No bridges, viaducts, or other obstructions shall be constructed, insofar as practicable, over tracks in a railroad yard over which switching movements will be made at not less than twenty-three feet (23?) in the clear, and over any other railroad tracks at not less than twenty-two feet, six inches (22’6″), measuring from the bottom of the lowest timber to the top of the rail on the tracks. An exemption may be granted from any and all requirements of this section; provided, however, that any exemption must be limited to the specific bridge, viaduct, or other obstructions upon agreement between the department of transportation, public utilities administrator, railroad company, and the designated labor representative representing the railroad employees whose duties are to be atop of cars while in motion; provided, further, the agreement shall fix and prescribe reasonable regulations governing the location exempted; and provided, further, that an agreement between the aforesaid parties must be consummated within fifteen (15) days from the date of the request for an exemption from any and all requirements of this section. In case of failure to consummate an agreement, the public utilities administrator shall issue an order on the request for an exemption. The public utilities administrator shall, when issuing an order, take into consideration that his or her paramount responsibility in his or her decision to issue the exemption must be the safety of the railroad employees whose duties are to be atop of cars while in motion.