Colorado Oversize Load Permits, Regulations & Axle Rules

Colorado ties its oversize windows to a daylight-only framework, but the details run deeper than a simple sunrise-to-sunset rule. The most restrictive cut is on width: a load wider than 14 feet is flatly prohibited during hours of darkness (sunset to sunrise) unless it carries a Chapter 6 Special permit. Loads between 8'6" and 12 feet wide at night don't need an escort but must run with flashing yellow lights front and rear. Loads between 12 and 14 feet wide at night add a pilot escort, front on two-lane roads, rear on four-lane. Overweight loads under 110,000 lbs GVW that are within all other legal dimensions and can sustain 40 mph on flat ground (30 mph on grade, or the minimum posted speed) are exempt from the hours restriction entirely. Emergency vehicles and emergency response moves are similarly exempt.

Weekends by themselves don't close Colorado roads to permitted loads, but the I-70 mountain corridor has its own seasonal rhythm that affects Friday-through-Sunday planning. Between the Morrison Exit (Exit 259) and the West Vail Exit (Exit 173), extra-legal vehicles are blocked in specific directional windows from December 1 through March 31: westbound is prohibited Fridays from 3:00 PM to 8:00 PM and Saturdays and Sundays from 7:00 AM to noon; eastbound is prohibited Saturdays and Sundays from 3:00 PM to 9:00 PM. From May 15 through September 15, westbound restrictions shift slightly (Fridays 4:00 to 8:00 PM from Morrison, 5:00 to 8:00 PM from East Idaho Springs; Saturdays 8:00 AM to noon) and eastbound Sundays from 3:00 PM to 9:00 PM are still off. Planning a heavy haul west of Denver on a holiday weekend in ski season means stacking the I-70 corridor windows on top of the holiday blackout.

Colorado restricts only three summer holidays for general extra-legal loads, Memorial Day, Independence Day, and Labor Day, prohibited from 6:00 AM to 9:00 PM on each holiday. The Friday afternoon before each also closes partway, from noon to 9:00 PM. New Year's Day, Thanksgiving, and Christmas carry no movement restriction for standard oversize vehicles. Longer Vehicle Combinations face a harder rule and are prohibited entirely on Memorial Day, Independence Day, and Labor Day.

Four metropolitan areas enforce peak-hour curfews on extra-legal vehicles, Monday through Friday only. Denver's curfew runs 6:00 AM to 9:00 AM and 3:00 PM to 6:00 PM on I-25, I-70, I-76, I-225, I-270, US 36, US 285, and several state routes through the metro. Colorado Springs applies 7:00 AM to 9:00 AM and 4:00 PM to 6:00 PM windows on I-25 and its primary corridors. Pueblo uses the same 7:00 AM to 9:00 AM / 4:00 PM to 6:00 PM window on a shorter I-25 segment plus SH 47 and SH 50. The Aspen-Carbondale corridor on SH 82 carries 7:00 AM to 9:00 AM and 4:00 PM to 6:00 PM curfews as well. All of these can be waived under a Chapter 6 Special or Super Load permit.

Two geographic hard stops are worth building into route planning before any permit is requested. The Eisenhower-Johnson Memorial Tunnels cap permitted loads at 13'11" in height; any load over that is prohibited from the tunnels regardless of permit. Loads over 11 feet wide must stop at the tunnel approach parking lot and get clearance from the tunnel superintendent before entering. Clear Creek Canyon (US 6 between SH 58 and SH 119) is closed to extra-legal vehicles at all times on a standard permit; only a Chapter 6 Special or Super Load permit can authorize that route.

Movement is prohibited when road conditions are hazardous from water, ice, snow, mud, wind, or rocks, with a minimum 1,000 feet of visibility required. Colorado does not establish a codified 24-hour continuous movement allowance for any load category.

A handful of commodity categories get dimensional treatment that differs meaningfully from the general oversize rules.

Stinger-steered automobile and boat transporters operate under their own length and overhang parameters: 80 feet overall (not counting safety devices or the transported vehicles themselves), front overhang capped at 4 feet, and rear overhang capped at 6 feet, tighter than the standard 10-foot rear limit.

Steel, fabricated beams, trusses, utility poles, and pipes get a significant length exemption. For these commodities the overall combination length limits don't apply; length is measured without regard to how far the commodity projects beyond the front or rear of the vehicle. The overhang caps still apply (4 feet front, 10 feet rear), so the exemption runs to combination-length restrictions, not to the physical overhang rules.

Mobile crane boom sections transported side by side as items essential to crane operation are exempt from Colorado's divisible-load prohibition, as long as the side-by-side assembly does not exceed 11'6" in total width. The trailer carrying boom sections must travel directly behind the crane at a distance of 100 to 500 feet.

Loose hay (including loosely bound round bales) may be up to 12 feet wide without a width permit. Rectangular hay bales are permitted up to 10'6" wide. Commercial snow removal vehicles within all legal limits except width, and no wider than 14 feet, are exempt from curfew restrictions, sign requirements, and pilot escort requirements while actively plowing.

Longer Vehicle Combinations (LVCs), Rocky Mountain Doubles, Turnpike Doubles, Triples, and certain truck-with-trailer configurations, require a special LVC permit and may only travel on designated routes: I-25, portions of I-70, I-76, I-270, I-225, and a segment of SH 133. LVCs must have 6 to 9 axles and no more than three cargo units, are exempt from oversize signage and pilot escort requirements for length, and may carry up to 110,000 lbs GVW on non-interstate routes with an overweight permit.

Colorado has a two-tier structure at the top of its permit hierarchy, and understanding both tiers matters for planning an extreme move.

The first tier, and the one most carriers will hit, is the Chapter 6 Special permit. This is Colorado's functional superload review: it's required when any load exceeds the Maximum Limits for standard annual permits, which means over 17 feet wide, over 16 feet high, over 200,000 lbs gross weight, over 130 feet long on a four-lane highway (over 120 feet on non-mountainous two-lane, over 110 feet on mountainous two-lane), over 25 feet of front overhang, or over 35 feet of rear overhang. It's a single one-way trip permit and is not issued for divisible loads. At minimum, a Chapter 6 Special requires one pilot escort in front and one in the rear, though the Colorado Department of Transportation (CDOT) may add Colorado State Patrol escorts, additional pilot vehicles, or flagpersons based on route conditions. The applicant must examine the proposed route in advance and resolve all conflicts with structures, overhead lines, and railroad crossings before the move. CDOT may also require a bond or escrow account to cover potential highway damage or the cost of department personnel accompanying the move.

The second tier is a Super Load permit, technically a sub-permit of the Chapter 6 Special and reserved for extreme weight. A Super Load permit applies to a combination vehicle weighing 500,000 lbs or more that occupies two lanes to haul its load, or to an unladen combination vehicle with an expandable dual-lane transport trailer occupying two lanes. A vehicle or load is considered to occupy two lanes when its total width exceeds 15 feet. Third-party weight documentation is required, manufacturer's certification, a certified weight ticket, law enforcement clearance certification, or a bill of lading, and the driver must carry a copy at all times. The 500,000-lb threshold is unusually high by national standards, which means loads other states would call a superload typically move under a Chapter 6 Special in Colorado, not a Super Load.

No fixed statutory lead time is published for Chapter 6 Special or Super Load applications, but the route examination, conflict resolution, bridge review, and escort coordination requirements mean these permits aren't quick to obtain. Filing well in advance of the move date is necessary.

Colorado requires a formal route survey under two specific conditions, and the Chapter 6 Special process imposes a separate but related route examination obligation.

The height trigger is 17'6": any load taller than 17'6" must submit a route survey for its travel route before the permit issues. This is in addition to the pilot escort with a height pole required at heights over 16 feet, and the licensed signal contractor required to accompany loads over 17 feet through intersections with overhead traffic signals. The three height requirements stack rather than substitute.

The length trigger is 130 feet of overall combination length: any load or combination exceeding 130 feet must include a route survey. Route surveys required for dimensional reasons other than height are valid for 30 days unless the department specifies otherwise.

Under a Chapter 6 Special permit, the applicant must independently examine the proposed route and identify conflicts with all structures, including overhead lines and railroad crossings, before applying. This is a carrier-performed pre-move review that must be completed and documented as part of the application, not a state-performed engineering analysis. For Super Loads, the same examination applies and all conflicts must be resolved prior to the move.

For all permitted loads, not just those requiring a formal route survey, CDOT makes clear that the permittee is responsible for checking every overhead structure and utility along the route to confirm adequate clearance. CDOT maintains a Vertical Clearances Map listing all state highway structures with less than 14'6" clearance. On loads over 200,000 lbs crossing bridges with a speed restriction, the vehicle must display a rear sign reading "CAUTION: THIS VEHICLE MAY SLOW TO 10 MPH TO CROSS BRIDGES."

Colorado State Patrol (CSP) is the law enforcement agency for oversize permit escort in Colorado, but their involvement is never triggered automatically by a load's dimensions. Police escort is entirely at CDOT's discretion and attaches only to Chapter 6 Special and Super Load permits. The factors CDOT considers include highway width, traffic volume, visibility, and whether the width of the load interferes with or blocks more than one lane of traffic. Standard single-trip and annual permits don't carry a police escort requirement.

When CSP escort is required as a permit condition, the cost may be charged to the permittee. CDOT may require a bond or escrow account to cover CSP costs alongside highway damage protection before the permit issues. That makes the financial exposure of a Chapter 6 Special open-ended in a way a standard single-trip is not.

Civilian pilot escorts are the norm for most oversize moves. Colorado's escort requirements are built around a color-coded route system: the state's Pilot Escort and Oversize Restriction Map designates each highway as Red, Blue, Yellow, Green, or White, and the number and position of pilot escorts required for a wide load depends entirely on which color route the load is traveling. Red routes (narrow and mountainous) are the most restrictive; any load over 8'6" wide on a Red route requires a Chapter 6 Special. Blue routes (restricted two-lane highways) require a front pilot escort starting at just over 8'6" wide and both front and rear from 11 feet, with Chapter 6 required over 13 feet. Yellow routes (standard highways) begin requiring escorts at 11 feet, run front-and-rear from 13 feet, and Chapter 6 at over 15 feet. Green routes (wider multilane highways) don't trigger an escort until 13 feet wide. White routes, which include interstates, require only a rear escort between 15 and 17 feet and Chapter 6 above 17 feet.

Height requires a pilot escort regardless of route color: over 16 feet, the front escort must carry a height pole (non-conductive tip, non-destructive flexible material, with secondary securement beyond compression fittings, and calibrated to no more than 6 inches above the maximum height of the load). For length, escort requirements are tied to road type rather than map color: loads over 85 feet on mountainous two-lane highways require a front escort, over 110 feet on non-mountainous two-lane roads require a front escort, and over 115 feet on four-lane roads require a rear escort.

All pilot escorts must carry lights visible 360 degrees at 500 feet, standard stop/slow paddles, triangles, flares, cones, two-way radios, and first aid gear. A pilot escort is prohibited from accompanying more than one extra-legal load at a time unless a Chapter 6 Special permit expressly authorizes it. Extra-legal vehicles traveling together must keep at least a half-mile separation.