Brandskyddet i Hamnpåfarten Värtan : En alternativ lösning med transversell ventilation och sprinkler

In cities, road tunnels are built to make room for homes and offices and in these tunnels millions of vehicles travel every year. Fires in these confined spaces can have severe consequences and must actively be worked with to prevent. In Värtahamnen, Stockholm, a short road tunnel at the end of the E20 is currently being projected between 2011 and 2013. The stretch is a known hazardous goods route and thus fire protection systems should be adapted accordingly.Fires in tunnels are problematic since the tunnels confined nature provides a very high re- radiation of heat, temperatures up to 1000°C is expected in early stages of the fire. Hamnpåfarten is a known hazardous goods route, and the fire protection is designed with a fireload of 100 MW.Safety in road tunnels is governed by a number of regulations, for tunnels over 500 m statutory rules in the act (SFS 2006:418) – and the ordinance (SFS 2006:311) on safety in road tunnels apply. Transportstyrelsen is originator ofTunnel 11, which although is not mandatory for other actors than Transportstyrelsen, municipalities may choose to use these guidelines in their own tunnel projects. ADR-S is the Swedish version of the European Agreement concerning the International Carriage of Dangerous Goods by Road. In this document tunnel classifications are defined, for whether hazardous good may be carried in a road tunnel or not.Hamnpåfarten is an about 200 meters long tunnel that is inclined about 5%, and makes a sharp turn. In the system document, no fixed fire fighting system is planned, instead an evacuation staircase in the middle of the tunnel is used. Hamnpåfarten is classified in tunnel class TB, and is expected to be classified as a B-class tunnel in ADR. The main risks identified in the tunnel include: collision between vehicles, spill of hazardous goods and explosion class 1. However, none of these risks are significantly large.Alternative methods to keep fire safety at a high level include fixed fire fighting systems and fire ventilation. In order to offer the same evacuation opportunities as an evacuation staircase, the effectiveness of half transverse ventilation combined with a foam based fixed extinguishing system is examined using simulations in FDS.The results from the FDS simulations showed that with the adopted parameters, the system is not capable of the high fire load. Only the northern end of the tunnel upholds the environmental standards for evacuation.The simulations carried out were made on the assumptions that the transverse ventilation must be approved according to Tunnel 11. It also appears some questions related to this result. How much money is it worth to invest in a system wich in the initial stages may not be able to control the large fire? It is displayed in Tyréns FDS simulations that critical conditions occur in the tunnel after 9 minutes, it may in other words not be possible to initiate the fire fighting systems systems after five minutes.Fixed fire protection in tunnels appear to be an interesting technical area, however, there are few tests performed on large scale fires in tunnels, which might be interesting to do more of that to be able to design protection systems that can handle these fires.Validerat; 20130820 (global_studentproject_submitter