(1)    No person shall operate upon a highway during hours of darkness any road machinery or motor vehicle used in highway construction or maintenance unless such vehicle or road machinery is equipped either as prescribed by par. (a) or (b):

      (a)    A red light visible from a distance of 500 feet shall be displayed on each side of the front and on each side of the rear to give adequate warning of the presence of such vehicle or machinery and to show safe clearance for passing or overtaking vehicles; or

      (b)    In lieu of the red lights prescribed by par. (a), 2 amber floodlamps may be used, one to be mounted on each side of the vehicle or machinery so as to illuminate its sides and its attachments, if any, to show safe clearance for passing or overtaking vehicles. Such floodlamps shall display an amber light of sufficient illuminating power to indicate safe clearance from a distance of 200 feet to the front and rear of such vehicle or machinery.

   (2)   The lights specified in sub. (1) need not be displayed upon motor vehicles used in highway construction or maintenance work when such vehicles are traveling along the highway at their normal operating speed in the ordinary course of traffic.

   (4)   No person shall operate upon the left-hand side of a highway during hours of darkness any road machinery or motor vehicle used in highway construction or maintenance, including snow and ice control, unless such vehicle or machinery is equipped with an auxiliary lamp or lamps projecting a flashing amber light visible from all directions for a 360-degree lens (beehive type lamp) or revolving type lamp and visible front and rear for reflectorized stationary directional type lamps. For flashing type lamps the number of flashes per minute shall be between 60 and 90. For revolving type lamps the revolutions per minute shall be between 45 and 90. The lenses of such auxiliary lamps shall not be less than 6 inches in diameter for the reflectorized stationary directional type lamp; 3-3/4 inches minimum diameter and 5-inch minimum height for the 360-degree lens (beehive type lamp); and 3-3/4 inches minimum width and 4-5/8 inches minimum height for the revolving type lamp. The lamps shall be equipped with bulbs of 50 candlepower minimum. The lamps shall be mounted approximately midway between the transverse extremities of the vehicle or machinery and at the highest practicable point.