Safer tunnels: new smart sensors to prevent fire risks

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In road tunnels, safety depends on rapid decisions and reliable real-time information. During a fire, understanding airflow dynamics and vehicle positions is essential to contain toxic smoke and support emergency response operations. To address these challenges, researchers from the SUPSI Institute of Systems and Applied Electronics (ISEA) developed a new generation of smart sensors designed to improve tunnel ventilation systems and strengthen emergency management.

The NGTSENS project (Next generation of tunnel safety sensor for preventing and managing critical situations), funded by Innosuisse and developed in collaboration with ACP Environment SA, a company specialized in tunnel sensor installation and maintenance, enables continuous monitoring of tunnel conditions by integrating real-time data on airflow, traffic and thermal variations.

The goal is twofold: ensuring efficient airflow management during normal tunnel operations while improving emergency and critical situation management through reliable live data. These measurements provide essential information for activating ventilation systems and limiting smoke propagation during incidents.

At the core of the innovation is a solid-state design. Unlike conventional systems, the new sensors contain no moving mechanical parts and rely entirely on static electronic components. This allows precise and continuous airflow monitoring even in harsh tunnel environments, while reducing the risk of failures caused by dust and corrosive fumes.

The measurement principles adopted by the system ensure accurate performance under all environmental conditions, eliminating the need for periodic recalibration of the electronic sensors during operation.

An integrated platform

At the heart of the project is the Single Point Flow Sensor, a compact wall-mounted station that combines multiple technologies within a single device. Powered by a high-performance STM32H7 microcontroller, the system processes data in real time and provides a comprehensive overview of tunnel conditions.

The sensor integrates three main functions:

  • Airflow monitoring
    Five transducers calculate airflow speed and direction along the tunnel’s three spatial axes (length, width and height), helping predict how smoke would move and spread in the event of a fire.

  • Traffic monitoring
    An integrated radar tracks vehicle movement and speed without physical contact, making it possible to detect congestion, queues or potentially dangerous situations in real time.

  • Fire prevention
    A thermal camera monitors the surface temperature of passing vehicles, enabling the early detection of abnormal overheating, such as faulty brakes or engines, before they develop into fires. 


Among the possible configurations of the developed solution are a wall-mounted variant, installable near the tunnel vault, and a variant designed to measure average velocity across the entire tunnel cross-section. A distinctive feature of the proposed solution is the system’s intrinsic redundancy, which ensures reliable data even in the event of failures affecting some device components.

The integration of multiple sensors into a single device makes it possible to promptly detect anomalies and potential risk situations, enabling targeted interventions before critical conditions develop. NGTSENS thus promotes an evolution in tunnel safety management: no longer limited to emergency response, but focused on the ability to prevent critical scenarios through continuous monitoring and data that are immediately available to support operational decision-making.

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