I'm sure we've all seen these devices which can "lock" and "unlock" vehicle entry and exit to an alley / road /etc.
They consist of one or several hefty steel or concrete "pillars" less than a metre high which can be lowered into the road surface.
They are strong enough that most vehicles couldn't just drive through them, at least not without substantial damage. But they let pedestrians and cyclists, perhaps even motorcycles, pass through easily.
Some like the one pictured have a place where somebody in a vehicle can use a keycard or such to gain access. Others I assume can only be opened by some remote access technology or perhaps by mechanical means.
In any case I don't know how to read up on them because all my attempts at Googling their characteristics to find a name have failed so far.