 All three highways take generally parallel tracks to Elmsford , where I @-@ 87 directly intersects the Saw Mill River Parkway at exit 7A . Not far to the north is exit 8 , a semi @-@ directional T interchange with I @-@ 287 ( the Cross @-@ Westchester Expressway ) . I @-@ 287 joins the Thruway here , following I @-@ 87 west across the Hudson River into Rockland County on the Tappan Zee Bridge . I @-@ 87 and I @-@ 287 remain overlapped for 15 miles ( 24 km ) through the densely populated southern portion of Rockland County , meeting the Palisades Interstate Parkway and the New York segment of the Garden State Parkway at exits 13 and 14A , respectively . The Thruway continues generally westward to Suffern , where I @-@ 87 and I @-@ 287 split at a large semi @-@ directional T interchange ( exit 15 ) near the New Jersey border . At this point , I @-@ 287 heads south into New Jersey while I @-@ 87 and the Thruway turn northward into the valley of the Ramapo River . 
