The deadliest year in automotive history was 1972. There were 54,589 driving-related fatalities in the United States that year, according to the National Highway Traffic Safety Administration. By that time, safety innovations such as collapsible steering-wheel columns had ensured that motorists were no longer impaled in front-end collisions, and laminated safety glass spared them decapitation, but the most important safety feature of all — the three-point seat belt — would not become federally mandated until 1974.
Since the 1970s, driving fatalities have steadily dropped, falling to 33,808 in 2009. Even more impressive is the decrease in the rate of fatalities relative to the overall population: In 1966, 26 people out of 100,000 died in car crashes, compared with 11 out of 100,000 in 2009. Seat belts aren't the only reason for the encouraging statistics, though. Here we highlight a handful of the most important automotive safety innovations and how they are evolving to protect motorists better.
Seat Belts
Volvo engineer Nils Bohlin (above) is credited with developing the three-point seat belt, first offered as standard equipment in the 1959 Volvo 122.
There's no question that three-point seat belts, the kind that strap over the shoulder and across the lap, save more lives than any other automotive safety device. "They keep occupants in a position where they are safest, and prevent ejection [in a collision]," says Gabriel Shenhar, senior auto test engineer at Consumer Reports. If all passenger-vehicle occupants 5 and older had worn seat belts in 2009, 16,401 lives could have been saved, according to NHTSA.
Volvo engineer Nils Bohlin is credited with inventing the three-point seat belt as we know it today. The Swedes began outfitting their cars with them in 1959. Various lap and shoulder belts had existed before then, in both cars and airplanes, but it wasn't until 1974 that three-point belts were mandated in the U.S. In 1981, Mercedes-Benz outfitted its S-Class cars with pyrotechnic pretensioners — not to be confused with the ubiquitous mechanical tensioners — that instantly tighten the belt against the body when a crash seems imminent. Ford is the latest innovator: It offers inflatable belts as a rear-seat option on its 2011 Explorer. They minimize injury by distributing crash forces over a greater area of the torso.
Electronic Stability Control
Electronic stability control, first introduced on the 1995 Mercedes-Benz S-Class, evolved from traction control, and helps to avert a crash by detecting and minimizing skids.
Following safety belts in importance is electronic stability control, Shenhar says. That's because devices such as airbags and safety cells make a difference only once a collision happens, whereas ESC helps to avert a crash altogether. By detecting and minimizing skids, ESC reduces the risk of fatal multiple-vehicle crashes by 32 percent and fatal single-vehicle crashes by 56 percent, according to the Insurance Institute for Highway Safety. That's huge, says Joe Nolan, head of the IIHS Vehicle Research Center.
German parts supplier Bosch developed electronic stability control in the 1990s. The first production car to use it was the 1995 Mercedes S-Class. Now ESC comes standard on many vehicles, and beginning with the 2012 model year, it will be a federally mandated requirement on all passenger vehicles.
ESC uses sensors to detect the intended path of the vehicle and determine whether it's starting to skid. The system can selectively brake one or multiple wheels to keep the vehicle on course. Some systems also reduce engine torque to help stabilize the vehicle. ESC is particularly helpful for SUVS prone to rollover. It evolved from traction control, which prevents wheel spin, but traction control doesn't help steer a vehicle back on course like ESC does.
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Airbags
By September 2012, all vehicles will be required to have "advanced" airbag systems, such as the one deployed by the Nissan LEAF in this 40-mph frontal crash test.
NHTSA estimates that as of January 2009, airbags had saved more than 28,000 lives. In frontal crashes, front airbags reduce driver fatalities by 29 percent and fatalities of front-seat passengers over 12 by 32 percent, according to NHTSA. Front airbags became required on cars in the U.S. for the 1998 model year, and for SUVs, pickups and vans for the 1999 model year.
Most manufacturers, however, offered them well before then. Chrysler made them standard on all of its cars starting in 1990. The earliest airbags date back to experimental Ford vehicles in 1971, and General Motors began offering them as an option on some full-size cars in 1974.
Airbags deploy by way of a controlled explosion that fills them in milliseconds with inert gas. NHTSA mandated that "advanced airbags," capable of deploying at different sizes based on weight sensors in a vehicle's seats, be phased into production starting with the 2004 model year. All vehicles must be equipped with advanced airbags by September 2012.
Side airbags are available on most cars now, too, but they aren't mandated. Side airbags that protect the head reduce a car driver's risk of death in driver-side crashes by 37 percent, and an SUV driver's risk by 52 percent, the IIHS says.
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Anti-Lock Braking System
The 1969 Ford Thunderbird was the first passenger car offered with an anti-lock braking system, but it controlled only the rear wheels.
Here's a shocker: Anti-lock brakes aren't huge lifesavers. But they're still a key safety innovation in the grand scheme of things. "ABS is important not in and of itself, but because it was the jumping-off platform for electronic stability control," Nolan says. "So by fitting vehicles with ABS, engineers were one step closer to being able to do what they can do with ESC."
ABS has also opened the door for other advances, such as electronic brake-force distribution and emergency brake assist. The first passenger car with ABS was the 1969 Ford Thunderbird, according to the IIHS, but it operated only on the rear wheels. In 1971, General Motors offered rear-wheel ABS as an option on some Cadillacs. Chrysler started offering four-wheel ABS that year on its Imperial.
ABS pulses the brakes to prevent wheel lockup and skidding. It is supposed to help shorten stopping distances and maintain control on slippery surfaces. The IIHS says it's unclear whether ABS has an appreciable effect in reducing the number or severity of car crashes, based on crash data and insurance claims for accidents involving cars with ABS compared with those without. A 2009 NHTSA report did find that ABS reduced the risk of crashing by 6 percent for cars and 8 percent for pickups and SUVs, but found that it had no effect on the risk of fatalities. Where ABS does make a huge difference is on motorcycles, where it reduces the rate of fatal crashes 37 percent per 10,000 registered vehicle years, according to the IIHS.
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Safety Cages
When the IIHS began its frontal crash tests in 1995, approximately half the vehicles earned poor or marginal ratings. Today, practically all cars get a good rating. The Hyundai Sonata, for instance, advanced from "poor" to "good" in its frontal crash test ratings between 1996 and 2006.
Over the past 20 years, automakers have made huge strides in creating structures that absorb and redistribute crash forces around a vehicle's cabin. Frontal crash tests and roof-strength standards instituted by the federal government in the 1970s laid the groundwork for modern safety cages with front and rear crumple zones. A 40-mph frontal crash test the IIHS began in 1995 sparked a change in the way automakers manage crash energy, by concentrating the impact on a smaller part of the safety structure, Nolan says. Today, the driver of a vehicle rated "good" by the IIHS is 46 percent less likely to die in a frontal crash, compared with a driver of a vehicle rated "poor."
Depending on the source, either Volvo in the 1940s or Mercedes in the 1950s first developed a safety cage with energy-absorbing front and rear crumple zones. Side-impact crash tests, started by NHTSA in 1996 and by the IIHS in 2003, spurred automakers to make further improvements. These tests were crucial, as SUVs had flooded the market and cars were proving no match for them in collisions.
"When we started the tests, some vehicles were getting ripped in half at the roof pillars," Nolan says. "Now, the same models 10 years later have very good crash-test ratings." As with all aspects of automotive safety, the technology is on a continuum of constant improvement.
Matthew de Paula wanted to be an automotive journalist ever since reading his first car magazine in grade school. After a brief stint writing about finance, he helped launch ForbesAutos.com and became the site's editor in 2006. Matthew now freelances for various outlets.
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