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Bumping Into Safety

Why today's bumpers aren't as strong as before

In the olden days, bumpers protected a vehicle from body damage in low speed collisions. Don't get us wrong, they still do; but, as bumper designs have evolved, so have their level of protection. To make the bumper even more vulnerable, the federal government's impact-test requirements were dropped from 5 mph to 2.5 mph in 1982. Think about that: a healthy person walks faster than 2.5 mph.

So, here's a brief history of the decline of the bumper, which should encourage readers to either look into beefier aftermarket bumpers or drive more defensively and very carefully.

Bumper Function

The function of the bumper is to absorb crash energy without significant damage to the bumper itself and no damage to the vehicle's front or rear end. Generally speaking, today's bumpers are made with a reinforcement bar of steel, aluminum, fiberglass composite or plastic with a plastic cover. The system includes crash absorbing mechanisms that compress on impact, such as polypropylene foam or plastic honeycomb. The most effective bumpers are positioned with distance between the reinforcement bar and the vehicle's sheet metal.

To guarantee that automotive bumpers worked well, the federal government developed safety standards in the early 1970s. The first standard prohibited damage to safety related equipment in low-speed, 5-mph crashes.

Prohibitive Damage

The next phase, effective for 1979 models, prohibited damage except to bumpers and their attachments in low speed crashes. These standards only applied to passenger cars, not the generic light-truck category that includes pick-ups, SUVs and vans or minivans.

Between 1980 and 1982, the standards got a little tougher, prohibiting all but minor cosmetic damage to bumpers. The area of protection was defined as 16 to 20 inches above the road surface. The automotive industry met these standards and in some cases exceeded it.

For instance, according to the Insurance Institute for Highway Safety, the 1981 Ford Escort not only survived the required minimum without a scratch, but also came out unscathed in even more demanding crash tests: the 5 mph front-into-angle-barrier test and the rear-into-pole test. These same tests on lesser, newer vehicles have resulted in damages in excess of $1,000.

Meeting Demands

Since then, auto manufacturers have to deal with conflicting demands: aesthetics, costs for consumer, and lighter weight vehicles to meet fuel economy requirements. The difficulties involved in meeting the 5 mph test resulted in a standard reduction in 1982. The new criterion became the 2.5-mph crash test, and the bumper and attachments could be destroyed during the test as long as the vehicle body panels were left intact.

Again, these standards only apply to passenger cars — which brings us to another sticky point. The protected area, defined by the standards for passenger cars, is 16 to 20 inches above the roadway. The bumper heights on light trucks vary, depending on modifications such as suspension lifts and the size of the vehicle.

Vehicle Height

Light trucks usually perform specific work functions that require greater clearance for approach and departure on steep grades, especially in off-road conditions. So what is happening is bumper mismatch: a one-ton pickup or SUV's bumper can be considerably higher, resulting in body damage to an impacted passenger car and, conceivably, damage to the truck below the bumper. This issue of bumper mismatch is gaining more attention simply because there are more light trucks on the road today than ever before, most being driven within the passenger car arena.

According to the National Highway Transportation Safety Administration, this mismatch is more than a bumper issue. It also involves the differences in vehicle characteristics such as weight, height, suspension stiffness, etc. Some states do have regulations limiting bumper height and the NTSA is exploring these compatibility issues.

5-MPH Bumper

You've probably heard auto advertisements that refer to a 5-mph bumper. Yes, they do exist. In addition to sustaining little or no damage from a 5-mph collision, they also result in reduced repair costs in crashes at higher speeds. California and Hawaii are the only two states with bumper disclosure laws. Automakers who advertise that they exceed federal standards are required to be specific about the speed at which they provide protection. While other states do not require this information, manufacturers voluntarily supply this information on the window sticker of all new vehicles.

If you're interested in additional information on bumper safety, the IIHS posts the results of four 5-mph crash tests on its web site (www.hwysafety.org) along with information on the cost to repair the damage. The estimated damage price tag on the 2002-2003 midsize passenger cars tested by the non-profit agency ranged from $1,497 to $6,796.

So what's the best advice for minimizing damage to your vehicle and its bumper? The bottom line, short of welding a massive, heavy steel beam to the front of your vehicle: drive carefully, even when crawling through a parking lot.