The Pigu-Knight-Downs paradox highlights the consequence of the Downs-Thomson paradox that, with public transport, an increase in the capacity of public roads does not lead to an improvement, but to a deterioration of the road situation. The motorist, while the “city is standing”, will look for alternatives and traffic jams will drop. Accordingly, there is some equilibrium point.
It consists of a huge number of factors:
- ease of use of a personal car;
- fare;
- travel time;
- the number of personal vehicles per 1000 population, etc.
Moreover, over time, the equilibrium point can shift both to the right and to the left. Over the past 10 years, she has slowly but surely moved to the right, towards the mark of 10 points, and this is a very bad trend. The task that confronts the authorities of any big city is the regulation of this equilibrium point, an artificial shift to the left, in the direction of reducing traffic jams. Such measures include improving the quality of passenger service by public transport, as well as unpopular measures that increase the inconvenience of using personal transport in the city. It is important to understand that despite the possible deterioration of the conditions for a certain group of people, an average improvement occurs for the average citizen in the city, and the average passenger travel time decreases due to reduced traffic congestion.
Research empirically reveals the Pigu Knight Downs paradox, in which states increase road capacity without decreasing travel time. Although theoretically fundamental in transport economics, the paradox still needs to be empirically supported. The study also generalizes the paradox, weakening its extreme network state, while one route is unstable.
Due to the complexity of studying behavior in route selection in the field, this study is conducted in the laboratory and potentially provides experimental evidence of paradox.
This observation is the essence of the Pigu Knight Downs phenomenon, it is also often called the "basic law of traffic congestion"
So, this paradox states that adding an additional throughput road does not reduce travel time.
This is because the movement may simply move to the updated road from another, making the updated road more crowded.