Photo taken on April 30, 2016 shows the Xinjiang-Tibet Highway passing through mountains in northwest China's Xinjiang Uygur Autonomous Region. As one of the world's highest motorable roads, Xinjiang-Tibet Highway, or China National Highway 219, connects Xinjiang and southwest China's Tibet Autonomous Region with an average altitude of over 4,500 meters. Originally made of graval in 1950s, the 2,340-kilometer highway was fully paved with asphalt in 2013. [Photo/Xinhua]

Photo taken on April 28, 2016 shows the Xinjiang-Tibet Highway running along the Bangong Lake in northwest China's Xinjiang Uygur Autonomous Region. As one of the world's highest motorable roads, Xinjiang-Tibet Highway, or China National Highway 219, connects Xinjiang and southwest China's Tibet Autonomous Region with an average altitude of over 4,500 meters. Originally made of graval in 1950s, the 2,340-kilometer highway was fully paved with asphalt in 2013. [Photo/Xinhua]

Photo taken on April 29, 2016 shows a part of the Xinjiang-Tibet Highway stretching in northwest China's Xinjiang Uygur Autonomous Region. As one of the world's highest motorable roads, Xinjiang-Tibet Highway, or China National Highway 219, connects Xinjiang and southwest China's Tibet Autonomous Region with an average altitude of over 4,500 meters. Originally made of graval in 1950s, the 2,340-kilometer highway was fully paved with asphalt in 2013. [Photo/Xinhua]

Photo taken on April 30, 2016 shows the Xinjiang-Tibet Highway passing through mountains in northwest China's Xinjiang Uygur Autonomous Region. As one of the world's highest motorable roads, Xinjiang-Tibet Highway, or China National Highway 219, connects Xinjiang and southwest China's Tibet Autonomous Region with an average altitude of over 4,500 meters. Originally made of graval in 1950s, the 2,340-kilometer highway was fully paved with asphalt in 2013. [Photo/Xinhua]

File photo taken on May 3, 2011 shows workers repairing a section of the Xinjiang-Tibet Highway along the Bangong Lake in northwest China's Xinjiang Uygur Autonomous Region. As one of the world's highest motorable roads, Xinjiang-Tibet Highway, or China National Highway 219, connects Xinjiang and southwest China's Tibet Autonomous Region with an average altitude of over 4,500 meters. Originally made of graval in 1950s, the 2,340-kilometer highway was fully paved with asphalt in 2013. [Photo/Xinhua]