If a local authority finds that a city street or county road under its jurisdiction adjacent to an airport has been specifically designed and constructed, with the prior approval of the local authority, so as to safely permit the use thereof by regular vehicular traffic and also the taxiing of aircraft thereon between the airport and the place where such aircraft are hangared or tied down, the local authority may by resolution or ordinance designate such street or road or portion thereof for such combined use and prescribe rules and regulations therefor which shall have the force of law. No such street or road shall be so designated for a distance of more than one-half mile from the airport, provided, the finding of the local authority in this respect shall be conclusive. Upon such designation becoming effective, it shall be the sole responsibility of the local authority to enforce the provisions of the Vehicle Code and all rules and regulations adopted by it upon such street or road. Upon such designation becoming effective it shall be lawful to taxi aircraft upon such street or road in accordance with the rules and regulations prescribed as aforesaid and said aircraft need not be licensed under this code or comply with other provisions thereof.