(1) Posted weight limits do not apply on any way, thoroughfare or place owned by a district formed under ORS chapters 545, 547, 551 or a corporation formed under ORS chapter 554.
(2) Posted weight limits do not apply on any road or thoroughfare or property in private ownership or any road or thoroughfare, other than a state highway or county road, used pursuant to any agreement with any agency of the United States or with a licensee of such agency or both.
(3) Posted weight limits do not apply to any vehicle, combination of vehicles, article, machine or other equipment while being used by the federal government, the State of Oregon or any county or incorporated city in the construction, maintenance or repair of public highways and at the immediate location or site of such construction, maintenance or repair.
(4) Posted weight limits do not apply to vehicles while being used on the roads of a road authority by mass transit districts for the purposes authorized under ORS 267.010 to 267.394, provided the weight of the vehicles is approved by the road authority for that road.
(5) Operations authorized to exceed weight limits by a variance permit issued under ORS 818.200 are subject to the terms of the permit. It shall be a defense to any charge of violation of ORS 818.040 if the person so charged produces a variance permit issued under ORS 818.200 authorizing the operation of the vehicle or combination of vehicles issued prior to and valid at the time of the offense. [1983 c.338 §511]