Phase 1, opened on December 28, 2013, runs through Wuchang in a northeast-southwest direction, connecting Wuhan Railway Station, Wuchang Railway Station and major commercial districts.[3] Phase 2 opened a year later and runs in an east-west direction, linking Hanyang and Wuchang, tunneling through the Yangtze river in the proximity of the first Yangtze river bridge and connecting with phase 1 at Wuchang railway station.[4] The opening of phase 1 of Line 4 will form the skeleton of Wuhan's metro system.But all stations on line 4 have been designed only to accommodate a six-car train (type B) in length and have no possibility to extend for future upgrading.A full train provides 176 seats, and can carry 1276 passengers by Chinese regulation of 9 people per square meter.