(1) The maximum speed limit through any maintenance, repair, or construction zone on the state highway system shall be thirty-five miles per hour in rural areas and twenty-five miles per hour in urban areas.
(2) Such speed limits shall take effect only after appropriate signs giving notice of the speed limit are erected or displayed in a conspicuous place in advance of the area where the maintenance, repair, or construction activity is or will be taking place. Such signs shall conform to the manual and shall be regulatory signs imposing a legal obligation and restriction on all traffic proceeding into the maintenance, construction, or repair zone. The signs may be displayed upon a fixed, variable, or movable stand. While maintenance, construction, or repair is being performed, the signs may be mounted upon moving Department of Transportation vehicles displaying such signs well in advance of the maintenance zone.
(3) The Director-State Engineer may increase the speed limit through any highway maintenance, repair, or construction zone in increments of five miles per hour if the speed set does not exceed the maximum speed limits established in sections 60-6,186, 60-6,187, 60-6,189, 60-6,190, 60-6,305, and 60-6,313. The Director-State Engineer may delegate the authority to raise speed limits through any maintenance, repair, or construction zone to any department employee in a supervisory capacity or may delegate such authority to a county, municipal, or local engineer who has the duty to maintain the state highway system in such jurisdiction if the maintenance is performed on behalf of the department by contract with the local authority. Such increased speed limit through a maintenance, repair, or construction zone shall be effective when the Director-State Engineer or any officer to whom authority has been delegated gives a written order for such increase and signs posting such speed limit are erected or displayed.
(4) The Department of Transportation shall post signs in maintenance, repair, or construction zones which inform motorists that the fine for exceeding the posted speed limit in such zones is doubled.