Except as otherwise provided in this article, the maximum speed limit shall be 55 miles per hour on interstate highways or other limited access highways with divided roadways, nonlimited access highways having four or more lanes, and all state primary highways. The maximum speed limit on all other highways shall be 55 miles per hour if the vehicle is a passenger motor vehicle, bus, pickup or panel truck, or a motorcycle, but 45 miles per hour on such highways if the vehicle is a truck, tractor truck, or combination of vehicles designed to transport property, or is a motor vehicle being used to tow a vehicle designed for self-propulsion, or a house trailer. Notwithstanding the foregoing provisions of this section, the maximum speed limit shall be 70 miles per hour where indicated by lawfully placed signs, erected subsequent to a traffic engineering study and analysis of available and appropriate accident and law-enforcement data, on (i) interstate highways; (ii) multilane, divided, limited access highways; and (iii) high-occupancy vehicle lanes if such lanes are physically separated from regular travel lanes. The maximum speed limit shall be 60 miles per hour where indicated by lawfully placed signs, erected subsequent to a traffic engineering study and analysis of available and appropriate accident and law-enforcement data, on U.S. Route 17, U.S. Route 23, U.S. Route 29, U.S. Route 58, U.S. Alternate Route 58, U.S. Route 301, U.S. Route 360, U.S. Route 460, U.S. Route 501 between the Town of South Boston and the North Carolina state line, State Route 3, and State Route 207 where such routes are nonlimited access, multilane, divided highways.