area voters overwhelmingly approved the ballot measure, which earned 74 percent average approval the following November. This marked the region's first successful vote approving public transportation. The Federal Transit Administration (the new name for UMTA) completed the funding package in 1991, granting $515 million to build the line up to 185th Avenue. It provided another $75 million in 1994 following the approval of the Hillsboro extension, which covered one-third of the segment's $224 million additional cost. Construction of the Westside MAX began in August 1993 with the excavation of the Robertson Tunnel. Several alternative alignments through the West Hills were studied, including an all-surface option along the Sunset Highway, an option with a half-mile-long (0.8km) "short tunnel", and an option with a "long tunnel". TriMet chose the "long tunnel" in April 1991. Frontier-Traylor, the project's general contractor, used conventional drilling and blasting techniques to dig through the west end. On the east segment, a tunnel boring machine was used to drill for two miles. Highly fragmented rock initially made machine excavation difficult, delaying the project for nine months. The $166.9 million tunnel was completed in 1997. It houses the Washington Park station, currently the system's only underground station and the deepest transit station in North America. Work along Oregon Highway 217 started in March 1994. Initially planned to run alongside freight trains through Beaverton and Hillsboro, the alignment was replaced with light rail following TriMet's acquisition of the BN right-of-way in June. The horseshoe tunnel below Sunset Highway was completed in July 1995 and all highway work ceased in December. Track work commenced west of 185th Avenue around the time the Elmonica Yard opened in January 1996. It was built to accommodate some of the 39 Siemens cars TriMet procured. The model SD660 low-floor cars, jointly developed by TriMet and Siemens, became notable as the first low-floor light rail vehicles in North America. The final rail spike was driven on Hillsboro's Main Street Bridge in October 1997. System testing took place in June 1998. Opening Owing to delays caused by tunneling work, the line's planned September 1997 opening up to 185th Avenue was postponed by one year. On August 31, 1997, the Westside MAX opened its first section, a two-station extension west to the Civic Stadium and Kings Hill/SW Salmon Street, in conjunction with the entry into service of the first low-floor cars. Grand opening celebrations for the entire $963.5million