Answer
The Xining–Ürümqi high-speed railway is the answer. It is a high-speed railway in China that connects Xining, the capital of Qinghai province, with Ürümqi, the capital of Xinjiang province. The railway has a total length of 1,776 km (1,104 miles) and was completed in 2017. It is the longest high-speed railway in China and the second longest in the world.