We are currently developing and demonstrating a pilot Rollover Occupant Protection Rating System.

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About Our Ratings

The U.S., European and Australian New Car Assessment Program (NCAP) and the Insurance Institute for Highway Safety (IIHS) produce ratings of new vehicle performance based on dynamic crash tests in frontal, side and rear crashes, and vehicle handling tests. No dynamic based crashworthiness ratings exist to date in relation to rollover crashes.

The NCAP is thirty years old, and has been successful in getting automakers to improve safety performance of new vehicles. Unfortunately, there is no rating for rollover occupant protection, a crash mode that is responsible for one-third of all light vehicle occupant fatalities. NHTSA has upgraded the roof crush requirements for new cars, but the time is overdue for an NCAP rating on rollover survivability. We have conducted extensive testing that provides a basis for such a rating. In particular the Jordan Rollover System (JRS) dynamic rollover test results, in conjunction with NHTSA and IIHS statistical analyses, and the biomechanical injury correlation studies provide that basis and are published in, A Proposed Rollover and Comprehensive Rating System ¹.

How NHTSA Publishes Their Ratings

On the NHTSA website they have a link to a public website called Safercar.gov. Their tag line read: “Nations premier source of vehicle safety information from the government, serving the public interest.” One of the sections on their site is a “star rating” of crash tests and rollover ratings on vehicles here in the U.S. The rollover ratings or stars are based on an Static Stability Factor (SSF). Below is how this factor is computed.

What is a Static Stability Factor (SSF)

The SSF of a vehicle is an at-rest calculation of its rollover resistance based on its most important geometric properties. SSF is a measure of how top-heavy vehicle is.

A vehicle's SSF is calculated using the formula SSF = T/2H, where T is the Track Width of the vehicle and H is the Height of The Center of Gravity of the vehicle. The track width is the distance between the centers of the right and left tires along the axle. The location of the center of gravity is measured in a laboratory to determine the height above the ground of the vehicle's mass. The lower the SSF number, the more likely the vehicle is to roll over in a single-vehicle crash.

SSF will only tell you how likely it is for the vehicle to rollover, NOT how well the vehicle structure will hold up if it does roll!

Star Safety Ratings Image

Conclusions (From our Ratings Paper – ESV 2009 ¹)

  • A consumer rollover rating system is long overdue. The best way to rate the crashworthiness injury potential of vehicles in rollovers is by utilizing a JRS dynamic test. Rating vehicles simply by Federal Motor Vehicle Safety Standard (FMVSS) 216 gives grossly misleading (both over and understated) injury rate results.
  • The ten vehicle JRS dynamic tests presented in this paper are a sample of the results that are achieved with dynamic testing and the basis for the consumer rollover rating system. Three of the vehicles would receive “good” ratings, two with “acceptable”, two with “marginal” and three “poor” ratings.
  • When evaluating a rating system based solely on FMVSS 216, in comparison to dynamic testing, anomalies abound. The Honda CRV is one such anomaly. The Honda CRV emulates the rollover roof crush performance of vehicles like the XC-90 and the VW Jetta with a high strength to weight. The Honda CRV may be a styling-derived, partial and non-optimized implementation of a geometric roof improvement discussed and validated in our companion geometry paper. (ESV 2009 “Vehicle Roof Geometry and its Effect on Rollover Roof Performance” ²)
  • The proposed comprehensive ratings system would include a factored and weighted analysis by fatality rate and frequency of a vehicle’s performance in all four major accident modes. This would provide an overall rating that consumers could use when purchasing a new or used vehicle.
  • 1. “A Proposed Rollover and Comprehensive Rating System”, ESV 2009, June 15-18, 2009, Stuttgart, Germany
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  • 2. “Vehicle Roof Geometry and its Effect on Rollover Roof Performance”, ESV 2009, June 15-18, 2009, Stuttgart,


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