I recently visited the abandoned Rochester Subway (reporting mark RSB) or Rochester Industrial and Rapid Transit Railway, at the recommendation of a friend from Buffalo, NY. The subway was an underground rapid transit line in the city of Rochester, New York from 1927 to 1956. Contemporary photos show it used single streetcars, like Boston's Green Line, as a light rail line, with a large portion underground. It ran on its own private, grade-separated right of way through its entire length.
In 1900, the Erie Canal was re-routed to bypass downtown Rochester, and in 1919 the abandoned canal was bought to serve as the core of the subway. The subway was built below, and the subway's roof was turned into Broad Street. Construction was completed and operations began in 1927. Only two miles were in the tunnel, the rest of the route in open cut. The term "subway" did not refer to the tunnel, but to the route being grade-separated and operated as rapid transit. Connecting interurban lines were routed into the subway and off city streets, easing developing traffic congestion.
When the Utica streetcar system was abandoned in the late 1930s, New York State Railways transferred the relatively new steel cars to Rochester to replace the 2000-series center-door cars that had been in service since the opening of the subway. The Utica cars ran until the end of passenger service on June 30, 1956. Car #60 was saved for preservation, and is currently undergoing restoration by the Rochester Chapter, National Railway Historical Society.
The subway from Court Street to Rowlands was replaced by the Eastern Expressway in 1956. Limited freight service operated by connecting railroads lasted on the subway route from Court Street to General Motors until 1976, when the City of Rochester elected to fill the cut to eliminate the numerous bridges. Rail freight deliveries in the subway tunnel continued until 1996, when Gannett Newspapers moved their printing operations to another location.
(info and photos taken from the web)