Tailgating and Phantom Traffic Jams – What They Are

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A brief outline of a proposal by researchers to curb phantom traffic jams. The article explains why tailgating leads to phantom traffic jams, the approach recommended by researchers, and how road users can incorporate these recommendations into their driving.

Self-Driving Cars: History and Future

Phantom Traffic Jams and Tailgating Explained

Tailgating is by no means a new phenomenon. It has been identified as the leading cause of phantom traffic jams, and we may all get to our destinations twice as fast without it.

Berthold Horn and Liang Wang are from the MIT Computer Science and Artificial Intelligence Laboratory. With an extraordinary amount of number crunching, they have proposed a potential approach for curbing the frustratingly frequent occurrence of phantom traffic jams. A phantom traffic jam is one that seemingly arises without cause. Particularly prominent in times of heavy traffic flow, they can cause the traffic to grind to a complete halt, and result in collisions.

Slamming on the brakes

There is so much happening on the roads that sometimes, drivers must brake, without warning. When there is adequate spacing between vehicles, this sudden braking is absorbed into the space. The driver behind may have to ease off the accelerator for a moment to allow the space to open up again. And, if the vehicle behind this second car also has left plenty of space, there should rarely be a need for further braking.

When drivers sit close to one another, instead of being absorbed into the flow, the severity of braking mounts with every car it passes through. It escalates to the stage where even those leaving a very respectable gap must slam on the brakes.

And so, a phantom traffic jam is born.

Lesson From Nature: A Bi-Lateral Approach to Tailgating

Horn and Liang’s research was inspired by the complete concordance of flocks of birds. In these spectacular murmurations of starlings – the birds apparently move as one. Any sudden change of speed, or ‘perturbation’, is absorbed seamlessly into the flock. They observed that the birds all keep equidistant from one another. And so, they propose that we extract a lesson from their synchrony. Their suggestion is a bilateral approach to the cruise control system of new vehicles: sensors are to be installed not just on the front of the vehicle, but also on the back.

They estimate that if even a small percentage of vehicles were equipped as thus, journey times for all would be significantly reduced due to the lower occurrence of phantom traffic jams.

Once again, nature shows us how it is done. Driving is not just about what is in front of you. It is also fundamental to be aware of what is behind you. However, a world in which all cars are equipped with front and back sensory centers is not on the immediate horizon. So, we must take matters into our own hands, and consider a few changes to the way we behave on the roads.

Uncouth Dynamics and Collisions

If you often find yourself with someone suddenly looming into your personal space from behind, it may be time to ask yourself a few questions. Is the traffic in the overtaking lane moving much faster than you? Could you be moving a lot slower than is common in your lane? Is there anything you could do about this?

Are you hogging the middle lane? This behavior also leads to uncouth dynamics and collisions. Is there really room for you in that gap you just squeezed into while changing motorway lanes? Do you have suitable reference points to help you to answer that question? In order to fit more of the road in, wing mirrors can give the illusion that things are smaller, and so further away. It can be good practice to instead use your rear-view mirror. Here’s a handy reference point: if you can see both their headlights, there is enough room. Look for the roof of the car if your rear head restraints are blocking the view.

Antagonizing Games

Admittedly, sometimes someone is just too close. You neither want to drive faster nor waste your time and fuel by pulling over for them. Dangerous overtakes are also best avoided. If the conditions are hazardous (snow, ice, wind, rain), flashing your hazard lights a couple of times to remind them that they are making a hazard out of the pair of you can help to increase the distance. While it is generally best not to engage in antagonizing games, keeping your washer fluid topped up, and giving them a thorough washing, rarely fails to lengthen the gap. If they are planning to overtake, the extra distance will make this a much safer operation.

And, if you find yourself frequently frustrated, having to slam on the brakes more often than you reasonably should, there are some questions you could ask yourself, too. Are you attempting to drive too fast for the traffic flow? Can you see the road ahead? That is, to the next bend, or several cars ahead. You won’t get there any faster if you spontaneously rear-end someone.

Final Thoughts on Tailgating

To achieve flow, it is good practice to keep awareness of fluctuations before they escalate. That way, instead of braking, you can ease off the accelerator a little in anticipation. It is a lot easier to drive with such foresight if most of your view is not taken up by the car in front.

We are all in this together. We all want to get home safely. We all want to get there faster.

Let us aim to drive with consideration, cooperation, and contemplation, and work towards the glorious harmony of our feathered friends.