Beijing, December 13 (Youth.cn) - Trial train arrived at Dongsishitiao Station of Beijing Subway Line 3 on December 12th. On the same day, Beijing Municipal Commission of Transport announced that phase I of Subway Line 3 (Dongsishitiao - Dongba North), Subway Line 12 (Sijiqingqiao - Dongba North), the remaining section of Phase I of the South extension of Changping Line (Xitucheng - Jimenqiao) and Zhufang North Station of the South extension of Changping Line will be put into trial operation. The new operating mileage is about 43 kilometers. By then, the total mileage of Beijing's rail transit will reach 879 kilometers. Photo/VCG