A. Notwithstanding the other provisions of this article, and except as otherwise provided in subdivision A 4 of § 46.2-1300, the Commissioner of Highways or other authority having jurisdiction over highways may decrease the speed limits set forth in § 46.2-870 and may increase or decrease the speed limits set forth in §§ 46.2-873 through 46.2-875 on any highway under its jurisdiction and may establish differentiated speed limits for daytime and nighttime by decreasing for nighttime driving the speed limits set forth in § 46.2-870 and by increasing for daytime or decreasing for nighttime the speed limits set forth in §§ 46.2-873 through 46.2-875 on any highway under his jurisdiction. Such increased or decreased speed limits and such differentiated speed limits for daytime and nighttime driving shall be effective only when prescribed after a traffic engineering investigation and when indicated on the highway by signs. It is unlawful to operate any motor vehicle in excess of speed limits established and posted as provided in this section. The increased or decreased speed limits over highways under the control of the Commissioner of Highways shall be effective only when prescribed in writing by the Commissioner of Highways and kept on file in the Central Office of the Department of Transportation. Whenever the speed limit on any highway has been increased or decreased or a differential speed limit has been established and such speed limit is properly posted, there shall be a rebuttable presumption that the change in speed was properly established in accordance with the provisions of this section.
B. Notwithstanding any other provision of this article, including the provisions of subsection A, the governing body of any town located entirely within the confines of a United States military base may by ordinance reduce the speed limit to less than 25 miles per hour on any highway within its boundaries, provided such reduced speed limit is indicated by lawfully placed signs.
C. If the Commissioner of Highways increases or decreases a speed limit as provided in this section, the Department of Transportation shall notify the primary liaison with the Department of Transportation in each locality in which such speed limit change will occur. If such speed limit change will occur in a town, the Department of Transportation shall notify the primary liaison in the town and the primary liaison in the county in which the town is located. If such speed limit change will occur in a community subject to the Property Owners’ Association Act (§ 55.1-1800 et seq.) or the Virginia Condominium Act (§ 55.1-1900 et seq.), the locality shall also notify the relevant board of directors, as defined in § 55.1-1800, or executive board, as defined in § 55.1-1900, respectively. Any notice sent to a locality, board of directors, or executive board as required in this subsection shall include the location where the speed limit change will occur, the effective speed limit change date, the new speed limit, and the reason for the speed limit change. Failure to comply with any provision of this subsection shall not affect the change in speed limit.