In 1912, the electric cars were replaced by a unique monorail system with an overhead rail and catenary. The cars had wicker seats for the best in Edwardian comfort but again, just for the Senate. Apparently these cars were used until 1960. The system underwent renovations then, and I believe it was at that time that, hurray! The House got trolleys, too!
Both sides of Congress now have their own subway lines. Operator-driven trains run back and forth all day. The Senate has another computer-automated line just like your favorite airport shuttle. At least one car in every train is reserved for elected officials only. Civilians can ride the subway as part of an escorted tour group, except during voting sessions.
So. How many of you rail nuts have actually taken a trip on the Congressional Subway? Sure, it doesn't look all that impressive, but hey. A subway for Congress. Just think 'bout that. Pretty awesome.