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This three-sided pole on an airport tram
(sh.itjust.works)
I had never seen one of these before today. They're great. Way better than reaching for a single pole in a crowded car and wrapping your hand around some stranger's fingers. And If you have the whole thing to yourself you can hook your arm through it.
There's a lot of inertia when stopping on the airport trams I've been on with these. It could very possibly break a weak arm if one were stuck inside two metal bars.
They can take about 15-20 second to decelerate in an emergency. This is a link to some train geeks talking about it.
In my experience being stuck on a lot of light rail, those numbers sound about right. Those things never stop like a car when the e brake gets pulled. It’s too dangerous to stop them quickly since people are standing, walking, and sitting without buckles and headrests.
The existence of the handrail is proof of the potential for heavy inertia
Its existence is also kind of proof that emergency stops are slow enough that people can remain standing and squeezing a poll with 5 fingers will suffice for safety.