Ala. Code § 11-49-4: Establishment of Speed Limits, Etc., Within Corporate Limits.

(a) Except as otherwise provided in this code, each municipality shall fix by ordinance the speed at which motor vehicles may be operated within its corporate limits and shall fix the punishment for any violation of the ordinance in accordance with state law.

(b) Notwithstanding subsection (a), a municipality may not fix the speed at which motor vehicles may be operated on a county-maintained street, as defined in Section 11-49-80, located within the corporate limits of the municipality unless the municipality conducts an engineering and traffic investigation and receives written approval from the county engineer to fix the speed based on the results of that investigation.