D.C. Mun. Regs. r. 18-2418
No persons driving or in charge of a motor vehicle shall permit it to stand unattended without first stopping the engine, locking the ignition, removing the key, and effectively setting the brake.
In addition to the requirements of § 2418.1, whenever a motor vehicle is standing on a grade, the driver or person in charge of the vehicle shall not permit it to stand unattended without first turning the front wheels to the curb or side of the highway.
No person owning, operating, or having control over the engine of a gasoline or diesel powered motor vehicle on public or private space, including the engine of a public vehicles for hire, buses with a seating capacity of twelve (12) or more persons, and school buses or any vehicle transporting students, shall allow that engine to idle for more than three (3) minutes while the motor vehicle is parked, stopped, or standing, including for the purpose of operating air conditioning equipment in those vehicles, except as follows:
No person shall throw or deposit upon any street, highway, sidewalk, or alley, any glass bottle, glass, nails, tacks, wire, cans, or any other substance likely to injure any person, animal, or vehicle upon the street, highway, sidewalk, or alleyway.
Any person who drops, or permits to be dropped or thrown, upon any street, highway, sidewalk, or alley, any destructive or injurious material, shall immediately remove the same or cause it to be removed.
Any person removing a wrecked or damaged vehicle from a street, highway, sidewalk, or alley shall remove any glass or other injurious substance dropped upon the street, highway, sidewalk, or alley from the vehicle.
A horse shall not be left unbridled or unattended in a street or unenclosed space, public or private, without being securely fastened or unless harnessed to a vehicle with wheels so secured as to prevent its being dragged faster than a walk.
No person shall stop, stand, or park a vehicle on a street that has been designated a play street or closed to vehicular traffic except as specifically directed to do so by a police officer or other law enforcement or public safety official or by an official traffic control device.
D.C. Mun. Regs. r. 18-2418