If you've ever taken the 456 at Union Square you may have noticed an oddity.
Unlike every other station in the NYC subway system, Union Square has a series of metal grates that shoot out when the train arrives, filling an otherwise awkwardly large gap between the train and the platform.
This gap exists because the station was built with quite a sharp curve.
Union Square station is one of the original IRT subway stations, which opened in 1904.
This entire line was built using "cut and cover" techniques, which involved building the subway directly underneath the road.
At this exact point around Union Square, Park Ave makes a bit of an awkward turn, which was baked into the station design.
This wasn't a problem at first because the original trains were smaller, but only 5 years after the station was built they were already talking about lengthening it.
And after they lengthened the station, and got new trains with doors that opened in the middle, all of a sudden the station had a gap problem.
And so they installed the gap fillers.
Originally, they were manually operated, but by the 60s they had been moved to accommodate new styles of trains, and in the process were automated.
For a long time, these weren't the only gap fillers in the system. The old times square shuttle used to have a gap filler due to some tight curves and South Ferry used to be a tight loop, which both required gap fillers and which couldn't fit the full train length. The doors could only open in half of the cars!
Both of these stations were later renovated, removing the moving platforms and leaving Union Square as the last remnant.
The gap fillers also aren't without issue. In 2010, a man fell between the train and the moving platform, and was crushed by it 167 times before they were able to turn it off. He received $10M after suing the city.
And in 2016, a faulty gap filler caused 625 train delays throughout the subway system.
Even without these extreme examples, trains have to dwell longer in the station because of these gap fillers, leading over time to a significant cost.
But, short of a full station redesign, the gap fillers are a compromise we're likely stuck with.
So what do you think? Do you like the gap fillers? Do you choose to use them or avoid them?