§ 3. Classification of highways. Highways are hereby divided into five classes.

1. State highways are those constructed or improved under this chapter at the sole expense of the state, including the highways specified and described in sections three hundred and forty and three hundred and forty-one of this chapter and acts amendatory thereof, including the highways heretofore classified or referred to as county highways elsewhere in this chapter and heretofore constructed or improved at the joint expense of state, county and town, or state and county as heretofore provided by law.

2. Controlled access highways are those state highways which are entirely or partly constructed, reconstructed or improved at a location where no public highway theretofore existed and to and from which the owners or occupants of abutting property or of any other persons shall have no right of access either as pedestrians, as operators of vehicles or in any other capacity, excepting at junctions of such highways with other public highways, and also excepting as such access may be reserved pursuant to the description and map of the property which has been or which hereafter shall be acquired in accordance with this chapter for the purpose of such controlled access highways.

3. State thruways are those highways specified and described in section three hundred forty-nine-a of this chapter, constructed, improved or reconstructed as provided in such section.

4. County roads are those roads constructed, improved, maintained and repaired under article six of this chapter and roads constructed or improved under a general or special law, which are maintained by the county.

5. Town highways are those constructed, improved or maintained by the town with the aid of the state or county, under the provisions of this chapter, including all highways in towns, outside of incorporated villages constituting separate road districts which do not belong to either of the two preceding classes.