SAFETY/RISK/O&M | INSIGHT
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 The trains in the non-incident single track rail tube need to be withdrawn to the surface to enable the rescue services to have access.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.
2 - SAFETY MANAGEMENT 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.
Above: Cover image of the recently published proceedings of the 10th
International
Symposium of Tunnel Safety and Security (ISTSS), held April 2023 in Stavanger, Norway IMAGE CREDIT: RISE RESEARCH INSTITUTES OF SWEDEN AB
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