Break-IN on FM and DAB+ for Road and Highway Tunnels: The Life-Saving Technology

Introduction

The Break-in FM and DAB system inside tunnels represents one of the most important technologies for safety in road and highway galleries. This functionality allows for instant interruption of radio transmissions to send critical messages to motorists, transforming the tunnel's radio infrastructure into an emergency communication tool.

What is the Break-IN System and Why is it Essential

The break-in message system, also known as VBI (Voice Break-In), is a system that allows overriding normal FM and DAB+ radio transmissions with priority messages. When a motorist drives through a tunnel listening to their favorite station, the system can automatically or manually interrupt the programming to transmit urgent communications.

This technology stems from the need to communicate rapidly with thousands of people simultaneously in enclosed environments where other means of communication might not be effective. In a tunnel, where visibility is limited and escape routes are predetermined, the ability to instantly reach all users can make the difference between orderly emergency management and a chaotic situation.

Break-IN System Applications in Tunnels

Emergency Management

Radio emergency systems find their most critical application in managing dangerous situations. In case of fire, the system can immediately transmit evacuation instructions, indicating the nearest emergency exits and procedures to follow. During a serious accident, messages can guide motorists on how to behave, where to stop, and how to facilitate access for rescue vehicles.

Traffic Information and Safety

Beyond emergencies, break-in messages are used to communicate information to users. These include warnings about sudden queues at the tunnel exit, allowing motorists to slow down safely, reports of stopped vehicles or ongoing work requiring special attention, and adverse weather conditions that could affect driving at the exit of the gallery or subsequent galleries.

Service Communications

The system can also convey service information such as scheduled closures of the highway section for maintenance, mandatory detours for road work, keeping users always informed and prepared.

The Break-IN Technological Infrastructure

The Heart of the System: Smart Amplifiers

The FM and DAB+ emergency message infrastructure is based on sophisticated amplifiers that represent the operational brain of the system. These devices receive the radio signal through external Yagi antennas strategically positioned outside the tunnel. The amplifiers boost the signal and integrate modules that allow insertion of break-in messages through various methods.

Message Activation Methods

The system can be activated through multiple channels, ensuring operational flexibility in every situation. Pre-recorded messages can be triggered automatically through API interfaces or SNMP protocols, allowing integration with tunnel monitoring systems. Smoke sensors, accident detectors, or video surveillance systems can automatically activate specific messages for each scenario.

A particularly innovative feature is the ability to make SIP VoIP calls directly to the Break IN system. This functionality allows control center operators to speak in real time with tunnel users, providing personalized instructions based on the evolving situation. The operator's voice is instantly transmitted on all FM frequencies and active DAB+ multiplexes in the tunnel.

Text Messages and Multimedia Content

Modern systems also support sending text messages that appear directly on vehicle infotainment displays. These text messages complement voice communications, providing information that remains visible for as long as necessary.

On DAB+, technology even allows transmission of images. In case of emergency, universally recognizable symbols that overcome language barriers can be sent. These images automatically appear on compatible vehicle displays, providing an additional level of immediate visual communication.

Radio Channel Selection and Management

FM Carrier Configuration

The VBI system amplifiers allow precise selection of which FM stations to amplify inside the gallery. This configuration is studied based on the tunnel's geographical area and local listening habits. The goal is to ensure that most motorists can continue listening to their favorite stations, thus maximizing the probability that they will receive any emergency messages.

DAB+ Ensemble Management

Regarding the DAB+ tunnel ensemble, the system allows selection of which digital multiplexes to retransmit inside the gallery. Each ensemble can contain various radio stations and data services. The choice of ensembles to amplify is made considering coverage of major national and local broadcasters, ensuring continuity of the most important information services.

System Benefits for Users and Managers

Service Continuity Under Normal Conditions

In the absence of emergencies, the system is completely transparent to the user. Motorists drive through the tunnel continuing to listen to their favorite radio station without interruptions. This service continuity significantly improves the driving experience, eliminating annoying radio silence.

Designed for Emergencies

When necessary, the system instantly transforms into an emergency communication channel. The ability to simultaneously reach all vehicles in the tunnel with clear and timely instructions can drastically reduce evacuation times and prevent dangerous behaviors driven by panic.

European Regulations and Safety Standards

European Directive 2004/54/EC establishes minimum safety requirements for tunnels in the European road network. While the directive applies to all galleries longer than 500 meters, the specific obligation to install emergency communication systems with break-in capability concerns galleries longer than 1,000 meters with traffic exceeding 2,000 vehicles per lane. In these tunnels, regulations require a broadcasting system capable of interrupting radio programs to broadcast safety messages from the control center.

Regarding technical standards, ETSI (European Telecommunications Standards Institute) has produced several documents describing the Voice Break-In function and recommendations for interoperability. An important reference is ETSI TS 102 182, developed by the EMTEL group, which illustrates how tunnel broadcasting systems should incorporate the VBI function to convey emergency messages on AM/FM/DAB. For DAB specifically, standard EN 300 401 defines the "Alarm Announcement" function that allows interruption of transmissions for priority messages.

Detailed operational specifications, such as minimum audio quality levels, maximum activation times, and periodic test protocols, are generally defined through managing entity specifications, guidelines from international organizations like PIARC and CEDR, and country-specific design standards. In Italy, these specifications are often contained in ANAS circulars.

Legislative Decree 5 October 2006 n. 264 fully implements the European directive in Italy, assigning tunnel managers the obligation to comply with minimum requirements, including those relating to emergency communications. Additional more stringent requirements can be introduced through technical annexes or ministerial update decrees, such as DM 12/07/2021, which can extend the break-in system obligation even to galleries shorter than 1,000 meters under particular risk or traffic conditions.

Emerging Technologies and Future Developments

The tunnel emergency systems sector is in continuous evolution. Integration with C-ITS (Cooperative Intelligent Transport Systems) promises to create an even more effective communication ecosystem. Connected vehicles will be able to receive detailed information about tunnel conditions even before entering, allowing proactive traffic management.

Artificial intelligence is introducing predictive capabilities in break-in systems. Advanced algorithms can analyze traffic patterns, weather conditions, and historical data to anticipate potentially dangerous situations and activate preventive messages.

5G Broadcast technology and particularly 5G FeMBMS (Further evolved Multimedia Broadcast Multicast Service) represents a significant breakthrough for tunnel communication systems. This evolution of multimedia broadcasting will allow simultaneous transmission of high-definition content to multiple users, optimizing bandwidth usage and ensuring even richer and more detailed communications in emergency situations. 5G FeMBMS will be particularly effective for distributing real-time video, high-resolution interactive maps, and complex multimedia content that could be vital during evacuations.

Maintenance and Reliability

A Voice break-in system must always be ready to function, especially in case of emergencies. For this reason, maintenance cannot be left to chance. Periodic tests go beyond simple technical verification: it's essential to ensure that messages are clear and understandable.

System reliability is based on redundancy. This means that if one component fails, others automatically take its place, ensuring that communication with motorists is never interrupted. It's like always having a backup plan ready to use.

Want to implement a Break-IN system?

Teleproject specializes in designing and installing emergency systems for road and highway galleries. Our Break-IN systems integrate the most modern technologies to ensure reliable communications in every situation.

We offer complete solutions that include:

• FM and DAB+ amplification systems with integrated Break-IN capabilities
• Support for real-time SIP VoIP calls
• Transmission of voice, text messages and images on DAB+
• Integration with tunnel monitoring systems
• Compliance with all European and national regulations