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From Jericho to Jersey Barrier

The ancient city of Jericho is described on one biblical Web site as surrounded by a great earthen rampart with a stone retaining wall at its base that was imposingly high and topped by a thick mudbrick wall. It was considered a formidable barrier that presumably gave the city great peace of mind. Unfortunately for the inhabitants, it was never tested for resistance to trumpets.

Vehicle barriers are for today's businesses what city walls were millennia ago. They represent a first line of defense against potentially devastating car-bomb attacks, which remain one of the most common and lethal weapons of choice for terrorists. If improperly designed, however, a vehicle barrier system may fail to prevent the intrusion of a threat vehicle. Great care must, therefore, be taken when selecting and designing this element of a security program.

The following overview of the proper process for the selection, placement, and installation of vehicle barriers can help companies avoid costly mistakes. The main considerations include a threat and risk assessment, an effective/appropriate design, and barrier selection.

Risk assessment.

One of the first steps in the design process of a vehicle barrier system is a threat and risk assessment of the target facility. The assessment should be conducted by a security consulting or engineering firm that has experience in protecting structures from the explosive-vehicle threat and that has performed assessments at facilities similar to the site being evaluated. An independent consultant with no affiliation with a vehicle barrier vendor or manufacturer should conduct the initial assessment. However, the consultant should seek assistance from a manufacturer or its representative during the design phase, to assist in the planning and design of the vehicle barrier system for that facility. The consultant should also have professional certifications such as the Certified Protection Professional (CPP) and should be able to supply references that can be contacted by the contracting facility.

The assessments should determine whether the facility is a potential target for terrorists. Some potential targets include national or local symbols such as monuments and buildings, and symbols of capitalism, like companies identified with Wall Street.

The consultant should include the following in the analysis: a description of any threats to the facility, including threats with a low probability of occurrence but high consequences, like the 9-11 attacks; the identification of assets requiring protection and an assessment of their potential vulnerabilities; and a cost estimate of both direct and indirect losses that could result from the destruction of or damage to these assets. The consultants should also offer recommendations on countermeasures to reduce these vulnerabilities.

A bomb-blast analysis should also be included. The blast analysis uses physical inspections and computer modeling to assess the structure's vulnerability to a blast, and it offers recommendations on protective measures.

Security directors can use the threat and risk assessment report as supporting documentation when they go to senior management to request funding of their physical protection program. The report should include an analysis of the cost of countermeasures versus the potential cost of leaving the risks unmitigated.


Once the threat level for the facility is identified and funding for the physical protection plan is in place, the design process for the vehicle barrier system can begin. The security consultant, the engineering firm, and the vendor should assist the security director with this part of the process.

Site survey. The first part of the design phase is the site survey and layout of the barrier system. The survey should use a scaled map that shows the terrain and identifies the location of structures, roads, and the property's perimeter. Based on this map, distances between the perimeter and the facility, the potential angles of approach to the target, and the maximum speed attainable by a vehicle can be analyzed. This information will help to identify the required levels of protection needed along the perimeter line. A traffic-flow study should also be conducted at the roadway entrances to see what effect vehicle-barrier systems would have on traffic entering the site.

Because force from an explosion decreases rapidly with distance, the most effective protection from an explosive- vehicle threat is a maximum setback zone. The setback zone, also known as the "standoff distance," is the distance between the vehicle bomb and the target building. For example, if the facility is 100 feet from an accessible location where a terrorist could park or drive a bomb-laden vehicle, then 100 feet is the standoff distance.

Vehicle barriers should be placed as far from the building as possible to ensure the maximum standoff distance from a bomb-laden vehicle. In one case the author worked on, building managers were planning to upgrade security by installing vehicle barriers around the perimeter of the building. However, they planned to place the barriers only seven feet from the building's façade. After the author made the point that a large car bomb could destroy a reinforced concrete wall from that standoff distance, they agreed to move the barriers to the curb line, which was 40 feet from the building.

Maximum footage is always desirable, but rarely practical in areas where real estate is valuable. In an urban environment, 12 feet--the distance from the curb to the face of the facility--may be the maximum achievable standoff distance. That's not ideal, but the placement of barriers at the curb may establish a physical and psychological deterrent. The barriers will also prevent a moving vehicle from penetrating the building and help to minimize any damage that could be inflicted by a stationary-vehicle bomb. Even at this reduced standoff distance, depending on the size of the bomb and design of the structure, a vehicle barrier may be sufficient to prevent partial or total collapse of the structure.

Barrier ratings.

The next step in the design phase is selecting the type of barrier that will stop a defined threat vehicle. Because barriers are created to withstand a variety of vehicles and situations, the potential threat vehicles should be identified before choosing the barrier type.

To determine the proper barrier, the designer must determine the threat vehicle's kinetic energy (the force with which the vehicle will hit an object). A mathematical equation using the threat vehicle's total weight and speed determines this energy. An effective barrier must have the ability to absorb the energy of the impact and transmit that energy to its foundation.

To determine whether the barrier will resist the level of threat, it is important to determine whether the product has been crash-tested or has been put through a computer analysis that demonstrates its performance capability. The Department of State and the Department of Defense have developed certifications based on their crash-testing processes that are used to determine these standards. Certification levels are based on how far a vehicle of a given weight will penetrate a barrier at 30, 40, or 50 miles per hour.

The Department of State uses K and L ratings for their certification levels. The K level defines the speeds of a vehicle that the barrier is able to withstand. The L level indicates maximum allowed penetration of the barrier by the vehicle or its major components on impact. The vehicle used in the tests weighs 15,000 pounds.

In one case, the author had a client with three access roads that led into the facility. To simplify the equipment purchase, the client planned to order the same threat-level barriers for each entrance. At the two access roads for which the barriers were designed, vehicles had to make 90-degree turns to enter the building, significantly reducing any vehicle's potential speed and ramming power. The third access point, however, was opposite a long straight road that could allow a large vehicle to increase its speed and ramming power before reaching the barrier. The proposed barrier could not meet the threat level of the third access point.

It was recommended that the company redesign the third entrance to slow potential threat vehicles or that it purchase a higher threat-level barrier. The company chose to purchase a higher threat-level barrier, which proved more cost effective than redesigning the access point.

Barrier types.

Many types of barriers and combinations of barriers can be used to provide the best possible defense. Barriers can be active or passive, fixed or movable, and they may be categorized by their form into the following categories: bollards, wedges, crash beams, sliding gates, and portable barriers. Less effective and often misused barrier options include Jersey barriers, planters, and fencing.

Active and passive. Vehicle barriers are categorized as either active or passive. Active barriers require some action either by people or equipment to be raised and lowered or moved aside to permit vehicle ingress and egress. These systems include barricades, bollards, beams, and gates that are operated manually, pneumatically, or by hydraulic power units. Sand-filled dump trucks or heavy construction equipment can be used as a temporary active barrier. Active barriers should be used at locations such as a driveway, a parking lot, or a loading dock entrance and should be located as far from the building as practical.

A passive barrier, on the other hand, has no moving parts. Examples include bollards, guardrails, ditches, large reinforced concrete planters, hardened trashcans, benches, water fountains, walls, raised planting beds, earth berms, boulders, and Jersey barriers. Passive barriers should be used along the perimeter line. It makes sense to use active barriers at entrances and passive barriers surrounding the rest of the facility.

Project designers should make sure that the barriers do not obstruct pedestrians or emergency vehicles. The local fire department should be consulted to ensure that the barrier would not impede firefighters' access to the building. It is also important for a facility with a standoff distance of more than 60 feet to create an easy access route to the building for emergency and maintenance services.

Fixed or movable. Depending on how they are made and used, both active and passive barriers can be fixed or movable. A fixed barrier is one that is permanently installed or requires heavy equipment to move or dismantle it. Examples of these include hydraulically operated wedge-type barrier systems or bollards set in concrete foundations.

A portable or movable barrier system is one that can be relocated from location to location. This type of barrier may also require heavy equipment to move. Hydraulically operated, sled-type barrier systems or Jersey barriers are typical examples.

Bollards. Bollards are metal posts that are embedded in a concrete foundation at a depth of four feet. These are the most versatile type of barrier and can be fixed or movable. Retractable bollards can be operated manually or automatically with a hydraulic pump unit. Spaced three to four feet apart, bollards do not obstruct pedestrian traffic and can be aesthetically pleasing. To blend with any environment, they can be equipped with a cast sleeve of aluminum, bronze, or stone. Logos and crests can also be incorporated into the sleeves.

A fixed and installed bollard may range in cost from $1,000 to $4,000. The price depends on the threat level and architectural enhancements that are required. A retractable 3-bollard system raised and lowered by a hydraulic power unit costs between $50,000 and $88,000 installed. As with the fixed bollard, the exact price depends on the threat level, architectural enhancements, and operating system requirements.

Wedge barriers. Wedge barriers are rectangular steel plates that rise from 24 to 38 inches from the surface of the road at a 45-degree angle. This barrier system can be surface mounted, so as not to interfere with buried utilities. It can also be installed completely below the roadway. This barrier, equipped with a hydraulic power unit for automatic operation, costs between $24,000 and $80,000 installed, depending on the threat level and operating system required.

It is important to choose the type of barrier best suited for the building's conditions. A former client of the author's planned to use bollards at the entrance to an underground parking garage that was being designed for a new office building. The bollards were to be installed at the top of the ramp before the security checkpoint. This design created a problem because the security officer would have to lower the barrier before he or she could check the driver's identification, defeating the purpose of the system and creating a vulnerability in the building's security.

Because of the limited space in the garage, the author recommended a surface-mounted wedge barrier that would be located just beyond the security checkpoint. With this design, the officers could check the driver's identification and carry out vehicle searches while keeping the barrier intact. The author worked with the building's architect to incorporate the barrier in the ramp design.

Crash beams. Crash beam barriers have hydraulic drop arms that are equipped with a 1-inch steel cable and are supported by concrete footings placed on both sides of the road. The drop arm can be raised to allow vehicle access. When in the closed position, the arm and cable lock into the concrete footing on the opposite side of the roadway, preventing a vehicle from penetrating the barrier.

This type of barrier system should be used at semiactive or inactive access roads because the process of opening and closing the barrier can be lengthy due to its design. Operated manually, this type of barrier can cost between $16,000 and $36,000 installed. When the barrier is equipped with a hydraulic power unit for automatic operation, the cost increases to between $24,000 and $49,000 installed.

Sliding gates. The sliding gate uses a cantilever or linear gate design. When in the closed position, the gate leaf locks into steel buttresses that are embedded in a concrete foundation on both sides of the roadway. These gates can be architecturally designed to match any facility's environment and can cost between $34,000 and $72,000 when installed with a hydraulic power unit.

Portable systems. Portable barriers are the most recent addition to the family of barriers. These barrier systems require no roadway excavation and can be assembled and made operational in less than four hours. They are either crash-beam or wedge barriers, equipped with steel buttress boxes that can be filled with sand or concrete to limit movement if a vehicle hits the barrier. Some of the wedge-type barriers are equipped with wheels that can be removed after the barrier has been towed into place.

A number of these barriers also have State Department crash ratings. There is a drawback to this design, however. When hit by vehicles, these barriers move. Therefore, placement and standoff distance must be carefully assessed before installing this type of barrier, which costs between $34,000 and $64,000 installed when equipped with a hydraulic power unit.

Less effective options. Not every barrier provides a defense in the sense of protecting against vehicle intrusion. For example, Jersey barriers are passive barriers that can give a false sense of security at a facility because of their size and mass.

Originally designed as highway dividers to stop vehicles approaching at a maximum angle of thirty degrees, they were not designed to be a high-speed vehicle-arrest system. Even if placed correctly or linked together, the usefulness of Jersey barriers is at best limited. If improperly placed, they may not counter the threat at all. This option should only be considered a temporary security measure, never a permanent solution.

Planters are another type of passive barrier often used incorrectly. Although aesthetically pleasing, they must be large, heavy, and constructed with reinforced concrete to be effective--otherwise, they are simply a psychological deterrent. Planters also require proper placement and should be anchored to the ground for maximum strength. Landscaping in and around the planter is also important because improper planting material could actually aid the terrorist by providing concealment of a small explosive device.

Perimeter fencing is not an obstacle to vehicle penetration and should not be considered adequate protection. Like the other barriers discussed, however, fortified fences may deter a minor attack. Installation of two 3/4-inch cables attached to anchors set in concrete foundations at both ends can be a cost-effective method for reinforcing a fence against the threat of penetration by lightweight vehicles.


It is important for planners to consider the climate and geography of the barrier site. For instance, in cold climates, hinges, hydraulics, or barrier surfaces may require heaters and snowmelt systems to resist freezing temperatures and snow and ice buildup. In warm climates the barriers may require protection from excessive heat and humidity. In urban areas barriers may require protection from dirt and debris. Similarly, along coastal areas the barrier may need protection from salt water, sand, and a high water table. The water table should be analyzed before installation to determine whether a sump pump or surface-mounted barrier should be installed.

Safety. Active vehicle barriers can cause serious injury, and the installation of safety devices is recommended to prevent activation either by operator error or equipment malfunction. Vehicle loop detectors should be used to prevent the barrier from being accidentally raised in front of or under an authorized vehicle.

Warning signs, audible alarms, and traffic-safety paint should mark the presence of a barrier and make it visible to oncoming traffic. Red and green traffic signals should be installed and operated in conjunction with the barrier. The red signal should go on as the barrier begins to rise, and the green signal should illuminate only when the barrier is down. In addition, pedestrian traffic must be channeled away from the barrier by using sidewalks, landscaping, or fencing.

In one case, the author had a client who refused to install a traffic light in conjunction with the barrier because, he said, it would have cost too much and would not have been aesthetically pleasing. Even though the author stressed that the light was a safety issue, management refused to install it.

After one month and a number of vehicle accidents, the client decided to install traffic lights. Because the lights were not included in the original design, the barriers had to be retrofitted, which cost the company more than if the light had been part of the original installation. The company is also facing possible litigation from persons who were involved in accidents before the light was added.

Other functional considerations. Frequently used perimeter entrances may require a pneumatic or hydraulic control system designed for repeated opening and closing. These barriers can be operated from a staffed entry-control station or from a remote location, using CCTV and remote controls.

If the barricades are not under continuous observation, then tamper switches should be installed to the hydraulic pump unit doors to ensure that the barrier system is continuously controlled. These switches should be connected directly to the central alarm station so that security can monitor the barriers around the clock. To make the system more redundant in high-security applications, the barrier should be controllable from both the entry-control station and from another secure location within the facility.

Barriers must be capable of operating continuously and handling the facility's normal traffic flow with minimal maintenance and downtime. A barrier should take between 3 and 12 seconds to move from a full down position to a full up position to satisfy security requirements and control normal traffic flow.

The barrier should also have an emergency operation feature that is capable of raising the barrier to the up position in a shorter time period--0.6 to 3.0 seconds is the accepted standard, depending on the barrier size. Backup generators or manual override provisions are also needed to ensure continued operation of active vehicle barriers during power failure or equipment malfunction.


Installation is one of the most critical steps in the design and implementation phases and must be well planned to avoid problems that can result in high maintenance costs. It is important to select a barrier manufacturer that has assembly experience, has developed an operations history of its products, and hires an outside company to regularly conduct tests and create comprehensive reports of its products. The selected barrier company should ideally have been in business for at least three years and should have a strong track record in the design and installation of vehicle barrier systems. It should also offer a warranty for its products.

Most manufacturers will resolve problems that arise in their barrier systems if they install them or a company that has been certified by them installs them. In addition, the manufacturer should certify the installers and technicians used.


Planning for barrier maintenance must start during the design phase. Manufacturers should provide the purchaser with wiring and hydraulic diagrams, maintenance schedules, and procedures for their systems. They should also provide barrier maintenance support in the form of training and operation manuals. In addition, the vendor should have an inventory of spare parts available to maintain any of its barrier systems in operation.

Maintenance contracts are available from most manufacturers and are recommended to ensure proper operation of the barrier and to provide assurance that the barrier will function as intended. These contracts should include inspection, adjustment, cleaning, pressure checks on hydraulic systems, and replacement of worn parts.

Operator training.

Training for security officers operating active vehicle barriers is strongly recommended to help prevent serious injuries, litigation, and damage to vehicles and equipment. Most manufacturers offer client companies operator training for their systems, which should be planned for during the design phase.

Security directors should also develop written procedures for the normal and emergency operation of the system. These procedures should include instructions for keeping the barrier in the up position until a vehicle has been properly identified and provisions for allowing emergency vehicle access. Training should also include how to identify a threat vehicle and how to handle an attack situation. In addition, security officers should be trained in how to check truck manifests and make cargo inspections.

Controlling costs.

Because of their moving parts, active barriers have higher installation and yearly maintenance costs than passive barriers. For semiactive or inactive entrances, a manually operated system may be the most practical and cost-efficient option.

Another cost-effective measure is to minimize the number of access points to the facility, thereby reducing the number of entrances requiring active barriers. Integrating traffic-calming features into the access route, such as medians and landscaped islands, or redesigning the access road to slow approaching traffic is another option; it allows for the use of a lower threat-level barrier, which in turn reduces the cost.

Barriers can be made more aesthetically pleasing with the help of landscape architects who can use everything from boulders to raised planting beds in the design. But aesthetics can add to the cost of the barrier system. Some passive barriers, such as planters, are intrinsically aesthetic, but their maintenance and upkeep can add an additional annual operating cost.

When estimating the costs of the barrier systems, security directors should make sure to include all ancillary expenditures, such as the creation of an access road and the addition of an entry-control station, vehicle inspection area, turnaround lane, and lighting. They should also make sure that the project plan is not cutting corners for the sake of cost savings. As the earlier example about the traffic light illustrated, savings at the expense of safety will cost the company more in the long run.

Vehicle barriers are not a total solution and should be integrated with other security components and options such as fencing, CCTV, and access control systems to provide a comprehensive protection plan. But when properly selected, installed, maintained, and operated, barriers can raise the deterrence factor for a facility and lower its risk of becoming the victim of a vehicular attack.

Richard Kessinger, CPP, is currently a lead physical security specialist with the United States Capitol Police. Formerly, he was a security consultant for a number of years following a 20-year career in law enforcement. He has been involved with the application and installation of barrier systems at government and private sector locations. He is a member of ASIS International.