Types of Rear Impact Automobile Collisions and How Bumpers Play a Role
Scientific and medical researchers have proven over the years that “rear-impact” type collisions produce the most injuries to occupants.
The way your spine is configured, the construction of automobile seats, chassis and bumpers all play a role in how you may become injured in a crash. The fact that a collision is a rear-impact versus a front or side impact, raises the odds of suffering an injury and worsens your prognosis (long-term outlook for recovery).
Car Crash 101
What happens when 2 cars collide? As an example we will say a vehicle is at a complete stop. This is the “target” vehicle. Another vehicle that is moving is known as the “bullet” vehicle. The bullet vehicle strikes the target vehicle in the rear. The moving vehicle has a mass and speed that will deliver a force to the stationary vehicle. This force is energy and according to physics, whatever energy is put into the collision an equal amount must come out of the collision. A minimal part of the energy is dissipated as sound, part of the energy is absorbed by the bullet vehicle deforming and the rest of the energy goes into the struck vehicle. If the struck vehicle crushes, energy will be bled off as the metal and plastic deforms and crushes. After deformation, there may still be energy left over. This energy moves through the chassis of the vehicle, it may make the struck vehicle move forward lessening energy even more. If more energy is left over, that energy causes forces on the occupant’s body and if it is enough, results in tissue damage.
There are many variables that dictate how much energy is created in a collision and how much energy there is that can be injurious. Things like size and weights of the vehicles, the speed the vehicles are traveling, how the vehicle’s bumpers line up, if the struck vehicle is manual or automatic transmission, if the road is wet or dry, is the struck vehicle is on an up or down slope, etc. The uniqueness of each crash is because of all the variables that can be involved.
The Role of Bumpers in Rear End Car Accidents
Rear end collisions can be further subdivided and injury potential increases or decreases with each variety. The possibilities of impact types are endless, so we will stick with the most common scenarios seen in the real world that you may become victim to.
Rear-impact, Well Aligned Bumpers That Crush
This is the most favorable of “rear enders.” If you have a choice in your car crash, pick this one! When 2 cars collide and the vehicle bumpers are roughly the same height, the bumpers strike each other and do their jobs, namely crush and absorb energy to protect you. Energy is transferred from the striking vehicle into the target vehicle. Energy is absorbed by crush of plastic and metal, sound and some heat. If a lot of energy is dissipated in this way, then less energy is transmitted through the chassis, into your seat and ultimately into your body. More energy to your body means more injury, so we want the bumpers to crush a lot. If each vehicle has crushable bumpers that line up well, the amount of injury you suffer is reduced.
Rear-impact Misaligned Bumpers; Striking Vehicle Hits above Target Vehicle Bumper
In this case, the 2 bumpers did not line up well. Maybe the striking vehicle’s bumper hits your bumper, but it mostly goes above it and strikes the rear trunk lid. This is less favorable than well aligned bumpers because the struck vehicle’s bumper did not get to bleed off energy. The rear of the car above the bumper may crush, but it does not contain energy absorbing materials that are scientifically designed to reduce energy, so more energy is sent through the chassis, into the seat and into your body.
Rear-impact Misaligned Bumpers; Striking Vehicle Hits below Bumper (Submarine impact)
It’s pretty easy to understand why these are called “submarine” impacts as the striking vehicle is like a sub that hits a ship below the water line. These impacts occur because the striking vehicle is lower than your vehicle or the striking vehicle is hard on the brakes trying to stop so its nose is low on impact. Sometimes the striking vehicle becomes wedged under the struck vehicle. Similar to above, the struck vehicle’s bumper does not get involved to reduce damaging energy, so you get hurt more. An added component that may cause more damage than above the bumper strikes is the force is delivered into the rear and there is an upwards component causing you to feel a quick pop up your spine not just front to back. This results in increased chance of lower back injuries.
Rear-impact, Well Aligned Bumpers, but Struck Vehicle has Steel Bumper or Trailer Tow Package Installed
Remember that the more the colliding bumpers crush, the less energy and therefore injury can occur to your body. What happens when the struck vehicle is a pick-up truck or SUV that has a steel, non-deformable rear bumper? These pretty, chrome step-bumpers look nice and can take a beating without showing damage, but what they also do is transmit large amounts of force through the vehicle chassis and directly into an occupant’s body causing damage. These bumpers can be struck at 20 mph and show very little damage. The striking car, if it has crushable front bumper, may look like a bug squashed against a windshield when they hit these bumpers. Having a trailer hitch or tow package also increases the amount of injurious energy into the occupant because they add rigidity to the rear of the vehicle, do not deform and are connected directly to the chassis. The converse of this situation is also true: if a vehicle with a steel, less deformable bumper strikes a conventional rear bumper, the amounts of force delivered by the steel bumper is more than if both cars had crushable bumpers. The frustrating dichotomy of this particular type of rear-end collision is that if you are in a vehicle with a steel bumper and suffer a rear impact, the potential for injury is greatly increased, BUT because there is low property damage, auto insurance adjusters tend to discount these cases. It is important to always take photos at the scene of an accident, not just of your vehicle but of any other vehicles involved as well. Pictures of a severely damaged vehicle that left only a dent on your steel bumper goes a long way to explaining damaging forces involved in the collision.
Rear-impact motor vehicle collisions have been shown to cause more damage than other types of crashes. Many variables are involved that predict bodily damage by a rear collision. Bumper design and vehicle alignment are a important variables that can predict if the occupant(s) of a struck vehicle will suffer relatively more or less injury. Each car collision is unique due to the myriad of variables involved in car crashes.