Crash compatibility
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Crash incompatibility, crash compatibility, vehicle incompatibility, and vehicle compatibility are terms in the
automobile A car or automobile is a motor vehicle with Wheel, wheels. Most definitions of ''cars'' say that they run primarily on roads, Car seat, seat one to eight people, have four wheels, and mainly transport private transport#Personal transport, pe ...
crash test A crash test is a form of destructive testing usually performed in order to ensure safe design standards in crashworthiness and crash compatibility for various modes of transportation (see automobile safety) or related systems and comp ...
ing industry. They refer to the tendency of some vehicles to inflict more damage on another vehicle (the "crash partner vehicle") in two-car crashes. Vehicle ''incompatibility'' is said to lead to more dangerous, fatal crashes, while ''compatibility'' can prevent injury in otherwise comparable crashes. The most obvious source of crash incompatibility is
mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different elementar ...
; a high-mass vehicle such as a
large MPV Minivan (sometimes called simply as van) is a North American car classification for vehicles designed to transport passengers in the rear seating row(s), with reconfigurable seats in two or three rows. The equivalent classification in Europe is ...
or
SUV A sport utility vehicle (SUV) is a car classification that combines elements of road-going passenger cars with features from off-road vehicles, such as raised ground clearance and four-wheel drive. There is no commonly agreed-upon definiti ...
will tend to cause much more serious damage in a crash with a lighter vehicle such as a typical sedan or
compact car Compact car is a vehicle size class — predominantly used in North America — that sits between subcompact cars and mid-size cars. "Small family car" is a British term and a part of the C-segment in the European car classification. However, p ...
. In particular, research by Michael Anderson and Maximilian Auffhammer suggests that "controlling for own-vehicle weight, being hit by a vehicle that is 1,000 pounds heavier generates a 40-50% increase in fatality risk." Incompatibility may also result from the specific shape, stiffness, or other design aspects of the impacting vehicles. For example, some SUVs and pickup trucks ride higher than cars and lack crumple zones to absorb impact energy. Another source of incompatibility is that heavier vehicles are required to have stronger front ends because of today's test requirements like the
NCAP A New Car Assessment Program (or Programme) is a government car safety program tasked with evaluating new automobile designs for performance against various safety threats. History The first NCAP was created in 1979, by the United States Nation ...
test. The
National Highway Traffic Safety Administration The National Highway Traffic Safety Administration (NHTSA ) is an agency of the U.S. federal government, part of the Department of Transportation. It describes its mission as "Save lives, prevent injuries, reduce vehicle-related crashes" rela ...
has done studies of the "aggressiveness" of vehicle designs. The term "aggressiveness" is used to denote the average injury risk a vehicle imposes on occupants of other vehicles during collisions. A 2003 NHTSA study estimated that in vehicle to vehicle crashes, the design of minivans was 1.16 times as aggressive as cars, pickups were 1.39 times more aggressive, and SUVs were 1.71 times more aggressive than cars. When weight was included in the analysis, light trucks (including SUVs) were estimated to be 3.3 times more aggressive than cars in head-on crashes and perhaps more so in side impact crashes. These studies have been controversial as they affect public perception and policy decisions on
CAFE A coffeehouse, coffee shop, or café is an establishment that primarily serves coffee of various types, notably espresso, latte, and cappuccino. Some coffeehouses may serve cold drinks, such as iced coffee and iced tea, as well as other non-caf ...
standards and light truck safety test standards as they exist today. NHTSA does not define a car or a light truck based on weight (e.g., the Chrysler PT Cruiser is classified as a light truck whereas a Lexus LS 600h L, a vehicle that weighs 66% more per published specifications, is classified as a car). So while there have been no proposals to eliminate light trucks (which includes minivans, SUVs and pickups), doing so would not eliminate incompatibility because there would still be lighter vehicles crashing into heavier vehicles. There has been extensive research and testing done by NHTSA, other governments, research organizations as well as automobile manufacturers to find solutions that improve safety in the small cars when colliding with larger vehicles. In the United States, a group of experts proposed major steps to improve compatibility and these have been accepted as a voluntary regulation by American automotive manufacturers as well as by most other companies selling vehicles in the U.S. The Canadian government has also accepted these recommendations. The recommendations require all manufacturers to either (a) lower the height of the primary structure (also called frame rail) of all SUV and pickup trucks so that they overlap the primary structure of the cars; or (b) add another structure (called Secondary Energy Absorbing Structure) to the SUVs and pickup truck that cannot meet the first option. Latest studies have shown that these have improved the safety in cars when struck by SUVs. However, no such benefit has been observed in pickup truck to car crashes. It is unclear whether or not certain aftermarket modifications are taken into account, such as "lift kits" which raise the frame or suspension of a vehicle for increased ground clearance. Such modifications would likely greatly reduce the effectiveness of modern auto-safety advances due to causing the rigid parts of a pickup or SUV to strike the weaker parts of lower vehicles, rather than the reinforced regions in an accident. State laws regarding the use of such modifications vary widely, and many have laws that aren't enforced. As of now, there are no Federal laws regarding the bumper height of trucks and SUV's. Although much of the crash incompatibility debate in recent years has centered on SUVs, the concept has been around far longer. When subcompact cars were introduced in the 1970s, there was a fear that incompatibilities of mass and design could lead to more serious injuries for drivers of these smaller, lighter vehicles. Crash incompatibility remains an area of active study.


See also

*
Car safety Automotive safety is the study and practice of design, construction, equipment and regulation to minimize the occurrence and consequences of traffic collisions involving motor vehicles. Road traffic safety more broadly includes roadway design. ...
*
Insurance Institute for Highway Safety The Insurance Institute for Highway Safety (IIHS) is a U.S. nonprofit organization funded by auto insurance companies, established in 1959 and headquartered in Arlington, Virginia. It works to reduce the number of motor vehicle traffic collision ...


References

*''Physics Today'', January 2006, "Vehicle Design and the Physics of Traffic Safety" *''NHTSA'', Bumper Q&A's


External links


Insurance Institute reports on vehicle compatibility (April 4, 2003)
*http://www.autoalliance.org/archives/archive.php?id=56&cat=Press%20Releases *http://www.nhtsa.gov/cars/problems/studies/Bumper/Index.html {{DEFAULTSORT:Crash Incompatibility Transport safety Automotive safety