Throughout the 20th century, road construction was primarily based on the premise that more infrastructure eases traffic. However, evidence shows that instead of reducing congestion, building more roads actually increases traffic. When driving times are reduced, convenience increases. Consequently, alongside the appeal of private vehicles as status symbols of wealth and social standing, people tend to make more trips by car. A recent study by researchers at the University of Barcelona analyzed data from 545 European cities between 1985 and 2005. It confirmed that efforts to expand road capacity over those two decades led to an increase rather than a reduction in vehicle traffic, and failed to ease congestion.
The opposite of traffic generation is a phenomenon known as “traffic evaporation”: the traffic that disappears when road space is reallocated from private vehicles to more sustainable modes of transport, such as walking, cycling, and public transit. Although traffic evaporation has been studied and well-documented for over 20 years, most decision-makers and opinion leaders still believe that reducing traffic lanes worsens congestion.
