a barrier set up by police to stop traffic on a street or road in order to catch a fugitive or inspect traffic etc.
render unsuitable for passage
block off with barricades
a barrier (usually thrown up hastily) to impede the advance of an enemy
prevent access to by barricading
something immaterial that stands in the way and must be circumvented or surmounted
an obstruction that stands in the way (and must be removed or surmounted or circumvented)