How Seat Belts and Airbags Work Together

seat belts and airbags work togetherOne of the most common excuses people give for not wearing a seat belt is that their car has airbags. They think airbags alone offer enough protection in a crash, but they are wrong. Seat belts and airbags are designed to work together. In fact, the combination reduces injuries and deaths so effectively that dual front airbags are now mandatory in all vehicles sold in the US. Here, we’ll explain how airbags work in conjunction with seat belts and discuss the types of airbags available.

What Happens During a Car Crash

In designing safety features, engineers consider crash physics and what happens to your body during a collision. One of the most basic and most applicable principles is Newton’s first law. It says that a moving object will continue at current speed and direction unless acted upon by an external force. (Your speed and direction together is also known as your velocity.)

You may not think of it this way, but when you’re riding in a car, you are a moving object. Your velocity will match that of your car. So, if you are driving 60 miles per hour, so is your body. If your car crashes into something, that obstacle will exert force against the car and make it stop. Your body will continue moving 60 miles per hour, however, unless something stops it. This is where the safety features of your car come in. They are designed to absorb the impact of the crash by exerting safe stopping forces on your car and your body.

These days, cars have crumple zones which will help absorb some crash impact. The rest is up to the safety features of the car interior, most notably the seat belts and airbags.

Seat Belts and Airbags

Seat belts and airbags are the first line of defense for protecting your body in a car crash. Your seat belt restrains you, keeping you from flying forward into the dashboard or out of the car. If you have ever been in a crash, even a low speed collision, you probably noticed your head still snap forward at impact though the seat belt kept your body in place. Airbags help cushion your head, neck, and chest when this happens in higher-speed crashes.

So, if the airbag will cushion you, why do you still need the seat belt?

  • To hold your body inside the car. The airbag will be no good to you if your body flies right past it. In fact, you may sustain an injury that’s even worse.
  • To keep your body in the right position for airbag cushioning. Remember that airbag design assumes that you’re wearing a seat belt, so it will deploy to protect you while you’re wearing it. Airbags are “supplemental restraints” and were never intended to replace seat belts.

Types of Airbags

Just as safety engineers have developed new types of seat belts over the years, there are now several different types of airbags available.

Front Airbags

These are probably what most people think of when airbags are discussed. Dual front airbags are now mandatory in all cars sold in the US. These airbags cushion the driver and front seat passenger during a crash. On the driver’s side, the airbag deploys from the steering wheel. On the passenger’s side, it deploys from the dashboard.

Some cars now have weight sensors so that the front airbags will not deploy for smaller passengers. Regardless, the back seat is the safest place for your smallest passengers. The American Academy of Pediatrics recommends that children under the age of thirteen should always ride in the back seat.

Side Airbags

Side airbags deploy to protect you during side impacts and rollovers.

  • Curtain airbags. These deploy from the top of the door rails, cushioning the head. They’re usually in both the front and rear seats.
  • Torso airbags. As the name suggests, these deploy from the sides to protect your body. They’re most common in the front seat, but some higher end cars include the option in the back seat, as well.
  • Front center airbags. This new type of airbag pops up between the driver and passenger seat in the front. It cushions them in case the car is hit on the opposite side from where they’re riding. This limits injuries by reducing the body’s range of motion during a side crash. It can also prevent the driver and passenger from colliding upon impact and injuring each other.

Knee Airbags

Knee airbags are another relatively new addition to modern cars. They deploy under the dashboard to cushion front seat riders’ knees in a head-on collision. Shattered knee caps and other leg injuries are quite common in such high-speed crashes.

Inflatable Seat Belts

These seat belt / airbag hybrids deploy during crashes to spread the force of impact more evenly over the body. This cushioning cuts down on bruising and other injuries from seat belts. Those injuries are minor compared to what the body would sustain without the seat belt, but an issue nonetheless.

Buckle Up Every Time You Ride

Airbags are a supplemental safety feature designed to work with seat belts, not replace them. The seat belt will keep you in the vehicle during a crash, while the airbag cushions your head and upper body to minimize injury. To stay safe, buckle your seat belt every time you ride, even if your car has airbags.