Some drivers don't know what a bike box is

A bike box is the equivalent of an "advanced stop line" for motor vehicles.  Motor vehicles are supposed to stop at the bottom line of the bike box and bicyclists are allowed to proceed to the front of the box/intersection, in order to receive a head start when the traffic signal changes.

This bike box is westbound on M Street at 17th Street NW.  There were no bicyclists in the box at the time, and the cars entered the box, illegally.

M Street NW has a one-way cycletrack operating in the western direction.