These signs are useful in case there is the need to limit the access to a road to vehicles above a certain height, in order to protect bridges and tunnels. They can also be used to restrict the access to parking, thus preventing caravans and heavy vehicles from entering.
Strike avoidance signs are custom built, in stainless steel or aluminium. In case the are to be used in car parks, it is possible to have a locking unlocking system for the overhead pole, in order to allow in emergency or cleaning vehicles.