United States federal law requires that all personnel working on any federally funded eligible highway must wear high visibility clothing starting on November 25, 2008. Firefighters are only excluded from this requirement while actively engaged in firefighting activities or hazardous materials situations. At all other times, hi vis apparel must be worn. In addition, paramedics, police officers not engaged in law enforcement activities (i.e. traffic stops), tow truck operators, and road workers are required by law to wear high visibility clothing.
Depending on the speed of the traffic and the distance of vision to the workers it must be determined whether Class 1, Class 2 or Class 3 high visibility clothing is required.