The opening of the Chrystie Street Connection to the Manhattan Bridge allowed the integration of four major routes of the combined system. The ' service of the IND was through-routed with the ' BMT West End Line service as the ', and the ' service of the IND was through-routed with the BMT Brighton Line service as the D. In 2004, the Brooklyn routes and terminals of the B and D trains were swapped as part of the Manhattan Bridge reconstruction from 1986 to 2004.