자동차 운행시 터널에서 발생되는 대기오염물질의 저감방안

Abstract

Since 1990's the air pollution caused by vehicles has become a social problem and the pollutants caused by emission from vehicles in large cities including Seoul metropolitan area exceeded 80% of total pollutants. Particularly, in case of specific constructions such as tunnels, the pollutants emitted in the tunnels are emitted through tunnel portals and the level and range of their impact may be considerably larger than that of common roads. However preceding domestic studies on tunnels were made focused on the quality of air in tunnels, and the studies focused on the impact of pollutants emitted from tunnel portals on near area and the countermeasure for reduction of the impact were very poor. Thus this study was made to suggest the most useful method through consideration of the standard of emitted pollutant calculation, the method to estimate the impact, and their control facilities. The emission factor used in calculation of emitted quantity of pollutants emitted by vehicles was the one reported in 1990's which was targeted 1980's vehicles on the roads, and it has been pointed out as one of the most important cause of over-estimation. This study intended to suggest an emission factor that may be used most reasonably through comparative analysis of the emission factors of vehicles reported in 1990's, the emission factors of vehicles reported in the U.S.A., Japan, and Europe, and permitted emission standard of new vehicles produced. As a result of this study, the emission factors or foreign countries were found to be difficult to substitute 1990's emission factor because their permitted emission standards are different from that of ours and because the share of old vehicles, condition of roads, and the habit of drivers are different from those of our country. Accordingly, it was resulted that the permitted emission standard of vehicles is adopted as emission factor is most reasonable for environment impact assessment for estimation of impact for five years at least and 20 years at most. The most important in estimation of the impact of pollutants emitted from tunnel portals is to consider the characteristics of emission from tunnel portals. There is tunnel exit velocity at the exits of tunnels caused by tunnel ventilation and flow of vehicles; the impact on near area is different by whether or not of consideration of these factors and the nearer to tunnel exits, the larger the impact. Thus this study was performed focused on how much impact estimation methods imply the characteristics of emission from tunnel exits and the classification/equivalent emission strength model of Japan was found to express the characteristics of emission from tunnel exits most excellently. But the classification/equivalent emission strength model was found to have a problem in dispersion coefficient and to be not applicable at the places with several hundred meters of distance from tunnel exits. Thus the result was made in this study that it is the most reasonable estimation method to use classification/equivalent emission strength model in case of the place with not more than 200m of distance from tunnel exits and to use ISC3 model (volume source), the most common atmospheric dispersion model, in case of the places with more than 200m distance. The pollutants from tunnels have the property of (mass flow) [large oily substances] and low density and a control facility is needed which is different from common air pollution control facilities. There has been an example of installment of electrical precipitator, a particulate pollutant treatment facility, in the country, however, there has not been any example of installment of gaseous pollutant control facility yet. In this study, data were collected focused on control facilities operated in Japanese or European tunnels and analyzed. The collected data were analyzed with differentiation by easiness in construction, economy, and efficiency, for maximum objectification of the analysis of data, and it was intended to suggest the most appropriate control facility with consideration of analyzed result. As a result of this study, it was concluded that appropriate control facility should be able to treat not only NOx, CO, SO2, and HC but also micro dusts and should require relatively small construction cost and maintenance/repair cost; however, if it is difficult to provide the sites near to tunnel exits, it may be more reasonable to use other facility. In this study, the reasonable control method of pollutants emitted from tunnel exits was derived. But this study has lots of limit because it was performed based on literatures, thus, continuous supplementation is required through additional studies in the future.