIT-BHU; no published per-locomotive deployment cost exists. The Railway Board issued an EOI in 2016 for development/implementation, but the system never reached full-scale deployment. |
| FogPASS (GPS-based) | ~₹35,000 per unit | Portable, standalone GPS navigation device; 19,742 units deployed across all zones as of January 2024. |
So the Trinetra prototype was actually cheaper (₹25,000) than the GPS FogPASS device (~₹35,000). However, Trinetra was a research prototype with a patented design (Indian Patent Application No. 201641045006) that was never mass-produced or fielded, while FogPASS became the widely deployed solution due to its simplicity, portability (≤1.5 kg), and compatibility with all locomotive types up to 160 km/h.
For reference, the heavier Kavach ATP system costs ₹70–72 lakh per locomotive — orders of magnitude more expensive than either anti-fog solution.
They solve the fog problem in fundamentally different ways:
| Aspect | FogPASS (GPS) | Trinetra (Sensor Vision) |
| Core principle | Passive GPS navigation — tells you where landmarks are | Active vision enhancement — shows you what is on the track |
| Mounting | Hand-held portable unit carried by the loco pilot | Fixed on the front of the locomotive |
| Sensors | GPS/GNSS antenna only | Optical camera + IR/thermal camera + RADAR + IR laser illuminator |
| Output | Display + voice alert ~500 m before next 3 landmarks | Live composite video of the track on a cabin monitor + radar obstacle warnings |
| Detects | Pre-loaded fixed landmarks (signals, level crossings, speed restrictions, neutral sections) | Any physical obstruction on the track up to 2 km, including track damage, small objects (~500 m), and signal aspects via IR |
| Signal aspect | ❌ Does not show red/yellow/green — pilot still reads the physical signal | ✅ Can read signals at 1–2 km via infrared |
| Works in | Fog only (GPS is unaffected by weather) | Fog, smog, heavy rain, and night (thermal + IR laser) |
| Limitation | No obstacle detection; no curve awareness | Cannot see objects behind curves |
In short: FogPASS is a navigation aid — it tells the pilot "a signal is 500 m ahead" but the pilot must still see and interpret it. Trinetra is a vision replacement — it actively images the track, detects obstacles, and displays a live picture of what lies ahead, making it a far more capable system but also far more complex and expensive to deploy.
FogPASS is the right call for Indian Railways today. Trinetra is the better technology, but FogPASS is the better system for this context. Here's why:
FogPASS wins on practicality:
Already at scale — ~20,000 units deployed, zero integration risk
Loco pilot carries it; no locomotive modification, no maintenance infrastructure needed
Works on every train type, old or new, without touching the rolling stock
Cost-effective enough to cover the entire fleet in fog-prone zones
Trinetra is the superior sensor, but it's a different problem:
It's essentially a low-cost, locomotive-mounted ATP precursor — obstacle detection, signal reading, night vision. That's closer to what Kavach is supposed to do, but at a fraction of the cost.
The real blocker was never the technology — it was industrialization. A ₹25,000 prototype is not a railway system. You need ruggedization, certification, spares, a service network, and a maintenance model before it touches a locomotive.
Indian Railways has shown (with Kavach's own deployment delays) that complex fixed systems move slowly.
The honest take:
Trinetra's vision stack (camera + IR + radar + laser) is what Indian Railways actually needs long-term — it addresses fog and the bigger problem of obstacle detection, which causes far more accidents than fog alone. But it should be treated as a next-generation platform, not a fog solution.
Ideal path: Keep FogPASS as the low-cost, immediate fog mitigation layer. Fund Trinetra-style sensor fusion as part of the Kavach ecosystem — essentially a cheaper, modular perception module that can ride alongside ATP. That way the vision capability gets the industrial backing it needs, and fog becomes just one of many problems it solves.
For fog specifically, the difference is stark:
| FogPASS | Kavach 4.0 | |
| Signal info in fog | Audio alert 500 m before signal — no aspect shown | Live signal displayed in the cab (red/yellow/green) |
| Permitted speed in fog | Capped at 75 km/h (pilot can't confirm signal aspect) | Full designated speed, up to 110 km/h |
| Auto-braking | ❌ None | ✅ Emergency brake if signal missed or overspeed |
| Collision avoidance | ❌ | ✅ Detects another train in same section |
| Level crossing horn | ❌ | ✅ Auto-hooter at LC gates |
| Track-side infrastructure | None (portable, pilot-carried) | Towers every ~1 km + cab units + under-engine units |
| Cost | ~₹35,000 per unit | ~₹50 lakh per km (track-side) |
| Coverage (Oct 2026) | ~30,000 units network-wide | 1,452 km (Delhi–Mumbai, Delhi–Howrah corridors) |
The operational gap: FogPASS tells the pilot "a signal is 500 m ahead" but the pilot still has to see it to know if it's red or green. That uncertainty forces the 75 km/h restriction. Kavach replaces the need to see the signal entirely — the aspect is transmitted via RFID to the cab display, so the pilot operates at normal speed with full awareness.
They're not substitutes — they're layers:
FogPASS covers the entire fog-affected network cheaply and immediately, on any locomotive, no track-side work.
Kavach is the endgame on high-density corridors, but at ₹50 lakh/km it will take years to reach the same geographic coverage.
Until Kavach reaches full network coverage, FogPASS remains the only fog mitigation on most routes.
There's no single "FogPASS equivalent" in cars — the capability is split across different sensor technologies, and no car brand markets a dedicated "anti-fog system." Here's how it breaks down:
Radar-based ADAS (closest to FogPASS — detects objects in fog)
Radar penetrates fog, so Adaptive Cruise Control + AEB + Forward Collision Warning all work in conditions where cameras fail. This is now common:
| Market | Examples |
| India (mid-range) | Tata Sierra, Kia Seltos, Hyundai Creta, Mahindra XUV700, Hyundai Verna |
| Global (premium) | Tesla Model Y, Mercedes CLA, VW T-Roc, Subaru Impreza, BYD Seal, NIO EL6 |
A 2026 ADAC fog test specifically evaluated 6 models in dense fog — the Mercedes CLA performed best, Tesla surprised positively, and VW scored lowest. More sensors (LiDAR + radar + camera) did not guarantee better fog performance.
Globally, hundreds of models now ship radar-based ADAS as standard or optional — it's no longer a differentiator.
Thermal / Night Vision (closest to Trinetra — sees through fog + dark)
This is the true "vision in fog" tech, but it's limited to luxury cars (~20–30 models worldwide):
| Brand | Models |
| BMW | 7 Series, 5 Series, X5, X6 |
| Mercedes-Benz | S-Class, E-Class, Maybach |
| Audi | A6, A7, A8, Q7 |
| Cadillac | CT6, Escalade IQ |
| Rolls-Royce | Wraith, Ghost, Phantom |
| Bentley | Bentayga |
| Lexus | LS |
| VW | Touareg |
| DS Automobiles | DS 7 Crossback |
These use infrared/thermal cameras mounted on the front — the same sensor class as Trinetra's IR camera. They detect pedestrians, animals, and obstacles in fog and darkness, but don't replace the driver's view the way Trinetra's composite video display would.
The gap nobody fills
No car today does what Trinetra does for trains: a live composite video feed of the road ahead shown on a cabin display, combining visible + IR + radar into one enhanced picture. Cars still rely on the driver's own eyes as the primary sensor, with ADAS as a backup. That's because cars have no "signal to read" — the driver is the system.
Bottom line: Radar ADAS (FogPASS-like) is in hundreds of models globally and ~5+ in India's mid-segment. Thermal vision (Trinetra-like) is in ~20–30 luxury models. A true "FogPASS for cars" — a standalone, cheap, portable device that tells you what's ahead in fog — doesn't exist as a product yet. The closest DIY attempt is a ₹5,000 radar alert device from a Team-BHP forum post that detects vehicles up to 70 m in thick fog.
Almost none — the truck segment is just barely starting.
What exists today
| Model / Range | OEM | Tech | Status |
| Prima 5532.S ADAS | Tata Motors | Wabco 77 GHz radar + Collision Mitigation System (CMS) + Lane Departure Warning | On sale (2026 catalogue) |
| Prima & Signa range (select trims) | Tata Motors | Same Wabco ADAS stack (deployed since 2018) | Optional on premium long-haul tractors |
| Fleet retrofits (various) | Ashok Leyland, BharatBenz, Volvo Eicher, Mahindra Truck & Bus | Radar AEB + LDWS (third-party) | Fleet-driven only — not retail, limited to premium logistics customers |
That's it. Heavy commercial vehicles account for only ~12% of India's ADAS sensor volume in 2025, and even that is mostly fleet retrofits, not factory-fitted trucks.
Why so few?
Cost sensitivity — a ₹20–40 lakh truck buyer won't pay a ₹1–2 lakh premium for ADAS when the alternative is "drive slower"
No mandate yet — the MoRTH rule (GSR 184(E)) makes ADAS mandatory for new N3 (heavy truck) and M3 (bus) models from April 2026, with full compliance by October 2027 and existing production models by April 2028
Retrofit ecosystem is nascent — Indian startup Starkenn Technologies is building radar-first ADAS specifically for Indian commercial vehicles, but it's still in early deployment
What the mandate will change
From October 2027, every new heavy truck sold in India must have:
1-AEBS (Automatic Emergency Braking System) — radar-based, works in fog
2-LDWS (Lane Departure Warning System)
3-DDAWS (Driver Distraction and Drowsiness Warning System)
This will force all five major OEMs (Tata, Ashok Leyland, Eicher, BharatBenz, Mahindra) to equip their entire heavy truck lineups. But that's 13 months away — today, if you're buying a truck for fog-prone routes, only Tata Prima/Signa with Wabco ADAS is a factory option.
The gap
No Indian truck has anything equivalent to FogPASS (a cheap, portable, pilot-carried GPS alert) or Trinetra (front-mounted camera + IR + radar composite video). The truck world is stuck between:
₹5,000 DIY radar (Team-BHP project — detects vehicles up to 70 m, fits any truck via USB)
₹1–2 lakh Wabco ADAS (Tata only, premium trims)
The IRF (International Road Federation) has urged India to make fog-sensing auto-activated lights mandatory on all vehicles — that's a different, cheaper problem than active sensing, and it's still not law.
Bottom line: Trucks are the biggest fog-accident risk in India, but the anti-fog tech answer is 13 months from becoming mandatory. Until then, Tata's Prima/Signa with Wabco radar is the only factory option.
This is a great question, but it rests on a cost misunderstanding that's worth correcting first:
The ₹25,000 was never the real price
That was the proof-of-concept prototype cost at IIT-BHU. The actual per-unit deployment cost was estimated at ₹56 lakhs by the makers themselves — that's what a Railway Zone official told TOI in 2016:
"The makers of this device have estimated the cost of each Trinetra device as Rs 56 lakhs, which is too high."
So the real comparison is:
| Trinetra (real cost) | Wabco ADAS (Tata Prima/Signa) | |
| Per-unit cost | ₹56 lakh (estimated) | ₹1–2 lakh |
| Status | Still in "extensive trials" since 2016 | Production-ready, deployed since 2018 |
| Service network | None | 260+ Wabco service centers pan-India |
| Certification | Under DRDO review (2016), never cleared | ARAI certified, ARAI is a Wabco member |
| Designed for | Fixed railway track — single lane, no intersections | Road traffic — mixed vehicles, two-wheelers, pedestrians |
Why Trinetra can't be dropped into a truck
Even if you ignore the cost gap, it's the wrong tool for the job:
Trinetra detects obstacles on a single track. It assumes a fixed, linear path. A truck faces intersections, unmarked rural roads, two-wheelers cutting in, pedestrians — a completely different perception problem.
No braking integration. Wabco ADAS is wired into the brake system (EBS/ESC). When it detects a collision, it actively brakes. Trinetra only displays an image — it's a vision aid, not an active safety system. A truck at 60 km/h in fog needs automatic braking, not a better camera feed.
No lane awareness. Trinetra has no concept of lanes. Wabco's LDWS does.
Not ruggedized for road use. Trinetra was designed for a locomotive front mount on a steel track. Trucks vibrate, hit potholes, and operate in dust/mud that would destroy an unsealed camera+IR+radar stack.
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