In this chapter, the following terms have the meanings indicated. Terms Defined. “Administration” means the State Highway Administration. “Authority” means the Maryland Transportation Authority. “Authority highway” has the meaning stated in Transportation Article, §21-1401, Annotated Code of Maryland. “Certified weights” means vehicle or axle weights that have been weighted on scales approved or accepted by the Commercial Vehicle Enforcement Division of the Department of State Police. Construction Equipment. “Construction equipment” means equipment used to build, repair, replace, or maintain structures, transportation facilities, or infrastructure. “Construction equipment” includes, but is not limited to: Demolition; Excavation; Grading; Digging; Stockpiling; Erection; or Placement of materials or supplies. Heavy Machinery. “Heavy machinery” means large stationery machinery transported on tractor-trailer combination vehicles. “Heavy machinery” includes, but is not limited to: Armored tanks; Transformers; Vessel tanks; Girders; Compressors; and Rotors. “Irreducible” means a vehicle configuration exceeding applicable size or weight limits which, if separated into smaller loads, would: Compromise the intended use of the vehicle, for example, make it unable to perform the function for which it was intended; Destroy the value of the load or vehicle, for example, make it unusable for its intended purpose; or Require more than 8 manhours to dismantle, using appropriate equipment. “Oversize” means dimensions of length, width, or height that exceed the limits allowed by Transportation Article, Title 24, Annotated Code of Maryland. “Overweight” means weights that exceed the limits allowed by Transportation Article, Title 24, Annotated Code of Maryland. “Self-propelled vehicle” means a single unit vehicle containing the means for its own propulsion within itself. “Spacing” means the distance measured lengthwise and horizontally between axle center lines or the center lines of exterior axles within a group. “Special mobile equipment” means a vehicle that is not used primarily for highway transportation of people or property and is operated or moved on a highway only as an incident to its nonhighway use. “Unit” means the Hauling Permits Unit of the Motor Carrier Division, Office of Traffic and Safety, within the State Highway Administration, and is the Unit that issues permits for oversize and overweight vehicles.