Most people die in rollover accidents because the roof fails as the vehicle overturns and the strength of the roof is insufficient to absorb the force of the roll. Weak rooftops are a design issue in all sorts of vehicles, from minivans and SUVs, to pickup trucks and sedans of all sizes.
Roof Weakness Causes Fatal Injuries in Rollover Crashes
In a motor vehicle accident, air bags exist to protect occupants from the force of impact. Safety features like seat belts and car seats also save lives.
However, many vehicles remain on the roads today that risk lives as their roof is weak and insufficient to withstand the force of an overturn. We have discussed this danger of “roof crush” before. See:
- What’s Causing These Deadly Rollover Accidents in Indiana and Illinois? Is It Roof Crush?
- Rollover Accidents in Indiana and Illinois: A Continuing Danger
- Passenger Van Accidents: Causes and Liability.
Testing for Roof Strength: NHTSA and IIHS
There are two well-known research studies that delve into this problem. One is the annual testing by the National Highway Traffic Safety Administration (NHTSA), as part of its duty to reduce “…deaths, injuries and economic losses resulting from motor vehicle crashes.”
NHTSA Testing for Rollover Risk
NHTSA Crash Tests do not evaluate every motor vehicle being sold in the United States. Their research is based upon either new models or revamped (redesigned) models that are being introduced into the marketplace.
The NHTSA testing focuses on several things, including “rollover resistance.” Once testing is completed, the vehicle receives a score between one (1) and five (5) stars. The more stars, the safer it is considered under the NHTSA safety analysis.
To search for a particular motor vehicle’s NHTSA overall safety rating, go to the safercar.gov website. For instance, a 2015 Toyota Camry rates 4 out of 5 stars for “rollover resistance,” while a 2015 Ford Transit Medium Roof 15 Passenger Wagon RWD rates 2 out of 5 stars in rollover testing.
The rollover resistance rating is based on an at-rest laboratory measurement known as the Static Stability Factor (SSF) that determines how “top-heavy” a vehicle is, and the results of a driving maneuver that tests whether a vehicle is vulnerable to tipping up on the road in a severe maneuver.
IIHS Testing for Roof Strength
The Insurance Institute for Highway Safety (IIHS) is an “…independent, nonprofit scientific and educational organization dedicated to reducing the losses — deaths, injuries and property damage — from motor vehicle crashes.” It compiles safety ratings for motor vehicles that are driven in the United States with a different approach than the federal government.
Data is obtained from the Highway Loss Data Institute (HLDI) shares insurance data regarding both personal injuries and property damages reported in insurance claims, tallied by vehicle make and model.
IIHS reports a “Top Safety Pick” each year as well as giving ratings for the “Top Safety Pick+” vehicle for that year. However, just as NHTSA, not all motor vehicles are tested. Only new models are reviewed by IIHS.
IIHS tests for two things: (1) crashworthiness (ability to protect occupants during crash) and (2) crash mitigation (ability to diminish severity of the crash). Roof strength is a component of IIHS’s crashworthiness testing. IIHS scores range from good (G), acceptable (A), marginal (M), or poor (P).
To search for a particular motor vehicle’s IIHS overall safety rating, go to its website. For instance, a 2015 Toyota Camry rates “good” for “roof strength.”
In the test, the strength of the roof is determined by pushing a metal plate against one side of it at a slow but constant speed. The force applied relative to the vehicle’s weight is known as the strength-to-weight ratio. This graph shows how the ratio varied as the test of this vehicle progressed. The peak strength-to-weight ratio recorded at any time before the roof is crushed 5 inches is the key measurement of roof strength.
A good rating requires a strength-to-weight ratio of at least 4. In other words, the roof must withstand a force of at least 4 times the vehicle’s weight before the plate crushes the roof by 5 inches. For an acceptable rating, the minimum required strength-to-weight ratio is 3.25. For a marginal rating, it is 2.5. Anything lower than that is poor.
Issue with IIHS Testing of Roof Risk
Under IIHS, not all models are tested for roof strength. For instance, there is no online result for the roof risk of a 2015 Ford Transit Medium Roof 15 Passenger Wagon RWD at the IIHS site.
Moreover, as NHTSA points out, another issue with IIHS testing of roof strength is IIHS is providing a “consumer information test” for select models, and when it does do roof strength testing IIHS only tests one side of the roof.
Accident Victim Claims for Rollover Injuries Based on Roof Failure
For those that are seriously injured or killed in a rollover accident, the issue may not be the negligence of any particular driver so much as the problem of product design with the vehicle’s roof.
If the roof failed, is the car maker then responsible for the fatal injuries sustained in the crash?
Rollover accidents, where the vehicle overturned, must be evaluated on a case by case basis to determine if there is a defective product or product liability claim to be advanced against the car maker.
Testing by safety advocates is not sufficient because it does not cover all makes and models of motor vehicles on the road today. It may be true that the first time an accident victim realizes that his or her vehicle has a weak roof subject to failure is when there is a crash.
Rollover accidents are often tragic and preventable accidents, sometimes with only the driver as the victim of the vehicle’s fatal roof failure. Let’s be careful out there!
