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Explanation for Holiday Traffic Jams

I can’t tell you how many times Jerry and I been driving on the tangle of southern California freeways, when of a sudden the traffic slowed to a creep, then finally was at a stall.

“Probably an accident or something,” often I have said.

“Most likely,” Jerry has agreed.

We stalled, crept, sighed with frustration, stopped, started, then at last our speed picked up, the traffic cleared before us and we were now moving at normal freeway speed. We’ve turned our heads in all directions looking for the wreck or the road construction or the detour signs, but in vain. There seemed to be no reason for the stalled traffic. Happened to you? Doubtless, if you live in an urban area. We’ve all puzzled over the phenomenon of a traffic jam to which there is no discernable cause.

Christmas lights and traffic. Tennessee, USA

QT Luong picture used under his “private” guidelines.
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.

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.

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 Gábor 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.”

So, as my early Christmas gift to my readers, I bring this explanation as to why you are now stalled in traffic in Los Angeles, Boston, New York City, San Francisco, San Diego, Chicago or Milwaukee. Relax, tune your radio away from the traffic alert station to one that is playing Deck the Halls with Boughs of Holly, or Grandma Got Run Over by a Reindeer, or best of all, Joy to the World…The Lord is Come!


My devotional blog is here.