(1) Except as otherwise provided in subsections (3) and (4) of this section, no special permit shall be issued for movement on any state highway or route of a state highway within the limits of any city or town where the gross weight, including load, exceeds the following limits:

(a) Twenty-two thousand pounds on a single axle or on dual axles with a wheelbase between the first and second axles of less than three feet six inches;

(b) Forty-three thousand pounds on dual axles having a wheelbase between the first and second axles of not less than three feet six inches but less than seven feet;

(c) On any group of axles or in the case of a vehicle employing two single axles with a wheel base between the first and last axle of not less than seven feet but less than ten feet, a weight in pounds determined by multiplying six thousand five hundred times the distance in feet between the center of the first axle and the center of the last axle of the group;

(d) On any group of axles with a wheel base between the first and last axle of not less than ten feet but less than thirty feet, a weight in pounds determined by multiplying two thousand two hundred times the sum of twenty and the distance in feet between the center of the first axle and the center of the last axle of the group;

(e) On any group of axles with a wheel base between the first and last axle of thirty feet or greater, a weight in pounds determined by multiplying one thousand six hundred times the sum of forty and the distance in feet between the center of the first axle and the center of the last axle of the group.

(2) The total weight of a vehicle or combination of vehicles allowable by special permit under subsection (1) of this section shall be governed by the lesser of the weights obtained by using the total number of axles as a group or any combination of axles as a group.

(3) The weight limitations pertaining to single axles may be exceeded to permit the movement of equipment operating upon single pneumatic tires having a rim width of twenty inches or more and a rim diameter of twenty-four inches or more or dual pneumatic tires having a rim width of sixteen inches or more and a rim diameter of twenty-four inches or more and specially designed vehicles manufactured and certified for special permits prior to July 1, 1975.

(4) Permits may be issued for weights in excess of the limitations contained in subsection (1) of this section on highways or sections of highways which have been designed and constructed for weights in excess of such limitations, or for any shipment duly certified as necessary by military officials, or by officials of public or private power facilities, or when in the opinion of the department of transportation the movement or action is a necessary movement or action: PROVIDED, That in the judgment of the department of transportation the structures and highway surfaces on the routes involved are capable of sustaining weights in excess of such limitations and it is not reasonable for economic or operational considerations to transport such excess weights by rail or water for any substantial distance of the total mileage applied for.

(5) Application shall be made in writing on special forms provided by the department of transportation and shall be submitted at least thirty-six hours in advance of the proposed movement. An application for a special permit for a gross weight of any combination of vehicles exceeding two hundred thousand pounds shall be submitted in writing to the department of transportation at least thirty days in advance of the proposed movement.

Federal requirements—1977 ex.s. c 151: See RCW 47.98.070.

Effective dates—Severability—1975-'76 2nd ex.s. c 64: See notes following RCW 46.16A.455.

Effective date—1975 1st ex.s. c 168: "This 1973 [1975] amendatory act is necessary for the immediate preservation of the public peace, health, and safety, the support of the state government and its existing public institutions, and shall take effect July 1, 1975." [ 1975 1st ex.s. c 168 s 4.]