Mississippi Oversize Load Permits, Regulations & Axle Rules

Mississippi runs permitted loads on a daylight rule, but the exact definition of "daylight" shifts with load width. For loads 12 feet wide or under, daylight is sunrise to sunset as reported by the National Weather Service. Push past 12 feet, and daylight tightens: the window shrinks to 30 minutes after sunrise and closes 30 minutes before sunset. That 60-minute narrowing is easy to underestimate on short winter days.

Night movement is available but tightly bounded. A load must be 12 feet wide or less, no more than 150,000 lbs, no longer than 99 feet overall, no taller than 13'6" (with the exact height ceiling depending on the route), and rear overhang may not exceed 4 feet. Certain forestry and agriculture products have a statutory night-travel allowance. Everything else stays off the road after dark.

Six holidays close the road entirely. No permitted movement is allowed after noon on the day preceding New Year's Day, Memorial Day, July 4th, Labor Day, Thanksgiving, or Christmas. Plan the cutoff as noon the day before, with movement resuming after the holiday itself; a holiday falling mid-week can effectively eliminate three days from a schedule. Mississippi does include an "unless otherwise permitted" qualifier, meaning MDOT can grant exceptions, but carriers shouldn't count on it.

Sunday movement is a documented ambiguity: older administrative rules prohibited it, and the current Permit Manual omits that restriction. Because the conflict is unresolved in the sources, carriers should confirm the current Sunday policy with MDOT before planning a Sunday move.

Loads wider than 12 feet must avoid three urban zones during weekday peak hours: Jackson, the Memphis/Southaven area, and the Gulf Coast (excluding I-10) from 7:00 AM to 8:30 AM and again from 4:30 PM to 5:30 PM. No additional city-specific curfews are identified in the sources beyond these three. Mississippi does not provide for continuous 24-hour movement on general permitted loads; the sealed container program is the main exception, with those loads authorized for around-the-clock movement seven days per week.

Weather halts movement independently of the schedule. No permitted load may move when visibility is below 500 feet, and overwidth loads are specifically prohibited during inclement weather; any pavement conditions, winds, or other hazardous conditions that compromise road safety are sufficient to stop the move.

Mississippi's commodity framework is substantially built around its agricultural and forestry industries, with several distinct permit types carrying real dimensional relief.

Timber and pole loads get the most generous overhang treatment in the state. The Pole Blanket Permit allows combinations up to 120 feet overall with up to 40 feet of rear overhang, the load may extend past the legal 8'6" width up to 9'6", and one rear escort is required with no more than two tractor-trailers convoying together. All Pole Blanket movement must be on state-maintained highways with at least 20 feet of pavement width; the Interstate is off limits, with narrow exceptions for loading and unloading. Loads must carry a red flag or cloth at least 16 inches square at the extreme rear, plus a rotating or oscillating amber strobe or LED light near the end of the load. For timber hauled at night, a separate Timber 12-Foot Rear Overhang Blanket Permit extends the travel window to two hours before sunrise through two hours after sunset and allows rear overhang up to 12 feet from the rear trailer lights, along with flashing amber lights on both sides of the rear.

Forest and agricultural products in their natural state may project up to 28 feet beyond the rear axle during daylight moves, secured with at least two chains, wire ropes, or nylon straps.

The Harvest Permit covers sand, gravel, fill dirt, and agricultural and forestry products at up to 88,000 lbs gross (80,000 lbs plus a 10% tolerance over the specific GVWR). If scales are available at the origin, no tolerance applies and the load may not exceed 80,000 lbs. Size must otherwise be legal (8'6" wide and 13'6" tall) except that unprocessed forestry loads may run up to 9'6" wide. The Harvest Permit is not valid on interstate highways (with narrow exceptions for loading/unloading or federally authorized corridors). Carriers needing interstate access for agricultural or forestry products must add a Special Interstate Agriculture Vehicle Permit: daylight movement only, and not available for gravel, sand, fill dirt, or asphalt.

Hay loads can run up to 14 feet high and 10'6" wide on a trailer no longer than 53 feet, daylight only, on both state-maintained and interstate highways.

Forestry equipment moves under the Forestry Equipment Blanket Permit at up to 100,000 lbs, 14 feet wide, and 14 feet high.

Sealed containers (containerized cargo for international import or export) are treated as non-divisible loads up to 95,000 lbs GVW with a tandem axle limit of 44,000 lbs. All other dimensions must be legal. The key operational advantage is 24-hour, seven-day-a-week movement, which is unavailable to general overweight loads. A bill of lading must be on board and a predetermined route is required.

Tractors towing dirt pans move under a combined 72-hour road use permit and oversize permit, limited to convoys of three units with both front and rear escorts, daylight only, using four-lane roads where available.

Mississippi calls its top-tier load a Super Load. A move becomes a Super Load the moment it exceeds any one of four thresholds: overall width more than 17 feet, overall length more than 121 feet, overall height more than 15 feet 7 inches, or gross weight at or above 189,999 lbs. Note the asymmetry: the three dimensional triggers are exclusive (the number must be exceeded), while the weight trigger is inclusive (189,999 lbs and above qualifies). A combination that just touches 17 feet wide or 121 feet long is not yet a Super Load on those dimensions, but a load at exactly 189,999 lbs is.

The Super Load permit process is documentation-heavy and manually reviewed by MDOT. No fixed advance-notice period is published, but the required package (route survey, traffic control plan, axle diagrams, and third-party notifications for extreme heights and lengths) makes this a process that should be initiated well ahead of the move date.

Required documentation includes the applicant's and shipper's names and addresses, origin and destination, gross weight and full dimensions of tractor, trailer, and load, and detailed diagrams showing the number, spacing, and weight of each axle, tire sizes, and a width/height profile of the load. Height pushes additional requirements in two steps: loads exceeding 16 feet 7 inches require written acknowledgement and permission from all affected utility and railroad companies. At 15 feet 7 inches, the Super Load threshold itself, a height pole becomes mandatory. On the length side, any move exceeding 120 feet requires written permission from affected railroad companies.

Travel on a Super Load permit is restricted to daylight. The escort requirements scale with the dimensions: a load at or above 15 feet 9 inches needs two blue light escorts plus a height pole escort; a load reaching 160 feet in total length needs two blue light escorts (one front, one rear); and a load at or above 300,000 lbs requires two blue light escorts. At widths of 18 feet and above, law enforcement may be required based on route and load conditions at the discretion of the Executive Director or the Commission. Additional escorts beyond the stated minimums may also be required at the MDOT Permit Division Director's discretion based on any combination of width, weight, and height. A detailed traffic control plan is required alongside the route survey: it must identify every point where the load encroaches into opposing traffic, the duration and distance of each encroachment, and how traffic will be stopped or managed at those points.

A physical route survey is required for every Super Load in Mississippi, without exception. The triggering thresholds track the Super Load definition: any move exceeding 17 feet wide, 121 feet long, 15 feet 7 inches tall, or reaching 189,999 lbs gross must submit a route survey as part of the permit application. The permit does not issue until the survey and all required documentation are in order.

The carrier performs the survey; MDOT does not conduct it. The survey must document three things. First, the full route or routes proposed for the move. Second, a list of every obstruction along the route and its shoulders: roadside and overhead highway signs, bridge rails, overhead traffic signals, overhead power lines, and every railroad crossing the load would encounter or approach from the shoulder. Third, identified pull-off areas sufficient to allow the tractor, trailer, and load to completely clear the roadway, including parking lots, truck stops, and other locations with adequate capacity. The pull-off documentation is operationally critical: Super Loads occupy entire lanes and traffic will accumulate behind them, so demonstrating where the combination can fully clear the road is a mandatory part of the review.

For loads exceeding 16 feet 7 inches in height, the survey requirement is compounded by the utility and railroad notification requirement: written permission from affected utilities and railroad companies must be secured and submitted, meaning the carrier must contact those parties and have their responses in hand before the permit application is complete. Loads longer than 120 feet carry the same railroad notification obligation.

Separately, carriers holding a Special Heavy Equipment Blanket Permit, which covers loads up to 150,000 lbs, cannot simply move on the annual permit alone. Before each trip they must obtain a secondary routing permit from the MDOT Permit Division or through MDOT's ExpressPass web routing system. That per-move routing step functions as a route-clearance check even for blanket-permit holders.

Mississippi uses the term "blue lights" to distinguish law enforcement escorts from civilian pilot vehicles. The police agency is the Mississippi Highway Patrol, operating under the Mississippi Department of Public Safety. Three Super Load thresholds trigger codified blue light requirements: 160 feet or more in total length (two blue lights, one front and one rear), 15 feet 9 inches or more in height (two blue lights front and rear plus a height pole escort), and 300,000 lbs or more in gross weight (two blue lights). At these thresholds, the requirement is firm.

Below those Super Load breakpoints, width at 18 feet and above creates a discretionary police trigger. A blue light escort may be required for loads 18 feet wide and over depending on the route and load conditions, at the discretion of the Executive Director or the Commission. This is not a guarantee, it is a "may require" authority that MDOT holds. The MDOT Permit Division Director can also require more blue light escorts than the stated minimums for any Super Load based on the combination of width, weight, and height.

For general permitted loads below Super Load thresholds, civilian escort vehicles handle the requirement. Escort vehicles in Mississippi must be a single motor vehicle equipped with a flashing or revolving amber light, two warning flags, an oversize or wide load sign, and two-way radio communication between the escort and the towing vehicle. Positioning turns on road type: on a two-lane roadway (one lane per direction), the escort leads; on a divided highway (two or more through lanes per direction), the escort follows. Loads that also require blue lights need both law enforcement and civilian escorts as specified.

The sources do not specify a fixed scheduling process for arranging Mississippi Highway Patrol escorts; carriers should coordinate through MDOT's Permit Division, which manages Super Load approval and has the authority to specify escort requirements before the permit issues.