An adaptable barrier system protects a site of value that is adjacent to a trafficable surface, from impact by a vehicle. The system includes traffic patterns to reduce speed, followed by a first impact element that causes a vehicle to become elevated from the trafficable surface. A bed having a deformable structure or material beyond the first impact element lowers the elevation of a vehicle that encounters the bed. A cover overlies the compressible material to allow passage of pedestrians and lightweight vehicles. An impact element line beyond the bed has sufficient height to impact a chassis of the vehicle having an elevation that is lowered by the bed, and prevent further progress of the vehicle. The combination of the first impact element, the bed and the impact elements line may be reproportioned with respect to each other to provide a barrier intended to suit a particular application.