Traffic congestion is a huge problem in urban areas nowadays, road networks are becoming rather complicated to design and extending the network is not always possible. But the, seemingly innocent and quite natural, idea to build more roads in order to solve the traffic problem can be sometimes quite a bad idea.
Of course when you build more roads you also give people incentives to use their cars more often because there is more infrastructure available. But that is not the only concern, adding an extra road, which may seem like a shortcut, will redistribute the traffic in the road network. Braess' paradox says that this redistribution of the traffic flow may lead to a larger average travel time! Want to learn more? Then watch this short video (also in Dutch).
If you want to read more about Braess paradox and the math behind it you can have a look at this article.