Platform gap filler

"Gap filler" redirects here. For the Space Shuttle thermal protection system, see Gap fillers. For the car accessory, see Drop Stop.
Platform gap fillers being trialled at Platform 3 of Lo Wu station in Hong Kong in 2009.
Carleton station on the Trillium Line is the only station with two platforms. Note gap fillers at solid yellow markings.

Gap fillers close the gap between platform and train cars in the area of doors. This prevents alighting passengers from accidentally getting stuck in the gap. There are train-mounted gap fillers, whereas platform gap fillers are movable platform edge extensions installed at subway or railway stations. Gap fillers are deployed once the train stops but before doors open, and retracted after doors are closed and before the train departs.