Tag Archives: power supply

Vestiges of DC’s streetcar network

IMAG0148700 Block, 8th St SE

Winter’s freeze/thaw cycle chipped enough asphalt away from 8th St SE to expose the remaining vault of DC’s old streetcar system.  The rails themselves are gone, but the underground vault that provided power for the system remains, as does one of the square access panels in the street.   The rest of 8th Street contains discolorations and visible stress in the asphalt where more of the square access panels would have been, indicating more of the vault structure remains just below the surface.

New York’s streetcars used similar conduit technology.  The extensive website nycsubway.org has some fascinating pictures from New York’s streetcar infrastructure remnants, as well as this handy explanation of the system:

line-linear

This isn’t your basic track of two rails and wooden crossties. The track structure extends some two and a half feet into the earth. Under the paving blocks are cast iron yokes 5 feet apart, the trapezoidal shape shown here and in the previous line drawing. The yoke holds the shape of the lengthwise pieces, keeping the rails the right distance apart and keeping the conduit open.

The diagram above shows a double-track cable installation, but the basics are the same on Broadway. There is a yoke every 5 feet, and a pair of insulator covers around the conduit every 15 feet, and a cleaning manhole cover every 105 feet, of which every fourth one (420 feet apart) was also a slightly larger feeder manhole. It’s a lot of cast iron and concrete.

The exact diagram used here is actually for a cable car track, not a streetcar conduit – but the engineering is essentially the same.  Some of DC’s old cable cars were converted to electric power.

Wikipedia also has a great image of track work at 14th and G Sts NW, showing the extensive cast iron underpinnings of these underground conduits:

DC_Streetcar_construction

GGW and PoP have also taken note of remnants of DC’s streetcar infrastructure in the past, some of the last remaining signs of a once extensive network.