Why aren't BMX bikes allowed in the skatepark?

Several cities have tried allowing BMX bikes in their skatepark with mixed results. If a skatepark has not been specifically designed for BMX bike use there has been significant damage associated with their use. The PSI (density) of the concrete and the thickness of the metal coping must be enhanced to withstand regular BMX bike use. Upgrading these items does increase the construction costs of a skatepark. Cities that have allowed BMX bike use have seen damage to both the concrete and the metal coping, repairing the damage is very expensive. Please note the attached pictures from a skatepark in New Mexico:

We have also worked with our city's Risk Management department and discussed safety issues related to having BMX bikes, skateboarders and inline skaters all using a skatepark at the same time. Because BMX bikes can go faster, jump higher, have pegs, handlebars and pedals the impacts of a crash with another user may be much more severe. If Scottsdale can find a way to develop a park that allows BMX bike use it will mostly separate the user groups by setting a schedule for each group.