Complex sentence: Fifth Avenue carries one-way traffic southbound from 135th Street to Washington Square North, with the changeover from two-way traffic taking place on January 14,1966, at which time Madison Avenue was changed to one way uptown (northbound).
Split into simpler sentences: Fifth Avenue carries one-way traffic southbound from 135th Street to Washington Square North. The changeover to one-way traffic south of 135th Street took place on January 14,1966, at which time Madison Avenue was changed to one way uptown (northbound).