Washington Legal Dimensions
Before determining whether a permit is necessary, carriers should compare their truck and load against Washington's legal dimensions. WSDOT lists the following general limits:
- 8 feet 6 inches maximum width
- 14 feet maximum height
- 53 feet for a tractor/semi-trailer
- 40 feet for a single unit
- 75 feet overall for a truck and trailer
- 3 feet maximum front overhang
- 15 feet maximum rear overhang
Exceeding these dimensions can trigger Washington's oversize permitting requirements.
What Commercial Carriers Need to Do
1. Determine whether the load is non-divisible.
Washington permits are generally issued only when the oversized portion cannot reasonably be separated or reduced.
2. Obtain the appropriate permit.
A common option is the single-trip oversize/overweight permit, which is route-specific and generally valid for up to three days. A dimensional-only permit is listed at $10, while overweight charges vary depending on the permitted weight and mileage.
3. Check the route before moving.
The carrier is responsible for checking restrictions, bridge limitations and overhead clearances. WSDOT specifically provides bridge-height information and a vertical-clearance trip planner.
4. Follow the restrictions printed on the permit.
Permitted movements can have restrictions concerning routes, travel times, holidays, bridges and other roadway conditions. The carrier must follow the conditions attached to the permit.
5. Determine whether pilot/escort vehicles are required.
Depending on the dimensions and route, an oversize movement may require pilot/escort vehicles. Particularly large loads require additional planning and may require specialized route and traffic-control arrangements.
When Does It Become a Washington Superload?
Washington defines a superload as a vehicle or combination carrying a non-divisible load that exceeds 16 feet wide, 16 feet high, 125 feet of load length, or 200,000 pounds. These movements cannot simply be handled like an ordinary oversize permit.
For example, applications for loads over 200,000 pounds must generally be submitted at least 30 days before the proposed movement, while applications for loads over 16 feet wide or 16 feet high must generally be submitted at least 7 calendar days beforehand.
Can You Self-Issue a Washington Oversize Permit?
Many routine permits can be self-issued through WSDOT's online permit system. WSDOT states that self-issued single-trip size/weight permits have limits of 16 feet wide, 16 feet high, 125 feet trailer/load length and 200,000 pounds gross weight, subject to the applicable permit conditions.
However, certain movements require WSDOT approval rather than ordinary self-issuance.
Important: State Roads vs. Local Roads
A Washington state oversize permit does not automatically authorize travel on every city street or county road. WSDOT states that carriers must contact the appropriate local jurisdiction for authorization to travel on city streets and county roads.
Bottom Line
For commercial truckers, the safest approach is to measure the complete vehicle and load, determine whether the load is non-divisible, obtain the correct Washington permit, verify the entire route and overhead clearances, and comply with every restriction listed on the permit. Oversize loads approaching or exceeding superload thresholds require significantly more advance planning and documentation.