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A seat belt, sometimes called a '''safety belt''', is a Safety Harness designed to secure the occupant of a Vehicle against harmful movement that may result from a Collision or a sudden stop. As part of an overall occupant Restraint System , seat belts are intended to reduce Injuries by stopping the wearer from hitting hard interior elements of the vehicle or other passengers (the so-called Second Impact ) and by preventing the wearer from being thrown from the vehicle. TYPES OF SEAT BELTS ]]
HISTORY Seat belts were invented by George Cayley in the 1800s . They were introduced in aircraft for the first time in 1913, by Adolphe Pegoud , who became the first man to fly a plane upside-down. However, seat belts did not become common on aircraft until the 1930s . Edward J. Claghorn was granted on February 10 , 1885 for a safety belt ''The Seat Belt, Swedish Research and Development for Global Automotive Safety'', ISBN 9163093898 , page 12 American physicians in the 1920´s advocated the use of seat belts in cars. Some of them even outfitted their cars with seatbelts. Plastic surgeon Claire L. Straith and physician C. J. Strickland were at the forefront of that demand. Strickland founded the ''Automobile Safety League of America''. The American public showed little interest ''The Seat Belt, Swedish Research and Development for Global Automotive Safety'', ISBN 9163093898 , page 13 Engineer Hugh De Haven invented the inertia reel and created the concept of "wearing" the car and "packaging" passengers. Safety belts were tested by Col John P. Stapp , using a Rocket Sled and himself as the guinea pig, among others. His studies explained the phenomenon that most people injured or killed in plane crashes didn't die when the plane hit the ground, but when the person hit the inside of the plane. Edward J. Hock invented the safety belt first used by the Ford Motor Company as standard equipment, while he was on active duty with the military as a flight instructor. In 1955 his idea was accepted by the naval authorities, and Hock was awarded $20.50 for his invention. The original schematic and Blueprint s shows that he utilized scrap Parachute strapping to implement his idea. He was never awarded anything other than the $20.50 award, a letter of recognition, a picture with military 'brass', and a newspaper article to his credit. The three point seat belt (the so-called ''CIR-Griswold restraint'') was patented in 1951 by the Americans Roger W. Griswold and Hugh De Haven. There's no information about this design being used in cars ''The Seat Belt, Swedish Research and Development for Global Automotive Safety'', ISBN 9163093898 , pages 15 and 16 Nils Bohlin of Sweden invented a particular kind of three point seat belt for Volvo , who introduced it in 1959 as standard equipment. Bohlin was granted for the device. Most US automobiles were sold with front seat belts standard in the 1964 model year. Rear seat belts were made standard in 1968. TECHNOLOGIES Most seat belts are equipped with locking mechanisms (or inertia reels) that tighten the belt when pulled fast (e.g. by the quick force of a passenger's body during a crash) but do not tighten when pulled slowly. This is implemented with a centrifugal clutch, which engages as the reel spins quickly. Alternatively, this function may be secured by a weighted pendulum or ball bearing: when these are deflected by deceleration or roll-over they lock into pawls on the reel. Types of inertia reel type seatbelts: NLR (No '''L'''ocking '''R'''etractor) - Commonly used in recoiling lap belts ELR V (Emergency '''L'''ocking '''R'''etractor - '''V'''ehicle sensitive) - Single sensitive mechanism, composed of a locking mechanism activated in an emergency by deceleration or rollover of the vehicle. Thus, the seatbelt is sensitive to the vehicle's motion. ELR VW (Emergency '''L'''ocking '''R'''etractor - '''V'''ehicle and '''W'''ebbing sensitive) - Dual sensitive means a seatbelt retractor that, during normal driving conditions, allows freedom of movement by the wearer of the seatbelt by means of length-adjusting components that automatically adjust the strap to the wearer, with a locking mechanism that is activated by two or more of the following:
Pretensioners and webclamps Seatbelts in many newer vehicles are also equipped with 'pretensioners' and/or 'Webclamps'.
There is some research and tort liability case findings which suggest that some seatbelts are subject to inertial release (explanation needed). Although the NHTSA has been urged to deal with this defect it has yet not been properly addressed. "In 1992, the Institute for Injury Reduction (IIR) petitioned NHTSA to investigate such defects, but after several months, NHTSA denied the petition. Its own laboratory results indicated that inertial forces could cause a buckle to open, but that it didn’t happen in real world accidents." Source: Seat Belt Defects Automatic seat belts Main article: Automatic Seat Belt Some vehicles have shoulder belts that automatically move forward to secure the passenger when the vehicle is started. A separate lap belt is usually included, and the lap belt must be fastened manually. Automatic seat belts have fallen out of favor recently, since the Airbag became mandatory in many countries. USE OF SEAT BELTS BY CHILD OCCUPANTS As with adult drivers and passengers, the advent of seat belts was accompanied by calls for their use by child occupants, including legislation requiring such use. It has been claimed that children in adult restraints suffer lower injury risk than unrestrained children. The UK extended compulsory seatbelt wearing to child passengers under the age of 14 in 1989. It was observed that this measure was accompanied by a 10% ''increase'' in fatalities and a 12% ''increase'' in injuries among the target populationRisk, by John Adams, UCL Press Ltd. University College, London 1995. In crashes, small children who wear adult seatbelts can suffer characteristic "seat-belt syndrome" injuries including severed intestines, ruptured diaphragms and spinal damage. There is also research suggesting that children in inappropriate restraints are at significantly increased risk of head injury The Danger of Premature Graduation to Seat Belts for Young Children, Winston FK, Durbin DR, Kallan MJ, Moll EK,, Pediatrics, Vol. 105, No. 6, June 2000, pp. 1179-1183, one of the authors of this research has been quoted as claiming that "The early graduation of kids into adult lap and shoulder belts is a leading cause of child-occupant injuries and deaths." Kids at Risk: When Seatbelts are NOT Enough, by Karp H, Reader's Digest (US Edition), November 1999 As a result of such findings, many jurisdictions now advocate and/or require child passengers to use specially designed child restraints. Such systems include separate child-sized seats with their own restraints and booster cushions for children using adult restraints. In some jurisdictions children below a certain size are forbidden to travel in front car seats. According to a national sample of child safety seat issued by the {Link without Title} National SAFE KIDS Campaign , the majority of child safety seats continue to be used incorrectly. This leaves cause for concern for the thousands of families who will travel by car during the upcoming holiday weekend. Through the {Link without Title} National SAFE KIDS Campaign 's child passenger safety program, SAFE KIDS BUCKLE UP, sponsored by the UAW-GM Center for Human Resources and General Motors Corporation, the Campaign analyzed the incorrect use patterns of more than 37,000 child safety seats and vehicle safety belts observed at SAFE KIDS BUCKLE UP Car Seat Check Up events from February 2001 to May 2002. Overall, 81.6 percent of the child restraints were used incorrectly, with an average of three errors per incorrectly used restraint. The most startling figures were found when looking at rear-facing seats and forward-facing seats with harnesses. Specific findings include:
"We are concerned to find that incorrect use of child safety seats continues to plague unknowing parents and caregivers across the country," said Heather Paul, Ph.D., executive director of the {Link without Title} National SAFE KIDS Campaign . "These seemingly small mistakes can lead to tragic consequences for children, especially when compounded by multiple errors." To address these common mistakes, the National SAFE KIDS Campaign continues to provide resources to educate parents and caregivers about the correct installation and use of child safety seats. Motor vehicle crashes remain the leading cause of unintentional injury-related death among children ages 14 and under. More than 1,600 child occupants ages 14 and under die every year, and an estimated 248,000 children suffer injuries. Changes are also being made in vehicles and child safety seats. LATCH (Lower Anchors and Tethers for Children), a system that can make child safety seat installation easier without using seat belts, will be required on all child safety seats and vehicles manufactured after September 1, 2002. Attachments on a LATCH-equipped child safety seat fasten directly to anchors in a LATCH-equipped vehicle. Although LATCH can make installation simpler for parents and caregivers, it will not completely solve the problem of incorrect use. Education on the correct use of child safety seats, as well as installation using LATCH, is a critical component. To keep children safe, whether installing a seat using LATCH or a seat belt system, the National SAFE KIDS Campaign recommends the following:
LATCH and the new inspection stations are good news for families, in light of the Campaign's study that found the majority of parents attending child safety seat checkup events continue to make mistakes when using child restraints. {Link without Title} REMINDER CHIME AND LIGHT In North America and some other parts of the world, cars sold since the early 1970s have included a seat belt light on the dashboard, reminding the driver and passengers to buckle up. These systems also included a warning buzzer which sounded for several seconds before turning off (with the warning light), regardless of whether the car was started. New cars sold in the United States in 1974 and the first part of the 1975 model year were sold with a special "ignition interlock," whereby the driver could not start the car until the seat belt was fastened; however, this system was short-lived. By the early 1980s, many car makers selling in the US market had replaced the buzzer (along with all other buzzers for functions such as headlights-on) with a seatbelt warning chime, though for some models, this change was not implemented until the 1990s or even the early 2000s. Today, many of these carmakers use a red figure with its seatbelt on to serve as its seatbelt warning light, and it may stay on for several minutes after the car is started and the driver's seat belt is not fastened. In Europe most modern cars include a seat-belt reminder light for the driver and some also include a reminder for the passenger, when present, activated by a pressure sensor under the passenger seat. In some systems (i.e. older Volvos), the seatbelt is connected to the Turn Signal relay, making clicking sounds constantly until the front passengers are buckled up. Some newer cars from Audi , BMW , Ford , Honda , Hyundai , and Toyota will intermittently flash the reminder light and sound the chime until the driver (and sometimes the front passenger, if present) fasten their seatbelt. LEGISLATION Main article: Seat Belt Legislation Observational Studies of Car Crash morbidity and mortality,123 Experiment s using both Crash Test Dummies and human Cadaver s indicate that wearing seat belts provide a reduced risk of Death and injury in the majority of car crashes. This has led many countries to adopt mandatory seat belt wearing laws. It is generally accepted that, in comparing like-for-like accidents, a vehicle occupant wearing a properly fitted seat belt has a significantly lower chance of death and serious injury. One large observation studying using US data showed that the Odds Ratio of crash death is 0.46 with a three-point belt, when compared with no belt.4 In another study, that examined injuries presenting to the ER pre- and post-seat belt law introduction, it was found that 40% more escaped injury and 35% more escaped mild and moderate injuries.5 The effects of seat belt laws are disputed by some, stemming from observed finding that following the passage of seat belt laws, road fatalities often did not decrease. Risk compensation Main article: Risk Compensation Some have proposed that the number of deaths was influenced by the development of Risk Compensation , which says that drivers adjust their behaviour in response to the increased sense of personal safety wearing a seat belt provides. In one trial subjects were asked to drive go-karts around a track under various conditions. It was found that subjects who started driving unbelted drove consistently faster when subsequently belted.6 Similarly, a study of habitual non-seatbelt wearers driving in freeway conditions found evidence that they had adapted to seatbelt use by adopting higher driving speeds and closer following distances7 (similar responses have been shown in respect of Anti-lock Braking System and, more recently, Airbags and Electronic Stability Control ). A 2001 analysis of US crash data aimed to establish the effects of seatbelt legislation on driving fatalities and found that previous estimates of seatbelts effectiveness had been significantly overstated. According to the analysis used, seatbelts were claimed to have decreased fatalities by 1.35% for each 10% increase in seatbelt use. The study controlled for endogenous motivations of seat belt use, which it is claimed creates an artificial correlation between seat belt use and fatalities, leading to the conclusion that seatbelts cause fatalities. For example, drivers in high risk areas are more likely to use seat belts, and are more likely to be in accidents, creating a non-causal correlation between seatbelt use and mortality. After accounting for the endogeneity of seatbelt usage, Cohen and Einav found no evidence that the risk compensation effect makes seatbelt wearing drivers more dangerous, a finding at variance with other research. Increased traffic Other statistical analyses have included adjustments for factors such as increased traffic, and other factors such as age, and based on these adjustments, a reduction of morbidity and mortality due to seat belt use has been claimed. However, Smeed's Law predicts a fall in accident rate with increasing car ownership and has been demonstrated independently of seatbelt legislation. REFERENCES SEE ALSO EXTERNAL LINKS
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