20 Metro routes using the tunnel. The Seattle Times called it a "qualified success", commenting that the tunnel was like a "mini-subway system". The paper's editorial board also requested that Metro expand tunnel hours to keep buses running for late-night workers and entertainment events held on weekends. On December 9, 1991, the SODO Busway opened, extending bus service from the tunnel into SODO and moving southbound routes off Interstate 5. Direct access from Interstate 90 to the bus tunnel was opened in February 1992 as part of a reversible express lane system for the new floating bridge. The first use of the tunnel by Sound Transit buses began on September 18, 1999, with the takeover of Metro's Seattle–Bellevue express route, which was renumbered from 226 to 550. To operate buses in the tunnel, Sound Transit leased 20 dual-mode buses from Metro, repainted them in the agency's colors, and contracted with Metro to operate the route along with other Sound Transit Express routes in King County. Renovation for light rail From the outset, the bus tunnel was intended to be converted for light rail trains at some point in the future. Metro approved the addition of tracks to the bus tunnel in 1988, appropriating half of the $5 million used to install them during tunnel construction, the remainder coming from federal sources. To save $1.5 million in costs, Metro eliminated most of the rail's electrical insulation, which would later render them unusable for rail service. A regional transit authority was formed in the early 1990s to build and operate a light rail system that would use the bus tunnel within Downtown Seattle. The authority, later named Sound Transit, gained voter approval in November 1996 to build a $3.9 billion system between Seattle–Tacoma International Airport, Downtown Seattle, and the University District. In 1998, Sound Transit found that the rails in the tunnel would need to be replaced at a cost of up to $110 million and require a full closure for two years. The plan would also require the purchase of new hybrid electric buses to replace the Breda fleet, as the electrical systems were incompatible. Convention Place station would have to be abandoned as it was too shallow to support a northern extension under Interstate 5. Sound Transit approved its route for the light rail project, named Central Link (now the 1 Line), in November 1999, including four of the five