Once installed, vehicle barriers should be well marked and pedestrian traffic channeled
away from the barrier system. For high-flow conditions, vehicle barriers are normally open
(allowing vehicles to pass) and used only when a threat has been detected. In this case, the barrier
must be located far enough from the guard post to allow time to activate and close the barrier before
the threat vehicle can reach it. For low-flow conditions, or where threat conditions are high, barriers
are normally closed (stopping vehicle flow) and lowered only after authorization has been approved.
Security. Vehicle barriers must be ready to function when needed. A potential for
sabotage exists when barriers are left unattended or are located in remote or unsecured areas. For
these installation conditions, tamper switches should be installed on all vehicle barrier access doors
to controllers or hydraulic systems. Tamper switches should be connected directly to a central
alarm station, so that security of the barrier system can be monitored on a continuous basis.
Reliability. Many barrier systems have been in production long enough to develop an
operations history under a variety of installation conditions. Reliability data from manufacturers
show less than a three-percent failure rate when these barriers are properly maintained. Some
systems have been placed in environments not known to the manufacturer, while others have
developed problems not anticipated by either the manufacturer or user. Most manufacturers will
help resolve problems that arise in their systems. Backup generators or manual override provisions
are needed to ensure continued operation of active vehicle barriers during power failure or
equipment malfunction. Spare parts and supplies should also be on hand to ensure that barriers are
quickly returned to full operation. If a high cycle rate is anticipated, or the environmental impact
from hydraulic fluid contamination is a concern, the selection of a pneumatic operating system,
instead of hydraulic, is recommended.
Maintainability. Many manufacturers provide wiring and hydraulic diagrams,
maintenance schedules, and procedures for their systems. They should also have spare parts
available to keep barriers in continuous operation. The manufacturer should provide barrier
maintenance support in the form of training and operation and maintenance manuals. Maintenance
contracts are available from most manufacturers and are recommended to ensure proper
maintenance of the barrier and assurance that the barrier will function as intended. Reliability and
maintainability data are available from most manufacturers. Yearly maintenance contracts are
usually available from the manufacturer at about $300 to $500 per month. Maintenance contracts
should include inspection, adjustment, cleaning, pressure checks on hydraulic systems, and
replacement of worn parts.
Cost. Traffic in restricted or sensitive areas should be minimized and the number of
access control points limited. Reducing traffic flow and the number of control points will increase
security and lower the overall cost of the system. Installation and operational costs are a significant
part of the overall cost of a barrier system and must be addressed during the barrier selection
process. Complexity and lack of standardized components can result in high costs for maintenance
requirements on the system also affect costs.