1. (a) It shall be unlawful for any individual to drive or move on any highway in this state any vehicle of a size or weight except in accordance with the following:

   1. (1) HEIGHT. No vehicle, semitrailer, or trailer shall exceed in height 13 1/2 feet, including load.
   2. (2) LENGTH. No vehicle shall exceed in length 40 feet; except, that the length of a truck-semitrailer combination, semitrailers, including load, used in a truck tractor-semitrailer combination, shall not exceed 57 feet; semitrailers and trailers, including load, used in a truck tractor-semitrailer-trailer combination, shall not exceed 28 1/2 feet each; and motor vehicles designed, used, or maintained primarily as a mobile dwelling, office, or commercial space, commonly called motor homes, shall not exceed 45 feet. Semitrailers exceeding 53 1/2 feet shall only be operated on highways designated pursuant to Section 32-9-1 and shall only be operated when the distance between the kingpin of a semitrailer and the rearmost axle or a point midway between the two rear axles, if the two rear axles are tandem axles, does not exceed 41 feet and if the semitrailer is equipped with a rear underride guard of a substantial construction consisting of a continuous lateral beam extending to within four inches of the lateral extremities of the semitrailer and located not more than 22 inches from the surface as measured with the semitrailer empty and on a level surface. For purposes of enforcement of this subdivision, lengths of semitrailers and trailers refer to the cargo carrying portion of the unit. Truck tractor units used exclusively in combinations transporting motor vehicles may directly carry a portion of the cargo, provided that the combinations are restricted to truck tractor-semitrailer combinations only and provided further that the overall length of these particular combinations shall not exceed 65 feet; except that the overall length of stinger-steered type units shall not exceed 80 feet. No truck tractor-semitrailer combination used exclusively for transporting motor vehicles shall carry any load extending more than four feet beyond the front or six feet beyond the rear of the combination. No other vehicle operated on a highway shall carry any load extending more than a total of five feet beyond both the front and rear, inclusive, of the vehicle.

   3. (3) WEIGHT.

      1. a.

         1. 1. Axle Weight. The gross weight imposed on the highway by the wheels of any one axle of a vehicle shall not exceed 20,000 pounds, or other weight, if any, as may be permitted by federal law to keep the state from losing federal funds; provided, that inadequate bridges shall be posted to define load limits.
         2. 2. For the purpose of this subdivision, an “axle load” shall be defined as the total load transmitted to the road by all wheels whose centers are included between two parallel transverse vertical planes 40 inches apart, extending across the full width of the vehicle.

         3. 3. Vehicles and combinations of vehicles shall not operate on the Interstate Highway System of Alabama that have a weight greater than 20,000 pounds carried on any one axle, including the allowable load tolerance, or with a tandem axle weight in excess of 34,000 pounds, including the allowable load tolerance, or overall gross weight on a group of two or more consecutive axles produced by application of the following formula:

            W=500 (LN/(N-1) + 12N + 36)

            where W = overall gross weight on any group of two or more consecutive axles to the nearest 500 pounds, L = distance in feet between the extreme of any group of two or more consecutive axles, and N = number of axles in the group under consideration; except, that two consecutive sets of tandem axles may carry a gross load of 34,000 pounds each, provided the overall distance between the first and last axles of the consecutive sets of tandem axles is 36 feet or more and the overall gross weight may not exceed 80,000 pounds, including the allowable load tolerance.

      2. b. Gross Weight. Subject to the limit upon the weight imposed upon the highway through any one axle as set forth herein, the total weight with load imposed upon the highway by all the axles of a vehicle or combination of vehicles shall not exceed the gross weight given for the respective distances between the first and last axle of the vehicle or combination of vehicles, measured longitudinally to the nearest foot as set forth in the following table:

         COMPUTED GROSS WEIGHT TABLE For various spacings of axle groupings

         Distance in feet between first and last axles of vehicle or combination of vehicles Maximum load in pounds on all the axles

         2 axles3 axles4 axles5 axles6 axles8 or less36,00042,00042,000 938,00042,50042,500 1040,00043,50043,500 11 44,00044,000 12 45,00050,00050,000 13 45,50050,50050,500 14 46,50051,50051,500 15 47,00052,00052,000 16 48,00052,50058,00058,00017 48,50053,50058,50058,50018 49,50054,00059,00059,00019 50,00054,50060,00060,00020 51,00055,50060,50066,00021 51,50056,00061,00066,50022 52,50056,50061,50067,00023 53,00057,50062,50068,00024 54,00058,00063,00068,50025 54,50058,50063,50069,00026 56,00059,50064,00069,50027 57,00060,00065,00070,00028 59,00060,50065,50071,00029 60,00061,50066,00071,50030 62,00066,50072,00031 63,50067,00072,50032 64,50068,00073,50033 65,00069,00074,00034 65,50070,00074,50035 66,50071,00075,00036 67,00072,00076,00037 68,00073,00077,00038 69,00074,00078,00039 70,00075,00079,00040 71,00076,00080,00041 72,00077,00081,00042 73,00078,00082,00043 74,00079,00083,00044 and over 75,00080,00084,000

      3. c. Special Permits. Except as provided by special permits, no vehicle or combination of vehicles exceeding the gross weights specified in paragraph a. or b. shall be permitted to travel on the public highways within the State of Alabama.

      4. d.

         1. 1. Allowable Load Tolerance. For purposes of enforcing this subdivision, all weights less than or equal to the sum of the weight otherwise prescribed by this subdivision, plus the allowable load tolerance, shall be deemed to be in compliance with the requirements of this section and shall not constitute violations thereof. No evidence shall be admitted into evidence or considered by the trier of fact in any civil action unless the evidence proffered would tend to prove that the weight of the vehicle exceeded the amount provided in this subsection. Nothing in this paragraph shall restrict or affect the right of any defendant to place in evidence such evidence tending to prove the defendant was in compliance with this section.
         2. 2. For the purposes of this subdivision, the allowable load tolerance is calculated by multiplying the weight prescribed by this subdivision by one-tenth (.10).

      5. e. Special Trucks.

         1. 1. Dump trucks, dump trailers, concrete mixing trucks, fuel oil, gasoline trucks, and trucks designated and constructed for special type work or use shall not be made to conform to the axle spacing requirements of paragraph b., provided that the vehicle shall be limited to a weight of 20,000 pounds per axle plus the allowable load tolerance; and, provided further, that the maximum gross weight of the vehicle shall not exceed the maximum weight allowed by this section for the appropriate number of axles, irrespective of the distance between axles, plus the allowable load tolerance. All axles shall be brake equipped.
         2. 2. Trucks delivering asphalt plant mix that do not exceed the maximum allowable gross weight and operate within 50 miles of their home base shall not be required to conform to the requirements of paragraph a.
         3. 3. Concrete mixing trucks that operate within 50 miles of their home base and do not exceed the maximum allowable gross weight shall not be required to conform to the requirements of paragraph a.
         4. 4. It is a violation if a vehicle named under this paragraph travels upon bridges designated and posted by the Director of Transportation as incapable of carrying the load.
      6. f. Driver Compliance. If the driver of any vehicle can comply with the weight requirements of this section by shifting or equalizing the load on all wheels or axles and does so when requested by the proper authority, the driver shall not be held to be operating in violation of this section.

      7. g. Portable Scales.

         1. 1. Portable scales may be used to enforce this section. To determine the weight of each axle, the axles of any vehicle described or commonly referred to as tandem or triaxle rigs or units, that is, vehicles having two or more axles in addition to a steering axle, shall be weighed simultaneously, and the total weight so derived shall be divided by the number of axles weighed in the group to arrive at the per axle weight, except that if any one axle in the group exceeds 20,000 pounds in weight, it shall not exceed the weight of any other axle in the group by more than 50 percent.

         2. 2. When portable scales are used to enforce this section and either the axle weight or the gross weight of a vehicle is determined to be in violation of this section, if the operator of the vehicle believes that the determination of a violation is based on inaccuracies of the portable scales, the operator may do either of the following:

            1. (i) Request that an enforcement officer accompany the operator and vehicle to the nearest platform scales certified by the Department of Agriculture and Industries and operated by a bonded operator within a distance of 10 highway miles to verify the accuracy of the portable scales used in determining the axle weight or gross weight of the vehicle. If the axle weights or gross weight of the vehicle is shown by the platform scales to be within the legal limits of this section, including the allowable load tolerance, the operator of the vehicle shall not be held to be in violation of this section.
            2. (ii) Proceed with the vehicle to the nearest platform scales certified by the Department of Agriculture and Industries and operated by a bonded operator within a distance of 100 highway miles to verify the accuracy of the portable scales used in determining the axle weight or gross weight of the vehicle without being accompanied by an enforcement officer. If the axle weights or gross weight of the vehicle is shown by the platform scales to be within the legal limits of this section, including the allowable load tolerance, the operator of the vehicle shall not be held to be in violation of this section upon providing a copy of the platform scale weight ticket and an affidavit, to be established and provided online by the court having jurisdiction over this matter within 48 hours of being weighed by the portable scales. Upon complying with this section, no court costs, fees, or penalties shall apply.
         3. 3. When using portable scales to enforce this section, not more than five vehicles may be detained at any one time, including a vehicle being weighed.
      8. h. County Highways. The governing body of a county, by appropriate resolution, may authorize limitations less than those prescribed in this section for vehicles operated upon the county highways of the county.
      9. i. Posted Roads and Bridges. The Department of Transportation may post or limit any road or bridge to weights less than those prescribed by this section. It is the legislative intent and purpose that this section be rigidly enforced by the Department of Transportation, the Alabama State Law Enforcement Agency, any other authorized law enforcement officer of this state, and any county, city, and incorporated town.
      10. j. Agricultural Commodities. Two and three axle vehicles being used exclusively for the purpose of transporting agricultural commodities or products to and from a farm and for agricultural purposes relating to the operation and maintenance of a farm by any farmer, custom harvester, or husbandman may not be made to conform to the axle requirements of paragraph a. or the gross weight requirements of paragraph b.
   4. (4) WIDTH. Vehicles and combinations of vehicles operating on highways shall not exceed a total outside width, including any load thereon, of 102 inches, exclusive of mirrors or other safety devices approved by the Department of Transportation. No passenger vehicle shall carry any load extending beyond the line of the fenders. No vehicle hauling forest products or culvert pipe on any highway shall have a load exceeding 102 inches in width.

2. (b)

   1. (1) Any vehicle utilizing an auxiliary power or idle reduction technology unit in order to promote reduction of fuel use and emissions because of engine idling shall be allowed an additional 400 pounds total to the gross, axle, tandem, or bridge formula weight limits defined in this section.
   2. (2) To be eligible for the exception provided in this subsection, the operator of the vehicle must provide written proof or certification of the weight of the auxiliary power unit (APU) and demonstrate or certify the idle reduction technology is fully functional at all times.
   3. (3) Written proof or certification of the weight of the APU must be available to law enforcement officers if the vehicle is found in violation of applicable weight laws. The weight allowed may not exceed 400 pounds or the actual weight proven or certified, whichever is less.
   4. (4) It is the intent of this subsection to apply at the state highway level the weight limit increase for vehicles using a functioning auxiliary power or idle reduction technology as provided in the Federal Energy Policy Act of 2005.

3. (c)

   1. (1) Any motor vehicle, if operated by an engine fueled primarily by natural gas, may exceed any vehicle weight limit, up to a maximum gross vehicle weight of 82,000 pounds, under this section by an amount that is equal to the difference between:

      1. a. The weight of the vehicle attributable to the natural gas tank and fueling system carried by that vehicle; and
      2. b. The weight of a comparable diesel tank and fueling system.
   2. (2) This subsection applies on federal interstate highways to the weight limit increases for vehicles using an EPA certified natural gas engine or an EPA approved conversion unit installed on the vehicle that allows the vehicle to operate primarily on compressed natural gas or liquefied natural gas.

4. (d) Nothing in this section shall be construed as effectuating either of the following:

   1. (1) Permitting size or weight limits on the National System of Interstate and Defense Highways in this state in excess of those permitted under 23 U.S.C. § 127. If the federal government prescribes or adopts vehicle size or weight limits greater than or less than those now prescribed by 23 U.S.C. § 127 for the National System of Interstate and Defense Highways, the increased or decreased limits shall become effective on the National System of Interstate and Defense Highways in this state.
   2. (2) Denying the operation of any vehicle or combination of vehicles that could be lawfully operated upon the highways and roads of this state on January 4, 1975.

(Acts 1927, No. 347, p. 348; Acts 1932, Ex. Sess., No. 58, p. 68; Acts 1939, No. 484, p. 687; Code 1940, T. 36, §89; Acts 1943, No. 179, p. 159; Acts 1947, No. 210, p. 72; Acts 1955, No. 245, p. 560, §1; Acts 1959, No. 413, p. 1052, §1; Acts 1961, No. 686, p. 980; Acts 1963, No. 295, p. 762, §1; Acts 1965, No. 879, p. 1645; Acts 1966, Ex. Sess., No. 334, p. 476; Acts 1975, No. 922, p. 1829, §1; Acts 1979, No. 79-792, p. 1445, §1; Acts 1979, No. 79-795, p. 1453; Acts 1985, 2nd Ex. Sess., No. 85-912, p. 188, §2; Acts 1989, No. 89-631, p. 1236, §1; Acts 1993, No. 93-308, p. 459, §1; Acts 1994, No. 94-305, p. 539, §1; Acts 1995, No. 95-758, p. 1774, §1; Act 2000-764, p. 1746, §1; Act 2010-543, §1; Act 2015-325, p. 991, §1; Act 2016-190, p. 440, §1; Act 2017-442, p. 1473, §1(b)(3); Act 2018-176, §1; Act 2022-181, §1; Act 2024-248, §1; Act 2025-272, §1.)