China National Highway 318 (G318) is a challenhing road running from Shanghai to Zhangmu on the China-Nepal border. It is the longest highway in China, crossing over eight provinces, with a length of 5.476 kilometres (3,403 mi).
Adverse weather conditions are common. Ice and snow can be on the way.One notable section of this road is the Si Du River Bridge, the bridge with the greatest vertical clearance in the world as of its 2009 completion. From Lhasa to Zhangmu it is also called Friendship Highway. The 115 km. continuation to Kathmandu is named Arniko Rajmarg. The surface of the road is paved. Tibet naturally has some of the harshest terrain in the world, so its not likely to have the best roads leading in and out. The highest point on this road is just less than 4,000m.
Remember this is is a mountainous area, climbing up a high mountain, with a notorius absence of oxygen. Altitude and extreme weather are always a factor. The state of this road leading into Tibet was one of the major reasons to build the Tibetan railway system to Lhasa, locals say this section of the road has four seasons per day, freezing, cool, warm, hot, which leads to needless injuries.