14To enhance the health of subway users, it is essential to investigate the generation, resuspension, and decay of 15 particles in an underground tunnel. In this paper, we analyzed the diurnal pattern of variation in particle 16 concentration in a subway tunnel. The mass concentration of particles was measured in a shelter located halfway in 17 the underground tunnel connecting Janghanpyeong station and Gunja station on Seoul Subway Line 5 by using an 18 aerodynamic particle sizer, a dust monitor, and a fast mobility particle sizer. The particle mass concentration 19 increased uniformly as a train passed through the tunnel, which was followed by an exponential decay. The particle 20 concentration in the tunnel decreased when the decrease of the number of particles between train operations 21 exceeded the number of particles generated and resuspended by a passing train, and increased in the opposite case. 22The diurnal variation of particle concentration in the tunnel according to train operation could be predicted by using 23 such a pattern of variation in the mass concentration of particles. 24 25

No abstract

No abstract

서 론도시철도는Abstract In railway tunnels, dust is generated when trains run due to the contact between the wheels and the rails.The generated dust is suspended due to the train-induced airflow, with some of it deposited due to gravitational sedimentation. In this study, the diurnal variation of the dust concentration was investigated in a railway tunnel. A single lane of a tunnel was selected in which to observe more easily the dust concentration due to the passing of a train. Four particle-measuring instruments were utilized to detect dust ranging from 5nm to 20µm. To synchronize the train passing time at the measuring location, a three-dimensional ultrasonic anemometer and a video camera were used. It was found that the dust concentration was significantly increased from 50µg/m 3 to 150µg/m 3 due to the train. Particularly, the dust concentration was greatly increased to more than 250µg/m 3 during the morning rush-hour times.

Since operation of railway trains is a major source of particle pollution in tunnel air, a particle removal device can be an effective measure to remove wear particles. To obtain design conditions of the particle removal device that will be installed underneath the railway trains, the wind speed and particle concentration underneath the trains were investigated using a three-dimensional ultrasonic anemometer and a DustTrak aerosol monitor, respectively. The measurements were made for the trains running on Seoul Metropolitan Subway Line 5 on February 10, 2015. The data were analyzed according to the track geometry (straight, curved) and train speed pattern (acceleration, cruising, and deceleration) between stations. Train speed was also analyzed. The average wind speed and PM 10 concentration underneath the trains were ~30% of the train speed and ~200 µg/m 3 for both straight and curved sections. Average PM 10 concentration for deceleration sections was higher than that for acceleration sections.