are posted at the transit centers in the City of Tucson. A customer service call center is operated for passengers to plan their bus trips with the assistance of a live customer service representative, information for Sun Tran, Sun Express, Sun Shuttle and Sun Link, fares and SunGO information, detours, comments and questions. The Sun Tran website also has an online trip planning function, and includes all schedules and maps featured in the Ride Guide. Regional Transportation Plan and streetcar system In May 2006, voters in Tucson approved a Regional Transportation Plan (a comprehensive bus transit/streetcar/roadway improvement program), and its funding via a new 20-year half-cent sales tax increment. The centerpiece of the Regional Transportation Plan is Sun Link, a modern streetcar system (inspired by the successful Portland Streetcar in Oregon) that travels through the downtown area, connecting the main University of Arizona campus with the Mercado District master plan area (known at that time as Rio Nuevo) on the western edge of downtown. In December 2010, a $63 million federal TIGER grant was awarded to the City of Tucson, meeting most of a remaining funding gap and allowing the modern streetcar project to move forward. An additional $6 million of federal funding was obtained through the Federal Transit Administration's New Starts program. Funding also came from utilities for relocation and improvements along the streetcar route, most significantly $10.6 million from Tucson Water. The Sun Link name was officially announced in the spring of 2012. Construction began in April 2012, with revenue service beginning in July 2014. Oregon-based United Streetcar manufactured the Sun Link vehicles. Sun Link maintains a fleet of eight vehicles, using up to six cars at once. Tucson placed an initial $26 million order for seven cars in June 2010. The eighth car was ordered for an additional $3.6 million in July 2012 in order to satisfy FTA requirements for a second spare. United's first model 200 car arrived in Tucson by flatbed truck on August 30, 2013. Sun Link is double-tracked, replacing a single-track configuration previously used by Old Pueblo Trolley (OPT), a volunteer-run heritage streetcar operation, begun in 1993, mainly used by tourists and local patrons (including University of Arizona students) of the numerous small shops, bars and restaurants along the line. The maintenance facility is located just west of the OPT car barn and yard on 8th Street west of 4th Avenue. OPT last