If you sit in a some gridlock this holiday season, you might come to the end of the line of cars and realize, hey, there's nothing there. No accident, no police on the shoulder, just a bunch of cars that aren't getting where they want to go. Over at the Universities of Exeter (in England), Bristol and Budapest, mathematicians now think they've figured out why this happens (and wastes lots of gasoline in the process).

The short answer: braking and full roads. When there are between 10 and 15 vehicles on a one-kilometer stretch of highway and the front one hits the brakes, a "backward travelling wave" is created that can sometimes lead to traffic jams. As Dr. Gábor Orosz of the University of Exeter's School of Engineering, Computing and Mathematics, said in a statement: "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." He 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."

This seems like a problem with no solution. Not braking could lead to accidents, which certainly don't make the highways easier to travel on. And removing cars from the road would be appreciated by many, until public transportation becomes a better option, it ain't gonna happen. So, if you get stuck on the way to or from grandmother's house this year, at least you now kind of know why.

[Source: University of Exeter via Scientific American]

Everybody hates traffic. But, that doesn't stop each and every one of us from getting stuck in it from time to time, does it? Especially if you live in L.A., the city with the worst traffic of all. How bad is it? According to a study performed by the Texas Transportation Institute, rush-hour drivers in L.A. spend an extra 72 hours a year on average stuck in traffic. Other major offenders are the metropolitan areas of San Francisco/Oakland, Washington, D.C./Virginia/Maryland, and Atlanta, where drivers spend about 60 hours in traffic during peak hours. It gets worse, too. No matter where you live, traffic increased in 2005, according to the study.

Obviously, this is a terrible time waster, but it's also a horrible waste of gas, with 2.9 billion gallons of extra fuel used up in 2005, for a total cost of $78 billion. As gas gets more expensive, this figure will rise. Of course, if your car does not idle, you are using less gas. Also, this is where hybrids and electric cars have a huge edge, as they can rely on battery power while slowly moving along in gridlock.

So, whatcha gonna do about it? See here for some suggestions and to see what is being done now. In the meantime, perhaps you should move to the Mojave Desert, where traffic is mostly non-existent. Just a thought.

[Source: Texas A&M University]