• This refers to the observation that increasing the supply of roads available for transit does not necessarily lead to less traffic congestion.
• It is named after economists Anthony Downs and John Michael Thomson who theorised that any increase in the supply of roads would bring additional demand for these roads from people who earlier used various forms of public transport.
• The phenomenon has been used by many economists to argue that the problem of traffic jams cannot be solved merely by increasing the number of road lanes. Instead, they recommend that citizens be charged a price for the use of roads.

Source:TH