only subsequent – and the final – use occurred on December 21, 2007, when the last two active Flyers (4006 and 4016) entered service briefly after all-night sleet-cutting duty (scraping ice off of the overhead wires). In its final years the network that served Cambridge and vicinity used a fleet of 28 vehicles. The order for these was placed in December 2000, in a single contract with the vehicles for the Silver Line, but the first vehicle (4101) was not completed and delivered until 2003. Except for the first unit, these trolleybuses (numbered 4101–4128) were delivered in 2004 and were the first low-floor trolleybuses in North America. The first day of service for trolleybuses in this series was June 4, 2004. Current fleet The present Silver Line fleet consists of 32 low-floor, articulated dual-mode buses (numbered 1101–1132). These were built by Neoplan USA and fitted with Škoda electrical equipment, and delivered in 2004–2005. Eight of the buses (1125–1132) were funded by Massport and came equipped with luggage racks for airport passengers (and fewer seats than the other buses, 38 instead of 47), for use on route SL1, which serves Logan International Airport. In January 2011, four more buses (1121–1124) were also equipped with luggage racks in place of some seats. See also List of trolleybus systems in the United States References External links MBTA – Bus MBTA – Route 71 Watertown Square–Harvard Station via Mt. Auburn St. MBTA – Route 72 Huron Ave.–Harvard Station via Concord Ave. MBTA – Route 73 Waverley Sq.–Harvard Station via Trapelo Road MBTA – Route 77 Arlington Heights–Harvard Station via Massachusetts Ave. nycsubway.org – Boston Transit: Trolleybuses MBTA bus Transportation in Cambridge, Massachusetts Boston Trolleybus transport in the United States 1936 establishments in Massachusetts