the Pioneer Zephyr for the Chicago, Burlington and Quincy Railroad in 1934, the first of several integrated streamliner trainsets. The General Pershing Zephyr of 1938 pioneered the use of disc brakes on railroad passenger cars. Budd built thousands of streamlined lightweight stainless steel passenger cars for new trains in the US in the 1930s through the 1980s. In 1949, Budd built ten prototype stainless steel R11 subway cars for the New York Board of Transportation; these were intended for the Second Avenue Subway. In the late 1940s, the Chicago, Burlington and Quincy Railroad sought a way to increase capacity on commuter trains serving Chicago, Illinois, without having to add more cars. Chicago Union Station charged railroads by the length of each train. Budd proposed coaches that were taller than the typical lightweight passenger car while keeping the streamlined car's length of 85 feet but with double the capacity of cars. To address the issue of the conductor collecting tickets without having to climb stairs, the upper level was designed with its center portion open so that the conductor could reach the tickets from upper-level passengers. Rows of individual seats on each side of the car provided the increase in seating capacity. The unique design of the upper level's open center section led to the cars being called "Gallery" cars. Burlington approved the design and ordered 30 cars. These cars, built as Budd lot 9679–041, were delivered between August 1950 and January 1951 and not only marked a change in how the commuters were handled but were the first cars in commuter service to have air conditioning. The Burlington retrofitted its earlier cars with air conditioning once the new cars entered service. With the first of the new commuter cars in service on the Burlington, the Atchison, Topeka and Santa Fe Railway also approached Budd to improve their rolling stock. In September 1952, the Santa Fe placed an order for two two-level prototypes, Budd's Lot 9679–129. Carrying the numbers 526 and 527, they were delivered in July 1954, at which time both were placed into service for evaluation. These prototypes had seating on both levels, stairs on one end to provide access to single-level cars, a stairway at the center of the car for access to toilets on the lower level, and a side door for passenger access. The lower floor also contained various mechanical and pneumatic equipment that otherwise would