The Downtown Seattle Transit Tunnel opened in 1990 and was designed for use by dual-mode buses built by Breda that would use electricity while driving through the tunnel and diesel while driving on the surface. After the tunnel was closed for refurbishment in 2005 to accommodate the Central Link light rail line, new diesel-electric hybrid buses were ordered as the post-refurbishment tunnel would not be able to accommodate both the light rail trains and buses relying upon the same electrical wires as a power source. The tunnel reopened in September 2007. Today, it is used by the Central Link light rail line, Sound Transit buses, and King County Metro buses.