The “Second Collision” Does Not Have To Be So Prevalent. We can do better at preventing death & horrific injuries.

Michael Lemov, in his book Car Safety Wars, sheds light on what has been responsible for so many deaths from vehicular crashes. The automotive industry has long claimed that “Safety doesn’t sell,” and consequently too-often did not include safety features in their vehicles. As a result, too many people have died from what has come to be known as the “second collision.”

Lemov describes it this way:

“During the first six decades of the twentieth century the American automobile industry seemed wedded to the idea that safe design was not its responsibility. There was no public demand, it was said, for safer automobile design. Nor did the industry seem to think it had much responsibility to inform the public about the risks of vehicle design and the omissions such as lap and shoulder belts.

“In the years before the enactment of the National Traffic and Motor Vehicle Safety Act in 1966, better-designed motor vehicles might have saved millions of drivers and passengers from death and injury in what had by then become known as the ‘second collision.’ This is the collision of the driver and passengers with the interior of their own vehicle during a crash.

“The basic physics of the ‘second collision‘ were described by Hippocrates in the fourth century BC when he contrasted the greater severity of wounds inflicted by a sharp penetrating object with the less-serious wounds produced by a blunt weapon. This established that when force is distributed over a larger area (say by safety belts over the shoulders, chest, and pelvis) rather than a small area (the face or head of a driver or  passenger) the force per unit of area is much less.

“Similarly, two centuries before the invention of the automobile, Sir Isaac Newton defined the relationship between velocity and deceleration of a moving object. Simply put, the greater the distance over which vehicle deceleration occurs the less injurious the force that is imparted to the occupant body, such as the head and neck. For example, the two-foot deformation, or crushing of the front end of a vehicle, is the stopping distance of an unrestrained passenger before striking the interior of the vehicle. In the same car, the stopping distance of the same passenger wearing a lap-shoulder belt, would be much greater, as the car decelerates over many feet, causing less injurious forces to the neck, skull, and body.5

“Detroit automotive engineers, of course, knew about these principles and problems of the physics of automobiles. Since at least the 1930s they had also known of some promising solutions.6 But their employers who called the shots were deterred either by cost, perceived engineering problems, or marketing considerations from doing anything much about applying them. Mostly the companies sold annual styling changes and more horsepower.7

“The reaction of the motor vehicle industry, dominated by General Motors, Ford, and Chrysler, to the increasing toll of death and injury (from about 33,000 deaths per year in 1950 to 53,000 in 1969)–was consistent. The manufacturers placed primary blame on the driver and on driver attitudes.” (Car Safety Wars; One Hundred Years of Technology, Politics & Death, by Michael R. Lemov, pp. 49-50)

Unfortunately, a similar attitude toward safety and truck underride guards has probably meant that underride prevention technology has been woefully inadequate and many people may well have unnecessarily died as a result.

In fact, the Insurance Institute for Highway Safety (IIHS) has told us in person that, “It is safer to run into a brick wall than into the back of a truck.” This is due to the fact that if you run into a brick wall with a vehicle equipped with a crush zone, that crush zone is able to go into effect and protect the occupants. However, if a vehicle hits the back of a truck and the underride guard fails, the vehicle goes under the truck so that the passenger compartment is intruded upon and the crush zone (air bags and seat belts) is not allowed to operate as designed.

George Rechnitzer, a professor and researcher from Australia who has done research with Transport and Road Safety Research (TARS) believes that the underride problem can be solved. In 2003, he authored this dissertation: The Improvement of Heavy Vehicle Design To Reduce Injury Risk In Crashes With Other Road Users. (2003)v=8b6a69875e67767ca2a4

In the introduction, Rechnitzer says that,

“The thesis concludes with presenting the important concept that crash protection for
occupants is a function of the nature of the interface between the impacting vehicles
and /or the person. This hypothesis provides an alternate perspective on what is feasible
in occupant protection in severe impact scenarios. It clearly shows that contrary to a
common view in road safety, vehicle mass per se is not the major determinate of injury
outcomes. Indeed this thesis demonstrates that injury protection is feasible against high mass vehicles be they trucks, trams or trains, by appropriate design of the interface between impacting objects.

Here are crash tests of the underride prevention protection designed by George Rechnitzer: .

Deadly second collisions do not have to be so prevalent; we can do this better!

Trip North May 2015 154

2 thoughts on “The “Second Collision” Does Not Have To Be So Prevalent. We can do better at preventing death & horrific injuries.

  1. Thanks for reviewing my book: “Car Safety Wars”, so effectively.
    I hope it helps in your personal effort to save lives.
    Michael R. Lemov

    1. Thank you for the feedback. Your book confirmed many of our observations and gave me new insights for strategies to continue this battle.

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