Construction of a large underground station under a station in operation

A four- and five-tier box-shaped underground station, measuring 25 m in width and 420 m in length, was constructed by East Japan Railway Company at a depth of about 25 m immediately under Yokohama Station through which about 2.3 million passengers pass each day, to link the Minatomirai Line with the Tokyu Toyoko Line. The construction work faced various challenges, including excavation through special geology, the high level of groundwater, tunneling for a railroad immediately under a large terminal station, and severe restrictions on construction due to live flows of passengers. These obstacles were overcome by meticulous engineering studies and technical development, as a result of which the underground station was finally completed two months ahead of schedule.