The Third Avenue Bridge spans the Harlem River, connecting East Harlem with Mott Haven in the Bronx. Motor vehicle traffic on the bridge flows southbound toward Manhattan but cyclists and pedestrians can go either direction.
Pedestrian and Bike Paths
There are shared bike/pedestrian paths on both sides of the bridge. There are stairs on both sides (yellow rectangles on the map). There is a roundabout way to avoid the stairs on the west side path, but it is hard. (See thin red and purple lines. Details below.)
The bike/pedestrian path is separated from the motor vehicle roadbed by a concrete and metal barrier. (This is the east side path, heading north.)
East Side Path
The Manhattan entrance is at the northwest corner of E. 128th Street and Third Avenue, underneath a pedestrian overpass (with stairs) designed to help you avoid heavy traffic at an intersection where traffic exiting the bridge moves through without a stop sign or light.
The stairs that serve as the east side path's Bronx entrance are hidden behind a building at Bruckner Boulevard and Third Avenue. There's a curb cut just outside the frame, to the left of the "one way" sign.
The east side path ends at the stairs that lead to street level, at right.
West Side Path
The Bronx entrance to the west side path is in an island at the southwest corner of Third Avenue and E. 135th Street, the elevated Major Deegan Expressway's service road.
The Manhattan entrance that is probably most direct for most trips is via this footbridge at the northeast corner of E. 129th Street and Lexington Avenue. Of course, for cyclists, that means carrying your bike up and down two sets of stairs.
As an alternative, the path continues . . . along a weedy pathway behind the back of a building and next to a Harlem River Drive off-ramp. (See the thin red line on the map above.)
This route's entrance/exit is the northwest corner of E. 128th Street and Second Avenue.
A third, shorter and less "off the beaten path" alternative is to cut through Harlem River Park (the purple line on the map), which has an entrance at the northeast corner of E. 128th Street and Third Avenue. There are gates at the entrance, and back behind along the bike/ped path coming off the bridge, implying that this cut-through is available only when the park is open.
Mass Transit
The Third Avenue Bridge carries the Bx15 local bus southbound.