Speed limits are posted to keep drivers safe. When creating a speed limit for an area, cities like Miami Beach consider many factors, including the state of the roads, natural dangers, road use, nearby schools and homes, traffic flow, and other factors. They choose a limit which allows for effective movement of traffic without increasing the risk of collisions.
When drivers exceed the posted speed limit, they put themselves and everyone around them at risk. Speed is a factor in many Miami Beach traffic accidents and especially in fatal and serious accidents.