bollard

A strong vertical post of timber or iron, fixed to the ground and/or on the deck of a ship, to which the ship's mooring lines etc are secured.

Today he had for bollard the unfinished monument half-erected to some all but forgotten anarchist.

He sat on a bollard, looking out across the water, a man more small and shabby than expected.

A similar post preventing vehicle access to a pedestrian area, to delineate traffic lanes, or used for security purposes.