The Bluebird, formally dubbed Compartment Car by its purchaser, the Brooklyn–Manhattan Transit Corporation (BMT), was an advanced design PCC streetcar-derived subway and elevated railway car built by the Clark Equipment Company from 1938 to 1940 and used on the New York City Subway system from 1939 to 1955. A total of six units were built, with one prototype and five production units. They were among the last cars to be ordered by the BMT before the city takeover in 1940. The cars were designed to operate on both elevated and subway lines; its lightweight design allowed it to run on the oldest elevated lines without the need to upgrade them to handle heavier cars, while its aluminum alloy body also allowed it to run in the newer subway tunnels, where wooden cars were strictly prohibited. The prototype Bluebird entered service in 1939. While the BMT ordered 50 production Bluebirds, only five were built, due to the New York City Board of Transportation cancelling the order when it took over operations of the BMT in 1940. The cars were in service until being retired in 1955. None were preserved. Design The articulated unit, long, wide and high, consisted of three compartments placed on four trucks, connected by fully enclosed, hinged passageways. The Bluebird was an example of Art Deco industrial design, presenting a clean and mildly streamlined appearance. The Bluebird was designed during the Great Depression as a fast, physically attractive, and comfortable mass transit vehicle that would attract passengers, while instituting significant economies in production, operation, and maintenance. The car's lightweight body and running gear, combined with its short truckbase and segmented body, permitted it to operate on the oldest elevated structures, with their light loading tolerance and sharp curves, as well as in tunnel sections, where policy prohibited the use of the wooden cars typically used on elevated lines. A single Bluebird unit, numbered 8000A/B/A1, was purchased by the BMT as a prototype for a planned fleet of equipment that could operate universally on both standard subway lines and older elevated lines. The BMT expected the Bluebird to preserve its investment in its elevated railway lines without expensive upgrading for heavier subway equipment, while attracting passengers with its interior comforts. Tests demonstrated that its greatly improved operating parameters could have cut significant time from existing elevated train schedules. Bluebirds were the first PCC-derived rapid transit cars utilizing the advanced