adjective

(of a road or place) so crowded with traffic or people as to hinder or prevent freedom of movement.

the congested streets of the West End

crowded,overcrowded,full,overfull,overflowing,full to overflowing/bursting,crammed full,cram-full,thronged,packed,jammed,teeming,swarming,overloaded,obstructed,impeded,blocked (up),clogged,choked,plugged,stopped up,snarled up,gridlocked,jam-packed,heaving,like Piccadilly Circus