The Beijing underground cross-city railway is a short railway connection in Beijing. This railway line includes the Qiansanmen Tunnel. The speed limit is 120 km/h. It connects the important transportation hubs Beijing railway station and Beijing West railway station via a tunnel. It also connects lines from southern and western areas with lines from northeast China. The railway has a length span of 9.156 km (5.689 mi), and has been officially operational since March 20, 2015.