Electrification is at 600 volts DC third rail. Some segments formerly used overhead wire.
Included are certain technical specifications, available from issues of "The Street Railway Journal". Most stations received a few expansions, indicated for each station is the original electrical capacity and the capacity listed for 1899.
SOUTH SIDE ELEVATED RAILROAD
40th St. and State St.
In use 1898-1928
8 (expanded to 12) Babcock & Wilcox boilers
4 (expanded to 6) Allis horizontal cross compound engines
4 (expanded to 6) Westinghouse generators
Total 3,200 kilowatts/expanded to 6,400 kilowatts
NORTHWESTERN ELEVATED RAILROAD
1356 W. Fullerton Ave., 1/2 mile west of line.
In use 1900-1914
24 Babcock & Wilcox boilers
4 Allis cross compound Corliss-type engines
4 Siemens & Halske generators
Total 5,300 kilowatts
LAKE STREET ELEVATED RAILROAD
Western Ave. at Washington Blvd.
In use 1896-1902
20 (later expanded) Stirling boilers
3 (later expanded) Fraser & Chalmers Corliss-type engines
3 (later expanded) Siemens & Halske generators
Total 4,500 kilowatts/expanded to 8,000 kilowatts
In 1902, when the shared generating station of the Yerkes companies proved to be inadequate, the Lake Street Elevated Railroad constructed two substations and began purchasing its electricity from Commonwealth Edison.
Commonwealth Edison was formed by Samuel Insull, as Chicago's electric utility company. In 1911, Insull acquired control of all four elevated companies, which became the Chicago Rapid Transit Co.
In 1913, the three generating stations which had been owned by elevated railroads were leased to Commonwealth Edison. Commonwealth Edison subsequently phased those stations out, in favor of the newer larger central generating stations. Insull controlled Commonwealth Edison and the Chicago Rapid Transit Co. until 1932. The Chicago Rapid Transit Co. actually was a subsidiary of Commonwealth Edison from 1924 to 1938.