Ala. Code § 32-5-16: State Trooper May Close Highways.

When it becomes apparent to any state trooper that a road is dangerous for use of motor vehicles on account of weather conditions, high water, damaged roadways or bridges, or from any other cause, or when in the opinion of any state trooper a road may be seriously injured by allowing traffic on same, then the state trooper is authorized to close such highway immediately by placing thereon a barricade, lights, or other sign stating that the road is closed, and immediately notifying the division engineer or some other official of the Department of Transportation. Such road shall remain closed until the hazard has been corrected and the road ordered opened by the Department of Transportation.