We all recognize a road tunnel as an elegant way for passing mountain massifs, an underwater passage or anything similar. Next to many advantages tunnels are providing, there are also a couple of drawbacks related to tunnels – safety is one of the most crucial in that context. Due to the fact the tunnel is a tube-shaped structure that can extend for several kilometres in distance (e.g., Laerdal Tunnel in Norway – 24,5 km, St Gotthard Tunnel in Switzerland – 16,9 km), we may assume that in case of an accident inside the tunnel, it would be difficult for people to evacuate, and it would be also difficult for the rescuers to reach the point of the accident. As well, closed structure of the tunnel would be problematic in case of fire, i.e., limited possibilities for removing smoke and heat may cause quick increase of the temperature inside the tunnel causing further implications. In fact, fire has been involved in most of the major tunnel accident in Europe : Mont Blanc (fire in year 1999 caused 39 fatalities), Tauern (collision and fire in year 1999 caused 12 fatalities), St Gotthard (collision and fire in year 2001 caused 11 fatalities), etc.
In modern road tunnels, safety issues have been addressed by using multiple active and passive safety systems. Tunnels are equipped by various sensors (e.g., smoke and flame detectors, temperature sensors, CO sensors, visibility sensors, etc.), video surveillance systems, air ventilation, fire hydrants, fire doors and service/evacuation corridors, etc. Data collected by various sensors and video surveillance serve as a data input for other tunnel systems and, as most important, for maintaining stable traffic conditions with the help of (smart) traffic signalization.
Although currently available systems described above already provide high level of safety, 5G can provide further improvements. Based on the 3GPP V2X standards, one of the main benefits would be collecting additional data – as of today most data collected in the tunnel come from sensors installed in the tunnel, while data sent by cars (e.g., V2X) and potentially also from the individuals can improve insight into the situation in the tunnel, being in normal conditions or in case of an accident (see also 5G-IANA blog post https://www.5g-iana.eu/2022/03/11/role-of-5g-networks-in-vehicle-to-infrastructure-telecommunications/ on 5G and V2X communications). Next to this, 5G as a global standard supporting industry requirements, enables applying many functionalities in standardized way (cyber security, distributed cloud-edge architecture, network automation, AI/ML, V2X, precise positioning, etc.) and enables unified data exchange among all stakeholders relevant to the tunnel security and safety, i.e., tunnel operator, traffic control centre, Police, fire-fighters, ambulance, Civil Protection especially in case they are located cross-border. Today, data exchange among various stakeholders still remains an issue. In particular, data exchange among Public Protection and Disaster Relief (PPDR) services is recognized and addressed as a major issue on the EU level mainly due to the cross-border incompatibility of communication systems [2, 3].
For the tunnel operator, it is required to be aware of situation in the tunnel at any time – to detect anomalies as soon as possible and to act with the goal of minimizing the (potential) damage. The perception of environmental elements and events with respect to time and/or space is called a “Situational Awareness” , which is a critical, yet often elusive, foundation for successful decision-making we want to improve by introducing 5G and therefore extend collecting data and enable access to data for multiple stakeholders, including those located cross-border.
Some situations, however, require first responders’ units to intervene. E.g., in case of a traffic accident in the tunnel, alarm notification would be forwarded to the public-safety answering point, as well, other relevant data and video streams should be forwarded to first responders to help them create “situational awareness” and to effectively commence the intervention. When first responders leaving station building, the system may also start collecting certain data related to the first responders’ unit (e.g., location of vehicles, speed, vehicle diagnostics) in order to complement data related to the incident itself. “Situational awareness” is of great importance for the intervention planning from its very beginning until its completion. In the beginning, incident commander can decide how many rescuers, what kind of vehicles and how many vehicles should be dispatched and also whether additional units are required (e.g., cross-border units). During the rescue phase, the incident commander can observe how the rescuing is progressing, what operations should follow at certain time, and whether additional resources should be activated. Based on the situation, the incident commander also instructs tunnel control centre operator to commit certain action, e.g., stop the traffic through the tunnel, stop or increase air circulation in the tunnel, etc. When the intervention is over, data collected and stored can be later of great importance for the intervention analysis.
 Malmtorp J, Lundin J, Lundman, P, Vedin P. Safety in Road Tunnels – Safety Target Proposal. International Journal of Applied Science; Vol. 2, No. 3; 2019.
 Broadmap project, http://www.broadmap.eu/.
 Broadway project, https://www.broadway-info.eu/.
 Situation awareness, Wikipedia, https://en.wikipedia.org/wiki/Situation_awareness.