Recently as I was driving with my son, we came upon several state police troopers with lights flashing parked on the side of the highway. Off of the highway, down a hill right up against some trees there was a small SUV with damage on every part of it. Clearly, the vehicle had left the road and rolled over several times.
I instinctively looked in the rear view mirror to make sure my son had his seat belt fastened. As we both looked at the scene, I said I hope everyone is alright and my son looking at the extensive damage asked how that could be possible. I thumbed the heavy nylon strap across my chest and said, these, seat belts make it possible to avoid serious injury and sometimes death.
Sadly, the driver of the vehicle was not wearing her seatbelt; she was ejected from the vehicle as it rolled over and she was killed. She was alone in the vehicle and she was just seventeen years old. My heart goes out to her family. I cannot fathom such a loss and don’t know how or if I could ever cope with such a tragedy.
Motor vehicle crashes are the leading cause of death among those ages 5-34 in the U.S. More than 2.3 million adult drivers and passengers were treated in emergency departments as the result of being injured in motor vehicle crashes in 2009(fn1). Adult seat belt use is the most effective way to save lives and reduce injuries in crashes(fn2). Yet millions of adults do not wear their seat belts on every trip.
In 1994 the seat belt use rate was fifty eight percent (58%) and unrestrained occupant fatalities were fifty-seven percent (57%). By 2009 the seat belt use rate rose to eighty four percent (84%) and unrestrained occupant fatalities dropped to forty-four percent (44%)(fn3). According to the National Highway Safety Transportation Administration (NHTSA), in 2010, the use of seat belts in passenger vehicles saved an estimated 12,546 lives. Seat belts have saved over 69,000 lives during the 5-year period from 2006 to 2010(fn4).
Who is least likely to wear a seat belt?
- Adults age 18-34 are less likely to wear seat belts than adults 35 or older. (CDC, 2010, unpublished data);
- Men are 10% less likely to wear seat belts than women. (CDC, 2010, unpublished data);
- Adults who live in rural areas are 10% less likely to wear seat belts (78% use) than adults who live in urban and suburban areas (87% use). (CDC, 2010, unpublished data);
- Seat belt use is lower in states with secondary enforcement seat belt laws or no seat belt laws (79%)
compared to states with primary enforcement laws (88%).
How do seat belts save lives?
The fundamental concept of a seat belt is simple: It keeps you from flying through the windshield or slamming into the dashboard or some other part of the interior when the vehicle you are in comes to an abrupt stop. The force that propels your body is known as inertia. Inertia is an object's tendency to keep moving until something else works against this motion. To put it another way, inertia is every object's resistance to changing its speed and direction of travel. You may have heard that an object at rest tends to stay at rest and an object in motion tends to say in motion unless acted upon by some type of force. When a car is traveling at 50 miles per hour, inertia continues to propel it at 50 mph in one direction. Friction between the tires and the road as well as air resistance work to constantly slow the vehicle down. The force from the power of the vehicle’s engine however, compensates for this energy loss from friction and air resistance and the vehicle continues to travel at 50 mph.
The occupants of the vehicle, the driver and passengers, all have their own inertia, which is actually separate from the vehicle's inertia. The vehicle accelerates the occupants to its speed. So when the vehicle is coasting at a steady 50 miles per hour, the occupants speed and the car's speed are basically equal. In other words the vehicle and the occupants are moving as a single unit.
If the vehicle were to suddenly crash into a telephone pole or other fixed object, it becomes obvious that the occupants’ inertia and the vehicle’s inertia are absolutely independent. The impact with the fixed object would bring the vehicle to an abrupt stop, but occupants speed would remain the same. Without a seat belt, the occupant would either slam into the steering wheel at 50 miles per hour or go flying through the windshield at 50 miles per hour. Just as the pole slowed the car down, the dashboard, windshield or the road would slow you down by exerting a tremendous amount of force.
Going back to the basic rule of inertia, no matter what happens in a crash, something would have to exert force on the occupant to slow them down. Where and how the force is applied determines if the occupant is killed instantly or if they walk away from the damage uninjured.
When the head strikes the windshield, the stopping power is concentrated on one of the most vulnerable parts of the body. It also stops the occupant very quickly, since the glass is a hard surface. This can easily kill or severely injure a person.
Occupant ejection in rollover crashes is a major source of motor vehicle-related casualties. According to the Fatality Analysis Reporting System (FARS) database, 7,128 completely ejected occupants died in motor vehicle crashes in the U.S. in 2005. 4,606 of these fatal ejections occurred in rollover crashes, which accounts for half of the 9,216 fatalities that occurred in crashes in which rollover was the most harmful event(fn5). Almost all of these ejections and deaths would not have occurred if seat belts were used.
A seat belt applies the stopping force to more durable parts of the body over a longer period of time(fn6). A seat belt also keeps the occupants inside the vehicle which is where they are safest during a crash. A typical three point seat belt consists of a lap belt, which rests over your pelvis, and a shoulder belt, which extends across your chest. The two belt sections are tightly secured to the frame of the car in order to hold occupants in their seats.
When worn correctly, the belt will apply most of the stopping force to the rib cage and the pelvis, which are relatively sturdy parts of the body. Since the belts extend across a wide section of your body, the force isn't concentrated in a small area, so it can't do as much damage. Additionally, the seat belt webbing is made of more flexible material than the dashboard or windshield. It stretches a little bit, which means the stop isn't quite so abrupt. The seat belt shouldn't give more than a little, however, or you might bang into the steering wheel or side window. Safe seat belts will only let you shift forward slightly.
It is extremely important that seat belts are adjusted properly for children. Typical vehicle seat belts will not properly fit a child until the child is at least 4 feet 9 inches in height. Booster seats are the transition from car seats designed for babies and toddlers to and adult seat belt. Through the use of the booster seat the child is raised up so the three point seat belt crosses the child’s chest and not their neck. Children have been seriously hurt and killed when they were placed in an adult seat belt without a booster seat. Some vehicles also allow for the adjustment of the shoulder portion of the seat up or down or provide a clip that keeps the belt across the child’s chest. The safest place for a child is always in the rear seat of the car. In Rhode Island any child under the age of eight (8), less than fifty-seven (57) inches in height and less than eighty (80) pounds must be transported in the rear seat of the vehicle .
Some people, especially here in the “Ocean State” don't wear a seat belt because they fear being trapped in the vehicle in the event of a wreck. However, the chances are greater of being killed or critically injured from being thrown from an automobile than it is to be trapped inside a wrecked vehicle. In addition, those who refrain from wearing seat belts because of a fear of being trapped should consider that the majority of people thrown from cars typically suffer injuries that are either irreversible or life-threatening. Individuals who survive a car crash and who were not wearing seat belts usually receive more serious injuries and require longer hospital stays. Additionally, people involved in automobile crashes that do not wear seat belts usually incur more medical expenses.
In the end it really is so easy, so quick and so effective to simply put on your seat belt, and make sure that your children and your family always wear theirs’. The life you save may be your own and certainly someone you love. A tragedy such as this is compounded if nothing is learned and actions don't change.
(fn1) CDC. Vital Signs: Nonfatal, motor vehicle-occupant injuries (2009) and seat belt use (2008) among adults— United States. MMWR 2011; 59.
(fn2) National Highway Traffic Safety Administration. Lives saved in 2009 by restraint use and minimum-drinking-age laws. Washington, D.C.: US Department of Transportation, National Highway Traffic Safety Administration: 2010. Publication no. DOT-HS-811-383. Available at http://www-nrd.nhtsa.dot.gov/pubs/811383.pdf. Accessed December 13, 2010.
(fn3) DOT HS 811 544 December 2011
(fn4) DOT HS 811 580 A Brief Statistical Summary February 2012
(fn5) Tom Harris - http://auto.howstuffworks.com/car-driving-safety/safety-regulatory-devices/seatbelt.htm
(fn6) http://www-fars.nhtsa.dot.gov
(fn7) R.I.G.L.§ 31-22-22. [Effective until 6/30/2013] Safety belt use - Child restraint
