What is tailgating and why is it bad?

If there's one habit that drivers need to unlearn, it's tailgating.

In a nutshell, tailgating is when one vehicle is driving too closely behind another vehicle - not leaving enough distance to stop safely in case the driver in front suddenly hits the brakes.

While a collision is the worst-case scenario, it isn’t its only byproduct. You might think slipstreaming behind another vehicle will help speed up traffic in the overall scheme of things because you’re going fast, well science says you’re wrong. What you’re doing is not only dangerous, it actually causes traffic to slow down and backup.

Tail me not – Tailgating and its terrible effects image

You might be asking, “what’s the proper distance to maintain then?” Old guards quote the ‘three-second rule’, which states that the vehicle you’re following should always be three seconds ahead. Newer models show that two seconds should be fine. Anything lower is considered tailgating.

A study done by really smart people from MIT’s (Massachusetts Institute of Technology) Computer Science and Artificial Intelligence Laboratory shows that driving at a steady and fixed pace with sufficient distance from the vehicle in front cuts travel time by almost 50%. This is called ‘bilateral control.’ Seems simple enough but plenty of hardcore math that looked like this xn=kd(xn+1−2xn +xn−1)+kv(xn+1 −2xn +xn−1) and terms like the damped-wave equation, Lyapunov function were used to prove it scientifically.

Tail me not – Tailgating and its terrible effects image

Driving too close to the vehicle ahead may result in what researchers call ‘perturbations’. It can be caused by anything from a huge pothole to a swerving PUB (public utility bus). The sudden braking of the affected vehicle will cause a ripple effect that will slow down the overall flow of traffic behind.

But just as tailgating is a major problem, so is driving too slow. The MIT GIF model below shows that even if just one car fails to observe bilateral control and slows down beyond the average pace of vehicular flow, the result is what they call ‘phantom traffic jam.’

Distancia Amigo: Why we need to un-learn tailgating image

And we’ve all been there, right? You’re surprised by heavy traffic along EDSA on a Sunday only to find out in the end that it was caused by a student driver taking weekend lessons.

“Our work shows that, if drivers all keep an equal distance between the cars on either side of them, such ‘perturbations’ would disappear as they travel down a line of traffic, rather than amplify to create a traffic jam,” says MIT professor and researcher Berthold Horn.

This goes to show that we all need the cooperation of every single driver if bilateral control is to work because it doesn’t matter if you’re doing the right thing, if just one is undisciplined three cars ahead or several cars back, everybody gets affected.

Tail me not – Tailgating and its terrible effects image

Even if traffic was the least of your worries because your time allowance is huge and you’re always in a zen state when you’re behind the wheel, you must know that vehicular congestion increases fuel consumption and CO2 emissions. That means more fuel wasted and more pollution in the air All in all, it’s still a lose-lose situation.

What should you do if you’re being tailgated? First, if you’re in the pass-only lane (the leftmost lane of any highway), shift over to the right so the driver can pass you as they may be in an emergency or just in a hurry. Second, speed up a little as long as you’re comfortable and not breaking the speed limit. If both options fail and the driver is just there to tick you off, consider turning right and changing routes to lose the tailgater.

Tail me not – Tailgating and its terrible effects image

Drivers tailgate usually because of four reasons: 1) they’re frustrated at the slow movement of the vehicle ahead, 2) getting ready to overtake, 3) trying to prevent another vehicle from moving in front or on the same lane, and 4) 'drafting' with other vehicles in order to save on fuel which is another whole can of worms. Either way, it’s a bad driving habit that’s unsafe for everyone on the road and the environment.

So, the next time you feel like speeding up unnecessarily, keep in mind the two-second or three-second rule (should go up to four seconds or higher when it’s raining). You’ll save fuel, perhaps save a life, be kinder to the planet, and best of all, you’ll actually be keeping traffic flow faster.