When the monorail began operating, the passenger terminal at Haneda Airport was located on the west side of the airfield, south of Seibijō, and this was the southern end of the line. Upon the opening of a new passenger terminal—now Terminal 1—in 1993, the monorail was extended to a new platform and another station, Shin Seibijō, was built for the employees of nearby maintenance facilities. Meanwhile, the former airport passenger terminal was razed and the monorail tunnel beneath it abandoned to make room for an extension of Runway B. The original Haneda Station, which was abandoned along with the tunnel, was rebuilt farther west along the new section of tracks and renamed Tenkūbashi Station in November 1998. Although the rails were removed and its entrance walled off, the now-unused tunnel remains otherwise intact today below the Runway B extension.