If you live in New York, you've probably driven along the New York State Thruway. A photo taken on the Thruway demonstrates what can happen if you tailgate.

Joey Giovanni was driving along the New York State Thruway when he came across a multi-car accident: one car under the one in front of it, four cars deep - with a truck at the end.

In his Facebook post, he made a plea for folks to think about the physics and how much space you need to leave between you and the car in front of you:

Average speed on the Thruway is probably 65mph. That is 95 feet per second. Average car length is around 15 feet, so in one second you travel around 6 car lengths.

 

When you see a hazard suddenly appear in front of you, it takes time for your brain to process the visual inputs and send a signal to your foot to switch from the gas to the brake. This is called reaction time - the amount of time it takes varies widely but it can be anywhere from around .5 seconds to 2 seconds - depends on what you see, your natural reaction speed, whether or not you panic, etc...

 

We'll say the average is around 1 second for the purpose of this example.

 

A typical car traveling at 65mph, it can take 200 or more feet to stop your vehicle. Though it does rapidly slow down along the way.

 

So take a scenario where a driver in front of you slams their brakes. In a few seconds, they will be a little over 200 feet further than from where they stopped.

 

You see it, and it takes you a second to even hit your brake, so you're already 95 feet closer, than you also travel the 200 feet to stop.

 

This means if you weren't over 95 feet behind them, or around 6 car lengths, you will hit them. We don't encounter this often because most people don't find themselves in a situation on a Thruway where they need to literally slam the brake with full force.

To those calculations, we'll add Newton's Law: Force = Mass (weight) x Acceleration - that means if your car strikes another car or, God forbid, a person - it will do so with a tremendous amount of force.

Joey goes on to say: "Giving someone a 100ft berth is a lot. And on a busy road it's very hard and people will continually merge into the space between you and the car in front of you, but it's worth it to slow down and keep the gap. It could save your life or the lives of others."