This was the final test in a series of fire and blasting tests that were performed in September within the framework of the Metro project in Arvika.
Two underground carriages were connected inside a tunnel. One of them had an explosive charge corresponding to the amount of explosives that can be carried in a backpack. The explosion was monitored by cameras and detectors inside the carriages, as well as on the walls of the tunnel and at the openings.
There was a group of smoke divers from rescue services present at the explosion. They entered the tunnel at a very early stage to study the damage to the carriages and potential fire reaction. FOI researchers subsequently documented all of the damage and measurement results. SP Technical Research Institute of Sweden took part to study heat release during an explosion.
- Major damage to the carriage with the explosive charge was readily evident. For example, some of the walls were torn open. The other carriage also sustained damage, but it was limited to the extent that it would hardly have resulted in any deaths, says Rickard Forsén, chief engineer at FOI.
The main beneficiaries of the research results are Swedish and foreign rescue services.
-The findings from the experiment give rescue services better understanding in terms of managing this type of situation, both as regards equipment and organisation, says Rickard Forsén.
The findings from the explosion will be shared in report form with clients and within FOI. The results will also be presented at seminars in Sweden and abroad, for example at the International Symposium on Tunnel Safety and Security in New York in March 2012.
Rickard Forsén believes many societal players will ultimately benefit from the work.
-In addition to rescue services, transport providers and medical care services will be better equipped to predict what type of damage an explosion may cause and thus better prepare for such incidents. Knowledge of the damage that arises in this type of explosion may also be useful for police investigations after bombings. FOI's military clients will also benefit from understanding the load sequence and how structures react to explosion load, says Rickard Forsén.
The Metro project is being run by Mälardalen University with funding from the Swedish Civil Contingencies Agency (MSB), the Swedish Transport Administration (Trafikverket), Stockholm Public Transport (SL), the Swedish Fortifications Agency (FORTV) and the Swedish Fire Research Board (Brandforsk).