When you see a big car on the street, its appearance gives you the impression that it is safe when it comes to behavior and resistance to a road event. But is a big car really safe in the event of a car accident? We will find out in this article.
A recent study by researchers from the University of Buffalo has revolutionized the idea of car crash safety. The study found that based on standard crash tests carried out by various organizations, many cars with the highest safety ratings are not always reliable for protecting the driver and passengers.
Unfortunately, the display ads of car companies and their five-star safety ratings do not really reflect the real level of danger or the absence of high risks in vehicles that are involved in road accidents.
A study by American scientists found that the smallest number of road traffic injuries came from owners of large pickup trucks and SUVs. Also, the least injuries were recorded among the owners of large or bigger cars. For example, the drivers and passengers of the Dodge Ram, Ford F-150, Range Rover, Volvo XC60, Audi A6, Toyota Tacoma, and Cadillac Escalade were the least injured in an accident.
The largest number of injuries that are recorded in people due to an accident was found in owners of small and compact cars like Kia Forte, Mitsubishi Galant, Nissan Sentra, Dodge Caliber, Scion TC, Nissan Versa hatchback, Chrysler 200, Nissan Rogue, and Ford Fiesta.
According to scientists from the University of Buffalo, as a result of the study, it was found that the weight and cost of a car directly affect the safety of a car in an accident . So with an increase in the weight of the car by 1100 lbs, the vehicle becomes safer by 19%.
“With a 500 kg increase in machine weight, the vehicle becomes 19% safer,” says Professor Dietrich Yehle, head of the research team at the University of Buffalo . – If we take into account that a large pickup, and even loaded, is 2.5 times heavier than a passenger car, then it is almost four times safer than it. If a large pickup truck collides with a tiny class B or C subcompact, its passengers will have a much better chance of surviving. ”
By the way, you can see here which car brands are most often involved in accidents in the USA.
It was also found that the more expensive the car, the higher its safety level. Apparently, this is due to the production cost. Many car manufacturers, trying to compete in the car market, try to reduce the final cost of cars. This often happens to the detriment of safety, as technologies to protect drivers and passengers from the consequences of accidents are too expensive in the auto industry.
As a result, according to the results of the study, it was possible to establish that if the value of the car is more for every 10,000 US dollars, then the level of vehicle safety increases by 12 percent.
It is noteworthy that many compact and small cars, which, as it was possible to find out a low safety indicator, have the highest ratings in the ratings of organizations conducting crash tests. This suggests that the top safety rating and top crash test scores do not mean that the car is really safe.
However, large and small cars were strikingly different in the nature of damage and injury among the owners. The number of serious injuries among SUV owners was 2-3 times less, although such cars were no less frequent in accidents than compact cars.
The impact momentum is significantly influenced not only by speed, but also by mass. Therefore, in a collision, cars of different weights behave differently.
For example, imagine that two cars with the same mass are driving towards each other on the road at the same speed of 37 mph. They collide. Under equal conditions, their total collision speed is 74 mph, and the equivalent damage speed is only 37 mph. They receive the same damage as when hitting a concrete wall at 37 mph.
The point is that the car develops equal energy and absorb it equally upon impact. The impulse is absorbed by two cars at once, so a correction factor is introduced into the formula for calculating the equivalent of the damage rate. For cars of the same mass, it is 0.5.
For a compact car and an SUV : 0.75 and 0.25, respectively.
For compact car and truck : 0.9 and 0.1.
For SUV and truck : 0.8 and 0.2.
SUV versus sedan in car crash safety
What happens at the moment of a frontal collision of a heavy car and a small, for example, an SUV weighing 2.5 tons and a sedan weighing 1.3 tons, at a speed of 37 mph? It can be calculated that the impact impulse of an SUV will be 1.9 times higher than that of a small car. So, it hits harder and does much more damage, but the SUV experiences less stress.
Thus, in order to find out the equivalent of damage to both cars, their total speed of 74 mph is multiplied by the coefficients proposed by the University of Buffalo. For a crossover and a small car with different masses, the coefficients are 0.25 and 0.75, respectively.
The impact of a collision on a Land Rover heavy SUV will be the same as a collision with a stationary wall at 19 mph. And for a small car Ford Focus – as in a collision at 56 mph. A large SUV will get off with damage to the bumper and hood, and the car will be crumpled like a piece of paper.
Safety of smaller cars
But people are least injured in large, full-size sedans such as the Mercedes S-Class, Chevrolet Malibu, Cadillac CT6, and other high-weight, low-slung vehicles. Why is this happening?
The fact is that when hitting an obstacle, the impact force is also influenced by the location of the center of gravity. If it is above the plane of application of forces, then the car experiences a turning moment equal to the product of the force and the length of the applied lever.
The higher the car, the higher its center of gravity, which causes the passengers to experience a whipping blow, throwing everyone up and overturning the car forward. And this blow causes considerable damage to the SUV and the people inside.
In sedans, the center of gravity is in the same plane as the passengers and the engine. Therefore, during a ramming impact, they do not experience the application of torque. The car rams the obstacle smoothly, without bouncing.
Thus, the safest car should be heavy and low so that it does not create parasitic torque on impact. These conditions are best met by armored limousines, which are long and weigh about 3 tons.