The Yomiuri reports that Odakyu’s newest Romancecar train uses a ’secret’ underground track belonging to Tokyo’s subway system:

Tokyo Metro is providing the underground track, which links its Chiyoda and Yurakucho subway lines, to allow Odakyu to run the Romancecar trains as a regular service.

It is the first time in the nation that regular train services using such a track have been offered.

By using two different Tokyo Metro lines, Odakyu will be able to run the train right across Tokyo’s web of subway tracks.

The connecting track is 584 meters long and connects Kasumigaseki Station on the Chiyoda subway line and Sakuradamon Station on the Yurakucho subway line. It was constructed in 1974, when the Yurakucho Line opened.

The connecting track has been used solely for empty trains, mainly from the Yurakucho Line, heading to a maintenance facility on the Chiyoda Line. The track has not been used for normal train services, though it has occasionally been used to run special trains for big events in Tokyo, such as fireworks shows.

The new attempt to use the track was prompted by the linkup between the Odakyu Romancecar line and the Chiyoda Line, which began in March. The linkup allowed trains to run between Kita-Senju Station on the Chiyoda Line and Hakone-Yumoto Station on the Hakone Tozan Railway Line.