http://www.risf.org/direction2.html

From Manhattan:
Get on the Triborough Bridge at East 125th Street. Stay left for the exit to Randall’s Island, immediately after the toll plaza.

From Long Island and Queens:
Get on the Triborough Bridge from the Grand Central Parkway. Stay right for the exit to Randall’s Island, immediately after the toll plaza.

From the Bronx:
Take the Major Deegan or Bruckner Expressway to the Triborough Bridge. Stay right for the exit to Randall’s Island, immediately after the toll plaza.

From Brooklyn:
Take the FDR Drive North to the Triborough Bridge exit (on right). Stay left up to and after the toll, following the signs to Randall’s Island.