(1)    Except as provided in sub. (3), the operator of any of the following vehicles before crossing at grade any track of a railroad, shall stop such vehicle within 50 feet, but not less than 15 feet from the nearest rail of such railroad:

      (a)    Every motor bus transporting passengers.

      (am)    Every vehicle painted and displaying markings in accordance with s. 347.44 (1).

      (b)    Every motor vehicle transporting any quantity of chlorine.

      (c)    Every motor vehicle which, in accordance with sub. (4), is required to be marked or placarded with a classification of marking or placarding that requires the vehicle to stop.

      (d)    Every cargo tank motor vehicle, whether loaded or empty, used for the transportation of any liquid having a flashpoint below 200 degrees Fahrenheit, as determined by the test method approved for that product by ASTM International.

      (e)    Every cargo tank motor vehicle transporting a commodity which at the time of loading has a temperature above its flashpoint as determined by the same standard method of testing as prescribed in par. (d).

      (f)    Every vehicle transporting a building, as defined in s. 348.27 (12m) (a) 1.

      (g)    Every cargo tank motor vehicle, whether loaded or empty, transporting a commodity under exemption in accordance with 49 C.F.R. part 107, subpart B.

   (2)   The operator of every vehicle required to stop before crossing any track shall listen and look in both directions along the track for any approaching railroad train or railroad track equipment, and shall not proceed until such precautions have been taken and until the operator has ascertained that the course is clear. Wherever an auxiliary lane is provided for stopping at a railroad, operators of vehicles required to stop shall use such lane for stopping.

   (3)   A stop need not be made at:

      (a)    A railroad grade crossing when a police officer or crossing flagman directs traffic to proceed.

      (b)    A railroad grade crossing when an official traffic control signal permits traffic to proceed.

      (c)    An abandoned railroad grade crossing with a sign indicating the rail line is abandoned.

      (d)    A railroad grade crossing which is marked with a sign in accordance with s. 195.285 (3). Such signs shall be erected by the maintaining authority only upon order of the office of the commissioner of railroads as set forth in s. 195.285.

   (4)   The department shall adopt rules for the marking and placarding of vehicles being used to transport hazardous materials which are potentially dangerous to life and property, which rules shall be in accordance with the regulations of the U.S. department of transportation. These rules shall identify classifications of markings or placarding that, consistent with federal regulations, when required on a vehicle also require the vehicle to stop as provided in sub. (1) (c).