(2) Any county road may be closed at the points where it runs into or intersects the throughway if the consent of the county court or board of county commissioners of the county in which the road is located is first obtained.
(3) After the establishment of a throughway, no county road shall be constructed running into or intersecting the throughway unless its plans and specifications have first been submitted to and approved in writing by the department. This approval shall be made a matter of record by the department and by the county court or board of county commissioners.