D.C. Mun. Regs. tit. 18, r. 18-4010
The intersections listed in this section shall have traffic signal devices installed and operated to control vehicular and pedestrian traffic. The signal devices shall be programmed to operate in a manner determined by the Director.
The intersections listed in this subsection shall be controlled by traffic signals which shall operate on colors twenty-four (24) hours per day; Provided, that in the event of an emergency or malfunction, these signals shall flash the RED indications and YELLOW indications in the signals facing traffic as set forth in the location listing.
The intersections listed in this subsection shall be controlled by traffic signals which shall operate on colors at all times; Provided, that these signals shall flash the RED indication and the YELLOW indication in the signals facing traffic as set forth in the specific location listing on Monday through Friday from 1:00 a.m. to 6:00 a.m., on Saturdays and Sundays from 3:00 a.m. to 6:00 a.m. (average of 4.43 hours per day), and in the event of an emergency or malfunction.
The intersections listed in this subsection shall be controlled by traffic signals which shall operate on colors during the hours set forth in the specific location listing. These signals shall flash the RED indication and YELLOW indication in the signals facing traffic as indicated in the specific location listing at all other times or in the event of an emergency or malfunction.
The intersections listed in this subsection shall be controlled by traffic signals which shall operate on colors twenty-four (24) hours per day; Provided, that in the event of an emergency or malfunction, these signals shall flash the RED indication in the signals facing all traffic.
D.C. Mun. Regs. tit. 18, r. 18-4010