For the purpose of this chapter, the following definitions shall apply unless the context clearly indicates or requires a different meaning.
HIGHWAY. Any public road, street, avenue, alley or boulevard, bridge, viaduct or trestle and the approaches to them.
VEHICLE. All agencies for the transportation of persons or property over or upon the public highways of the commonwealth and all vehicles passing over or upon the highways, excepting road rollers, road graders, farm tractors, vehicles on which power shovels are mounted, other construction equipment customarily used only on the site of construction and which is not practical for the transportation of persons or property upon the highways, vehicles as travel exclusively upon rails, and vehicles as are propelled by electric power obtained from overhead wires while being operated within any municipality or where the vehicles do not travel more than 5 miles beyond the city limits of any municipality.