December 28, 2007
Now more than ever, safety features are a key selling point for new cars, and as a result, cars get safer each year. But one thing has remained the same through the years — and you might need to brace yourself for this one — accidents happen, and they’re unpredictable.
The effect of a crash on the occupants of a vehicle is just as unpredictable as the crash itself. Any change in the speed of the vehicle or the angle of impact can dramatically alter the outcome an accident. So how do automotive manufacturers come up with ways to ensure the safety of you and your loved ones in the face of so many different accident scenarios?
They consult dummies.
You Can Still Learn a Lot from a Dummy
“You can learn a lot from a dummy,” states a memorable 1990s Public Service Announcement. Crash test dummies did have a place in the pop culture landscape of that time, even having their own cartoon for a while. But lost in that exposure was the intricate engineering behind them. Dummies are still essential to each new development in automotive safety technology. They’re constructed to simulate the weight, movement and durability of each member of the entire nuclear family.
In addition to sturdy plastic limbs that are built to withstand immense pressure, the dummies’ spines are composed of alternating discs of rubber and metal to recreate human flexibility. But the most impressive technologies are three types of devices implanted in each dummy: accelerometers, load sensors and motion sensors. Each of these devices records exactly what happens to a dummy over the course of impact. Accelerometers measure the speed at which a part of the dummy moves, and in which direction. They’re placed in the head, chest, legs and various other locations. Load sensors are also placed in numerous locations, and measure the amount of force a crash creates; movement sensors are used to measure the amount a dummy’s chest arches when absorbing the force.
With a final artistic touch, various parts of the dummies are painted different colors to provide visual evidence of in-car collision. The paint shows exactly where a given part of the dummy hit in the vehicle’s interior — that data is then matched up with the accelerometer readings to determine the severity of the collisions.
Points of Vehicle Impact
As each dummy is constructed and set up to exact specifications, so too are the tests. These are governed by the National Highway Traffic Safety Administration (NHTSA). The two major tests simulate the impact of crashes to the front and the side of the test vehicle.
Front-impact tests are done by crashing the test vehicle into a stationary concrete barrier at 35 mph — this simulates the vehicle colliding head-on with a comparable vehicle at the same speed. Side-impact tests are performed using a sled weighing over 1½ tons to simulate two like vehicles colliding in an intersection, also at 35 mph. Along with the various recording devices placed within each dummy, each crash is recorded by more than a dozen constantly snapping cameras placed at all angles, even directly below the vehicle.
Though the violent crashes in each of these tests last less than a second, all the careful planning provides engineers with all the information they need to determine where they can make improvements. Test vehicles are often drastically damaged during these tests, but for engineers this is a sign of success: every bit of force the vehicle can absorb is force that a vehicle’s occupants don’t have to.
Rating Systems
Crash tests provide comprehensive facts and figures, reducing each collision to its most important measures of speed and force. But these numbers are only meaningful to engineers, and not the people whom they affect the most. So what can you do to better understand the technology that keeps you safe?
First, you can refer to the strict list of Federal Motor Vehicle Safety Standards (FMVSS), which every vehicle must meet before mass production. The FMVSS govern standards for every part of the vehicle, from the locations of essential interior controls, to the brightness of headlights, to seatbelt regulations.
Beyond that, NHTSA instituted its New Car Assessment Program (NCAP) to further challenge carmakers to bolster their safety systems. The NCAP rates each new vehicle’s front- and side-impact crash tests on a five-star scale; a vehicle’s rating is determined by the likelihood of a passenger suffering a serious injury to certain areas of the body. For front-impact, the rating is based on the likelihood of injuries to the head, chest and legs; a five-star rating means a 10% or lower chance of serious injury. Side-impact star ratings are determined by potential injuries to the chest and pelvis, with a five-star rating given to vehicles with a 5% or lower chance of serious injury.
The Future of Safety
Without these tests, automotive enhancements such as airbags and seatbelt pretensioners, which preemptively tighten the belt before the airbag activates, would not be nearly as effective as they are today. In addition, crash tests have been integral to the development of other key automotive safety technologies, such as Antilock Brake Systems (ABS) and Electronic Stability Control (ESC).
The next wave of safety technology will be marked by efforts to make safety systems “smarter.” This means the development of airbags that can sense the severity and point of impact of a crash and tailor their deployment according to those factors. Smarter seatbelts will also tailor their performance to a passenger’s weight and shape to better manage forces during a crash.
Top-of-the-line safety equipment has been a growing trend in recent years, and the public has responded. This means car manufacturers will remain increasingly willing to make their vehicles hold up to the most rigorous standards, which is good news for everybody — except the dummies.
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