Complex sentence: At the turn of the decade, the New York Dock Railway installed a pontoon float bridge, moved from a site in Manhattan, which was used until about 1990; it's wreck is still in the water just off the northwest corner of the yard.
Split into simpler sentences: At the turn of the decade, the New York Dock Railway installed a pontoon float bridge, moved from a site in Manhattan. It's wreck is still in the water just off the northwest corner of the yard.