zigzagingeighteen bends of tianlu on national highway 318

318 abundance alpine altitude bend bends bolang county crossing curve deck densely difficult dominated eighteen extend fir foggy foot forested gong gravel highest highway jianziwan jianziwanshan jizhugou kazila kham like litang mountain national northwest observation overlook pass pastures peak pine province ridge river road roads scissor section shaluli sichuan slope southeast spruce standing surrounding tianlu tibet tibetan watershed west winding xianggezong yajiang yalong