UIC Leaflet 756: Passenger Information and Communication Systems

What is UIC Leaflet 756?

UIC Leaflet 756 is the international standard titled “Telecommunications installations on passenger trains.” It governs the systems used to transmit voice and data within the train for the benefit of both the crew and the passengers.

In an era of high Interoperability, it is critical that a passenger coach from one country can be coupled to a locomotive or multiple-unit from another without losing the ability to make announcements or trigger emergency alarms. UIC 756 provides the technical blueprints for these Transmission Systems to ensure they function seamlessly across international borders.

Core Functional Requirements

The leaflet specifies several mandatory systems that contribute to both Operational Safety and passenger comfort:

• Public Address (PA) System: Standards for voice clarity and volume levels to ensure announcements from the driver or guard are audible in all areas of the train.
• Passenger-to-Driver Intercom: The technical requirements for emergency call points. This system must be robust enough to operate during power failures or accidents.
• Visual Information Systems: Requirements for internal and external LED/LCD displays that show destinations, next stops, and connections.
• Seat Reservation Displays: Standardized data protocols for electronic seat numbering and reservation status updates.

Technical Integration and Digital Standards

Modern versions of UIC 756 focus on the transition from analog wiring to digital Information Technology solutions, such as the Train Communication Network (TCN) and Ethernet Train Backbone (ETB):

• Standardized Connectors: Defining the physical pins in the UIC 18-pole or 24-pole jumper cables used between coaches.
• Data Protocols: Ensuring that the software used by a “Brand A” display can read the station data sent by a “Brand B” train computer.
• Acoustics: Defining the Signal-to-Noise ratio required to meet TSI PRM (Persons with Reduced Mobility) standards, ensuring announcements are clear for the hearing impaired.

Safety and Emergency Functions

The most critical aspect of UIC 756 is the Emergency Communication. The standard mandates that:

• Emergency calls must have priority over any other Passenger Information Systems (PIS) or music broadcasts.
• The system must include a “talk-back” feature, allowing the driver to reassure passengers or gather information during an incident.
• Back-up power supplies (batteries) must keep the communication system alive for a minimum specified duration after a total train power loss.

Comparison: Analog vs. Digital Train Communication (UIC 756)