Traffic problems - by Peter

We live in a village, and the only traffic problems we know are the farmers with their tractors and harvesters. They are too slow, so when we drive fast by car, we sometimes must brake extremely because a tractor stands in the middle of the street. Since January, in the cities, for example in Hanover, there are areas where it is forbidden to drive into by car. Unless you have a sticker on your windshield in red, yellow or green. It says how clean the engine of your car is. It's because of smog. So they told us. I think it's because the country needs money.
Since the introduction of these stickers we have had no problems with smog. The big problem everybody thinks is a traffic problem, is the industry, mainly in the USA.
Peter