In all counties of the first class not having a charter form of government which hereafter establish a county-urban road system, proceeds of the road bond construction fund may be used in the construction, reconstruction, improvement, maintenance and repair of any street, avenue, road or alley in any incorporated city, town or village when the street, avenue, road or alley or any part thereof has been designated by the county commission to be a road of the county-urban road system. Whenever proceeds of the road bond construction fund are used by the county for the construction, reconstruction, improvement, maintenance and repair of any street, avenue, road or alley which has been designated by the county commission to be a road of the county-urban road system and which lies wholly or partially within the corporate limits of any city, town or village, the county commission may enter into contracts with the city, town or village for the construction, reconstruction, improvement, maintenance and repair which contracts need not be limited in duration to one year.