Fire crews responded to a gas main break at 16th Street and Park Road NW at about 9 a.m. this morning. Traffic was backed up on southbound 16th Street while firetrucks blocked one lane, and firefighters shut down a section of the sidewalk on the west side of the street. A strong smell of gas wafted across the intersection, and one firefighter instructed a pedestrian to put out his cigarette when he approached. A 3 inch gas main was struck by a worker operating a backhoe; construction on Park Road between 16th and 17th has been ongoing for weeks.