D.C. Code § 9-1201.10
It shall be the duty of the Council of the District of Columbia, and it is hereby authorized and empowered, whenever it considers it a public benefit, to grant the Baltimore and Potomac Railroad Company permission to lay, maintain, and use sidetracks and sidings from the main line or lines of said railroad into any real estate in the said city abutting on the streets or avenues on which such line of such company is or may be situated, east of Four-and-a-half Street and south of Virginia and Maryland Avenues, which may be used or occupied for manufacturing, commercial, or other business purposes by parties desiring the use of such facilities. Such sidetracks or sidings shall be laid and maintained under the direction of the Mayor of the District of Columbia and in such manner as shall least obstruct the use of the public streets for ordinary purposes: Provided, that the right to revoke the use of said sidetracks or sidings is reserved to Congress.
D.C. Code § 9-1201.10