Traffic jams are caused by keeping the wrong distance between cars, maths study finds

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Traffic jams, they just seem to know don’t they?

It’s almost like they can sense exactly when you’re making an important journey and absolutely have to be somewhere on time.

In cases when there might be an accident, traffic jams are bound to happen but when there are build ups for no apparent reason, that’s when it’s likely to get motorist’s blood boiling.

So, where do these traffic jams come from? And what can you do about it?

A study in IEEE Transactions on Intelligent Transportation Systems mathematically explains the implications of the larger problem at hand here- and that is the fact that you’re not keeping to the right distance from the car behind you.

Now, although this may seem a little strange given that you don’t have much control over how far away you are from the car behind you, the maths details that if every car stuck to an equal distance between the cars behind and in front, this would allow traffic to move twice as fast.

You see, traffic is an example of ‘emergent property’, meaning that individual things collate and form something more complex together. An example of emergent property in the natural world would be starlings forming a murmuration created by thousands of individual birds.

Taking inspiration from this, as you’re driving on the motorway, instead of solely focusing on the car directly in front of you but keeping to equal distances to the front and behind of you, this would be the optimal ideal to ease traffic. This is known as bilateral control.

Talking of traffic jams, study co-author Berthold Horn from MIT said: “This is what happens when you have a control system that is simply trying to keep up with the vehicle in front. And its job is not to make the world better, to have hundreds of cars moving in unison. It’s very myopic.”

Now imagine this bilateral approach ringing true for all other drivers in the traffic jam and you can see why the specific emergent property of traffic isn’t currently travelling in harmony.

But wait, hold the blame as it’s also true that a human behind the wheel simply doesn’t have the capacity to continually calculate both distances. Sadly, you can’t take this acquired knowledge and attempt to make the change yourself.

Technology does have this capacity however with more and more cars featuring adaptive cruise control, a feature that tells the vehicle to follow the car ahead at a safe distance. If such vehicles also possessed the same technology to the rear of the car then we would be able to make a real difference.

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But, as Horn commented: “To get the full benefits of this, a significant fraction of the cars would have to have this.

“In terms of societal implementation that’s a big factor, because even if it’s relatively cheap, people who implement it will question whether the first car that gets it is worth that investment, because until other cars get it, it doesn’t do a whole lot of good.

“It sounds pretty drastic, but the benefits are huge. We’re talking about a potential doubling of throughput, huge decreases in CO2 emissions, a lot of aggravation reduced and fuel used.”