"Elevated location" means a bridge, overpass, highway ramp, building, artificial structure, hill, mound, or natural elevation above or adjacent to and above a highway.
"Object" means any object or substance that by its size, weight, or consistency is likely to cause great bodily harm to any occupant of a motor vehicle.
"Overpass" means any structure that passes over a highway.
"Motor vehicle" and "highway" have the meanings as defined in the Illinois Vehicle Code.
720 ILCS 5/12-5.02