Raymund Ryan, a curator of both the Heinz Architectural Center and the Carnegie Museum of Art, has a sparkling description of Pittsburgh's sister inclines in this article about urban characters in cities.
"Known as the Monongahela and the Duquesne, and dating from the 1870s, each consists of a double run of track and a contiguous cable, with one car ascending as its twin descends.
Entry is through chalet-like structures at both the base and top of each Incline; only the upper station is manned by an operator in a dedicated control box. The Monongahela cars are stepped in section with three small interior tiers; the red Duquesne cars are consolidated volumes, like miniature railway carriages. You climb aboard and the car shunts gently away from its berth. At night, the Monongahela track is marked by blue lights, the Duquesne by red."
To read more of Ryan's description and see what other cities mention in this interesting article, click here