School Zone with Obscured Light

My question involves a traffic ticket from the state of: Alabama

I received a ticket for speeding in a school zone. I was traveling below the normal speed limit but above the school zone speed limit. The flashing light that is used to change the speed in the zone is obscured multiple times by other installed signs and plants. Is there a code or regulation that the state must follow to maintain the flashing light clear and visible?

Thanks,

School Zone with Obscured Light