The China Railway K3/4 train is a weekly international K-series train from Beijing to Moscow via Ulaanbaatar mainly using the Trans-Siberian and Trans-Mongolian railways. The train started running in 1959, covering a distance of 7826km, and is the 4th longest passenger train service in the world. The Beijing to Moscow train (K3/003/003З) departs every Wednesday from Beijing station and takes 131 hours and 31 minutes to arrive at Moscow Yaroslavsky station, while the Moscow to Beijing train (K4/004/004З) departs every Tuesday from Moscow and takes 129 hours and 50 minutes to arrive at Beijing.