Research On The Related Factors Of Pollutant Concentrations In Urban Traffic Canyon

The Urban Traffic Canyon, which seems a “valley” like narrow outdoor space, isenclosed by the city frontage buildings and urban roads and makes an important part of theurban outdoor space.In recent years, as the rapid growth of vehicle population and the constant increase of thestreet buildings. The Urban Traffic Canyon as one of the most active places in outdooractivities, where its air quality is being deteriorated by vehicle exhaust and other pollutants,which cannot be diluted and diffused in time. However, the contamination concentration inthe canyon will not only have a bad impact on the physical and mental health of people inoutdoor activities, but also determines whether the air quality in the frontage buildings indooris good or not. Therefore, it is very necessary to have a study on urban traffic Canyon.Basing on the field observation method, this paper has analyzed the related factors whichwould have effects on the diffusion of air pollutants concentration in the canyon. Within twomonths, by taking an investigation on81streets in the Third Ring of Xi’ an, we have primarilyconfirmed the related factors and analyzed the manner and mechanism of the diffusion ofpollutants concentration which these factors mentioned above made.After statistical analysis, we make a research by choosing the20east-west and20north-south typical streets as the test objects. Every canyon arranges three points, point1is onthe edge of motor vehicle road, point2is in the midpoint which between the edge of motorvehicle road and the buildings, point3is in the place which has one meter away the buildings.We have measured and get the real-time value of the canyons of high aspect ratio, leaf areaindex, the concentration of CO, wind speed, temperature, humidity and other variousinfluencing parameters in each test point.Analyzing the correlation of data, which affected the spread of the CO concentration byeach individual factor, we have used SPSS getting corresponding regression equation bymaking multiple linear regression to the data of combined effects of factors and analyzed theimpact of various factors on the dispersion of pollutants. the resluts show that: Motor vehicleroad at the edge: CO emission intensity is the greatest impact on CO concentration; The region of sidewalk: street geometry on the CO concentration in the greatest impact, followedby wind speed;1meter away from the building: street geometry on the CO concentration inthe greatest impact, followed by LAI.Based on this, we put forward the design strategy of improving city traffic condition ofCanyon micro environmental from the mode of canyon green, green space of canyon thewindward and the leeward and site layout.By actual measurement, this paper takes a study on the related factors and the extent ofinfluence the diffusion of CO concentration in urban traffic within the canyon. We havecalculated and analyzed the laws of all relevant factors affect diffusion of CO concentrationby using SPSS, which could provide support to optimize the micro-environment of the urbantraffic Canyon andthe urban open space.