Complex sentence: At its north end, Riverside Drive merges with the northbound lanes of the Henry Hudson Parkway, which were originally part of the road; the section exiting the parkway at the Dyckman Street exit and ending at Broadway is still known as Riverside Drive.
Split into simpler sentences: At its north end, Riverside Drive used to merge with the northbound lanes of the Henry Hudson Parkway, which were originally part of the road. The section exiting the parkway at the Dyckman Street exit and ending at Broadway is still known as Riverside Drive.