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" Traffic jams seem to appear out of nowhere and sometimes for no good reason other than to frustrate you. If you&amp;#039;ve ever wanted to see just how easy it is for a jam to get started, take a look at traffic-simulation.de, a traffic simulator that shows how traffic jams and slowdowns can form in real time. The simulator shows how jams naturally occur with a bunch of cars driving around a ring. You can toy with the controls, changing the settings for car density and speed limits to see how that affects the flow of vehicles. The site promises that other shapes, like an on-ramp, will soon be available.  Traffic jams are often caused by bottlenecks: things like lane closures, intersections, and traffic lights\u00A0that slow down or stop traffic. But they\u00A0can also be caused by &amp;quot;traffic perturbations&amp;quot;\u2014sudden braking or lane changes that cause\u00A0other cars to slow down. If the perturbation is big enough, it can set off a chain reaction that leads to a traffic jam. One of the ways to\u00A0prevent or minimize traffic jams is by enforcing a speed limit. When all the cars are traveling at the same speed, there&amp;#039;s no reason to brake or change lanes. If there are no sudden perturbations, traffic flows smoothly and there are no jams. Even so, this means that all it takes is one jerk to ruin it for everybody. "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/cars/a21280/traffic-simulator-jams/>