Is an engineering study required for posting speed limits?
It depends. Maximum statewide speed limits are established by state legislatures according to road class (e.g., Interstate highways) and geographic area (e.g., rural vs. urban areas). The legislated maximum speed limit generally applies to all roads of a particular class throughout the State. This is referred to as a statutory maximum speed limit, which applies “unless otherwise posted” and above which a speed limit cannot be legally posted. For example, the statutory maximum speed limit for rural freeways in a given State might be 65 MPH. No engineering study would be needed to post a 65 MPH speed limit on a rural Interstate highway in that State, and even if an engineering study indicated that 75 MPH might be a more appropriate speed for the conditions, the statutory maximum would prohibit the State from posting any limit higher than 65 MPH. Similarly, statutory maximum limits are often legislated for urban streets within city limits, such as 30 MPH. However, State and local governme
