(1) Are there any weight exemptions for natural gas engines?

Yes, for the interstate system and no more than one mile access to and from the interstate system, natural gas vehicles, if operated by an engine fueled primarily by natural gas, may exceed vehicle weight limits set in RCW 46.44.041 up to two thousand pounds with a maximum gross vehicle weight of eighty-two thousand pounds. The increase in weight shall equal the difference between:

(a) The weight of the vehicle attributable to the natural gas tank and fueling system carried by that vehicle; and

(b) The weight of a comparable diesel tank and fueling system.

(2) What weights are authorized for emergency vehicles to travel on the interstate system?

(a) Emergency vehicles may operate without a permit on the interstate system and no more than one mile to and from the interstate system to a maximum gross vehicle weight of eighty-six thousand pounds and axle weights of:

(i) Twenty-four thousand pounds on a single steering axle;

(ii) Thirty-three thousand five hundred pounds on a single drive axle;

(iii) Sixty-two thousand pounds on a tandem axle; or

(iv) Fifty-two thousand pounds on a tandem rear drive steer axle.

(b) In this section, the term emergency vehicle means a vehicle designed to be used under emergency conditions:

(i) To transport personnel and equipment; and

(ii) To support the suppression of fires and mitigation of other hazardous situations.

(3) Operators of emergency vehicles described in this section shall check their route on Washington state department of transportation, commercial vehicle services website for restrictions prior to travel. These vehicles shall obtain approval/permit from the local jurisdiction when traveling on any local roads. Any firefighting apparatus or emergency vehicle shall obtain a permit from commercial vehicles services office prior to traveling on state highways that are not part of the interstate system if their weights exceed what is prescribed in RCW 46.44.190(4).