all previous designs. The cars were built with a very strong frame that utilized truss construction and allowed thin metal to be used for the side plating. This made the A/B Standards, foot for foot, lighter than similar all-steel IRT subway cars, but with a body twice as strong. Therefore, A/B Standards were considerably safer than any previous design, as they would not telescope in a collision. The strength of the design proved itself over and over again. Even in the 1960s, when the A/B Standards were at or approaching 50 years of age, a couple of cars were involved in minor yard collisions with newer cars. Yet in each case, the older cars appeared to have gotten the better of the collision afterward. Motorized A/B Standards (motor cars 2000–2899) were built with 2 "maximum traction" type trucks where wheels closest to the center of the car were 341/4 inches in diameter, while wheels closest to the ends of the car were just 31 inches in diameter. The motors were attached to the axles that bore the larger wheels. This design was believed to better distribute the car's weight to provide the best adhesion between the wheels and the rails to prevent wheelslip. Unpowered BX trailer cars 4000–4049 used more conventional trucks where all wheels were 31 inches in diameter. Innovations for riders Seating was designed to be comfortable and spacious. The A/B Standards had short rattan benches arranged in both transverse (forward- or rear-facing) and longitudinal (sideways-facing) positions. Two to three people could fit comfortably on each bench. This gave each rider more legroom and personal space. Supplemental seats located by each side door could be folded down for rider use at a conductor's discretion. When lowered, these seats would block side door leaves, so they were protected by lock to ensure only a conductor could lower them. Many of these latter were removed in later years. On the outer side doors, these were situated toward the center of the cars on cars 2000–2299 and toward the end of the cars on cars 2300–2899 and 4000–4049. Under regular conditions, 78 seats were available for riders in each car. During the 1950s, many (but not all) of the rattan seats were replaced by sprung leather or a plastic compound (velon) that replicated the feel of rattan. For standees, the cars featured four poles by each side door and small handles