NHTSA - SUV ROLLOVER RATINGROOF CRUSH TESTING, STATISTICS & REPORTS ROLLOVER RESISTANCE RATINGS & STATISTICS

National Highway Traffic Safety Administration (NHTSA) has studied rollovers for decades.Nhtsa has concluded that rollover crashes are one of the most significant safety problems for all classes of light vehicles especially light trucks (pickups, sport utility vehicles, and vans -- LTVs). For 1992 through 1996, there were an average of approximately 227,000 rollover crashes per year. (Rollover crashes are ones in which rollover is the first harmful event.) These rollovers resulted in an average of 9,063 fatalities per year (29 percent of all light vehicle fatalities) and over 200,000 non-fatal injuries per year. NHTSA's Rollover Resistance Rating System is an estimate of your risk of rolling over if you have a single vehicle crash. Rollover Resistance Rating does not predict the likelihood of that crash. The Rollover Resistance Rating essentially measures vehicle characteristics of center of gravity and track width to determine how "top-heavy" a particular vehicle is. The more "top-heavy" the vehicle, the more likely it is to roll over. The Rollover Resistance Ratings of vehicles were compared to 200,000 actual single vehicle crashes, and the  rollover ratings were found to relate very closely to the real-world rollover experience of vehicles. Based on these studies, NHTSA found that taller, narrower vehicles, such as sport utility vehicles (SUVs), are more likely than lower, wider vehicles, such as passenger cars, to trip and roll over once they leave the roadway)

ROLLOVER INJURIES & DEATHS

In terms of fatalities per registered vehicle, rollovers are second only to frontal crashes in their level of severity. The rollover problem is more serious for light trucks, especially sport utility vehicles. State crash data indicates that, for all types of collisions, LTV’s are only in 68 percent as many crashes per registered vehicle as are passenger cars. However, for rollover crashes, LTV’s are in 127 percent as many crashes per registered vehicle as are passenger cars.

ROLLOVERS RESULTING FROM VEHICLE TRIPPING

Most rollovers result from the vehicle leaving the roadway and tripping. While unfortunate (and all too often tragic), the causes of tripped rollover are well understood. Any vehicle will roll over if it impacts a suitable tripping mechanism with sufficient lateral velocity.Examples include impact with grass turf, gravel shoulder, curbs, driveways, edge of pavement, ravines, gulleys, guardrails, and even ice on the roadway.On-road untripped rollovers due to vehicle maneuvering are responsible for only a small portion of the rollover safety problem. NHTSA’s past research has estimated that less than 10 percent of all rollovers are on-road, untripped, events. Even though this is a small part of the overall rollover crash problem, considerable attention is given to this problem by proponents of rollover safety. This is because this type of rollover is considered to be egregious. Furthermore, there is a perception that on-road, untripped rollovers are primarily caused by vehicle-related factors and can be prevented by an appropriate safety standard.In comparison with tripped, off-road rollover, the causes of untripped, on-road rollover are not well understood. Past NHTSA research has never found a light vehicle for which, when empty, the most severe attainable steady state turn exceeds the vehicle’s rollover threshold. Since placing a load in a vehicle increases the load on the tires thereby decreasing the available tire-road coefficient of friction, loaded vehicles are also not expected to rollover due to steady state turns unless the load has a very high center of gravity.The Rollover Resistance Ratings estimate the risk of rollover in event of a single vehicle crash, usually when the vehicle runs off the road. Electronic Stability Control (which is offered under various trade names) is designed to assist drivers in maintaining control of their vehicles during extreme steering maneuvers. It senses when a vehicle is starting to spin out (over steer) or plow out (under steer), and it turns the vehicle to the appropriate heading by automatically applying the brake at one or more wheels. Some systems also automatically slow the vehicle with further brake and throttle intervention. What makes Electronic Stability Control (ESC) promising is the possibility that with its aid many drivers will avoid running off the road and having a single vehicle crash in the first place. However, ESC cannot keep a vehicle on the road if its speed is simply too great for the available traction and the maneuver the driver is attempting, or if road departure is a result of driver inattention.

NHTSA- ROLLOVER ROOF CRUSH ROOF CRASH PROTECTION

At NHTSA in order to improve crash survivability in rollover crashes by preventing occupant ejection and by mitigating the severity of impacts that an occupant experiences during rollover in 1991 they mandated that the agency initiate rulemaking on rollover protection.Subsequently, a rulemaking plan titled "Planning Document for Rollover Prevention and Injury Mitigation" was published for public review (Docket 91-68 No. 2, Sept 1992). This program identifies the current research activities in support of the crashworthiness programs in this document.On average, 7,797 annual rollover involved fatalities were reported by the Fatal Accident Reporting System, FARS, between 1988 and 1994. There were also between 43,000 and 58,000 annual rollover involved incapacitating injuries between 1988 and 1994, as reported by NASS GES. Approximately 16 percent of serious injuries to passenger car occupants and 42 percent of serious injuries to light truck occupants occurred in vehicles that rolled over. Light trucks, including vans, experienced the highest rollover involvement rate, 25.9 percent, compared to 15.3 percent for passenger cars.Approximately 59 percent of the rollover fatalities come from the 10 percent of the rollover involved occupants who are ejected, partially or completely, from the vehicle. Of the fatal ejections, 56 percent are ejected through side glazing and 13.9 percent are ejected through side doors. Belt use is a significant factor in ejection, 92 percent of the fatal ejections reported in FARS between 1988 and 1994 were unbelted.Rollover accidents have a wide variety of accident types and injury mechanisms. This research program integrates many different aspects of rollover protection. Countermeasures involving upper interior padding, improved restraints, alternative side window materials, improved door latches, and upgraded roof strength requirements are being studied. Some of these countermeasures are being addressed in separate research programs, but still have significant benefits for rollover accidents. Ejections through door latches are being addressed in B.01.04, ejections through side windows are being researched in B.01.05, and the research under B.01.06 will evaluate the rollover benefits of upper interior padding.The wide variety of accident types and injury mechanisms makes it impractical to define a single test or a series of tests that can reasonably assess a vehicles rollover crashworthiness. This program will use the previous full scale crash tests to establish a baseline for computer simulations. These simulations will be used to evaluate injury causation mechanisms and possible countermeasures for a variety of rollover environments. Promising countermeasures will be developed into prototype systems that can be tested in component or full scale crash test environments. A long range procedure for possibly upgrading FMVSS No. 216 is under development. (B.01.13 UPGRADE OF ROLLOVER CRASH PROTECTION)

PROBLEMS WITH THE NHTSA ROLLOVER  RESISTANCE RATING

National Highway Traffic Safety Administration (NHTSA) proposed rollover - stability standard for vehicles, particularly sport utility vehicles (SUVs) may not adequately address the problem. Rather than issue a minimum safety standard that all vehicles must meet, NHTSA has chosen to issue only a consumer information rating system, which will not require safer vehicles. It calls for a "static" stability test that would rate vehicle stability on mathematical measurements of tire-track width and vehicle height. The test results are to be purely informational. But unfortunately, consumers won't have access to this vital information at the point of sale. And manufacturers won't be required to do a thing to make their vehicles less prone to rolling over. What is needed is the rating to be based on a dynamic test, (a real-world test in which a vehicle is driven on the road). Anything short, doesn't meet the mark.