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A Stricter Standard for Crash Barriers

by Dean Alberson

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The terrorist attacks of Sept. 11, 2001, on targets in the United States, altered America’s priorities. As buildings burned and smoke obscured Washington, D.C., and New York City, domestic security and the security of sovereign installations around the world became America’s number one priority.

American embassies and other governmental installations abroad have long been a favorite target of terrorists. This was made clear beginning with the 1998 embassy bombings in Kenya and Tanzania. Embassies and other governmental facilities are frequently located in populated urban areas, are staffed with prominent administration or military personnel, and are often squeezed into high traffic areas on small lots — appealing targets for terrorists looking to strike quickly from nowhere.

Such attacks most often occur in the form of a bomb-laden car or truck. ASTM Committee F12 on Security Systems and Equipment, responding to the need for increased safety and security against such bombs, is expanding upon the existing U.S. Department of State standard used for anti-ram barriers to literally stop terror at the gates and walls of U.S. facilities around the world to create a standard with broader applicability.

Barriers to Terror

United States facilities, particularly those abroad, must have mechanisms in place to stop vehicles from crashing and intruding into protected areas. While having a substantial setback area is the most effective countermeasure by keeping a bomb at a distance, this is not always feasible. Anti-ram barriers and gates, placed around buildings and facilities, are intended to prevent vehicular intrusions, thereby protecting buildings and their occupants.

Different types of barriers are necessary to meet the unique needs of facilities around the world. Anti-ram barriers are typically used around government buildings, airports, military installations, embassies, United Nations facilities, ports and waterways, power plants, or any location where terrorist activity is a threat. Tall, concrete perimeter walls can sometimes be used to protect the facility. However, some buildings, such as U.S. embassies abroad, require a more open and aesthetically pleasing barrier system where the expectation of terrorist activity is less.

Some barriers are designed to admit pedestrians but not vehicles, while other barriers are designed to let vehicles pass intermittently.

Gauging the direction and threat level against a facility is the common consideration when choosing an appropriate barrier. Because of the diversity of the locations in which barriers are used, Committee F12 is developing a new standard to thwart modern threats. Once this standard is approved, each facility will then be able to choose the barriers that are most appropriate for its situation. The committee is receiving input from the State Department, the U.S. Army Corp of Engineers, and other governmental agencies.

Why Develop a New Standard?

The State Department recently updated the standard that is currently in use: Department of State Certification Standard Test Method for Vehicle Crash Testing of Perimeter Barriers. However, new security threats necessitate new approaches to combating terror. Thus, Committee F12 was asked to develop a new standard that can be adopted by the Department of Defense, the Department of Energy and other organizations. The new standard for anti-ram barriers will address some performance specifications deleted in the recent State Department standard, and broaden some of the test parameters to accommodate more test vehicles and anticipated impact scenarios.

What Will the New Standard Include?

Security threats of many shapes and sizes are of concern to facilities around the world. To meet the diverse needs of the various groups that will use the anti-ram barrier standard, the types of test vehicles and the test conditions included in the document will need to be expanded. Most State Department facilities, such as embassies in foreign countries, are located in close proximity to other buildings and streets. They do not have the luxury of large properties that would allow a large setback. In all cases, a vehicle ramming into a perimeter barrier must be contained within a very short distance to protect the facility, and more important, its occupants. The safety of building occupants is enhanced with every metre between the facility and a terrorist’s bomb. Air bases and military bases are typically surrounded by wide open spaces, lending to a much greater stopping distance.

Tests will include evaluating barriers for their ability to stop and contain a ramming vehicle. Barriers under the State Department’s previous standard are classified as one of the following:

• Level 3 — A barrier allowing a vehicle to crash through and intrude only three feet [0.91 m];
• Level 2 — A barrier allowing 20 feet [6.1 m] of intrusion;
• Level 1 — A barrier allowing 50 feet [15.2 m] of intrusion.

Under the recent update to the State Department standard, test Levels 1 and 2 were deleted. The new ASTM standard will restore some longer stopping distances for other users.

Many facilities will only be able to use barriers that meet Level 3 criteria because of the limited distance between the barrier and the facility it is protecting. It is important to note that in testing with trucks (not passenger cars), the amount of intrusion is measured to the front of the cargo bed of the truck, where explosives would typically be located.

The State Department standard currently only tests with a single-unit diesel truck. The new standard will include additional vehicles and measurement criteria. The smallest vehicle will be a uni-body sedan, included because there are situations where a small vehicle, such as a small sedan, may be able to penetrate a barrier that would stop a larger, heavier vehicle like a single-unit truck or tractor-trailer.

Another vehicle to be considered in the standard is a 3/4-ton [2,000 kg] pickup. The largest vehicle will likely be a 60,000-pound [27 metric ton] tractor-trailer or dump truck. This heavy truck will be used to test the limits of the barrier. Security officials believe this is the largest vehicle that could present a significant threat. The single unit truck that is currently used in the standard will be retained.

In addition to testing more vehicle types and intrusion levels, the committee is evaluating test reporting and instrumentation requirements. The committee will also recommend that high-speed film (minimum 400 frames per second) continue to be required during testing, and that on-board accelerometers remain optional. Procedures for repeat tests will be included.

Stopping Vehicles, Saving Lives

In addition to protecting high-profile buildings at home and abroad, anti-ram barriers also have roadside safety applications. Barriers can protect parts of roadway infrastructure such as overpasses, tunnels, and bridges from errant drivers. In these cases, it is necessary to protect the roadway structure while safely stopping the vehicle and helping the occupants of the vehicle to survive the impact. Therefore, the committee will likely recommend that barriers being evaluated for safety performance be tested to safety standards currently in place for such devices.

Improving Safety

“Hope for the best. Plan for the worst.” This is one major lesson learned after Sept. 11. Committee F12 enters its 32nd year by modernizing the approach to securing embassies and other installations around the world. A modern safety standard for barriers — part of planning for the worst — will help reduce the threat of catastrophic damage to facilities and those who work within them. //

Copyright 2004, ASTM International

Dean C. Alberson, Ph.D., is an associate research engineer with the Texas Transportation Institute, Texas A&M University. He is a registered professional engineer and full-time researcher in highway safety devices and anti-ram barriers and gates.