Policemen check tyre chains of the passing vehicle on a road in Meihua Mountain, southwest China's Guizhou Province, Feb. 4, 2018. The S102 provincial highway is the highest one in Guizhou, which is also a vital line to reach Yunnan and Sichuan provinces. Thus, it is significant to ensure the smooth running of the road, especially during winter time. (Xinhua/Tao Liang)