by Paul Niquette
Internet Version of an article first published in the April 1954
edition of California Engineer, appearing here by permission of the publisher.
Research in the field of reducing traffic injuries is essential if this problem is ever going to be solved. No matter how well the traffic engineer designs intersections and freeways and regardless of the amount of money appropriated for highway safety, accidents cannot he entirely eliminated as long as human beings are still in the driver's seat of moving automobiles. Of course the first solution is: Stop all motion and you stop all accidents. This is very impractical. The next solution would appear to be one of protecting passengers against injury due to these inevitable accidents.

Annual statistics on motorist injuries and deaths convince us that steps should be taken to reduce the injury toll. The Institute of Transportation and Traffic Engineering (ITTE) lias been carrying on a crash-injury research program during the past five years for the purpose of investigating various protective devices for occupants in moving cars. The past four months work on this project has led to the preparation of two carefully controlled experimental crashes which took place last February.

THE DUMMY in the foreground had no protective device in this second crash. His head hit the ceiling of the car. leaving a convex dent about an inch deep. The other dummy, protected by a shoulder-type harness, seemed to suffer the least injury. The remote steering motor can also be seen in this picture as well as an accelerometer mounted on the door post.

Under the supervision of Derwyn Severy, project engineer, two identical 1937 automobiles were instrumented and crashed into a rigid barrier of utility poles backed with tons of dirt. The speed at impact was about twenty-eight miles per hour. Two anthropometric dummies, to simulate motorists, were used in testing a total of four different conditions of restraint. Although the instrumentation data is currently being evaluated, preliminary observations suggest that the shoulder harness offered the greatest crash protection followed closely by a chest level restraint. A lap belt appeared to offer little impact protection. In fact, essentially the same damage occurred when no restraint was used. The lap belt does serve the purpose of holding the passenger from being thrown from the car and would give some protection to rear seat passengers.

The dummies weighed about two hundred pounds each and had joints with movement and fixation closely resembling that of a person forewarned of an impending collision. An instrumented carryall truck was used to push the car up to speed, and a one-hundred foot electric cable joined the crash car to the instrument truck. This cable is laid out automatically from a platform on the hood of the truck when it slows down to a gradual stop while the crash-car coasts ahead to hit the barrier. On top of the truck, two 110-volt AC portable power units were kept running to supply continuous power to the floodlights in the car, the remote controlled steering mechanism, the remote controlled push-button brakes, and to supply power for the instruments. A twenty-four channel recording oscillograph mounted in the instrument truck captured information from tensiometers on the seat belts as well as the accelerometers mounted on the various parts of the car and dummies. The photography involved in these experiments is a major undertaking in itself. An Eastman high-speed camera was directed on the crashing car. Moody Institute of Science cooperated with ITTE by obtaining additional crash pictures with their high-speed camera. A good deal of the data for the tests are contained in these films. Not only do the pictures (taken at speeds between 1000 and 2400 frames per second) reveal deceleration rates of the car and dummies, but also deceleration patterns of the car frame by means of small metal targets mounted on rods which are in turn welded at several points along the frame.

Two GSAP movie cameras mounted on the shelf behind the back seat of the crash-car revealed additional information on the dummies' motion during impact. Another camera located thirty feet from the barrier panned the movement of the car and truck as they sped toward the carrier. A similar motion picture camera mounted on top of the instrument truck, trained forward on the car and barrier, points up steering problems and crash behavior.

A speed graphic camera with an electronic timing device took a still picture of the car two-hundred milliseconds after the car first contacted the barrier. This was the time of zero forward velocity, approximate maximum deceleration, and greatest crush-in volume.

Synchronizing the high-speed camera with the oscillograph was accomplished by putting a strobe light on the car within range of the camera. A detector on the front of the car opened the circuit, turning off the strobe light and simultaneously marking a pulse on the oscillograph record as the car contacted the barrier. Also, the camera was modified by the provision of a metal blade on the shaft of the camera motor which cuts the field of an electromagnet once every ninth frame. The pulse thus generated was transmitted to the oscillograph through a small cable dragged by the truck. Further, a standardized sixty-cycle electrical pulse was fed into a miniature gas-filled light which was directed against the edge of the film inside the camera to provide a time reference used for accurately determining the film speed.

In addition to deceleration targets on the car frame, small screws were set in the frame at various stations. Before and after the crash, the car was placed over a recording platform. This platform was marked using a plumb bob hung at each of the screws. Measurements of the distances between these points were made, and methods of triangulation can then be applied to compare deformation of the car.

THE SPEED of this automobile at impact was about twenty-eight miles per hour. An electronic timer tripped the Speed Graphic camera which took this picture 200 millseconds after impact. This was the time of maximum deceleration and crush in volume. The dummy, visible through the plastic door, was being protected by a chest level restraint. The steering wheel can be seen as it was pushed by the motor against the dummy's chest.

After the crashes a doctor examined the dummies for the purpose of evaluating inferred injuries and their consequences. The unrestrained dummy did not go through the windshield as might have been expected, but struck the top of the car leaving a dome-shaped dent about an inch deep in the sheet metal covering. Previous crash tests suggest that the dummies may have decelerated at as much as 20 g's.

THE 24-CHANNEL recording oscillograph is given a final check by Paul Niquette just before the car is pushed to destruction. This instrument records tension in the seat belts and accelerations of various parts of the crash-car and dummies.

In conclusion, the objectives of these crash injury research experiments are as follows:

  1. To develop a system of instrumentation for accurately evaluating the physical factors associated with automotive crash deceleration.
  2. Evaluation, protection-wise, of chest, shoulder and lap type safety belts as motorist restraints.
  3. Analysis of belt loadings and accelerations of head shoulder and hip of each dummy.
  4. Additional data on permanent deformation of the car frame for a twenty-five mph. barrier crash.
  5. Measurement of deceleration with respect to time of each six inch segment of the front portion of the car frame in order to determine the geometry of peak loadings.
  6. Measurement of the longitudinal and vertical patterns of deceleration of the intact portions of the car.
  7. Provide movie films of the dynamical features of crash deceleration of both the car and occupants for later review and evaluation.
  8. To secure additional data on pre-impact velocity versus crush-in volume. This information may eventually lead to the development of empirical formulas for estimating the pre-impact velocity of wrecked vehicles.
  9. To secure data on what factors lead to injury of the unrestrained human body during a crash.
The fulfillment of these objectives may eventually lead to much safer driving conditions for you and me.
Epilog:  For the story of the photograph above of that crashing car see Historic Car Crash.

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