Since shortly after the first automobiles rolled off an
assembly line, guardrails, bridge rails, crash cushions, and other safety
devices have been installed on roadways in an effort to improve the safety of
the traveling public. Just as automotive
safety design has improved tremendously over the years, the design and application
of roadside safety appurtenances has improved vastly as well. State Highway Departments and the Federal
Highway Administration were the original driving force behind many of these
safety improvements, but over the last 30 years or so private industry has
provided much of the innovation that has led to products which make the roads
safer. This is especially true with
guardrail terminals.
The purpose of a guardrail is to shield motorists from
natural or man-made obstacles located along either side of a traveled way. An impact with a guardrail system should
prevent contact with the hazard being shielded, and be less severe than an
impact with that hazard. A typical
guardrail system is anchored on both ends, and when an errant vehicle impacts along
the length of guardrail, tension is developed in the rail and the vehicle is
redirected away from the hazard. The
ends of the guardrail system are potential problem locations, as a vehicle
impacting an untreated guardrail end can be stopped abruptly resulting in high
deceleration forces for the occupant, or the guardrail could penetrate the
occupant compartment and cause serious injury. In the early days these guardrail ends were
left untreated, resulting in many vehicles being ‘speared’ with the guardrail
during a collision.
Guardrail “Terminals” were eventually developed to improve
the impact performance of the ends of the guardrail systems. These terminals started out as basic as
twisting the guardrails and anchoring it at ground level, and have evolved over
the years to sophisticated “energy absorbing” terminals which capture the
errant vehicle and bring it to a controlled stop. The technology used for many of these modern guardrail
terminals is proprietary, and are only available for purchase from the company
owning rights to the patents.
Having worked for ten years designing and crash testing
roadside safety appurtenances, Dr. Brian Pfeifer had the opportunity to lead the development
of several of these lifesaving designs, and has seen first-hand the difference
that this technology can make in the dynamics of a collision. Of course, guardrails and guardrail
terminals cannot be designed to safely bring vehicles to a stop under every
impact condition, but they must be crash tested under specified impact
conditions and approved for use by the Federal Highway Administration before
they can be used in any projects using federal funds (a large majority of
roadway projects receive at least some amount of federal funding).
Even with all of this improved safety
technology, people die as a result of impacts with guardrail terminals every
day. Some of these deaths are the result
of extreme or unusual impact conditions, but many are the result of poor
product design, improper terminal selection, or faulty installation. If you have a case that involves these issues,
it is very important to understand the role that the safety device played. In order to understand these issues, it is
important to involve an expert familiar with the design and operation of
roadside safety devices early on in your investigation.
Please contact Brian Pfeifer, Ph.D., P.E. and our team of engineers and technicians and put our experience and expertise to work for you.
