The Pennsylvania Railroad's class P5 comprised 92 mixed-traffic electric locomotives constructed 1931–1935 by the PRR, Westinghouse and General Electric. Although the original intention was that they work many passenger trains, the success of the GG1 locomotives meant that the P5 class were mostly used on freight. A single survivor, prototype #4700, is at the National Museum of Transportation in St Louis, Missouri. They had an AAR wheel arrangement of 2-C-2, or 2′ in the UIC classification system — three pairs of driven wheels rigidly mounted to the locomotive, with a two-axle unpowered truck at each end. This is an equivalent to a 4-6-4 in the Whyte notation. The PRR did not have any 4-6-4 steam locomotives, so the P5s were the only 4-6-4 type locomotives owned by the PRR. The first P5s were built with box cabs. A grade crossing accident in which the crew were killed led to the substitution of a central cab to give better crash protection, a streamlined steeple type, in later production, a design which was also applied to the GG1. When the GG1s were put in passenger service, the P5s were regeared and used in freight service for many years. The last of the class was withdrawn from service in April 1965. P5 prototypes Two prototype locomotives were outshopped from the PRR's Altoona Works in 1931. They were essentially the PRR's 2-B-2 O1 design lengthened by adding another pair of driving wheels; while the O1 was an "electric Atlantic" equivalent to the E6s steam locomotive, the P5 was an "electric Pacific" designed to match or better the performance of the PRR's ubiquitous K4s Pacifics. These prototypes had electrical equipment from both Westinghouse and General Electric; the design was by both companies and the PRR's electrical department, and the equipment from each manufacturer was identical. P5a production locomotives Orders were placed for 90 production locomotives classified P5a due to minor changes from the prototypes (notably, larger traction motor blowers). Production was split between General Electric and Westinghouse; the GE examples were assembled at GE's Erie, Pennsylvania facility, still a locomotive assembly plant today, while final assembly for the Westinghouse order was subcontracted to the Baldwin Locomotive Works. P5a (modified) steeplecabs A fatal grade crossing accident on the New York Division confirmed traincrews' concerns about safety when the crew were killed after colliding with a truckload of apples. A redesign was undertaken, giving the locomotives a