UIC 555: Electric Lighting in Passenger Rolling Stock – 2026 Design Guide

A comprehensive technical guide to UIC 555 regarding interior lighting standards for railway vehicles. This analysis covers the critical requirements for Average Illuminance ($E_{av}$), Uniformity Ratios, Color Rendering (CRI), and mandatory Emergency Lighting autonomy to ensure passenger safety and visual comfort.

UIC 555: Electric Lighting in Passenger Rolling Stock – 2026 Design Guide
September 23, 2023 9:54 am
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💡 2026 Technology Update: While the original UIC 555 focused on fluorescent tubes, modern compliance requires integration with EN 13272-1 (LED Systems). This guide interprets UIC requirements through the lens of modern Solid State Lighting (SSL) and intelligent dimming controls.

Lighting in a train is not merely aesthetic; it is a safety system. UIC 555 establishes the regulations for the electric lighting of passenger rolling stock, ensuring that passengers can read, move safely, and evacuate in emergencies without visual fatigue or disorientation.

1. Illuminance Levels (The “Lux” Requirements)

The core of the standard defines “How bright must it be?” Lighting levels are measured at the “Working Plane” (usually 0.8m above the floor or on the table surface). UIC 555 dictates specific values for different zones:

Zone / AreaMinimum Average Illuminance ($E_{av}$)Purpose
Reading Areas (Seats)150 – 300 LuxComfortable reading without eye strain.
Vestibules & Gangways100 – 150 LuxSafe movement between cars and boarding.
Toilets (WC)100 Lux (at mirror height)Hygiene and personal care visibility.
Emergency Mode> 5 Lux (on floor axis)Panic prevention during power loss.

2. Quality of Light: Uniformity and Glare

High brightness alone is not enough. UIC 555 emphasizes the quality of the light distribution to prevent “Zebra Effect” (bright and dark patches).

  • Uniformity ($U_0$): The ratio of minimum lux to average lux ($E_{min} / E_{av}$) should generally be > 0.6. This ensures the whole carriage feels equally lit.
  • Glare Control: Direct light sources must be shielded to prevent blinding passengers. In modern LED fixtures, this requires Diffusers or Lenses to soften the point-source intensity.
  • Color Rendering ($CRI$): Light sources should have a CRI (Ra) > 80, ensuring that colors (especially safety signs) look natural.

3. Emergency Lighting (Safety Critical)

When the catenary power fails (OCS outage), the train goes dark. UIC 555 mandates an independent Emergency Lighting System powered by the vehicle’s batteries.

  • Autonomy: The batteries must sustain emergency lighting for a minimum duration (typically 3 hours) to allow for evacuation or rescue.
  • Independent Circuitry: Emergency lights must be wired separately from the main lighting. Often, they are cross-wired so that if one fuse fails, not all lights go out.
  • Location: Must illuminate door areas, steps, and safety equipment (fire extinguishers/emergency hammers).

4. Power Supply and Voltage

Lighting converters must handle the fluctuating voltages defined in UIC 550.

  • Static Converters: Modern trains use DC/DC or AC/DC converters to step down the battery voltage (e.g., 110V DC) to LED driving voltage (e.g., 24V DC).
  • Flicker Free: The lighting must remain stable even when the train passes through neutral sections (dead zones) on the line.


Engineering Note: Lighting design must also comply with TSI PRM (Persons with Reduced Mobility), which mandates specific contrast levels and lighting at door thresholds.
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