A bullet train runs on a viaductin Bishan County, southwest China's Chongqing Municipality on Dec. 26, 2015. The high speed rail (HSR) connecting Chengdu and Chongqing, both in southwest China, was open to operation on Saterday. The Chengdu-Chongqing high speed railway is 308 kilometers long with the operation speed of 300 kilometers per hour. (www.cq.xinhuanet.com/Chongqing UAV squadron)