The campus where I work is connected by areas mainly intended for pedestrians. To encourage this, there are several of these automatic gates, which I think only open for campus service vehicles.
I have a hard time envisioning the logistics of this, because the arm only rises when a vehicle comes through. Which means, in order to be hit by the arm, you also must be walking directly into a moving vehicle, which to my mind would be at least an equally large problem.
But apparently the descending arm thing has happened, this gate has been wrapped with foam:
So maybe, I should feel superior because I've never walked into a service truck then gotten hit on the head by an electronic arm.
On the other hand, last week I was running an errand while reading a text, and I almost did this:
Can someone make me a sign for this? I'll afix it to the barrier. Think how many tripping texters we could save.