Washington State Weigh Stations, Ports of Entry, and Bypass Rules

Commercial vehicle operations in Washington are governed by the Washington State Department of Transportation (WSDOT) and the Washington State Patrol (WSP) Commercial Vehicle Division. All vehicles with a Gross Vehicle Weight Rating (GVWR) exceeding 16,000 pounds must stop at open weigh stations. There are approximately 50 fixed scale sites across the state, including major Port of Entry facilities on Interstate 5, Interstate 90, and Interstate 82. The primary objective of these stations is to ensure compliance with RCW 46.44, which dictates legal weight limits, bridge formulas, and safety requirements. Failure to stop at an open station is a traffic infraction that can lead to significant fines and potential Out-of-Service orders during a Level I, II, or III inspection. Efficiently navigating these points of entry requires precise route planning that accounts for station locations and operational hours. DispatchTool integrates truck-safe routing that alerts drivers to upcoming weigh stations and helps dispatchers manage estimated times of arrival while accounting for potential inspection delays. By automating document management and IFTA mileage tracking within the platform, carriers can ensure their paperwork is ready for any unexpected roadside inspection at WSP facilities. Create a DispatchTool account to streamline your Washington route planning and maintain organized compliance records for your fleet.

Washington Weight and Dimension Limits

Washington follows the Federal Bridge Formula B for weight distribution on the Interstate system. The maximum legal gross weight is 80,000 pounds, provided the axle spacing is sufficient. Single axles are limited to 20,000 pounds, while tandem axles are limited to 34,000 pounds. Under RCW 46.44.041, vehicles may exceed these limits only with a valid oversize/overweight permit issued by WSDOT. The maximum width for any vehicle is 8 feet 6 inches, and the maximum height is 14 feet. Standard semi-trailer length is limited to 53 feet on the National Network, and any combination exceeding 75 feet in total length requires specific routing approval and signage.

Major Port of Entry Locations

Washington operates several high-volume Port of Entry (POE) stations near state borders. The Ridgefield POE on I-5 Northbound (Milepost 15) handles traffic entering from Oregon, while the Bow Hill POE on I-5 Southbound (Milepost 235) monitors traffic coming from the Canadian border. On the eastern side, the Plymouth POE on I-82 (Milepost 1) and the Stateline POE on I-90 near Spokane (Milepost 299) are critical inspection points. These facilities are often staffed 24 hours a day and utilize Weigh-in-Motion (WIM) technology to screen trucks at highway speeds. Drivers must be prepared for random Level I inspections, which include a full mechanical check of the tractor and trailer.

PrePass and Electronic Bypass Programs

Washington is a member of the PrePass system, allowing carriers with high safety scores to bypass scales without stopping. According to WSDOT, there are over 40 sites equipped with PrePass transponder readers. The bypass criteria are based on the carrier's ISS (Inspection Selection System) score, which is calculated using FMCSA safety data. A carrier with an ISS score between 1 and 49 is generally eligible for a bypass, while those between 50 and 74 may be pulled in randomly. Any score above 75 results in a mandatory pull-in. WSP also utilizes Drivewyze at selected locations, providing a software-based alternative to hardware transponders.

WSP Commercial Vehicle Enforcement

The Washington State Patrol Commercial Vehicle Division is responsible for enforcing safety regulations under Title 480 WAC. In addition to fixed scales, WSP utilizes mobile enforcement teams equipped with portable scales to monitor secondary highways and county roads. In a typical year, WSP conducts over 100,000 commercial vehicle inspections. Fines for weight violations are calculated based on the number of pounds over the legal limit. For example, a violation of 1,000 to 2,000 pounds over the limit can result in a fine of 3 cents per pound, while exceeding the limit by more than 10,000 pounds can result in fines exceeding $1,000 plus court costs.

Special Permits and Pilot Car Requirements

For loads exceeding standard dimensions, WSDOT issues various permits through the Self-Service Permit system. An Oversize/Overweight (OSOW) permit is required if the load exceeds 8 feet 6 inches in width or 14 feet in height. If a load exceeds 14 feet 6 inches in width or 16 feet in height, WSDOT requires at least two pilot cars and a specific route survey. Permits for 'Superloads' (gross weights exceeding 200,000 pounds) require a minimum of 30 days for engineering review. All permitted loads must carry a hard copy or digital version of the permit and strictly adhere to the designated travel hours, which usually exclude holidays and high-traffic commuter windows in Seattle and Tacoma.

Chain Requirements and Winter Operations

Washington has strict winter traction requirements, particularly for mountain passes like Snoqualmie (I-90) and Stevens (US-2). Under WAC 204-24-050, all vehicles over 10,000 pounds GVWR must carry chains from November 1 to April 1. On I-90, if chains are required, vehicles must have at least five chains for a standard tractor-trailer combination: two on the outer drive tires, two on the inner drive tires (or staggered), and one on the trailer. Failure to carry chains when required results in a $500 fine. Weigh stations often serve as the primary enforcement point for checking chain inventory during inclement weather events.

Sources

Washington State Department of Transportation (WSDOT) (2024) — https://wsdot.wa.gov/commercial-vehicle/permits Washington State Patrol (WSP) Commercial Vehicle Division (2024) — https://www.wsp.wa.gov/commercial-vehicle-division/ Revised Code of Washington (RCW) Chapter 46.44 (2024) — https://app.leg.wa.gov/rcw/default.aspx?cite=46.44 FMCSA SAFER System (2025) — https://safer.fmcsa.dot.gov/

Frequently asked

What is the weight limit for a single axle in Washington?

In accordance with RCW 46.44.041, the maximum weight allowed on a single axle is 20,000 pounds on the Interstate system.

Do empty trucks have to stop at Washington weigh stations?

Yes, all commercial vehicles with a GVWR over 16,000 pounds must stop at open stations, regardless of whether they are loaded or empty, unless they receive a green light from a bypass system like PrePass.

What is the fine for bypassing a weigh station in Washington?

Bypassing an open weigh station is a violation of RCW 46.44.105, typically resulting in a traffic infraction fine of $124 or more, and the driver may be pursued and escorted back to the scale by WSP.

How many tire chains must a tractor-trailer carry in Washington?

Vehicles over 10,000 pounds must carry enough chains to fit at least 4 tires on the drive axles and 1 tire on the trailer, totaling 5 chains for a standard semi-truck configuration during winter months.

Does Washington use the Drivewyze bypass system?

Yes, Washington State Patrol supports the Drivewyze PreClear bypass service at many of its fixed scale locations alongside the PrePass transponder system.