Colorado OS/OD Overview
Permit Required
Yes – any vehicle/load over legal size or weight requires a permit from the Colorado Department of Transportation (CDOT).
Legal Limits (Without Permit)
- Width: 8'6"
- Height: 14'
- Length: 75' (combo); 85' with some exemptions
- Weight: 80,000 lbs GVW (with axle group limits)
Permitted Load Maximums (Typical Upper Limits)
- Width: Up to 17' with escorts and route approval
- Height: Over 16' requires route survey and utility clearance
- Length: Over 110' possible with review
- Weight: Up to 250,000+ lbs with detailed axle spacing and engineering analysis
Superloads require special routing and CDOT bridge/structure approval.
Travel Hours
- Daylight only: For loads over 12' wide or 85' long
- Weekend/Holiday: No travel on major holidays or Sundays for larger loads
- Night travel: May be allowed for loads under 12' wide with permit
- Mountain routes: May have additional seasonal or weather-related restrictions
Escort Requirements (Standard Guide)
| Dimension | Escort Requirement |
|---|---|
| Width > 13' | 1 Escort (usually front in rural areas) |
| Width > 15' | 2 Escorts (front and rear) |
| Height > 16' | High pole car and route survey |
| Length > 110' | 1 or 2 Escorts depending on route |
Additional Notes
- Warning signs, flags, and amber lights are required as per permit
- Loads must follow CDOT-designated oversize routes
- Mountain passes may close in winter or require traction devices
- Permits issued via the Colorado COOPR system
Detailed Information
PERMITS: Permits valid for five days.
OPERATING TIME: Sunrise to Sunset. Up to 12' wide, night travel is allowed with proper lighting (see Signs, Flags, & Lights, below). Over 12' wide but not over 14' wide requires an escort for night running.
RESTRICTED TRAVEL: Curfew times are shown on the addendum that accompanies an oversize permit. Eisenhower Tunnel on I-70: maximum overall height allowed is 13'11". Higher loads use US6 to bypass the tunnel. Over 11' wide permitted loads must pull over and call to get clearance to pass through tunnel, but wider loads can use it. Loads into or out of Denver require a city permit for city streets, but Denver is very slow in turning them around (average 2-3 days).
LEGAL DIMENSIONS: Width: 8'6" Height: 14' 6" designated highways, 13' non-designated. Length: 57'4" trailer & load legal on interstate or designated Overhang: 4' front, 10' rear. Over 4' rear needs lighting for night running (see Signs, Flags, & Lights, below) highways. Weight: 80,000 Gross on Interstate, 85,000 on non-Interstate.
Steer – 20,000 Single – 20,000 Tandem – 36,000 Tridem – 54,000
ROUTINE PERMIT LIMITS: Width: 17' Height: 16’ over 14’6” requires a survey Length: 130' (4-lane highways).
Weight: Single – 22,000-27,000 Tandem – 42,000-50,000 Tridem – 55,000-65,000 Maximum permitted weights depend on route classification and axle spacings. Loads exceeding 17' wide or 200,000 GVW are Super Loads and require 6-10 days for approval. Quad – 60,000-72,000
ESCORTS:
Width: over 13’– 1 rear escort or one flashing yellow light in rear. The following requirements apply to most routes ("Green Routes"); some smaller routes may require more: Two-lane highways: Width over 13' – 1 escort; over 15' – 2 escorts, or 1 front escort and flashing yellow light in rear. Four-lane highways: Width over 13' – 1 rear escort or one flashing yellow light in rear; over 15' - 2-escorts, or front escort and flashing yellow light in rear.
Height: Over 16' – 1 escort with high pole. Over 17'6" - route survey and utility clearance letters also required.
Length: Over 85' on some portions of 2 and 4-lane highways – 1 escort. Over 110' on 2-lane or over 115' on 4 or more lanes – 1 escort. Overhang: Over 25' – 1 escort. Note: All pilot car vehicles must be over 60" wide for CO.
MISCELLANEOUS: Dozer blade can be detached and hauled with the dozer on same trailer if the load would be
overweight with or without the blade. Colorado Chain Law: All commercial vehicle truck-tractors operating on I-70
between Dotsero (milepost 133) and Morrison (milepost 259) between September 1st to May 31st must carry sufficient chains to be in compliance with the Colorado chain law. You can be fined for failure to comply. A permit is now available for overweight divisible loads on tractor/trailers with tandem, tridem or quad trailer.
SIGNS, FLAGS & LIGHTS: "Oversize Load" signs are required front and rear for all oversize loads. They are not
required and should not be used for overweight only loads. Flags are required at all four corners of any extremities for wide and over length loads, and at the end of load projections greater than 4 feet. For night travel of wide loads, a flashing yellow light mounted on front of the vehicle and two or three mounted to the extreme rear are required. Over length or with rear overhang (over 10') may run at night with a flashing yellow light
mounted to front of vehicle and from one to three cluster lights mounted to overhang (red for rear overhang, yellow for front overhang). For night travel with legal overhang (10' rear or less) but greater than 4' rear, a red light or lantern plainly visible for 500 feet is required at the end of load projection.