At a location with a marking indicating a streetcar stop, vehicles may pass freely when the streetcar is not stopped, but when the streetcar is stopped and passengers are boarding or alighting, vehicles must come to a complete stop behind it unless there is a safety zone.

Answer: True

Explanation

The Rules of the Road state that the streetcar stop marking indicates the location of the stop, and when a streetcar is stopped and passengers are boarding or alighting, following vehicles must come to a complete stop behind the stop unless there is a safety zone. When there is a safety zone or when passengers are not boarding or alighting, vehicles may pass at a slow speed. This is an important rule to protect the safety of passengers.