As I-495 was being built across Long Island, it was specifically designed to accommodate certain topographical conditions and proposed interchanges. Exit 30 was originally a partial cloverleaf interchange with the Cross Island Parkway, while eastbound exit 30S was for Easthampton Boulevard with a connecting ramp to the southbound Cross Island Parkway. Exit 31 was originally a westbound only interchange for Douglaston Parkway; it was later combined with the exit for the Little Neck Parkway. Exit 39A was intended for the proposed extension of the Wantagh State Parkway near Powell Road in Old Westbury. It was intended to be a full Y interchange with an east-to-southbound-only off-ramp and a north-to-westbound-only on-ramp running beneath Powell Road.