(a) An agricultural service vehicle, as defined in subdivision 4(71) of this title, shall be exempt from the provisions of sections 1400 and 1400a and subsection 1434(c) of this subchapter if the gross weight does not exceed 60,000 pounds.
(b) Municipalities shall not be liable for injuries or damages to agricultural service vehicles or their operators that result from crossing a posted bridge with an agricultural service vehicle that weighs more than the posted weight limit.