The first objective of ECFs is to maintain perimeter security for installations. Installations should focus on reducing threats at the first line of defense, the installation perimeter. ECFs must accommodate strict identification and inspection procedures; and have security features that protect against vehicle-borne threats and illegal entry. Active vehicle barriers close a roadway when a threat vehicle is detected. These are the final line of defense within the ECF to secure the installation. Passive barriers contain the perimeter of an ECF and prevent vehicular access off the roadway. The active barriers and passive barriers secure the ECF from the installation.