Published: September 20, 2026 | Category: Buying Guide | QSCompute
Rail is where industrial computing goes to be tested for twenty years. A box that survives a food plant or a steel mill for a decade can still fail a metro contract outright, because rail asks different questions: fire and smoke behaviour, rolling-stock temperature classes, train network protocols, and a support horizon measured in decades rather than warranty years. This guide covers what actually runs in a trackside cabinet or on board a train, which standards gate the purchase, and how to size compute without overbuying.
Rail workloads split cleanly between wayside and train-borne, and the two have almost nothing in common technically. Wayside cabinets get mains power, reasonable ambient conditions and a maintenance window; train-borne racks get 110 V DC that sags during acceleration, vibration from the bogie, and no access until the depot visit.
| Workload | Where it runs | Compute shape |
|---|---|---|
| Platform screen door & gap obstruction vision | Platform edge, station rooms | Fanless node, 24/7 duty, 2–4 TOPS per camera stream |
| Track intrusion & trespass detection | Tunnel portals, open sections | Thermal + visible fusion, low-light, wide temperature |
| Rolling-stock inspection (wheel, brake, pantograph) | Depot and wash plant | Multi-camera, high frame rate, GPU class |
| Tunnel SCADA, ventilation and lighting | Tunnel technical rooms | Deterministic I/O, industrial Ethernet, PLC-adjacent IPC |
| Passenger information, PA and CCTV head-end | Station comms room | Rackmount NVR with RAID storage |
| Faregates and passenger counting | Concourse | Small fanless ARM nodes, PoE-powered |
| Condition monitoring (axle box, gearbox) | Train-borne | Rugged, wide-input DC, EN 50155 class TX |
The AI workloads cluster in the wayside and depot, not on the train. Inference for intrusion detection, gap obstruction and inspection runs where power and cooling are cheap and the box can be serviced. Train-borne compute stays small and rugged, mostly acquisition, buffering and condition monitoring, with anything heavy shipped to the depot over Wi-Fi when the train stables.
Rail projects die late for certification reasons. A generic fanless IPC that passes IP67 and a wide-temperature range still fails an EN 45545-2 fire and smoke review, and an EN 50121-4 EMC review cannot be retrofitted with a filter and a prayer.
| Standard | Scope | Practical requirement |
|---|---|---|
| EN 50155 | Rolling-stock electronics | Class TX: −40…+70 °C; 24/36/48/72/110 V DC nominal with supply variations and interruption ride-through |
| EN 50121-3-2 / -4 | EMC | -3-2 for apparatus on rolling stock, -4 for signalling and trackside apparatus |
| EN 45545-2 | Fire and smoke on rail vehicles | Requirement sets R22/R23, hazard levels HL1–HL3; enclosure, cable and PCB materials all in scope |
| EN 61373 | Shock and vibration | Category 1 (body), 2 (bogie-mounted), 3 (axle-mounted) — the mounting point decides the category |
| IEC 61375 | Train communication network | TRDP over Ethernet as the modern backbone, MVB for legacy vehicle buses |
| IEC 62439-3 | Network redundancy | PRP or HSR rings with zero recovery time, not 50 ms spanning-tree reconvergence |
| EN 50159 | Safety-related communication | Applies only to safety functions; do not drag a CCTV appliance into its scope |
The usual failure is scope creep: a passenger-information appliance gets written into the safety case and suddenly needs EN 50159 and a much longer approval. Keep the safety envelope around the signalling and protection functions, and keep the analytics outside it with a documented interface.
Buy the narrowest tier that meets the frame rate and the temperature class. Rail cabinets run for 20–25 years, so the thermal headroom and the availability guarantee matter more than peak TOPS.
| Tier | Typical 2026 platform | Cost band | Fit |
|---|---|---|---|
| Fanless ARM gateway | RK3588, i.MX 8M Plus, Jetson Orin Nano Super | $200–700 | PoE camera concentration, faregates, sensor interfaces |
| Fanless wide-temp x86 IPC | Atom or Core i3, −25…+70 °C, dual GbE | $900–2,500 | SCADA, deterministic I/O, ventilation and lighting control |
| Conduction-cooled GPU IPC | Jetson Orin NX / AGX Orin, entry RTX embedded | $2,500–8,000 | Intrusion detection, multi-camera analytics, platform vision |
| 19″ rackmount industrial server | Dual CPU + GPU, redundant PSU, RAID | $8,000–25,000 | Depot inspection, on-premise CCTV head-end, training offload |
Two sizing rules separate rail from general industry. First, never size an intrusion or obstruction detector from a benchmark run: a tunnel portal at night with headlights entering frame is the worst case, not the average frame. Second, keep a PoE budget in writing — a 100 m copper run cannot be extended by hoping, and a heated PTZ camera that pulls 30 W is a budget line, not a rounding error.
A tunnel technical room is a hostile thermal environment with generous IP ratings and no airflow. Ambient sits at 30–40 °C year round with no cooling assist, brake-pad and wheel dust settles into every filter, and the room may sit 300 m of cable away from the nearest switch. Conduction-cooled enclosures with no moving parts are the default answer; a fan is a maintenance item scheduled for a closure window. Network topology is the second constraint: signalling and security traffic share a ring, so the box needs two independent Ethernet ports and hardware support for PRP or HSR rather than a software bond. Redundancy is designed into the cable plant, and single-line power is normal — size the input for the full EN 50155 variation range rather than the nominal label on the distribution board.
Specifying a metro or mainline deployment?
Send us your standard references, mounting point and camera count — we return a certification-mapped hardware shortlist with the EN 50155 class, EMC scope and redundancy topology spelled out.
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