The human body is both remarkably durable and remarkably fragile. It’s designed to take quite a bit of abuse, but only in certain directions: belted into a seat, in a modern car equipped with airbags, many frontal and rear impact crashes are survivable. The body can absorb a substantial dorsal or ventral impact, especially if the force is spread over a wide area (as is the case with seat belts and air bags). Cars have energy absorbing crumple zones up front and to the rear, which adds to crash survivability. Side impacts, on the other hand, have the potential of being much more dangerous for many reasons.
The human body is not designed to take a serious and sudden lateral impact. The heart, for example, can move much farther left or right in the chest cavity than it can front to back. Tear the aorta, and no amount of medical attention on the scene is going to do you much good. Cars, just like people, don’t offer much side impact protection when compared to front and rear impacts. Sure, side door beams, high strength steel and side curtain airbags have made cars safer, but cars still lack significant structure and intrusion protection on their sides. A recent IIHS study took a look at cars equipped with side curtain airbags, but scored differently for side impact protection. The results are dramatic.
Drive a car rated as “Good” for side impact protection by the IIHS, and your chance of dying in a side impact crash decreases by 70% compared to a car rated as “Poor” for side impact protection. Even a car listed as “Acceptable”, the institute’s second highest rating, is 64% less likely to produce fatal injuries, while a car rated as “Marginal” is 49% less likely to cause a side-impact fatality than one rated as “Poor”. Since all cars tested were equipped with side curtain airbags, the real difference is in structural integrity and intrusion protection. The stronger the side of the car, the safer it will be in a side impact crash.
The IIHS study is meant to drive improvements in side impact protection among automakers. Conventional methods, such as adding more high-strength steel or using additional side door beams, add weight (which is one reason why today’s cars are less fuel efficient than those of 30 years ago). Automakers must balance the need for safer cars against the need to produce light, more fuel efficient ones. Short of building cars from exotic materials (aluminum and carbon fiber, for example), there is no easy or inexpensive way to meet both demands.
Source: NY Times Wheels