Nothing in this title shall be construed to prevent the application and installation of traffic control measures to reduce the negative effects of traffic through residential areas on any component of the secondary highway system that meets the definition of “residence district” in § 46.2-100, even if such component also provides access to a “business district” as defined in the same section. Installation of traffic control measures on any state-maintained highway shall be approved by the Department prior to installation. Furthermore, nothing in this title shall be construed to prevent the acceptance by the Department of private financing for the application and installation of traffic control measures if and when such measures meet the Department’s standards.