Q&A: Safety belts

July 2012

1 How do safety belts protect vehicle occupants?

Lap and shoulder belts are designed to keep motorists in their seats during a crash. Without belts, people risk hitting things inside their vehicle and being ejected altogether. Even though their vehicle may have slowed or stopped after colliding with another vehicle or object, unbelted occupants keep moving at the same travel speed until they catch up with and crash into what's in front of them. Safety belts help to prevent or reduce injuries from this second collision by securing people to their seats so they slow down with the vehicle as its crush zone absorbs most of the kinetic energy associated with the vehicle and the occupant's precrash motion. The longer people "ride down" a crash, the less likely they are to be injured.

Worn properly, safety belts are designed to spread crash forces across the stronger bony parts of the upper body. Safety belts also prevent occupants from being ejected from the vehicle, an event associated with high risk of injury and death. Relative to occupants who are not ejected from vehicles, occupants who are ejected in nonrollover crashes are nearly twice as likely to die, and those who are ejected in rollover crashes are 4 times more likely to die. National Highway Traffic Safety Administration. 2010. Incremental risk of injury and fatality associated with complete ejection. Report concerning Federal Motor Vehicle Safety Standards, Ejection Mitigation; Phase-In Reporting Requirements. Docket Document No. NHTSA-2009-0183-0054, November 10, 2010. Washington, DC: U.S. Department of Transportation.

2 Do most people use safety belts?

Yes. Nationwide safety belt use in 2011 was 84 percent for drivers and 82 percent for right-front seat passengers. Pickrell, T. M. and Ye, T. J. 2011. Seat belt use in 2011: overall results. Report no. DOT HS-811-544. Washington, DC: National Highway Traffic Safety Administration. In 2010, 15 states and the District of Columbia had use rates of 90 percent or higher. Washington and Hawaii had the highest belt use rates — 98 percent. The lowest use rates were found in New Hampshire (72 percent) and Massachusetts (74 percent). National Highway Traffic Safety Administration. 2011. Traffic safety facts: Seat belt use in 2010, use rates in the states and territories. Report no. DOT HS-811-493. Washington, DC: US Department of Transportation.

The 2011 observed belt use rate among front-seat occupants was 6 times the rate observed in 1983 (84 percent vs. 14 percent). Pickrell, T. M. and Ye, T. J. 2011. Seat belt use in 2011: overall results. Report no. DOT HS-811-544. Washington, DC: National Highway Traffic Safety Administration. Transportation Research Board. 2003. Buckling up: technologies to increase seat belt use (Special Report 278). Washington, DC: Transportation Research Board of the National Academies. Insurance Institute for Highway Safety. 2012. [Unpublished analysis of 2010 data from the U.S. Department of Transportation's Fatality Analysis Reporting System]. Arlington, VA. The following figure shows the changes in belt use during this time period.

Observed front-seat occupant safety belt use in the United States, 1983-2011

Less than half of passenger vehicle drivers (46 percent) and passengers (41 percent) killed in 2010 were using
belts. Insurance Institute for Highway Safety. 2012. [Unpublished analysis of 2010 data from the U.S. Department of Transportation's Fatality Analysis Reporting System]. Arlington, VA. Belt use rates are lower among fatally injured occupants than among the general population because risk of death is much higher when not using a safety belt. Plus, people who don’t use belts tend to be riskier drivers.

3 How effective are safety belts?

When lap and shoulder belts are used, research has shown a 45 percent reduction in the risk of a fatal injury to people in front seats of cars. The risk of a moderate to critical injury is reduced by half. For people in front seats of SUVs, vans and pickups, the use of lap and shoulder belts reduces the risk of a fatal injury by 60 percent and a moderate to critical injury by 65 percent. National Highway Traffic Safety Administration. 2011. Traffic safety facts, 2009: occupant protection. Report no. DOT HS-811-390. Washington, DC: National Highway Traffic Safety Administration.

For information on the effectiveness of restraints for children, see the child passenger safety Q&A.

The National Highway Traffic Safety Administration (NHTSA) estimates that safety belts saved the lives of 12,546 people in 2010 and more than 69,000 lives during the five-year period from 2006 through 2010. An additional 3,341 lives could have been saved in 2010 if all passenger vehicle occupants older than age 4 had used safety belts. National Highway Traffic Safety Administration. 2012. Traffic safety facts: lives saved in 2010 by restraint use and minimum drinking age laws. Report no. DOT HS-811-580. Washington, DC: National Highway Traffic Safety Administration.

4 Have passenger vehicles always had safety belts?

No. It took a long time to get safety belts in all new vehicles. Prior to a federal standard, many manufacturers began installing lap belts in front seats in response to state laws requiring safety belts in new cars. It wasn't until 1968 that the federal government required lap and shoulder belts in the front outboard seats of all new cars sold in the United States except convertibles.

In 1973, federal regulators upgraded the safety belt standard to require three-point lap and shoulder belts with inertia reels that lock the belt during a rapid deceleration. Lap and shoulder belts were mandated in the rear seats of cars sold in the U.S. starting in model year 1990, and in pickups, passenger vans, and SUVs starting in model year 1992. A requirement for three-point belts for inboard rear seating positions was phased in between Sept. 1, 2005, and Sept. 1, 2007. National Highway Traffic Safety Administration. 2004. Title 49 Code of Federal Regulations (CFR) Part 571 Section 208, Occupant Crash Protection. Washington, DC: Office of the Federal Register, National Archives and Records Administration.

5 I have airbags in my vehicle, so why do I need to wear my safety belt?

Occupant protection is maximized when safety belts are used in conjunction with airbags. Frontal airbags are designed to work with lap and shoulder belts to prevent people's heads and chests from hitting the steering wheel, instrument panel or windshield. If occupants strike these surfaces hard, they can sustain serious or fatal injuries.

See Airbags Q&A

6 Is it important to use a safety belt in the back seat?

Yes. People sitting in back should use safety belts for the same reasons they should use them in the front seat: to reduce serious injuries and fatalities in a crash. Lap and shoulder belts reduce the risk of fatal injury by 44 percent among back-seat outboard occupants in passenger cars and 73 percent among back-seat outboard occupants of vans and SUVs. Morgan, C. 1999. Effectiveness of lap/shoulder belts in the back outboard seating positions. Report no. DOT HS-808-945. Washington, DC: National Highway Traffic Safety Administration. In a frontal crash, drivers and front-seat passengers are at increased risk of injury from unbelted back-seat passengers, and in a side-impact crash, passengers sitting adjacent to unbelted passengers are at increased risk of injury. Exposure to unbelted occupants increases the risk of injury or death to other occupants in the vehicle by 40 percent. MacLennan, P.A.; McGwin, Jr., G.; Metzger, J.; Moran, S.G.; and Rue III, L.W. 2004. Risk of injury for occupants of motor vehicle collisions from unbelted occupants. Injury Prevention 10:363-67.

7 What if my vehicle has only lap belts?

A lap belt is better protection than no belt in a crash. In a study of potentially fatal crashes involving back-seat occupants age 5 and older, lap belts reduced the risk of fatal injury for outboard occupants by 32 percent in cars and 63 percent in vans and SUVs. Morgan, C. 1999. Effectiveness of lap/shoulder belts in the back outboard seating positions. Report no. DOT HS-808-945. Washington, DC: National Highway Traffic Safety Administration. Although lap-only belts weren't as effective as lap and shoulder belts, particularly in frontal crashes, using lap-only belts provided more protection than being unrestrained. The addition of a shoulder belt in the center rear reduces the risk of injury by 81 percent among children seated in this position compared with lap-only belts. Arbogast, K.B.; Durbin, D.R.; Kallan, M.J.; and Winston, F.K. 2004. Evaluation of pediatric use patterns and performance of lap shoulder belt systems in the center rear. Annual Proceedings of the Association of the Advancement of Automotive Medicine 48:57-72. For the best protection, children should ride in the back seat in an appropriate child safety seat or a properly fitted lap and shoulder belt.

See Keeping children safe in crashes: What if my vehicle doesn't have shoulder belts?

8 What if my safety belt doesn't fit properly?

For safety belts to do their job, it's important that they fit right. That's why it is so critical for children who have outgrown their forward-facing child restraints to use belt-positioning boosters.

See booster evaluations

A properly fitted shoulder belt should lie snugly across the center of the chest and shoulder, not on the neck or face or falling off the shoulder. The lap belt should lie snugly across the upper thighs or low on the hips, not the belly.

When shopping for a new vehicle, try on the safety belts to see whether they are a good fit for you and the other passengers who will be riding in the vehicle. In many vehicles, belts can be customized for a better fit. For example, adjustable D-rings allow shoulder belts to be raised or lowered as needed. Ask your dealer or consult the vehicle manual for more information. If your safety belt is not long enough, it may be possible to lengthen it with a belt extender from your vehicle manufacturer.

Any restraint is better than none at all, but a properly fitting belt offers the best protection.

9 Do all states have laws requiring vehicle occupants to buckle up?

New Hampshire is the only state without a safety belt law for adults. In all other states and the District of Columbia, front-seat occupants are required to use belts. However, adult rear-seat passengers are covered by the laws in only 26 states and the District of Columbia.

10 Can police stop drivers for not using safety belts?

Yes, but only in states with primary belt laws. Primary, or standard, enforcement laws allow a police officer to stop and cite a motorist solely for not using a safety belt. In states with secondary enforcement, police can only enforce the law if the motorist has been pulled over for another violation first. Legislators in some states were reluctant to enact primary laws because of concerns that police would use the safety belt law to harass minorities. Farmer, C.M. and Williams, A.F. 2005. Effect on fatality risk of changing from secondary to primary seat belt enforcement. Journal of Safety Research 36:189-94. However, several studies found that changing from secondary to primary enforcement resulted in proportionally equal or fewer tickets for minorities. Preusser, D.F.; Solomon, M.G.; and Cosgrove, L.A. 2005. Minorities and primary versus secondary belt use enforcement.Transportation Research Circular (E-C072), 23-29. Washington, DC: Transportation Research Board of the National Academies. Solomon, M.G.; Cosgrove, L.A.; and Preusser, D.F. 2000. A summary of the results from studies measuring the change from secondary enforcement of safety belt laws to primary enforcement; emphasizing the effects on race. Presented at the National Highway Traffic Safety Administration's Restraint Use Strategy Workshop, Crystal City, VA. Solomon, M.G.; Preusser, D.F.; and Nissen, W.J. 2001. Evaluation of Maryland, Oklahoma, and the District of Columbia's seat belt law change to primary enforcement. Report no. DOT HS-809-213. Washington, DC: US Department of Transportation. Today, 32 states and the District of Columbia have primary laws, while 17 states have secondary safety belt laws.

More information on safety belt laws

11 What are the penalties for safety belt violations?

The maximum fine for a first offense ranges from $5 to $200, depending on the state. Primary enforcement states tend to have higher fines. Only New Mexico and the District of Columbia assess points for belt violations.

12 Have belt laws increased belt use?

Yes, but numerous studies show that publicized enforcement is key to sustaining high levels of compliance over time. Well-publicized enforcement campaigns such as "Click It or Ticket" can achieve high levels of belt use. Williams, A.F; Wells, J.K.; McCartt, A.T.; and Preusser, D.F. 2000. "Buckle Up NOW!" An enforcement program to achieve high belt use. Journal of Safety Research 31:195-201. Williams, A.F.; Reinfurt, D.; and Wells, J.K. 1996. Increasing seat belt use in North Carolina. Journal of Safety Research 27:33-41. In 1993, North Carolina implemented the first statewide "Click It or Ticket" campaign. Institute research found that driver belt use increased from 64 percent before the campaign to 80 percent after the first three-week enforcement period. Williams, A.F.; Reinfurt, D.; and Wells, J.K. 1996. Increasing seat belt use in North Carolina. Journal of Safety Research 27:33-41. The first nationwide "Click It or Ticket" campaign was held in May 2003. An evaluation of the 2007 campaign found that belt use increased in 38 states, the District of Columbia and Puerto Rico. Increases were seen in states with and without primary laws. Solomon, M.G.; Preusser, D.F.; Tison, J.; and Chaudhary, N.K. 2009. Evaluation of the May 2007 Click It or Ticket Mobilization. Report no. DOT HS-811-239. Washington, DC: National Highway Traffic Safety Administration.

Some belt laws are more effective than others at increasing belt use. In 2011, states and territories with primary enforcement had observed front-seat occupant use rates 11 percentage points higher than states with secondary enforcement (87 vs. 76 percent). Pickrell, T. M. and Ye, T. J. 2011. Seat belt use in 2011: overall results. Report no. DOT HS-811-544. Washington, DC: National Highway Traffic Safety Administration. Based on drivers' self-reports, the frequency of never using a safety belt was twice as high in states with secondary enforcement compared with states with primary enforcement laws. Beck, L.F and Shults, R.A. 2009. Seat belt use in states and territories with primary and secondary laws- United States, 2006.Journal of Safety Research 40:469-72. States that went from secondary to primary enforcement laws saw a 14-percentage-point median increase in observed belt use. Shults, R.A.; Elder, R.W.; Sleet, D.A.; and Thompson, R.S. 2004. Primary enforcement seat belt laws are effective even in the face of rising belt use rates. Accident Analysis and Prevention 36:491-93.

In states that require belt use in all seating positions, 79 percent of back-seat passengers were observed using safety belts in 2010, compared with 69 percent of back-seat passengers in states that require only front-seat belt use. Pickrell, T. M. and Ye, T. J. 2011. Occupant restraint use in 2010: results from the National Occupant Protection Use Survey Controlled Intersection Study. Report no. DOT HS-811-527. Washington, DC: National Highway Traffic Safety Administration.

Higher fines for safety belt violations also are associated with higher rates of observed belt use and higher rates of belt use among fatally injured front-seat occupants. An increase in fines from $25 to $60 was associated with 3-4 percentage point increases in belt use, while increasing fines from $25 to $100 was associated with 6-7 percentage point increases. Nichols, J. L.; Tippetts, A. S.; Fell, J. C.; Auld-Owens,; A., Wiliszowski, C. H.; Haseltine, P. W.; and Eichelberger, A. 2010. Strategies to increase seat belt use: an analysis of levels of fines and the type of law. Report no. DOT HS-811-413. Washington, DC: National Highway Traffic Safety Administration.

13 Have belt laws reduced injuries and fatalities?

Yes. Systematic literature reviews show that both primary and secondary laws reduce deaths and nonfatal injuries, but primary laws have the greater effect. Dinh-Zarr, T.B.; Sleet, D.A.; Shults, R.A.; Zaza, S.; Elder, R.W.; and Nichols, J.L.; Thompson, R.S.; and Sosin, D.M. 2001. Reviews of evidence regarding interventions to increase use of safety belts. American Journal of Preventive Medicine 21(4S):48-65. Rivara, F.P.; Thompson, D.C.; and Cummings, P. 1999. Effectiveness of primary and secondary enforced seat belt laws. American Journal of Preventive Medicine16:30-39. The incremental effect of primary versus secondary laws on fatalities is estimated at 3-14 percent. Dinh-Zarr, T.B.; Sleet, D.A.; Shults, R.A.; Zaza, S.; Elder, R.W.; and Nichols, J.L.; Thompson, R.S.; and Sosin, D.M. 2001. Reviews of evidence regarding interventions to increase use of safety belts. American Journal of Preventive Medicine 21(4S):48-65.

Institute research has shown that switching from a secondary law to a primary law reduces passenger vehicle driver deaths by 7 percent. Based on this research, if all states that still had secondary laws in 2010 had switched to primary laws, 258 lives could have been saved that year. Farmer, C.M. and Williams, A.F. 2005. Effect on fatality risk of changing from secondary to primary seat belt enforcement. Journal of Safety Research 36:189-94.

14 Who is least likely to use a safety belt?

Safety belt use is lowest among younger people and males. In 2010, 79 percent of 16-24 year-olds in the front seat were observed using their belts compared with 86 percent of those 25-69 years old and 88 percent of those 70 and older. Eighty-eight percent of female front-seat occupants were observed using their belts compared with 83 percent of males. Belt use also is lower in the back seat. In 2010, 74 percent of rear-seat occupants were observed using belts compared with 85 percent of front-seat occupants. Pickrell, T. M. and Ye, T. J. 2011. Occupant restraint use in 2010: results from the National Occupant Protection Use Survey Controlled Intersection Study. Report no. DOT HS-811-527. Washington, DC: National Highway Traffic Safety Administration.

Research also shows that belt use is lower among occupants of older vehicles and among drivers who have been drinking alcohol. Mackay, M. 1997. The use of seat belts: some behavioural considerations. Proceedings of the Risk-Taking Behavior and Traffic Safety Symposium, October 19-22, 1997, 1-14.Washington, DC: National Highway Traffic Safety Administration. Partyka, S.C. 1989. Belt use in serious impacts estimated from fatality data. Research Notes. Washington, DC: National Highway Traffic Safety Administration. In 2011, observed belt use was lowest among occupants of pickups (74 percent), compared with occupants of vans and SUVs (87 percent) and cars (85 percent). Pickrell, T. M. and Ye, T. J. 2011. Seat belt use in 2011: overall results. Report no. DOT HS-811-544. Washington, DC: National Highway Traffic Safety Administration. Although safety belt use has increased over the years, many disparities in belt use continue. For example, in an analysis of 10 years of data on belt use among fatally injured occupants, use was consistently about 18 percentage points lower at night than during the day. Tison, J,; Williams, A. F.; and Chaudhary, N. K. 2010. Daytime and nighttime seat belt use by fatally injured passenger vehicle occupants. Report no. DOT HS-811-281. Washington, DC: National Highway Traffic Safety Administration. Analyses of traffic and criminal records show that nighttime unbelted drivers have more previous traffic violations and criminal arrests than nighttime belted drivers and daytime drivers (belted or unbelted). Thomas, III, D.; Blomberg, R. D.; and Van Dyk, J. 2010. Evaluation of the first year of the Washington nighttime seat belt enforcement program. Report no. DOT HS- 811-295. Washington, DC: National Highway Traffic Safety Administration.

15 Why don't people buckle up?

A nationwide telephone survey in 2003 found the top reasons for not using a safety belt were forgetfulness, discomfort, inconvenience, low perceived risk of crashing (e.g., driving on private roads or short distances), pressure from other unbelted occupants and lack of safety belts in the vehicle. Eby, D.W.; Molnar, L.J.; Kostyniuk, L.P.; and Shope, J.T. 2005. Developing an effective and acceptable safety belt reminder system. Proceedings of the 19th International Technical Conference on the Enhanced Safety of Vehicles (CD ROM). In another national survey in 2007, forgetting and driving a short distance were the most common reasons given for not wearing belts, especially for people who sometimes or often wore belts. Drivers who rarely or never wore belts tended to cite other reasons such as discomfort. About one-third of all drivers thought safety belts were just as likely to harm as to help, and perceived harm was greater among less frequent belt users. The youngest drivers (ages16-20) were most likely to think that belts were potentially harmful. Boyle, J. M. and Lampkin, C. 2008. 2007 Motor Vehicle Occupant Safety Survey volume 2, seat belt report. Report no. DOT HS-810-975. Washington, DC: National Highway Traffic Safety Administration.

16 Do safety belt reminder systems increase use and reduce crash deaths?

Not all safety belt reminders are effective in raising belt use. Federal safety standards require a reminder system in the front seat to warn drivers when their safety belts are unbuckled. A light and an audible warning of 4-8 seconds are required. However, vehicle manufacturers are permitted to have reminder systems that go beyond the minimum standard, and most equip their vehicles with enhanced safety belt reminder systems. Of 2012 models sold in the United States, 91 percent came with enhanced safety belt reminder systems for the driver as standard equipment, while 77 percent had the reminder systems for right-front passengers. Only 3 percent of 2012 models had reminder systems that detected safety belt use for back-seat passengers. Of vehicles on the U.S. market, Volvo was the first manufacturer to alert the driver when back-seat passengers didn’t buckle up. Federal Register, vol. 75, no. 124, June 29, 2010, pages 37343-37350.

Enhanced belt reminders have been shown to increase belt use among drivers and front-seat passengers. NHTSA observed safety belt use among occupants of vehicles with and without enhanced belt reminders and found higher belt-use rates in vehicles with the reminders. Freedman, M.; Levi, S.; Zador, P.; Lopdell, J.; and Bergeron, E. 2007. The effectiveness of enhanced seat belt reminder systems: observational field data collection methodology and findings. Report no. DOT HS-810-844. Washington, DC: National Highway Traffic Safety Administration. A 2010 Institute study found that driver fatality rates were 6 percent lower in vehicles with enhanced safety belt reminders compared with vehicles without them. Farmer, C.M. and Wells, J.K. 2010. Effect of enhanced seat belt reminders on driver fatality risk. Journal of Safety Research 41:53-7.

17 What technologies increase safety belt use?

Safety belt ignition interlocks were used briefly in the 1970s. Interlocks prevented a driver from starting the vehicle if the driver was unbelted. These proved so unpopular that Congress prohibited the government from requiring ignition interlocks to increase safety belt use. Transportation Research Board. 2003. Buckling up: technologies to increase seat belt use (Special Report 278). Washington, DC: Transportation Research Board of the National Academies. Other types of interlocks have been developed but aren’t in wide use. Gearshift interlocks prevent or delay the vehicle from being put in gear if the driver isn't buckled up, while entertainment interlocks disable the radio or entertainment system. A pilot study of commercial fleet drivers studied the effects of a safety belt reminder chime combined with a delay of 8 seconds before an unbelted driver could place the vehicle in gear. The study found the system increased safety belt use by about 20 percentage points. Van Houten, R.; Malenfant, J.E.L.; Reagan, I., Sifrit, K.; and Compton, R. 2009. Pilot tests of a seat belt gearshift delay on the belt use of commercial fleet drivers. Report no. DOT HS- 811-230. Washington, DC: National Highway Traffic Safety Administration.

Another technology involves tactile feedback. In a pilot test with a small sample of commercial drivers, unbelted drivers who drove faster than 25 mph experienced resistance of the accelerator pedal. Drivers could continue to drive faster than 25 mph without buckling up, but the pedal resistance continued until they fastened belts. The effect was an immediate increase in safety belt use to 100 percent, and the drivers found the system acceptable. Van Houten, R.; Hilton, B.; Schulman, R.; and Reagan, I. 2011. Using haptic feedback to increase seat belt use of service vehicle drivers. Report no. DOT HS-811-434. Washington, DC: National Highway Traffic Safety Administration.

18 What technologies have been developed to improve safety belts' effectiveness?

Most passenger vehicles today are equipped with three-point lap and shoulder belts, but other safety belt technologies have been developed to keep people even safer in crashes. Four-point safety belts are designed to keep occupants closer to their seats in case of a sudden stop or collision, and they provide better protection by distributing the belt load to torso areas. Bostrom, O. and Haland, Y. 2005. Benefits of a 3+2-point belt system and an inboard torso side support in frontal, far-side and rollover crashes. International Journal of Vehicle Safety 1:181-99. These belts are sometimes referred to as X 4-point belts or V 4-point belts. Rouhana, S.W.; Bedewi, P.G.; Kankanala, S.V.; Prasad, P.; Zwolinski, J.J.; Meduvsky, A.G.; Rupp, J.D.; Jeffreys, T.A.; and Schneider, L.W. 2003. Biomechanics of 4-point seat belt systems in frontal impacts. Stapp Car Crash Journal 47:367-99. These belts aren't currently available in passenger vehicles.

Many newer vehicles are equipped with safety belt pretensioners that tighten up slack in the belt when triggered by vehicle sensors. The pretensioner tightens the belt almost instantaneously in the event of a crash.

The industry's first inflatable belts, designed to better protect rear-seat occupants, were developed by Ford and were first available on certain 2011 Explorers. Inflatable safety belts aim to reduce head, neck and chest injuries by deploying over the occupant's torso and shoulder during a crash so that crash forces are distributed to an area of the body 5 times larger than with conventional safety belts. Ford introduces industry's first inflatable seat belts to enhance rear seat safety. 2011. Press release, January 26, 2011. When vehicle sensors determine that a severe collision is occurring, the belt's airbag fills with cold compressed gas and expands sideways across the occupant's body. The inflatable belt should operate like a conventional safety belt for everyday use. Ford introduces industry's first inflatable seat belts to enhance rear seat safety. 2011. Press release, January 26, 2011. For children in child safety seats, caregivers should consult the vehicle and child seat owner's manuals or contact the child seat manufacturer for guidance on whether the seat can be used with the inflatable belt.

3-point belt

X 4-point belt

V 4-point belt

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