A Crash Course on Hardening Soft Targets

David Dickinson is senior vice president of vehicular barricade and physical access control firm Delta Scientific.

At almost every one of its locations, CarMax employs cable beam barricades for vehicular control.

At 50 miles per hour, a vehicle has 25x the kinetic energy it has at 10 mph.

Portable vehicle barricades like this one can be towed into place to provide temporary security, such as for events.

Decorative bollards, like these in use at the Reagan Presidential Library, offer vehicle control and design that can meet stringent requirements from architects.

Surface mount barricades can be permanent solutions when ground intrusion is not a good choice. They are often used when faced with such problems as soil water drainage issues.

Sometimes vehicle control points require a multitude of solutions, from barriers to design elements that force a slower approach, to additional perimeter fencing.

Keeping retail shoppers safe, shielding structures from accidental or intentional automobile crashes, protecting hotel patrons from suicide car bombers, and keeping employees and visitors from harm have always been a concern...today more so than ever. From pedestrian-filled farmers markets and universities to new and used car lots, a wide variety of businesses and agencies find peace of mind through the use of barriers, bollards, barricades and crash gates for vehicle-based physical access control at the perimeter.

For those areas where a vehicle will never enter, fixed bollards and barriers are the norm. However, at entrances, barriers that go up and down are needed to let authorized vehicles through.

Risk Assessment Starts With Physics 101

To evaluate the security risk for a given facility, particular attention must be focused on the weights and velocities of vehicles that would be used to attempt penetration into sensitive areas.

A vehicle moving towards a barricade has kinetic energy, the major measure of how much "hitting power" it possesses. Mathematically, kinetic energy is derived from the vehicle velocity and its weight (mass). On impact, some of this energy is converted to heat, sound and permanent deformation of the vehicle. The barricade must absorb the remainder of this energy if the vehicle is to be stopped.

The amount of remaining energy depends on many factors, primarily the velocity of the vehicle at the moment of impact. The amount of kinetic energy posed by a vehicle changes as the square of its velocity. For example, a vehicle moving at 50 mph has 25 times as much kinetic energy as it would at 10 mph. Thus, an armored car weighing 30 times as much as a Toyota Corolla and moving at 10 mph would have less hitting power than the Toyota moving at 60 mph!

Upon designing a way to slow down vehicle approach, take precautions to stop the attacking car from making a "corner cutting shot" at a barricade. Often, only a light post defines a turning point and a speeding car can take it out and not even hesitate. Knolls and other impediments should be considered.

Failing to understand this and not using the proper equipment to counter the threat may lead to a false sense of security.