That's actually one of the most basic principles of traffic design.
Roads built in the Netherlands and Germany are designed so that you absolutely can't drive safely at speeds higher than the supposed speeds - it feels unsafe, and you just don't.
For example, in areas before schools, you usually limit the road to one lane, and switch which side that is every 50 meters, requiring cars to drive slalom, which in turn requires cars to slow down (or crash into concrete).
You don't make it actually unsafe (there's enough space that it won't ever cause any fatal accident), it just has to feel unsafe.
EDIT: More examples:
Another example are the emergency lanes and outer lane markings on the Autobahn: they are a lot louder to drive on intentionally, so if you accidentally steer onto them, you'll hear a very loud noise, and your car will vibrate just slightly - if you fell asleep and steered onto them, you'll instantly wake up again. Another example would be speed bumps.
they are a lot louder to drive on intentionally, so if you accidentally steer onto them, you'll hear a very loud noise, and your car will vibrate just slightly - if you fell asleep and steered onto them, you'll instantly wake up again.
Roads built in the Netherlands and Germany are designed so that you absolutely can't drive safely at speeds higher than the supposed speeds - it feels unsafe, and you just don't.
For example, in areas before schools, you usually limit the road to one lane, and switch which side that is every 50 meters, requiring cars to drive slalom, which in turn requires cars to slow down (or crash into concrete).
You don't make it actually unsafe (there's enough space that it won't ever cause any fatal accident), it just has to feel unsafe.
EDIT: More examples:
Another example are the emergency lanes and outer lane markings on the Autobahn: they are a lot louder to drive on intentionally, so if you accidentally steer onto them, you'll hear a very loud noise, and your car will vibrate just slightly - if you fell asleep and steered onto them, you'll instantly wake up again. Another example would be speed bumps.