When utility or public utility vehicles are parked, stopped or standing at the site of work as described in Section 22512, warning devices shall be displayed as follows:

A warning flag or barricade striping on the front and rear of the vehicle.

A warning flag, sign, or barrier on the highway not more than 50 feet in advance of the vehicle and not more than 50 feet to the rear thereof, except that in zones where the speed limit is in excess of 25 miles per hour the

50-foot distance may be increased up to 500 feet from the vehicle as circumstances may warrant.

One or more flashing amber warning lights on the vehicle giving warning to approaching traffic from each direction.

A warning light, flare, fusee, or reflector on the highway not more than 50 feet in advance of the vehicle and not more than 50 feet to the rear thereof, except that in zones where the speed limit is in excess of 25 miles per hour the 50-foot distance may be increased up to 500 feet from the vehicle where circumstances may warrant.