Building tunnels is expensive, with no room for compromise on safety. When the Swedish Transport Administration was selecting a new fire safety system for the Northern Link in Stockholm, it was able to find a safe and cost-effective solution – largely thanks to RISE’s specialist knowledge of tunnel fires.
At 3.6 kilometres, the Northern Link is Sweden’s second-longest road tunnel. When it opened to traffic in 2014, it was fitted with something new to Swedish roads; a new type of sprinkler system specifically designed for tunnels.
“We were involved in the process with our expertise and testing; something that allowed the Swedish Transport Administration to rest easy in utilising a new solution,” says Haukur Ingason, fire and protection specialist at RISE.
Sprinkler systems common in Japan and Australia
Sprinkler systems have rarely been used in Swedish road tunnels, although they are common in other parts of the world, especially in Japan and Australia. During the planning of major Stockholm infrastructure projects, emergency services have repeatedly expressed their preference for sprinkler systems; something that had fallen on deaf ears during previous tunnel construction projects. In planning the Northern Link, however, the Swedish Transport Administration called in a number of parties to consult on the possibility of identifying a sprinkler solution that was safe for Swedish conditions.
“We have built up a great deal of competence and respect over the course of many years when it comes to these issues,” says Haukur Ingason.
Haukur Ingason is careful to point out that it was not RISE who developed the sprinkler system. RISE’s role was that of an independent institute, carrying out assessments and testing.
“We are experts in the development of fires. In such situations, there are not always predefined standards or requirements to be met; however, we have the knowledge to assess whether the measures are sufficient to extinguish or prevent the spread of the fire.”
Large socioeconomic savings
The sprinkler system developed by the Swedish Transport Administration and fire protection specialists Brandskyddslaget also proved to be value for money. According to a report from engineering consultancy company Ramböll commissioned by RISE, the socioeconomic savings can be calculated at SEK 440 million.
“This kind of major effect wasn’t a consideration during the process,” says Haukur Ingason.
The sprinkler system was subject to severe testing during its development; Haukur Ingason himself attended the testing carried out inside the tunnel.
“No matter how carefully you plan, setting a fire inside a tunnel for a largescale test can be somewhat nerve-wracking.”