Washington OSOW Regulations (WSDOT)

Legal Dimensions (No Permit Required)

• Width: 8'6" (8' on local roads)
• Height: 14'
• Length - Semi-trailer: 53'

Legal Weights (No Permit Required)

• Gross vehicle weight: 80,000 lbs maximum (105,500 lbs maximum legal weight allowed)
• Single axle: 20,000 lbs
• Tandem axle: 34,000 lbs
• Tridem axle: 42,000 lbs
• Two tire axle: 500 lbs per inch width
• Steer axle: 600 lbs per inch width

Permit Requirements

Non-Divisible Loads Only

• Permits only issued for loads that cannot be divided
• If load can be reasonably reduced, it must be reduced
• Permit will not be granted for divisible loads

When Permit Required

• Vehicles over legal dimensions and/or weight
• Required before entering state or moving within state

Maximum Permit Weight Limits

General Requirements:

• Permits issued only if load cannot reasonably be reduced
• WSDOT must determine structures/roads can sustain weight without undue stress

Weight Limits:

• 600 lbs per inch of tire width maximum
• 22,000 lbs on single axle maximum
• 43,000 lbs on tandem axle maximum

Special Single Axle Exception (up to 45,000 lbs allowed):

• Equipment with single pneumatic tires: rim width 20"+ and rim diameter 24"+
• OR dual pneumatic tires: rim width 16"+ and rim diameter 24"+
• OR specially designed vehicles manufactured and certified for special permits prior to July 1, 1975

Axle Series Weight Formula:

The weight allowed on any series of axles computed by:

Important:

• Lesser of any calculations governs capacity of any series of axles
• Bridge restrictions may limit single axle capacities to 21,500 lbs or less on selected highways

Permit Types

Over Axle Permit (Overweight)

For loads within legal gross weight, but axle(s) over legal weight limit:

• Over axle weight exceeds 20,000 lbs on single axle
• Over axle weight exceeds 34,000 lbs on tandem axle
• Tridem weight depends on measurement between three axles (check vehicle weight table)
• Pricing: Calculated based on weight over legal axle weight and number of miles traveled

Important:

• Operators may be fined for either over axle OR over gross violation, whichever produces greater fine
• Drivers may NOT shift load to avoid over axle citation
• Permit is void if violated

Superload Definition

Superloads exceed:

• 200,000 lbs gross weight, OR
• 125' length, OR
• 16' width, OR
• 16' height

Escort Vehicle Requirements

When Pilot/Escort Vehicles Are Required

Certified pilot/escort operator required when:

Width Requirements

Over 11 feet wide:

• Two-lane highways: 2 pilot/escort vehicles required (1 front, 1 rear)

Over 14 feet wide:

• Multilane highways: 1 escort vehicle required at rear

Over 20 feet wide:

• Multilane undivided highways: 2 pilot/escort vehicles required (1 front, 1 rear)

Over 12 feet wide on multilane highway with height requiring front escort:

• 1 rear pilot/escort vehicle required

Length Requirements

Trailer length (including load) exceeds 105 feet:

• Two-lane highways: 1 pilot/escort vehicle required at rear
• OR when rear overhang measured from center of rear axle exceeds 1/3 of trailer length

Trailer length (including load) exceeds 125 feet:

• Multilane highways: 1 pilot/escort vehicle required at rear

Front overhang exceeds 20 feet (measured from center of front steer axle):

• All two-lane highways: 1 pilot/escort vehicle required at front

Rear overhang exceeds 20 feet on single unit vehicle (measured from center of rear axle):

• Two-lane highways: 1 pilot/escort vehicle required at rear

Height Requirements

Over 14 feet 6 inches high:

• All highways: 1 pilot/escort vehicle with height measuring device (pole) required at front

Visibility Requirements

Operator cannot see 200 feet to rear (using rearview mirrors, measured from either side of edge of load or last vehicle):

• All highways: 1 pilot/escort vehicle required at rear

Department Discretion

• Department may require pilot/escort vehicle(s) to protect traveling public
• Must be authorized through department's administrator for commercial vehicle services

Temporary Reassignment of Pilot/Escort Position

Allowed when road conditions dictate:

• Example: Rear escort on overlength load may be temporarily moved to front to warn oncoming traffic on curvy highway segments where load encroaches on oncoming lane

Certified Flag Person Substitution

Special permit may authorize:

• Riding flag person in lieu of pilot/escort vehicle
• Flag person not required to ride in pilot/escort vehicle
• May ride in transport vehicle with transporter's authorization

Pilot/Escort Vehicle Operator Certification

REQUIRED - Washington State Certification Mandatory

Washington State Driver's License Holders:

• Must have valid Washington state pilot/escort vehicle operator certificate/card
• Must be on operator's person while performing escort duties

Out-of-State Driver's License Holders:

• May acquire Washington state escort vehicle operator certificate/card, OR
• Operate with certification from another jurisdiction approved by the department
• Subject to periodic review of issuing jurisdiction's certification program
• Current list of approved programs maintained by WSDOT commercial vehicle services office

Important Notes:

• Certification does NOT exempt operator from complying with all state laws
• Operators must comply with requirements of the state in which they're traveling

Certification Requirements:

• Attend 8-hour classroom training course
• Offered by business, organization, government entity, or individual approved by the department
• Successfully complete written test with minimum 80% passing score
• Certification cards renewed every 3 years

Pilot/Escort Vehicle Specifications

Vehicle Type

In addition to being in safe and reliable operating condition:

• Single unit passenger car (including passenger van), OR
• Two-axle truck (including non-placarded service truck)
• Maximum gross vehicle weight or weight rating: 16,000 lbs
• Body width: Minimum 60 inches, maximum 102 inches
• Must not exceed legal limits of size and weight (RCW 46.44)
• Equipped with outside rear-view mirrors on each side of vehicle
• Cannot tow a trailer while escorting

Passenger Restrictions

Pilot/escort vehicle may NOT contain passengers (human or animal) except:

• Certified individual in training status (with approval of pilot/escort operator)
• Necessary flag person (with approval)
• Service animal (must be located somewhere other than front seat)

Equipment/Load Restrictions

May carry items, equipment, or load if properly secured, UNLESS:

• Exceeds height, length, or width of pilot/escort vehicle
• Overhangs the vehicle
• Impairs recognition as pilot/escort vehicle by traveling public
• Obstructs view of flashing/rotating amber lights or "OVERSIZE LOAD" sign
• Causes safety risks
• Impairs performance of operator or pilot/escort vehicle duties

Required Equipment

Lighting

• Minimum 1 flashing or rotating amber (yellow) light or strobe
• Positioned above roof line
• Visible from minimum 500 feet to approaching traffic from front or rear
• Visible full 360 degrees around pilot/escort vehicle
• Light bars with appropriately colored lights meeting visibility minimums are acceptable
• Lights activated ONLY while:
  • Escorting extra-legal vehicle, OR
  • Stopped at roadside taking height measurements during route prerun
• Vehicle headlights must also be activated while escorting

Signs

• "OVERSIZE LOAD" sign required
• Dimensions: Minimum 5 feet wide x 10 inches high
• Lettering: Black letters, minimum 8 inches high in 1-inch brush stroke
• Background: Yellow
• Mounting: Over roof of vehicle
• Display: Only while performing as pilot/escort of extra-legal load
• When not escorting: Sign must be removed, retracted, or otherwise covered

Communication

• Two-way radio communications system required
• Capable of providing reliable two-way voice communications at all times
• Between pilot/escort vehicle(s) and extra-legal vehicle(s)
• Nonemergency electronic communication PROHIBITED except between pilot/escort and transport vehicle during movement

Additional Required Equipment (Must Be Carried)

1. Standard 18-inch STOP AND SLOW paddle sign
2. Three bi-directional emergency reflective triangles
3. Minimum one 5-pound B, C fire extinguisher (or equivalent)
4. High visibility safety garment - Class 2 specifications (ANSI/ISEA 107-1999)
   • Colors: Fluorescent yellow-green, fluorescent orange-red, or fluorescent red
   • To be worn when performing pilot/escort duties outside vehicle
5. Highly visible colored hard hat (per WAC 296-155-305)
   • To be worn when performing pilot/escort duties outside vehicle
6. Height-measuring device (pole) - when required by special permit
   • Must be non-conductive and non-destructive to overhead clearances
   • Upper portion constructed of flexible material to prevent damage
   • May be carried outside vehicle when not in use
7. First-aid supplies as prescribed in WAC 296-800-15020
8. Flashlight in good working order with red nose cone
   • Additional batteries should also be on hand

Height-Measuring Device (Pole) Requirements

Required when escorting loads over 14 feet 6 inches high (unless alternative authorization granted on special permit)

Specifications:

• Must extend 3 to 6 inches above maximum height of extra-legal vehicle or load
• Compensates for effect of wind and motion
• Mounted on front of lead pilot/escort vehicle
• When not in use: Must be removed, tied down, or otherwise reduced to legal height

Insurance Requirements

For-hire certified pilot/escort vehicle operators REQUIRED to have:

• $100,000 for bodily injury to or death of 1 person in any one accident
• $300,000 for bodily injury to or death of 2 or more persons in any one accident
• $50,000 for damage to or destruction of property of others in any one accident

Proof of insurance:

• Must be carried at all times by pilot vehicle operator
• Must be displayed upon request by law enforcement officer

Multiple Load Restriction

Pilot/escort vehicle CANNOT escort more than one extra-legal load at same time

• Unless department determines special circumstances
• Must have express authorization on special permit

Pretrip Procedures (Required)

Pilot/escort operator must:

1. Discuss with extra-legal vehicle operator:

   • Vehicle configuration
   • The route
   • Responsibilities to be assigned or shared

2. Prerun the route (if necessary)

   • Verify acceptable clearances

3. Review special permit conditions with extra-legal vehicle operator

   • When permit is single trip extra-legal permit displaying routing information:
   • Pilot/escort operator(s) must have copy of permit, including all special conditions and attachments

4. Determine proper position of required pilot/escort vehicles

   • Set procedures to be used among operators

5. Check mandatory equipment

   • Each operator responsible for his/her own vehicle

6. Check two-way communication system

   • Ensure clear communications between pilot/escort vehicle(s) and transport vehicle
   • Predetermine channel to be used

7. Acknowledge electronic communication prohibition

   • Nonemergency electronic communication prohibited except between pilot/escort and transport vehicle during movement

8. Prepare vehicle

   • Adjust mirrors
   • Mount signs
   • Turn on lights

Responsibilities of Front Pilot/Escort Operator

The operator shall:

1. Provide general warning to oncoming traffic of permitted vehicle presence

   • Use signs and lights

2. Notify extra-legal vehicle operator and trailing escort(s) about conditions affecting:

   • Safe movement of extra-legal vehicle
   • Safety of traveling public
   • Provide sufficient time for corrective action
   • Conditions include: road surface hazards, overhead clearances, obstructions, traffic congestion, pedestrians, etc.

3. Provide guidance to extra-legal vehicle through:

   • Lane changes
   • Egress from one designated route and access to next
   • Around any obstacle

4. In event of traffic buildup:

   • Locate safe place adjacent to highway for temporary stop
   • Notify extra-legal vehicle operator and trailing escort(s) in sufficient time
   • Allow extra-legal vehicle to move out of traffic flow
   • Allow following traffic to pass safely

5. Maintain proper distance ahead:

   • Be far enough in front to allow extra-legal vehicle to stop or take corrective action
   • Be far enough ahead to signal oncoming traffic to stop safely and timely before entering narrow structure or restricted highway
   • Do NOT be farther ahead than reasonably prudent considering speed, traffic, and highway conditions
   • Do NOT exceed distance that would interfere with maintaining clear two-way radio communication

6. Assist in emergencies:

   • Guide to safe place when extra-legal vehicle becomes disabled
   • Provide traffic control as needed

Responsibilities of Rear Pilot/Escort Operator

The operator shall:

1. Provide general warning to traffic approaching from rear

   • Use signs and lights

2. Notify extra-legal vehicle operator and lead escort(s) about conditions affecting:

   • Safe movement of extra-legal vehicle
   • Safety of traveling public
   • Provide sufficient time for corrective action
   • Conditions include: objects coming loose, flat tires, rapidly approaching traffic, vehicles attempting to pass, etc.

3. Notify about traffic impacts:

   • Traffic buildup behind extra-legal vehicle
   • Other delays to normal traffic flow

4. In event of traffic buildup:

   • Notify extra-legal vehicle operator and lead escort(s)
   • Assist extra-legal vehicle move out of traffic flow to safe place
   • Allow following traffic to pass safely

5. Maintain proper distance behind:

   • Be far enough behind to provide visual warning to approaching traffic to slow or stop in timely manner
   • Consider speed of extra-legal vehicle, other traffic, highway conditions (limited sight distance, mountainous terrain, narrow corridor)
   • Do NOT follow more closely than reasonably prudent
   • Do NOT exceed one-half mile distance to maintain radio communication (except when necessary for long narrow highway section)

6. Tillerman duties PROHIBITED:

   • Pilot/escort operators shall NOT perform tillerman duties while performing escorting duties
   • Tillerman = individual who operates steering of trailer or trailing unit

7. Assist in emergencies:

   • Guide to safe place when extra-legal vehicle becomes disabled
   • Provide traffic control as needed

Uniformed Off-Duty Law Enforcement Officers

When using official police car or motorcycle for escorting:

• Spirit of rules remains the same
• Specific rules may be modified to fit the situation

Trip and Fuel Permits (IRP / IFTA)

Temporary Trip Permit

Purpose: Provides temporary vehicle Washington State Licensing for 3 consecutive days in lieu of regular licensing

Capacity:

• Up to 40,000 lbs for single vehicle
• Up to 80,000 lbs for combination vehicles

Cost: $25.00

Temporary Fuel Use Permit

Required upon entering Washington State when:

• Commercial vehicle equipped with 2 axles with GVW exceeding 26,000 lbs, OR
• 3-axle vehicle regardless of GVW
• Powered by special fuel (diesel, propane, etc.)
• Does NOT pay fuel tax under International Fuel Tax Agreement (IFTA)

Cost: $30.00

Annual Permits

Collection Truck Permit

For: 2 or 3 axle single unit permit for limited excess weight

• 2-axle: $252.00 per year
• 3-axle: $336.00 per year

Empty Apple Bins Permit

Permits height up to but not to exceed 15 feet

• 30-day periods up to one year
• Cost: $20.00 per month / $240.00 per year

Hay Bales Permit

Permits height up to but not to exceed 15 feet

• 30-day periods up to one year
• Cost: $20.00 per month / $240.00 per year

Double Trailer Permit

Allows divisible loads on double trailers up to 68 feet

• 30-day periods to one year
• Cost: $10.00 per month / $100.00 per year

Log Tolerance Permit

Permits weights in excess of federal bridge formula

• For 3-axle log truck pulling 2-axle pole trailer
• Quarterly periods up to one year

Tow Truck Permit

Permits excess weight on axles of towing vehicle and towed vehicle

• Depending on method of tow and class of tow truck
• Class B: $75.00 (Annual)
• Class C: $150.00 (Annual)

Tarping System Permit

Permits divisible load width up to 9 feet

• For loaded vehicles equipped with tarping system
• Cost: $20.00 per month / $240.00 per year

Temporary Additional Tonnage Permit

Temporarily increases licensed weight of single units or combinations

• For legal weights only
• Minimum: 5-day periods
• Cost: $14.00 per ton

Manufactured Housing Monthly/Annual Permit

Maximum Limits:

• Height: 15 feet
• Width: 15 feet (includes 12-inch eave)
• Trailer length: Not to exceed 75 feet (including tongue length)

Valid for: 30-day period up to one year Cost: $30.00 per month / $360.00 per year

Note: Manufactured Housing Monthly Permit is a self-issue permit type Processing time: 1 business day Method: Online Commodity specific: Truck specific

Overweight / Oversize Fines

Overdimension-Only Violation

Fine: $122.00

• For dimensional violations (width, height, length) without overweight

Overweight Violation Fine Structure

Basic Penalties:

• First Offense: Not less than $50
• Second Offense: Not less than $75
• Third or Subsequent Offense: Not less than $100

Additional Fines Based on Excess Weight:

Minimum Fine: $150

Second Violation Within 12 Months (same power unit):

• Additional fines apply
• Registration suspended for not less than 30 days

Important Notes:

• Fines calculated based on permit weight
• Permit is void if violated
• Operators may be fined for either over axle OR over gross violation, whichever produces greater fine
• Drivers may NOT shift load to avoid over axle citation

Operating Times

Standard Hours

• 1/2 hour before sunrise to 1/2 hour after sunset
• Including Saturdays and Sundays

Night Movement (Limited)

Vehicles/loads not exceeding 12' wide, 14'6" high, and 105' long (including legal overhangs):

• May run at night with proper lighting
• Monday through Friday only

Commuter Curfew Restrictions

Time/width curfew restrictions for vicinity of:

• Seattle-Everett
• Tacoma
• Olympia
• Vancouver
• Kelso

Details: Listed on Commuter Curfew Hours sheet which accompanies permits

Holiday Restrictions

Movement on state highways RESTRICTED on:

• New Year's Day
• Memorial Day
• Independence Day
• Labor Day
• Thanksgiving Day
• Christmas Day

Additional restriction: Commencing at noon of the day preceding said holidays

Load Equipment Requirements

Warning Lights

When Night Movement is Allowed:

Loads Projecting Beyond Sides of Vehicle:

• Amber lights at outermost extremities
• Visible from front and side

Rearmost Edge(s) of Projecting Load:

• Red lamp required
• Visible from rear and side

"Oversize Load" Banner Requirements

Required for all oversized loads:

Sign Specifications:

• Dimensions: 7 feet long x 18 inches high
• Lettering: Black letters, minimum 10 inches high
• Background: Yellow

Sign Placement:

• Front of tractor at height of 5 feet from ground level
  • Or as high as practicable on vehicle or load if cannot accommodate 5-foot height
• Rear of vehicle

Flag Requirements

Flags must be displayed:

• On all four corners of all overwidth loads
• At extreme ends of all protrusions, projections, or overhangs

Tire Regulations

Tire Chain Requirements (November 1 to April 1)

All vehicles and combinations over 10,000 lbs shall carry sufficient tire chains on the following routes:

Interstate Highways:

• I-90: Between North Bend (MP 32) and Ellensburg (MP 101)
• I-82: Between Ellensburg Exit 3 (MP 3.00) and Selah Exit 26 (MP 26.00)

State Routes:

• SR-2: Between Dryden (MP 108) and Index (MP 36)
• SR-12: Between Packwood (MP 135) and Naches (MP 187)
• SR-14: (MP 18) to Junction 97 (MP 102)
• SR-20: Between Tonasket (MP 262) and Kettle Falls (MP 342)
• SR-97: Between Junction SR-14 (MP 4) Columbia River and Toppenish (MP 59)
• SR-155: Between Omak (MP 79) and Nespelem (MP 45)
• SR-410: From Enumclaw to Naches
• SR-542 (Mt Baker Highway): Between (MP 22.91) and (MP 57.26)
• SR-970: Between (MP 0) and (MP 10)

Exemption:

• Vehicles making local deliveries as indicated on bills of lading
• NOT crossing mountain pass
• Operating outside of chain-required area

Chain/Traction Control Area Restrictions

WSDOT or Washington State Patrol may prohibit any vehicle from entering chain/approved traction tire control area when:

• Determined vehicle will experience difficulty safely traveling the area

Oversize Load Movements - Prohibited When Following Signs Displayed:

1. "Traction Advisory/Oversized Vehicles Prohibited"
2. "Vehicles over 10,000 GVWR, Chains Required"
3. "Chains required on all vehicles except all-wheel drive"

Frost Laws (Load and Speed Restrictions)

WSDOT may impose load and speed restrictions when:

• Freeze-thaw conditions may subject roadway to damage from normal traffic
• Other conditions threaten roadway integrity

Emergency Load Restrictions

Applied to any road when:

• Untreated pavement layers (base course and sub-grade) are supersaturated and unstable

Severe Emergency Load Restrictions

Applied only to roadways with:

• Surfacing depth insufficient to resist subgrade swell pressure
• Surfaced with thin bituminous treatment

When Restrictions Must Be Imposed:

• Post road with appropriate signs
• Notify Commercial Vehicle Services
• Provide courtesy notices to principal road users as circumstances allow

Work Zone Safety

Washington averages almost 850 highway work zone injuries each year

• 96% of people injured or killed in work zone collisions are drivers and passengers
• Top 3 causes: distracted/inattentive driving, following too close, speeding

Work Zone Survival Tips:

1. Slow Down - Drive posted speeds for your safety
2. Be Kind - Workers are helping keep you safe and improve roadways
3. Pay Attention - To workers directing you and surrounding traffic; put phone down
4. Stay Calm - Expect delays, leave early or take alternate route; no meeting worth risking life
5. Eliminate distractions
6. Merge as soon as possible
7. Observe posted signs until you see "END ROAD WORK"

Drivers in Work Zones:

• Follow work zone signs and directions
• Watch for cones, barrels, barriers, pavement markings, work trucks
• Distracted/inattentive drivers not prepared for sudden slowdowns and last-minute lane changes

Contact Information

Washington Permit Department

Phone: 360-704-6340 Fax: 360-704-6350 Hours: 7:00 AM - 5:00 PM Pacific Time

Websites:

• http://www.wsdot.wa.gov/commercialvehicle
• https://wsdot.wa.gov/travel/commercial-vehicles/commercial-vehicle-permits
• https://www.wsdot.wa.gov/CommercialVehicle/permits.htm
• https://www.wsdot.wa.gov/CommercialVehicle/permitting.htm

State: Washington Agency: Washington State Department of Transportation (WSDOT)

Regulatory References

• Washington State Department of Transportation (WSDOT)
• WSDOT Commercial Vehicle Guide
• RCW 46.44 - Size, weight, load limits for vehicles and loads
• WAC 296-155-305 - Hard hat requirements
• WAC 296-800-15020 - First-aid supplies requirements
• ANSI/ISEA 107-1999 - American National Standard for High Visibility Safety Apparel (Class 2)
• https://wsdot.wa.gov/travel/commercial-vehicles/commercial-vehicle-permits
• https://wsdot.wa.gov/travel/commercial-vehicles/commercial-vehicle-permits/permit-types-descriptions
• https://jjkellercompliancenetwork.com/regsense/oversize-and-overweight-movements-washington

Last Updated: 2025-11-11