Washington OS Load info.

Washington OS/OD Overview

Permit Required

Yes – all oversize or overweight loads require a permit from the Washington State Department of Transportation (WSDOT).

Legal Limits (Without Permit)

• Width: 8'6"
• Height: 14'
• Length: 75' (combo); 53' trailer allowed
• Weight: 80,000 lbs GVW (with legal axle spacing)

Permitted Load Maximums (Typical Upper Limits)

• Width: 16' routine (14' on two-lane highways); wider is handled case by case. Escorts step in well below that — at 11', 14' and 20'. See the escort table below
• Height: 16' routine, and the permit does not guarantee clearance on the route. The escort trigger sits lower: a height-pole escort is required above 14'6"
• Length: 125' trailer and load routine. The rear-escort trigger splits by road type — above 105' on two-lane highways, above 125' on multilane
• Weight: Over 200,000 lbs with bridge/engineering analysis

Superloads require prior planning, structural review, and coordination with local jurisdictions and utilities.

Travel Hours

• Standard: ½ hour before sunrise to ½ hour after sunset
• Weekend: Travel allowed all day Saturday and Sunday
• Holidays: Permitted oversize/overweight moves may be restricted on New Year's Day, Memorial Day, Independence Day, Labor Day, Thanksgiving Day and the day after Thanksgiving, and Christmas Day, commencing at noon of the preceding day (WAC 468-38-175(1)). The rule says “may be restricted,” not “no movement” — it is discretionary, so read the restriction notice that comes with your permit instead of assuming it either way
• Night travel: A vehicle or combination that does not exceed 12' wide, 14'6" high and 105' overall combined length is exempt from the night-movement restriction and may run at night with proper lighting (WAC 468-38-075(3)). Outside that envelope you need “Night movement approved” noted on the permit. All three dimensions have to be inside it — a 10'-wide load standing 15' high is outside the envelope even though it is narrow

Escort Requirements (WAC 468-38-100)

These are measured against the trigger word Washington actually uses. Every requirement in WAC 468-38-100(1) reads “exceeds,” so the figure itself is clear: a load measured at exactly 11'0" wide or exactly 14'6" high needs no escort on that count. If you have seen 12' given as Washington's first width trigger, 16' as the height trigger, or 125' as the only length trigger — and those versions are common — they are wrong. Washington's first escort comes a full foot earlier than most states at 11', the height pole starts at 14'6", and on a two-lane the rear escort starts at 105'.

Certification and insurance: Washington requires a certified pilot/escort vehicle operator — 8-hour initial course, 4-hour recertification, 80% to pass, renewed every three years — and minimum insurance of $100,000/$300,000/$50,000 (WAC 468-38-100(4) and (16)(a)–(c)). On reciprocity: the WAC publishes no list of accepted out-of-state cards. 468-38-100(4)(b) says only that the department's commercial vehicle services office maintains the current list of approved programs. The fixed state lists that circulate online are not in the rule, so call WSDOT Commercial Vehicle Services before relying on an out-of-state certification here.

Where this page stands: my dataset does not carry Washington as fully verified. Not because the figures are soft — each one above is quoted from WAC 468-38-100 with its subsection — but because the certification entry is recorded against width alone, so it does not surface for a narrow load that needs an escort for height or length. So the figures are quoted, but the entry they sit in is not a verified one, and I am not going to dress it up as one: confirm them with WSDOT Commercial Vehicle Services before you rely on them, and especially if your load is over-dimension in height or length but legal on width.

Additional Notes

• All oversize loads must display “Oversize Load” signs, red/orange flags, and amber lights
• Mountain passes, ferries, and weather can impact travel—check conditions before moving
• Permits are issued through the WSDOT Electronic Permit System (WEP)

Detailed Information

PERMITS: Permits valid for three days. Must have permit prior to entering the state. Washington permits can no longer be purchased at POEs.

OPERATING TIME: One half hour before sunrise to one-half hour after sunset, All day Saturdays and Sundays. In addition, vehicle/loads not exceeding 12' wide, 14'6” high and 105' long, including legal overhangs, may run at night with proper lighting. Overweight only may travel 24/7 if they can maintain the flow of traffic.

RESTRICTED TRAVEL: Monday through Friday time/width commuter curfews apply in the Seattle–Everett, Tacoma, Olympia and Vancouver corridors. The Commuter Curfew Hours sheet that accompanies your permit is the controlling list of times and locations — read it, because it is the version the enforcement officer is working from.

LEGAL DIMENSIONS: Width: 8'6" Height: 14' Length: 53' semi-trailer (a 56' trailer and load permit is available for legal loads) Overhang: 3' front, 15' rear from center last axle to end of load. Weight: 80,000 Gross or more, depending on number of axles and their spacings Steer – 600 lbs. per inch of width (13,200 for 11" steers) Single – 20,000 Tandem – 34,000 Tridem – 42,000 (with at least 8' of axle spacing) Divisible Loads Exceeding 80,000: You can exceed 80,000 gross without a permit on state highways and on Interstate highways as long as you are legal on all axle/group weights and you are licensed for at least the amount of your gross weight.

ROUTINE PERMIT LIMITS: Width: 16' (14' on 2-lane highways) Height: 16' Length: 125' trailer and load Note on Height Clearances: Washington state oversize permits do not guarantee height clearances on permitted routes. Weight: 99,200* (5 axles) 108,000* (6 axles) 134,000* (7 axles) *Depending on axle spacings Steer Axle – 600 pounds per inch of tire width (13,200 pounds maximum with 11 inch tires) Single – 22,000 Tandem – 43,000 Tridem – Depends on spacings (4'2" spacings get about 54,080 pounds; 4'6" spacings get about 58,500 pounds, etc.) Register for up to 105,500 pounds to permit for that much or more. Loads exceeding these dimensions or exceeding 200,000 pounds are considered as Super Loads.

ESCORTS: On multilane highways: width over 14' – 1 escort at the rear (WAC 468-38-100(1)(b)); width over 20' on multilane undivided highways – 2 escorts, one in front and one at the rear (1)(c), with the rear escort from (1)(b) still in force. Trailer length including load over 125' – 1 escort at the rear (1)(d). On two-lane highways: width over 11' – 2 escorts, one in front and one at the rear (1)(a); trailer length including load over 105' – 1 escort at the rear (1)(d). On any highway: height over 14'6" – 1 escort in front with a height-measuring pole (1)(h); front overhang over 20', measured from the center of the front steer axle rather than from the bumper – 1 escort in front (1)(f); rear overhang over 20' on a single-unit vehicle, measured from the center of the rear axle – 1 escort at the rear (1)(g); and on a tractor/trailer or truck/trailer combination, rear overhang exceeding 1/3 of the total trailer and load length – 1 escort at the rear (1)(d). The one-third test and the 20' single-unit test are two separate triggers, not two readings of the same one. Note also that the length figures measure the trailer including the load, not overall combination length. I have dropped the “over 16' – case by case basis” line that used to sit in this paragraph: there is no such escort step in WAC 468-38-100. 16' is a routine permit width ceiling, not an escort trigger.

MISCELLANEOUS: All lift axles must be on the ground if exceeding legal axle weights. Overweight single piece loads must be reduced when possible. Loads created by means of welding, bolting, or tying will be considered to be reducible.

SIGNS, FLAGS & LIGHTS: "Oversize Load" signs are required for all oversized loads at the front of the tractor at a height of 5' from ground level (or as high as practicable on the vehicle or load if it can not accommodate the 5' height), and at the rear of the vehicle at a height of 5' to 7' from ground level (or as high as practicable on the vehicle or load if it can not accommodate the 5' to 7' height). Signs are not needed for overweight only loads. Flags must be displayed on all four corners of all overwidth loads, and at the extreme ends of all protrusions, projections, or overhangs. When night movement is allowed, loads projecting beyond the sides of the vehicle must have amber lights visible from the front and side at the outermost extremities. Rearmost edge of the projecting load must be marked with a red lamp visible from the rear and side.