its own, but pliable under the weight of a car or truck. When struck, flexible bollards give way to some extent, reducing damage to vehicles and surrounding surfaces, and return to their original, upright position. Some flexible bollards do not provide physical protection from vehicles; rather they offer clear visual guidance for drivers. Other flexible bollards have been designed to provide physical protection as well as reduced damage by incorporating strong elastic materials. These can be all plastic or plastic/steel hybrids but combine varying degrees of stopping power and flexibility. Protective Bollards are used by government agencies and private businesses to protect buildings, public spaces, and the people in them from car ramming attacks. These bollards protect utilities, electronics, machinery, buildings, or pedestrians from accidental or intentional collisions with vehicles. As collisions also cause damage to vehicles, operators, or the bollards themselves, new bollards have been developed that absorb some of the impact energy, lessening the violence of the collision. Some are made of forgiving plastics while others are made of steel but fitted with an elastomer to absorb the impact energy. Bollards are widely used to contribute to safety and security. The American Bar Association (ABA) states that bollards are used to contribute to homeland security. The American National Institute of Building Sciences site—the Whole Building Design Guide (WBDG)—recommends in its Design Guidance that open spaces surrounding and contiguous to buildings be included as integral parts of a security design. There are two main kinds of security-related bollard: Non-crash-resistant bollards. Crash- and attack-resistant bollards used to protect places at risk of being attacked. According to the National Institute of Building Sciences, non-crash-resistant bollards are "perceived impediments to access" and address the actions of two groups: Law-abiding persons who comply with civil prescriptions of behavior as defined by the manner in which bollards are put to use; Potentially threatening and disruptive persons for whom bollard applications are proscriptive by announcing their behavior is anticipated, and that additional levels of security await them. High security bollards are impact-tested in accordance with one or more of three major crash test ratings for vehicle barriers. These are PAS 68 (UK), IWA-14 (International) and ASTM (US). Bollard sleeves in various alloys or finishes are designed to cover security bollards to enhance their visual attractiveness. U-shaped bollards are typically used for the protection of equipment and are common in areas that need coverage over a