Cities . People . Technology

Why Do Traffic Jams Happen?

Road traffic can be viewed as a system the cars are flowing into. Traffic jams are the result of disruptions in the system. What kind of disruptions, you ask?

The fundamental problem of traffic

Mathematicians from the University of Exeter developed a mathematical model to simulate traffic behaviour and found that much of the traffic jams arise from two things. They identified that overbraking is the lead cause of congestion and not necessarily the volume of traffic itself.

When a vehicle brakes due to an unexpected circumstance such as the crossing of pedestrian, the slow reaction of the driver will lead to braking more than what is needed. This will also lead to the driver behind him braking even more. This goes on and on until a vehicle actually comes to a complete halt.

A video by CGP Grey beautifully illustrates the fundamental problem of traffic:

In his video, CGP Grey identified three main sources of traffic jams.

  1. Slow reaction times. As explained earlier, slow reaction times lead to overbraking which amplifies until one car in the succession of overbraking cars comes to a complete stop.
  2. Intersections. Intersections worsen the problem of slow reaction times since there are four directions where chaos among drivers can ensure. The dreaded traffic gridlocks we hear from the news emphasize just how bad are the congestion intersections can make.
  3. Splits and merges. Apart from the exits, the highway is pretty much devoid of intersections. This is why travelling on highways are noticeably faster than in a typical city road.

However, when vehicles cross from one lane to another, that is where the problem comes in. A vehicle crossing will lead to — you’ve guessed it right — a car overbraking until one car eventually comes to a full stop.

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All these three sources root from the latent problem that is discoordination. If humans are coordinated enough, traffic jams will be no more.

CGP Grey himself suggested that a solution to traffic will be the change in human behaviour. If drivers will avoid tailgating and keep an even distance between the vehicles at the front and at the back, then the impact of slow reaction time will be minimized.

However, to put the solution in the hands of the humans is admittedly too idealistic. If we can’t rely on what is flowing in the system to change its behaviour, then we should look into the other aspects of the system that we can feasibly address.

Putting an end to traffic jams

When traffic jams are mentioned, the expansion of roads always come to mind. As noted in this article, expanding our roads will only be helpful to some extent. Besides, we cannot expand the roads forever since our land is a limited resource.

One way we can deal with this is to let the drivers reconsider the way they travel. Singapore implements this through their Electronic Road Pricing (ERP) which employs the pay-as-you-use principle, charging the drivers based on the congestion level and the time of day they are using their car.

To complement methods such as ERP, providing alternatives to the use of private transport is also recommendable. Mass transit and vehicle sharing systems will help in reducing the number of vehicles that flock the road to begin with.

A futuristic solution will be the use of self-driving cars. In a future where autonomous vehicles are dominant, the issue of slow reaction will no longer be an issue since smart vehicles can communicate lightning-fast with one another. This will eliminate discoordination and in extension even the need for traffic regulation mechanisms such as traffic lights.

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On the whole, the issue of traffic congestion is quite difficult to crack, requiring pretty much an overhaul of the traffic system that we’re used to. But if we want to put an end to this eternal dilemma, there are no shortcuts — we must be willing to do the tough work.

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