D.C. Code § 34-1921.05

All subways, conduits, manholes, and overhead lines constructed or erected under the provisions of this subchapter shall be subject to such reasonable regulations as the Council of the District of Columbia may from time to time prescribe as to inspection, location, character of conduit construction, and height of poles and wires; provided, that in all conduits so constructed, such space shall be furnished to the District government and the United States as may be necessary for purposes related exclusively to the government and public safety, free of charge; provided further, that the number of ducts so reserved in any one conduit shall not be more than 2.