Three themes among many at the 10th International Symposium of Tunnel Safety and Security (ISTSS), held in Norway last April, were focused on active management – of Safety, Emergency and Evacuation in underground transport. But while themes exist as do disciplines and specialisms, there was also a message of whole systems thinking – to appreciate and work with lies beyond your own discipline for the greater, safer, good

A host of themes were discussed at the most recent International Symposium of Tunnel Safety and Security (ISTSS) the 10th, held in Norway last year.

While technical aspects often get the spotlight, here this short review briefly looks at three key themes that deal with wider approaches to preparing for safely operating underground transport, both road and rail including Emergency management (see below), and Evacuation, and Safety Management, respectively (see box panels). The Keynote presentations also covered a variety of themes.

One such topic among the Keynotes is an overarching theme: the benefits from holistic systems. But, in the paper, the topic was discussed from the perspective of the origins of its opposite fragmentation. Taking that as a beginning, the paper discussed research underway led by the University of Stavanger to do something about it. FIGHTING FRAGMENTATION The cultivation of a wide spectrum of competencies, and different players working closer together in construction and operations spheres, are important steps to overcoming what is argued to be the fragmented nature of tunnel safety for underground transport, according to a keynote speaker at the 10th International Symposium of Tunnel Safety and Security (ISTSS), held.

The argued picture of fragmentation arose from a safety regime that is contingent on the tunnel history, where tunnel safety emerged through events, says the keynote paper by Prof Ove Nj, who specialises in risk and emergency management at the University of Stavanger. He is a member of the Scientific Committee of ISTSS.

The safety approach has usually developed iteratively and progressively over time, responding to different classes of problems and risk. The result, therefore, also fragments how well the different professionals involved with transport tunnels come to work together from their own disciplines, or don’t. This is a hazard in itself, according to the studies.

There is no unifying discipline or education that brings them together, says Prof Nj in the paper.

A strategy to overcome the fragmentation is to have tunnel safety competence as a key concept in safety management systems, he says. He adds that competence is not addressed by regulations and that significant uncertainties exist over what is perceived to be good in terms of tunnel safety.

The keynote paper discusses research and the process to obtain a state of competence tool, drawing upon a combination of learning and systems safety theories, respectively. This work has been undertaken through the Tunnel Safety Study (TSS), led by the university in structured courses.

The paper comments that, at an academic level, the TSS looks at how experiences become theory, and how different groups in tunnel infrastructure and operations should gather and review data and knowledge. The TSS is organised in credit-earning learning/research modules for students. Part of the work involves cross checking the stance of different disciplines in their risk perspectives, and of planners and users too. The aim is to find an holistic approach, a theory, founded upon real-world, broad inputs based on practical lessons and experiences from the different disciplines.

The research challenges the issue of tunnel safety competence, moving appreciation of it to be seen as more than, simply, the absence of unwanted events but how its complex parts and parties function and are experienced, and the resulting outcomes. Competence in transport tunnel safety, then, is argued to be a topic that calls for far-reaching appreciation of hard and soft systems creating a whole context and environment.

Further, safety is more than the responses of and to some niche, functional parts of an underground asset.

In the era of digitalisation drawing pieces of infrastructure together more easily, in Building Information Modelling (BIM) and Digital Twins (DT), the possibilities of greater benefit coming from the whole being more than the sum of the parts should be easier to engage with. The challenge even then, though, is handling the non-engineered elements, and adding those dimensions to a obtain a more effective analysis.

Perhaps there needs to be less onus on seeing safety in the frame of assets that happen to be used by people but, rather, as combined systems of technical-human interaction if they are to be viewed as being competently enhanced in terms of safety.


The ISTSS event had Emergency Management and Safety Management in two themes.

Emergency Management

Four papers were presented in the theme Emergency Management. They looked at transport tunnels in parts of four countries Belgium, Austria, Norway and Sweden.

The first two papers concern rail tunnels, then second two road tunnels.

Antwerp rail tunnels:

Infrabel, the Belgian publicly-owned rail network owner, presented a paper of safety management enhancement for three main passenger tunnels in Antwerp. The upgrade works on installations followed works on other systems in other important rail tunnels in its network and digesting the lessons learned.

A preliminary risk analysis pointed the way to the upgrades, including improved links with control room operators. Both the visualisation system and instruction for emergency services are to be standard for the entire Belgian rail network.

Koralm rail tunnel:

Graz TU and OBB, the Austrian federal rail company, presented a paper on incident management in long rail tunnels, drawing upon Koralm tunnel as an example. Its focus was on ventilation solutions to aerodynamic questions of ensuring smoke-free zones persist to support evacuation of trains. The aerodynamic questions arise from trains still active in the unaffected tube, which is put into overpressure as a barrier to smoke entry along with passengers.

Koralm is a twin-tube tunnel that will be almost 33km-long under an overburden of almost 1200m. During regular operations it is ventilated by the air mass being moved along by train traffic. In the middle of the tunnel is an almost 1km-long emergency station. However, the high overburden prevented construction of a shaft-based smoke extraction system due to technical/economic reasons.

A coordinator must be told by the train operatives of a problem to then manually activate emergency measures. There is no automatic trigger of the system.

The trains in the non-incident single track rail tube need to be withdrawn to the surface to enable the rescue services to have access. Simulations have helped to establish the trains must slow significantly to prevent disruption of the smooth-running over-pressure flow and so keep the air sufficiently smoke-free near the exits for as long as possible. Significant co-ordination of all the data gathering and supervision systems involved is vital.

Norway Gudvanga and Oslofjord tunnels:

Evolution of emergency preparedness is examined through the study of two single-tube, bi-directional road tunnels with long ventilation. The paper was by Western Norway University of Applied Sciences and University of Stavanger, respectively. Part of the reason they were selected was that each had three fires over 2011-2021 involving heavy vehicles, giving possibility to examine how emergency preparedness changed and evolved.

The paper concludes, in observing that the recommended ventilation strategy during a fire is a topic well discussed after several large fires, and that regulatory recommendations are in place but the authors do not consider that a single strategy should be in place for all road tunnels in Norway. Whichever approach is selected for a tunnel after investigations, a surveillance system will be critical.

Stockholm Northern Link:

In September 2022, a full-scale tunnel fire exercise was undertaken at the Northern Link road tunnels with a an initial three-car scenario and which was then deliberately, progressively, escalated under the test designed by fire safety consultancy Brandskyddslaget AB, which presented a paper on the study. A key outcome was the exercise clearly shows that the majority of practicing organisations generally have low orientation skills within the tunnel network and more of the training and familiarisation events were sought.

A further aspect of extra need is to practice how active safety systems ventilation and fixed fire-fighting system (FFFS) should be used. Taken all together, collaboration is key.


As part of safety management, one paper put a focus on sufficiency of medical knowledge on health effects from chemicals and gases in tunnel fires. The work was discussed by Stavanger University Hospital and the University of Stavanger, respectively.

It was emphasised that there is abundant knowledge on medical effects of exposure to different types of chemicals but we lack evidence on the connection between exposure and subsequent health effects especially long-term health effects of acute exposure to gases from tunnel fires.

Again, researchers advocate using systems-thinking and collaboration in design to overcome silo-based, fragmented approaches by specialists. In doing so, they see possibilities for inclusion of toxicology criteria in fire safety design for tunnels, including on ventilation aspects.


Under the theme of Evacuation, one of the papers at the ISTSS 2023 symposium examined the growing interest in use of shelters inside single-tube road tunnels in Norway, albeit with such possibility considered only for some and with Oslofjord tunnel the primary focus, for now.

The research concludes that evacuation shelters could offer a cost-effective solution to a major challenge of enhancing the self-rescue principle that is the case in many of the country’s numerous single-tube road tunnels. The paper describing the work is by Western Norway University of Applied Sciences, University of Stavanger and the national roads authority (Statens Vegvesen, or NPRA).

As the paper notes, most of Norway’s road tunnels have limited traffic volume as well as complex geometry and steep gradients. But more than 500 of its single-tube tunnels are more than 500m long, and almost 100 are more than 3km in length. No requirements exist for emergency exits in existing tunnels. With all these factors, the self-rescue principle could be a challenge for drivers in many cases.

The shelters are being studied through the Oslofjord installation, which was installed only as an interim, preliminary step pending construction of a second tube tunnel.

Also in Norway, this time presented in a papers by Sintef researchers, there was again discussion of rescue rooms in road tunnels but from the perspective of users acceptance and doing so through using virtual reality (VR) systems to get feedback on layout designs. The research involved 37 people look at five designs and pointed to two key factors in helping acceptance by users, and increased feelings of safety approach to lighting, and use of separate areas (for injured).

The researchers say: The outcomes of this study show that design and spatial factors are crucial if rescue rooms are to be implemented and used in road tunnels.

A further Keynote paper, and also from Sintef, discussed this research and the findings as part of a focus on human behaviour during fires in tunnels.


While digitalisation was touched upon in some papers across various themes, at the ISTSS 2023 symposium it was also a theme in itself.

Four papers were given to the event covering separately: decision support; control centres; Digital Twin (DT) for real-time incident monitoring; and, locating people with wi-fi technology.

Additionally, in the poster session there were papers on computer aided resilience assessment and computational assessment of critical velocity in rail tunnels, respectively.

On the DT paper, its authors are from The Hong Kong Polytechnic University and Southeast University, Nanjing, respectively. It discussed using an artificial intelligence (AI) enabled system that draws together data from sensory networks (like an Internet of Things (IoT) this is a network of Things, and is given the acronym AIoT).

The authors paper presents information on developing their AIOT based smart Digital Twin to monitor fire in real-time in a tunnel.

The test area for the Digital Twin-based system was a full-scale (8m x 6m in section) and 140m long. Before the test, the AI model had to be trained on data and only then could the Digital Twin-based system be used in the full-scale, short tunnel used to validate the modelling. They said the modelling was 98% accurate in predicting fire information. Trained and validated, the AI system can generate different tunnel fire scenarios to study.

AI was also used in another paper, by ILF consulting Engineers and Germany’s Federal Highway Research Institute, to help establish how tunnel control centres can analyse real-time data to carry out risk assessment of safety.