Photo taken on Jan. 1, 2019 shows Shixia Tunnel of the Xinglongkou-Yanqing section of Beijing-Chongli Expressway, which gets through Beijing's Changping district and Yanqing district, in Beijing, capital of China. After more than three years' construction work, the 42.2-km-long Xinglongkou-Yanqing section of Beijing-Chongli Expressway linking northwest Beijing's Xinglongkou Village in Changping district and Yanqing district opened to traffic on Tuesday. (Photo: Xinhua)

Beijing-Chongli Expressway starts from Beijing and ends at Chongli of north China's Hebei Province. It will serve the Beijing International Horticultural Exhibition 2019 and the Beijing 2022 Winter Games, which are to be held in Yanqing and Chongli respectively.(Photo: Xinhua)

Aerial photo taken on Jan. 1, 2019 shows the Xinglongkou-Yanqing section of Beijing-Chongli Expressway in Beijing, capital of China. (Photo: Xinhua)

Aerial photo taken on Jan. 1, 2019 shows the Xinglongkou-Yanqing section of Beijing-Chongli Expressway in Beijing, capital of China. (Photo: Xinhua)

Aerial photo taken on Jan. 1, 2019 shows the Xinglongkou-Yanqing section of Beijing-Chongli Expressway in Beijing, capital of China. (Photo: Xinhua)

Photo taken on Jan. 1, 2019 shows Shixia Tunnel of the Xinglongkou-Yanqing section of Beijing-Chongli Expressway, which gets through Beijing's Changping district and Yanqing district, in Beijing, capital of China. (Photo: Xinhua)

Aerial photo taken on Jan. 1, 2019 shows the Xinglongkou-Yanqing section of Beijing-Chongli Expressway in Beijing, capital of China. (Photo: Xinhua)