Class\r Type of Worker\r \r \r \r \r Class 1\r Parking service attendants, warehouse workers in traffic, shopping cart retrievers and those doing sidewalk maintenance.\r \r \r Class 2\r School crossing guards, parking and toll gate personnel, airport ground crews and law enforcement personnel directing traffic.\r \r \r Class 3\r Roadway construction flaggers, workers in high speed traffic areas, workers in cluttered backgrounds that could interfere with visibility.