在北京北部昌平、延庆的大山里,蜿蜒着京藏高速、京新高速、110国道三条大动脉。每天,这三条公路上流淌着由3万多辆大货车组成的车流,车上拉载的是供应北京以及周边省区供暖发电所需的煤炭,以及牛羊肉、奶制品、蔬菜等市民生活必需品。维系着这三条公路正常运行的,是一群大山里的交警。 In the mountains of Changping and Yanqing in the north of Beijing, meandering the three major arteries of Beijing-Tibet Expressway, Beijing-New-Expressway and State Road 110. Every day, the three highways run by more than 30,000 large trucks traffic flow, the car is loaded with the supply of coal in Beijing and neighboring provinces for heating and power generation, and beef, mutton, dairy products, vegetables and other public necessities . Maintaining the normal operation of these three roads is a group of traffic police in the mountains.