The Trinidad car barn at 15th and H Streets, NE, was once the last remaining structure in the city to have once housed a cable car power plant. According to a 1970 Washington Post article, the mechanism — which was gone long before the building was demolished in 1971 — consisted of a stationary steam engine that continuously propelled a steel cable beneath the streets for the full length of the line. This pulled the cars along at about 6 miles per hour from the car barn to the Treasury.
The structure was erected in 1895 to replace a horse-car barn that was erected when the line first opened in 1871. The cable service that replaced the horse cars on May 9, 1895, lasted only four years before being replaced by faster electric cars. The Trinidad barn was used by electric streetcars until 1942, when it was converted to a bus garage.
A few years before it was demolished by the Redevelopment Land Agency for moderate-income housing, it was abandoned by D.C. Transit and sold for $500,000 to help pay off some of D.C. Transit’s debts.
More pictures below.