Washington Oversize Load Permits, Regulations & Axle Rules

Washington has no default daylight-only rule for permitted loads. A permitted vehicle measuring no more than 12 feet wide, 14'6" high, and 105 feet in overall combined length may travel at night without any special authorization. Loads outside that envelope can still move at night if the permit specifically states "Night movement approved," but absent that notation, once a load exceeds any one of those three dimensions, daylight is effectively required. Check whether night approval is on the face of the permit before moving after dark.

Washington also has no statewide Saturday or Sunday travel ban. The only day-of-week restrictions run Monday through Friday and apply only to specific urban highway segments during commuter hours. Six holidays are travel blackouts for vehicles displaying "Oversize Load" signs, and the restriction begins at noon the day before each holiday and runs through the holiday:

- New Year's Day - Memorial Day - Independence Day - Labor Day - Thanksgiving (the restriction also includes the day after Thanksgiving, a Washington-specific addition, so it runs from noon the day before through the day after) - Christmas

An overweight-only load that stays within all legal dimension limits is entirely exempt from holiday, commuter curfew, nighttime, and winter restrictions, provided it can maintain posted speed, a useful carve-out for heavy but dimensionally legal freight.

Commuter curfews apply Monday through Friday on specific urban segments and affect only loads required to display oversize load signs. The Seattle-Everett corridor (I-5, I-405, I-90, and connecting state routes) restricts loads wider than 9 to 10 feet during morning peaks generally from 6:00 to 9:00 AM and afternoon peaks from 3:00 to 7:00 PM, varying by segment and direction. Tacoma restricts loads over 10 feet wide on I-5, SR 16, and SR 512 from roughly 6:30 to 8:30 AM and 3:00 to 7:00 PM. Olympia's I-5 window is narrower, running 4:00 to 6:00 PM only. Vancouver restricts I-5 and I-205 from 6:00 to 9:00 AM and 3:00 to 7:00 PM, Kelso's SR 433 (Lewis and Clark Bridge) from 6:00 to 9:00 AM, and Spokane's I-90 from 6:00 to 9:00 AM and 3:00 to 7:00 PM. Spokane uses a wider width threshold of 11'2" before the curfew engages; every other listed area uses 9' or 10'.

Weather halts all permitted oversize movement when daytime visibility drops to 1,000 feet or less. During night movement the floor is 500 feet, and no movement may occur when hazardous roadway conditions exist: snow, ice, mudslide, wind, or water flooding over the road. Any permitted oversize vehicle caught by deteriorating weather must stop at the nearest safe location and may not resume until it gets clearance from a WSDOT or WSP office. No continuous 24-hour movement type is authorized in Washington; extra-legal vehicles requiring escorts are also prohibited from traveling in convoy unless WSDOT specifically authorizes it.

Washington grants distinct treatment to several commodity classes, though the relief is structured differently for each.

Farm implements occupy a narrow legal window that permits movement without a permit at widths up to 16 feet. From 16 to 20 feet, a written application to CVS is required, along with 24 hours' advance notice to local WSDOT offices before each trip and 8-hour notification to maintenance areas. The hard ceiling is 20 feet wide, 16 feet high, 70 feet total length, and 65,000 lbs. In Whatcom, Skagit, Island, Snohomish, and King counties, farm implements are subject to a tighter 14-foot height restriction. Convoying is allowed for farm implements with properly equipped escorts, an exception to the general convoy prohibition.

Empty apple bins and rancher's hay (from own fields for own livestock) may be permitted up to 15 feet high and are specifically exempt from the front escort requirement that would otherwise apply at that height.

Milk double trailer combinations running up to 129,000 lbs and 85 feet of load length are exempt from both holiday restrictions and commuter curfew, a meaningful advantage on milk collection routes. The commodity-specific restriction is that loads must stay within legal axle limits.

Poles, pipe, machinery, or other structural objects that cannot be dismembered are exempt from length limitations when operated by a public utility for emergency repair of public service facilities. That exemption is narrower than in many states: it is limited to public utility emergency work, not general transport.

Washington uses the standard term Superload. Any nondivisible load triggering any one of four thresholds enters this tier: more than 16 feet wide, more than 16 feet high, trailing unit(s) plus load more than 125 feet long, or gross weight more than 200,000 lbs. All four are exclusive thresholds: the load must exceed the number, not merely reach it. The 200,000-lb weight threshold and the 125-foot length trigger are both relatively low compared to most states, so moves that might be routine permits elsewhere can push into superload territory in Washington.

Lead time is mandatory and varies by what makes the load a superload. Loads over 200,000 lbs require a written application submitted at least 30 calendar days before the move. Loads exceeding 16 feet wide or 16 feet high (but under the weight threshold) require at least 7 calendar days of advance notice. Loads over 300,000 lbs must go to WSDOT's pavement division for structural analysis, and that requirement is in addition to, not instead of, the 30-day notice.

All superload permits are issued out of WSDOT's Commercial Vehicle Services (CVS) office in Olympia, not by local regions. Required documentation includes:

- Evidence and purpose for the move, with a statement that alternate transportation modes (rail, barge) are not feasible and that the move serves the public interest - Nondivisible certification: a sketch or photograph explaining why the load cannot be shipped in sections - A vehicle sketch with detailed axle loadings, axle spacings, tire sizes, tires per axle, overall width, height, and length - Proposed route with complete mileposts; any applicable county or city permits - Traffic control plan showing the route, estimated delays, lane restrictions, escort and flag person assignments, overhead obstacle arrangements, and railroad crossing pretrip analyses

Loads over 16 feet high or over 300,000 lbs additionally require a shipper's letter describing why alternate transport modes are not feasible and how the movement serves the public interest.

WSDOT performs bridge analysis for every structure on the proposed route and pavement analysis when warranted by load weight. For loads where that analysis requires significant department resources, the applicant may be required to share those costs. If any structure or pavement is found inadequate, the permit is denied. The applicant must find an alternate route or reconfigure the load. Signal coordination is built into the height review: loads over 16 feet high trigger a notification to WSDOT signals, and loads over 16'6" require signal approval before the permit itself is finalized. WSDOT's Traffic Management Center is notified with the approved request and restriction sheets before travel begins.

Washington's route review for superloads is state-performed, not carrier self-survey. Every load that qualifies as a superload triggers WSDOT bridge and pavement analysis of the proposed route. This is the practical equivalent of a route survey, and it must be complete before the permit issues. The carrier submits the proposed route (with full mileposts) as part of the application; WSDOT reviews each structure. Loads over 300,000 lbs require an additional, more detailed pavement division analysis with a full schematic drawing showing side view, top view, end view, tire dimensions, tire pressure, weight, and axle spacing.

For height-sensitive loads below the superload threshold, the obligation shifts entirely to the carrier. Issuing a permit does not guarantee the route is clear of overhead obstructions. That responsibility belongs to the permit applicant, who must either check or prerun the proposed route and arrange safe detours around any obstructions before the move starts. Escort operators are required to prerun the route if necessary to verify overhead clearances as part of their pretrip procedures.

Railroad crossings get specific treatment under superload applications. Each crossing along the proposed route must be identified, with utility contact information, and a pretrip analysis must confirm the vehicle combination will clear the grade crossing. That documentation is part of the permit file before movement is authorized.

There is no general carrier self-survey obligation for loads that fall short of superload triggers, beyond the standard duty to check overhead clearances on height-sensitive moves. Superload surveys are on file before the permit issues. They are a precondition, not a post-permit task.

Washington has no codified dimensional or weight threshold that automatically requires a law enforcement escort. Police involvement is discretionary and situational, not triggered by crossing a specific number on any dimension chart.

The one hard rule is notification: for any superload move, the carrier must contact the Washington State Patrol (WSP) at 360-596-3800 at least 48 hours in advance. That notification requirement is not optional and does not depend on WSP ultimately providing an escort. It is a standalone obligation for every move that qualifies as a superload.

More broadly, additional law enforcement vehicles may be required on any superload as a result of the load's dimensions, speed, route, or time of day. That determination is made case by case during the permitting review, not from a published threshold table. WSDOT also has discretionary authority to require additional civilian pilot and escort vehicles when deemed necessary to protect the traveling public, assigned through the CVS administrator.

Civilian certified escorts handle the codified escort thresholds throughout Washington. Width, height, length, and overhang triggers all use civilian pilot vehicles, not police. When an off-duty uniformed law enforcement officer in an official vehicle performs escorting, the rules may be modified to fit that situation while preserving the underlying safety intent. All for-hire civilian escort operators must be certified for Washington state (or a reciprocity state: Arizona, Colorado, Georgia, Minnesota, Virginia, North Carolina, Oklahoma, or Utah), hold an active 8-hour initial training certificate renewed every 3 years, and carry insurance of at least $100,000/$300,000/$50,000 per incident.