Gap filler

Platform gap fillers are movable platform edge extensions at subway or train stations where the curvature of the platform creates a significant gap between the platform and subway or train car door.

Some Japanese railway stations have platform gap fillers, called kadō steppu in Japanese. Over 200 fillers are used in the Tokyo subway.

The Interborough Rapid Transit Company's first cars were built with only two doors on each side, at the extreme ends of the car, lining up with the curved platforms so as not to leave a wide gap between the train and the platform. When the IRT modified existing cars and ordered new cars with a middle door, gap fillers were needed because the middle door was not near the platform. After the City of New York bought the IRT in 1940, new car designs (starting with the R12) had the end doors away from the extreme ends of the carbody, which also required the use of gap fillers at certain stations.

IRT stations with gap fillers are:

Platform gap fillers are used in the Mass Rapid Transit system of Singapore, namely the North South MRT Line and the East West MRT Line. Platform gap fillers are also planned for installation on trains on the North East MRT Line and the Circle MRT Line as well, because newer trains can be equipped with gap fillers.

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