6.1.1 Perimeter Line

The perimeter line of protection is the outermost line that can be protected by facility security measures. The perimeter needs to be designed to prevent carriers of large-scale weapons from gaining access to the site. In design, it is assumed that all large-scale explosive weapons (i.e., car bombs or truck bombs) are outside this line of defense. This line is defended by both physical and operational security methods. 

It is recommended that the perimeter line be located as far as is practical from the building exterior. Many times, vulnerable buildings are located in urban areas where site conditions are tight. In this case, the options are obviously limited. Often, the perimeter line can be pushed out to the edge of the sidewalk by means of bollards, planters, and other obstacles. To push this line even further outward, restricting or eliminating parking along the curb can be arranged with the local authorities, but this can be a difficult and time consuming effort. In some cases, eliminating loading zones and street/lane closings are an option.