Longitudinal ventilation of road tunnels combined with air cleaning technology

The longitudinal ventilation of road tunnels has been widely used in Norway. On the National highways 620 tunnels are covering a distance of 477 km. The longest tunnel is the Gudvanga with a length of 11,4 km - situated in the west of Norway in Sogn and Fjordane. If it is necessary a tunnel is divided into ventilation sections by use of shafts or side adits. This makes it possible to renew the air in the tunnel. New technology makes it also possible to clean the polluted air in stages along the length of the tunnel. In 1989, research was started in Norway to determine the possibility of cleaning polluted tunnel air by electrostatic persipitator. As a result the technology for extracting particle pollution (soot and dust) with very high extraction rate are now known. The tests for a pilot system removing N02 - gas are going on, and has been installed in the Oslo tunnel since 1992. So far, after running 1 1/2 years, the cleaning system for removing N02-gas seems to be a very interesting project with high extraction rate. In the full text paper I will give an information about how we are planning to use the new air-cleaning technology for both particles and N02-gas in a longitudinal ventilated road tunnel in different cases depending of the purpose.