Aerial photo taken on June 26, 2019 shows three helical bridges along Sichuan-Tibet Highway in Yajiang County, southwest China's Sichuan Province. Along the Sichuan-Tibet Highway, there are various new and old bridges. Crossing mountains and rivers, these bridges are not only the key junctions on this line, but also splendid landscapes. Over the past 60 years, the highway and the bridges along it have been continuously upgraded and perfected, which has become a miniature of the highway traffic development in China. (Xinhua/Jiang Hongjing)