Bilevel cars were a clever design to solve the problem of increasing passenger capacity on railcars, without squeezing more (smaller) seats into the same space and/or decreasing the pitch (distance between seats).

If one couldn't add cars or increase the length of the car, there was only one direction to go - and that would be UP.

While it would be possible to reduce the lower floor height closer to the rails and add a separate upper level floor, another problem would arise.

That problem is the physical limitation on the conductor to verify, collect payment and sell tickets to such a large concentration of passengers in one car, especially in suburban passenger service, owing to the short distance between stops.

The ingenious solution came in the form of the design of the "gallery" car, which featured a upper levels, which were really mezzanines running along both sides of the car, with an open area between the mezzanines, hence the term "gallery".

This enabled the conductor(s) walking along on the lower level to easily reach up and punch/validate tickets of the passengers seated on the mezzanine level.

Pasengers would simply place their tickets in clips along a lengthwise panel, located slightly above the conductor's head and within easy reach. The conductor would then quickly check tickets and move to the next car.