Traffic Jam Mystery Solved By Mathematicians
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Mathematicians from the University of Exeter have solved the mystery of traffic jams by developing a model to show how major delays occur on our roads, with no apparent cause. Many traffic jams leave drivers baffled as they finally reach the end of a tail-back to find no visible cause for their delay. Now, a team of mathematicians from the Universities of Exeter, Bristol and Budapest, have found the answer and published their findings in leading academic journal Proceedings of the Royal Society.
The team developed a mathematical model to show the impact of unexpected events such as a lorry pulling out of its lane on a dual carriageway. Their model revealed that slowing down below a critical speed when reacting to such an event, a driver would force the car behind to slow down further and the next car back to reduce its speed further still. The result of this is that several miles back, cars would finally grind to a halt, with drivers oblivious to the reason for their delay. The model predicts that this is a very typical scenario on a busy highway (above 15 vehicles per km). The jam moves backwards through the traffic creating a so-called “backward travelling wave”, which drivers may encounter many miles upstream, several minutes after it was triggered.
Dr. Gabor Orosz of the University of Exeter said: “As many of us prepare to travel long distances to see family and friends over Christmas, we’re likely to experience the frustration of getting stuck in a traffic jam that seems to have no cause. Our model shows that overreaction of a single driver can have enormous impact on the rest of the traffic, leading to massive delays.”
Drivers and policy-makers have not previously known why jams like this occur, though many have put it down to the sheer volume of traffic. While this clearly plays a part in this new theory, the main issue is around the smoothness of traffic flow. According to the model, heavy traffic will not automatically lead to congestion but can be smooth-flowing. This model takes into account the time-delay in drivers’ reactions, which lead to drivers braking more heavily than would have been necessary had they identified and reacted to a problem ahead a second earlier.
Dr. Orosz continued: “When you tap your brake, the traffic may come to a full stand-still several miles behind you. It really matters how hard you brake - a slight braking from a driver who has identified a problem early will allow the traffic flow to remain smooth. Heavier braking, usually caused by a driver reacting late to a problem, can affect traffic flow for many miles.”
The research team now plans to develop a model for cars equipped with new electronic devices, which could cut down on over-braking as a result of slow reactions.
6 Comments
Bryan Price
December 20th, 2007
at 6:32am
The What do you think? links are getting passed through into the RSS feed, and I had to click through because it was reading “;Hacking Mystery’ solved by Microsoft, Is Encryption Doomed?” and I’m like wtF?
John T. McClanaghan
December 20th, 2007
at 10:39am
Anyone who has spent a significant amount of time driving on the highway doesn’t need mathematical models to explain this! And they call this research? I weep for these students. It’s hard to teach morons anything!
How about some articles for the smart people who subscribe?
scottklarr
December 20th, 2007
at 11:22am
wow it took a team of scientists to come up with that theory? I came to the same conclusion while day dreaming in traffic one day lol
Zachary Shaw
December 20th, 2007
at 12:20pm
I have been a commercial driver for the past 35 years {3.5 million miles} in the SF Bay Area. It was my observation years ago that traffic congestion followed a wave function . I marvel at the stupidity of the general motoring public and how they cannot see past the hood of their car. How they will find a brief clear lane on the freeway and accelerate into stopped traffic. Other than an emergency there is ZERO reason EVER to stop on a freeway. The only reason for stopped traffic on a freeway {other than an emergency} is DRIVER INCOMPEDENCE!
If the average car driver did not remove their brain from their head when they picked up the car keys they would note TRAFFIC FLOW and ADJUST their speed in accordance. Distance is your friend. Observe the FLOW of traffic as far down the road as you can see. Adjust your speed and distance so you DO NOT HAVE TO STOP. If the dope in the B.M.W. wishes to jam in front of you so he may speed ahead for 600′ and slam on his brakes, let him, you back off. Remember traffic flow, do not stop on a freeway!
If you perform this maneuver correctly you will start to cancel the wave. You will notice that you will continue to move while the traffic in the adjoining lanes are stopped.
If you have difficulty understanding a wave and how to cancel a wave hang up your keys and take a bus.
.
SpaceFace
December 21st, 2007
at 10:35am
As a commuter on a major Minneapolis highway, i must say that Zach is so spot on. - I would also like to add that i never understand why people insist on staying in the right lane when their exit isn’t for three or four miles (or more). Get to the center or left side. then calmly move to the right when your exit is within 1-2 miles.
Amerigo M. Cimino
December 24th, 2007
at 4:46am
“Traffic Jam mystery solved by mathematitions.” Where have you been?
This has only been a mystery because your memory has been blank for almost 70 years! This phenomenon was commonplace before and during the second world war, when convoys of trucks and cars were going to a common destination. If the driver in the lead vehicle took his foot off the accellerator, the driver in the last vehicle had to come to a panic stop. This of course was a convoy of 30 to 70 vehicles in the convoy. We have more vehicles involved in modern day traffic, but the idea that mathematitions solved a mystery, is Monday morning quarter-backing.