Third Avenue is an important two-way avenue in Brooklyn, stretching from Flatbush Avenue in Downtown Brooklyn to the foot of the Verrazano Narrows Bridge at Shore Road in Bay Ridge.
Upon leaving Downtown Brooklyn, 3rd Avenue provides two lanes through the mixed-use area. A one-way, southbound buffered bike lane stretches from Dean Street to 15th Street. At 3rd Street, the northbound side gains one more lane till 15th Street where the bike lane is replaced by a second lane for southbound traffic. At Prospect Avenue, 3rd Avenue runs directly under the Brooklyn Queens Expressway, Gowanus Expressway and Prospect Expressway interchange and becomes a six-lane arterial boulevard running under the Gowanus Expressway viaduct. Just south of 54th Street, 3rd Avenue grows to ten-lanes, with six express lanes and four local lanes. The center six-lanes curve westbound and follow the Gowanus Expressway while the local lanes turn into two-lanes after 64th Street and retain this characteristic until the road ends at Shore Road.