Motor Vehicle Accidents:
Little or No Damage Collisions & Demonstrable Verification of Energy Transferences to Cause Bodily Injury
By: Patrick Sundby, Accident Investigator
Specializing in Low Speed and Catastrophic Crashes
Mark Studin DC, FASBE(C), DAAPM, DAAMLP
In the last two writings we explored how low speed collisions can have substantial energy transfers with minimal (if any) damage. Here we will discuss the myth of “no damage = no injury” from a vehicle appearance / design point of view and how it relates to injury during a collision.
In order to get into this topic, we need a little history lesson first. The automotive industry exploded after World War II, with vehicle style being the topic of focus. The jet age influenced bumpers, headlights, interior components, taillights, even excess in the design – fins. Something else happened too, for the first time in the automobiles history vehicles were more than “around town” horse-less buggies; the power of the engines and speeds possible dawned a whole new arena – safety. In the 1960’s vehicle aesthetics began to compromise with safety. Automotive designers began to consider topics such as; structural integrity, occupant restraints, and crash worthiness.
The industry faced slow growth and change into the 1980’s, each revision or change did bring with it progress and improvement but not enough at any one time to be a huge leap forward. The changes which were necessary were too cost prohibitive, too experimental, or simply too market risky. Then in the mid 1980’s a revolution in industry began to take hold – the computer. The standard personal computer allowed for design changes to be done with much greater efficiency. Once plugged in and switched on the days spend calculating variables and double checking work became no more complicated than a few clicks.
The computer made it possible for car manufacturers to reduce years of standard research and design practices into just a few months and at the same time it allowed for much more cost effective experimentation and new process development.
Now that we have completed history 101 let’s discuss the topic of point – “no damage = no injury”
Vehicle design, as an approach or concept, has undergone a substantial overhaul in recent years. The change has influenced the standard use of bumper covers. The long standing tradition in automotive design has been to put the bumper outside or separate from the body and to make them of a robust alloy. (Think about all those classics in “American Graffiti”). The bumper was designed to be a visual compliment to the overall appearance of the vehicle. The safety perspective was non-existent with respect to bumpers as they were no more than a sacrificial lamb to save the body from expensive repair.
In the early 1970’s federal mandates designed to make vehicles safer forced the manufacturers to engineer larger and more structurally sound designs. The most noted changes where the moving of bumper away from the body itself to an integral part of the body of the car. This “afterthought” look borrowed from the truck world was the norm until the late 1980’s. Three things changed in the 1980’s: First, bumpers began to move to behind urethane bumper covers in widespread use. This gave vehicles a modern look and concurrently helped with aerodynamics. Secondly, because aesthetics were no longer part of the equation, bumpers became much stronger and included the use of energy absorbing material between the bumper cover and the bumper structure. Finally, automotive paints had also advanced, including the superior ability to resist cracking & flaking, and paint had become flexible.
These changes also had another positive side effect; because of the elastic properties of urethane and the paint, minor collisions, even those which damaged the bumper behind them, no longer appeared as serious. Often times a bumper cover needed little more than some prep and paint, where previous designs necessitated changing the whole bumper.
The biggest change between old design and the new one, is the inherent elasticity of the new bumper covers. These covers can, and often do, rebound to the original design they were formed in and the use of flexible paint means the paint is very likely to rebound as well. While signs of impact are obvious the assessment of speed from damage is now deceptively poorer. Obviously when a steel bumper is distorted it stays that way leaving no room for underestimation.
Notice how we have not discussed how these design changes have benefited energy transfer; and this is no mistake. There simply aren’t any groundbreaking points to discuss. Changes in vehicle design will not facilitate violation of laws of physics. All these design changes have accomplished is make the energy transfer in a low speed crash less obvious and less costly.
However, there are simply demonstrable measures that can be taken to assess the effects of energy transfer in no apparent damage collisions: