The junction serves as the western terminus of NY 347 and the eastern terminus of the Northern Parkway. NY 347 and NY 454 become concurrent, crossing through Hauppauge and residential properties for the next two miles (3.2 km), intersecting with local roads. After bending around Forestwood Park, Routes 454 and 347 follow the town line and pass the Stoubrough Golf Course, where NY 347 forks to the northeast.
The junction is the western end of NY 347 and the eastern terminus of the Northern Parkway.  NY 347 and NY 454 merge for two miles (3.2 km) before intersecting with local roads, passing through Hauppauge and residential areas. After a turn around Forestwood Park, Routes 454 and 347 continue along the town boundary, passing by the Stoubrough Golf Course, where NY 347 splits to the northeast.