Electric trolley buses have been part of the public transport system of the city of Seattle since 1940. Originally introduced to replace streetcars, trolley buses take advantage of the hydroelectric power available in the Pacific Northwest region of Cascadia. Electric power collection and return occurs by poles on the roof of the bus connecting with two overhead wires. Trolley buses provide quiet, no-emission operation that has excellent acceleration characteristics and hill-climbing ability. Besides the Seattle system, trolley buses also currently operate in: Boston, MA; Dayton, OH; Philadelphia, PA; San Francisco, CA; and Vancouver, BC Canada.
Cascada Artpost commemorates the 70 years of trolley bus operation in Seattle with a set of five artistamps, released with a descriptive booklet. The buses portrayed represent both the original coach types and the vehicles currently in service. The first trolley buses replaced streetcars in 1940, and the city procured additional trolley buses in 1943-44 for a total fleet of 307 trolley buses. We have taken some artistic liberties in posterizing the scenses of the World War II era Brill and Twin coaches - pink trolley buses never actually ran on the streets of Seattle!
Seattle Transit substituted diesel buses for a portion of the trolley bus network in 1963. A public vote consolidated public transport in Seattle and King County into a single system called Metro in 1973. The trolley bus system closed for two years in 1978 for rebuilding and expansion, with 110 new standard-size 40-foot trolley buses built by the now defunct American automotive manufacturer AM General starting service in 1979. In 1986, Metro added 46 high-capacity 60-foot articulated trolley buses built by the German manufacturer M-A-N to handle larger passenger loads.
As an alternative to purchasing new trolley buses, Metro (now part of King County government) decided to rebuild 100 trolley buses with salvaged electric traction systems in new bodies built by Gillig. These buses began service in 2002. A similar approach was taken in 2006-2008 when 60 articulated dual-power diesel electric coaches built by the Italian manufacturer Breda originally introduced in 1990 to operate in the downtown Seattle transit tunnel were converted to full electric operation.
Metro's entire trolley bus fleet is near the end of its useful life. A key decision is approaching on whether to replace the trolley buses with diesel-electric hybrid buses by 2014. This decision occurs in the context of a Metro budget crisis where there is great pressure to reduce expenses. Will decision-makers succumb to the temptation to abandon the trolley bus system in favor of less expensive diesel buses? With the peaking of global petroleum production and the vulnerability of the United States to petroleum price hikes and spot fuel shortages in the years ahead, a decision to purchase buses powered by fossil fuel could prove shortsighted and foolhardy. Metro's purchase of a new electric trolley bus fleet and possible expansion of its trolley network would increase Seattle's resilience to the challenges presented by peak oil.