(A) On Class III and non-designated state and local highways, the total outside width of any vehicle or load thereon shall not exceed eight feet.
(B) Except during those times when, due to insufficient light or unfavorable atmospheric conditions, persons and vehicles on the highways are not clearly discernible at a distance of 1000 feet, the following vehicles may exceed the eight-feet limitation during the period from a half hour before sunrise to a half hour after sunset:
(1) Loads of hay, straw or other similar farm products provided that the load is not more than 12 feet wide.
(2) Implements of husbandry being transported on another vehicle and the transporting vehicle while loaded. The following requirements apply to the transportation on another vehicle of an implement of husbandry wider than eight feet six inches on the National System of Interstate and Defense Highways or other highways in the system of state highways:
(a) The driver of a vehicle transporting an implement of husbandry that exceeds eight feet six inches in width shall obey all traffic laws and shall check the roadways prior to making a movement in order to ensure that adequate clearance is available for the movement. It is prima facie evidence that the driver of a vehicle transporting an implement of husbandry has failed to check the roadway prior to making a movement if the vehicle is involved in a collision with a bridge, overpass, fixed structure, or properly placed traffic control device or if the vehicle blocks traffic due to its inability to proceed because of a bridge, overpass, fixed structure, or properly placed traffic control device.
(b) Flags shall be displayed so as to wave freely at the extremities of overwidth objects and at the extreme ends of all protrusions, projections, and overhangs. All flags shall be clean, bright red flags with no advertising, wording, emblem, or insignia inscribed upon them and at least 18 inches square.
(c) "OVERSIZE LOAD" signs are mandatory on the front and rear of all vehicles with loads over ten feet wide. These signs must have 12-inch high black letters with a two-inch stroke on a yellow sign that is seven feet wide by 18 inches high.
(d) One civilian escort vehicle is required for a load that exceeds 14 feet six inches in width and two civilian escort vehicles are required for a load that exceeds 16 feet in width on the National System of Interstate and Defense Highways or other highways in the system of state highways.
(e) The requirements for a civilian escort vehicle and driver are as follows:
1. The civilian escort vehicle shall be a passenger car or a second division vehicle not exceeding a gross vehicle weight of 8,000 pounds that is designed to afford clear and unobstructed vision to both front and rear.
2. The escort vehicle driver must be properly licensed to operate the vehicle.
3. While in use, the escort vehicle must be equipped with illuminated rotating, oscillating, or flashing amber lights or flashing amber strobe lights mounted on top that are of sufficient intensity to be visible at 500 feet in normal sunlight.
4. "OVERSIZE LOAD" signs are mandatory on all escort vehicles. The sign on an escort vehicle shall have eight-inch high black letters on a yellow sign that is five feet wide by 12 inches high.
5. When only one escort vehicle is required and it is operating on a two-lane highway, the escort vehicle shall travel approximately 300 feet ahead of the load. The rotating, oscillating, or flashing lights or flashing amber strobe lights and an "OVER-SIZE LOAD" sign shall be displayed on the escort vehicle and shall be visible from the front. When only one escort vehicle is required and it is operating on a multilane divided highway, the escort vehicle shall travel approximately 300 feet behind the load and the sign and lights shall be visible from the rear.
6. When two escort vehicles are required, one escort shall travel approximately 300 feet ahead of the load and the second escort shall travel approximately 300 feet behind the load. The rotating, oscillating, or flashing lights or flashing amber strobe lights and an "OVERSIZE LOAD" sign shall be displayed on the escort vehicle and shall be visible from the front on the lead escort and from the rear on the trailing escort.
7. When traveling within the corporate limits of a municipality, the escort vehicle shall maintain a reasonable and proper distance from the oversize load, consistent with existing traffic conditions.
8. A separate escort shall be provided for each load hauled.
9. The driver of an escort vehicle shall obey all traffic laws.
10. The escort vehicle must be in safe operational condition.
11. The driver of the escort vehicle must be in radio contact with the driver of the vehicle carrying the oversize load.
(f) A transport vehicle while under load of more than eight feet six inches in width must be equipped with an illuminated rotating, oscillating, or flashing amber light or lights or a flashing amber strobe light or lights mounted on the top of the cab that are of sufficient intensity to be visible at 500 feet in normal sunlight. If the load on the transport vehicle blocks the visibility of the amber lighting from the rear of the vehicle, the vehicle must also be equipped with an illuminated rotating, oscillating, or flashing amber light or lights or a flashing amber strobe light or lights mounted on the rear of the load that are of sufficient intensity to be visible at 500 feet in normal sunlight.
(g) When a flashing amber light is required on the transport vehicle under load and it is operating on a two-lane highway, the transport vehicle shall display to the rear at least one rotating, oscillating, or flashing light or a flashing amber strobe light and an "OVERSIZE LOAD" sign. When a flashing amber light is required on the transport vehicle under load and it is operating on a multilane divided highway, the sign and light shall be visible from the rear.
(h) Maximum speed shall be 45 miles per hour on all such moves or five miles per hour above the posted minimum speed limit, whichever is greater, but the vehicle shall not at any time exceed the posted maximum speed limit.
(3) (a) Portable buildings designed and used for agricultural and livestock raising operations that are not more than 14 feet wide and with not more than a one-foot overhang along the left side of the hauling vehicle. However, the buildings shall not be transported more than ten miles and not on any route that is part of the National System of Interstate and Defense Highways.
(b) All buildings when being transported shall display at least two red cloth flags, not less than 12 inches square, mounted as high as practicable on the left and right side of the building.
(c) A State Police escort shall be required if it is necessary for this load to use part of the left lane when crossing any two laned state highway bridge.
(C) Vehicles propelled by electric power obtained from overhead trolley wires operated wholly within the corporate limits of a municipality are also exempt from the width limitation.
(D) (1) A recreational vehicle, as defined in ILCS Ch. 625, Act 5, § 1-169, may exceed eight feet six inches in width if:
(a) The excess width is attributable to appurtenances that extend six inches or less beyond either side of the body of the vehicle; and
(b) The roadway on which the vehicle is traveling has marked lanes for vehicular traffic that are at least 11 feet in width.
(2) As used in this division (D) and in division (E) of this section, the term appurtenance includes a retracted awning and its support hardware and any appendage that is intended to be an integral part of a recreation vehicle.
(E) A recreational vehicle that exceeds eight feet six inches in width as provided in division (D) of this section may travel any roadway of the state if the vehicle is being operated between a roadway permitted under division (D) of this section and:
(1) The location where the recreation vehicle is garaged;
(2) The destination of the recreation vehicle; or
(3) A facility for food, fuel, repair, services, or rest.
(F) (1) A vehicle and load traveling upon the National System of Interstate and Defense Highways or any other highway in the system of state highways that has been designated as a Class I or Class II highway by the department, or any street or highway designated by local authorities, may have a total outside width of eight feet six inches, provided that certain safety devices that the department determines as necessary for the safe and efficient operation of motor vehicles shall not be included in the calculation of width.
(2) Section 5-35 of the Illinois Administrative Procedure Act (ILCS Ch. 5, Act 100, § 5-35), relating to procedures for rule-making shall not apply to the designation of highways under this division.
(G) Mirrors required by ILCS Ch. 625, Act 5, § 12-502 and other safety devices identified by the department may project up to six inches beyond each side of a vehicle, and that projection shall not be deemed a violation of the width restrictions of this section.
(ILCS Ch. 625, Act 5, § 15-102)