In 2012, the Broadway Extension, on the other side of the river from downtown Kansas City, was closed for renovation and improvement. The Broadway Bridge across the Missouri River stayed open to provide access to Kansas City Municipal Airport. The detour, though, started at the northwest end of the downtown freeway loop in Kansas City, hence all the construction signs seen in this 2012 view from Broadway at West 6th Street on the north end of the Garment District downtown.
The Broadway Bridge and the Broadway Extension are designated US 169.
The "6th Street Trafficway" was the original name of the northern leg of the downtown freeway loop (Interstate 70), running parallel to 6th Street itself. The sign on the signal mast arm is the only sign I've seen using that name.