The global megatrend of the last century’s migration from rural to ever-larger conurbations has created immense gains to society through economies of scale and benefits from agglomeration. These include – other things remaining equal – a lesser need for transport because a bigger share of peoples’ activities can be reached within the relative close distances of the city. However, urbanisation has also led to significant disadvantages, of which transport accounts for some of the most severe. Traffic accidents and emissions of air pollutants and noise take heavy tolls in terms of people killed and injured, although in many countries the situation has improved over recent decades. Two major issues, however, have proven very difficult to cope with, to the point where the problems they cause are not yet diminishing.