No motorist likes the butterfly effect. It works like this: On the Autobahn, a car overtakes a truck at 110 km/h. The driver behind the car in the left lane steers quickly to get the vehicle in front to hurry – but has to brake sharply to 110 km/h to avoid a rear-end collision.
Those following are forced to slow down as well. Like a chain reaction, this continues backwards. A traffic jam appears to appear out of nowhere – the butterfly effect.
Two German physicists are behind the 30-year-old theoretical approach of “phantom traffic jams” that form when drivers do not keep a safe distance. The two are called Kai Nagel and Michael Schreckenberg and the “NaSch model” is named after them.
It provides road traffic forecasts, especially density and flow. The model is based on the idea that each car on a road has a limited speed and space.
Such processes are also used as a basis for investments. In Great Britain, for example, the London ring road M25 should be widened by one lane on a certain section. The aim was to reduce travel time. A computer simulation predicted an increase in traffic and higher speeds.
However, she underestimated the amount of traffic and speed, as it later turned out in reality. As early as the 1960s, the German mathematician Dietrich Braess found that upgrading a road often does not lead to better traffic flow.
The ADAC traffic jam balance for the past year shows: 474,000 times there were traffic jams or slowdowns with a length of around 733,000 kilometers. 330,000 hours, i.e. an average of more than 900 hours every day, people waited on one of the 123 German autobahns for things to continue. Before Corona, however, it was much worse: in 2019, the ADAC counted 521,000 hours of traffic jams.
Whether the safety distance is too small or there are too many vehicles on the route – standing still on the road costs the general public and individuals money. According to calculations by the German Economic Institute (IW) from 2018, traffic jams in Germany cause around 80 billion euros in damage every year.
A large part is caused by the time lost by the participants and the increased fuel consumption. The expenses for the maintenance of roads and bridges, which are stressed by the increased traffic, must also be taken into account.
Other indirect costs of traffic jams, such as the health effects of increased air pollution or the psychological stress that driving in traffic jams can cause, will probably also be included in the calculation in the future.
The use of artificial intelligence in the evaluation of data could make traffic flow more smoothly. So far this has rarely happened. “Classic navigation systems use so-called selfish routing methods. That means: All drivers get the same recommended route,” says Alexander Meister, who is responsible for Smart Mobility at the navigation system provider Graphmasters.
The Hanover-based company says it uses what is known as load-balanced routing. Using traffic and mobile phone data as well as high-speed software, each driver is shown an individual route in real time.
However, standing still is not only a problem on the roads. Crowds are also common on the world ocean routes and in the ports. This was particularly striking during the corona pandemic, when ships were backed up in front of the ports.
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