What is the Lowest Speed for an injury?

'What Is' type questions related to highway safety, accident reconstruction and vehicle simulation
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What is the Lowest Speed for an injury?

Post by MSI »

Q: What is the lowest speed a vehicle could be traveling that would still be considered a high impact injury?

A: Impact severity is generally based upon the impact speed change which is the time rate of change of the vehicle/occupant during a collision.
  • There are many variables which go into the determination of impact severity. Some of the variables are impact type, occupant position in the vehicle, the vehicle type, weight, structure, the occupant age, sex, size, what occupant protection devices are present (belts? Airbag? ), etc. etc.
You ask for “the lowest speed that a vehicle could be traveling that would still be considered a high impact injury” ; realize that a vehicle can be stopped and/or parked and struck by another vehicle.
As a starting point for your research you might look into the ‘fire/no fire’ range for airbags.
  • Generally (ballpark) it is for an impact speed change of 9 to 14 MPH.
    These values were determined at some point by NHTSA as the impact speed change at which injuries could occur for an unbelted driver.
    However now we have many (most?) occupants belted.
    • From a May 2013 NHTSA report:
      • "nationwide seat belt use was at a record high of 86 percent in 2012, seat belt use at night continues to be lower than during the day."
    So the question which should be asked is: Should the fire/no-fire range for airbag deployment be changed?
    And also, as part of your research you will find that in some instances the airbag has actually killed or seriously injured an occupant in a minor (no damage) collision! (generally an unbelted front seat occupant, or a child or small adult sitting with seat in forwardmost location, or when pre-impact braking causes the unbelted passenger into move forward into the airbag deployment area).
    So in those instances, it wasn’t the accident severity which caused the injury or death, it was the safety device in the vehicle.
I believe you will find a plethora of related information on the NHTSA website.

Another item frequently brought up when 'threshold for injury' is discussed is the EggShell skull theory
  • The eggshell skull rule (or thin skull rule) is a legal doctrine used in some tort law systems, with a similar doctrine applicable to criminal law. This rule holds one liable for all consequences resulting from his or her tortious (usually negligent) activities leading to an injury to another person, even if the victim suffers an unusually high level of damage (e.g. due to a pre-existing vulnerability or medical condition). The term implies that if a person had a skull as delicate as the shell of an egg, and a tortfeasor who was unaware of the condition injured that person's head, causing the skull unexpectedly to break, the defendant would be held liable for all damages resulting from the wrongful contact, even if such damages were not reasonably foreseeable, or the tortfeasor did not intend to cause such a severe injury.
For additional information, please see EggShell skull theory
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