🔗 Downs–Thomson paradox

🔗 Economics 🔗 Transport

The Downs–Thomson paradox (named after Anthony Downs and John Michael Thomson), also known as the Pigou–Knight–Downs paradox (after Arthur Cecil Pigou and Frank Knight), states that the equilibrium speed of car traffic on a road network is determined by the average door-to-door speed of equivalent journeys taken by public transport.

It is a paradox in that improvements in the road network will not reduce traffic congestion. Improvements in the road network can make congestion worse if the improvements make public transport more inconvenient or if it shifts investment, causing disinvestment in the public transport system.