UIC Leaflet 751-3: Technical Standards for Ground-to-Train Radio Communication

What is UIC Leaflet 751-3?

UIC Leaflet 751-3 is the international standard titled “Technical characteristics of radio-electric equipment used in ground-to-train radio links.” This leaflet provides the foundational technical parameters for the communication systems that connect train drivers with traffic controllers (dispatchers) and infrastructure managers.

Reliable communication is a prerequisite for safety and Interoperability. UIC 751-3 ensures that radio equipment—whether installed on a locomotive or along the trackside—adheres to unified frequencies, modulation techniques, and message priorities. While modern networks have largely transitioned to GSM-R, the principles established in 751-3 remain the basis for functional radio requirements.

Core Functional Requirements

The leaflet specifies that a ground-to-train radio system must perform several critical safety functions under all operational conditions:

• Emergency Calls: Immediate prioritization of emergency broadcasts to all trains within a specific radio cell or area.
• Selective Calling: The ability for a dispatcher to call a specific train by its 12-digit Rolling Stock Identification number or functional train number.
• Data Transmission: Frameworks for sending short data messages, such as movement authorities or technical status reports, to the Cab Radio.
• Handover Protocols: Ensuring that communication is not dropped when a train moves at high speed between different radio base stations (cells).

Evolution from Analog to Digital (GSM-R)

Historically, UIC 751-3 covered analog radio systems operating in the 450 MHz (UIC Band). As technology evolved, the requirements of this leaflet were integrated into the EIRENE (European Integrated Railway Radio Enhanced Network) specifications, which defined the GSM-R standard.

Comparison: Analog Radio vs. GSM-R (based on UIC 751-3 principles)

Operational Impact on Interoperability

Before the standardization of UIC 751-3, locomotives often had to carry multiple radio sets to operate across different national borders. By standardizing the Ground-to-Train Radio interface, this leaflet allowed for a single Cab Radio unit to be used across multiple networks, significantly reducing equipment costs and simplifying driver training.