Lighting the Way: UIC 476 Headlamp & Marker Standards

Definition and Scope

UIC Leaflet 476 establishes the requirements for the layout, control, and performance of external lighting systems on locomotives, driving trailers, and multiple unit trains. Its primary function is to ensure that a train is clearly visible to trackside workers and the public (“to be seen”) while providing sufficient illumination for the train driver to observe the track ahead (“to see”).

This leaflet standardized the iconic “A-Signal” configuration—the triangular arrangement of three white lights at the front of the train—which has become the universal face of European railways. It also dictates the logic for switching between white front lights and red tail lights based on the direction of travel.

Key Technical Specifications

UIC 476 covers both the physical positioning of the lamps and their photometric properties (light intensity and color).

1. The “A-Signal” Layout

To ensure instant recognition of a train, the front lights must form an isosceles triangle:

• Two Lower Lamps: Mounted at the same height above the rail level (typically between 1500mm and 1700mm).
• One Upper Lamp: Mounted centrally above the windscreen.
• Purpose: This unique shape distinguishes a train from road vehicles (which typically have two horizontal lights) at level crossings.

2. Luminous Intensity and Modes

The standard differentiates between lighting modes to prevent blinding oncoming train drivers while maintaining safety:

• Full Beam (Headlamp): High intensity for open track running at speed. Used to illuminate signals and obstacles.
• Dimmed Beam: Reduced intensity mandated when passing another train, approaching stations, or within shunting yards to avoid glare.
• Marker Light (Position Light): Low intensity, used to indicate the presence of the train when parked or acting as a tail light (red).

Comparison: Headlamp vs. Marker Lamp

Understanding the distinction between these two functional types is critical for compliance with UIC 476 and modern TSI standards.

Operational Logic

UIC 476 requires automated logic in the control circuitry. When a driver changes the active cab (reverses direction), the lighting system must automatically switch:

• New Front: Displays three white lights (A-Signal).
• New Rear: Displays two red tail lights.

This prevents the dangerous situation of a train displaying white lights to the rear, which could confuse signalers or following trains into thinking the train is moving towards them.