Does this change in approach have any scientific basis?
Of course it does. Scientific research lying at the heart of sustainable mobility has shown that expansion of infrastructure leads to more travelling, but not necessarily more efficient travelling. What’s more – by travelling more, we negativelly destroy both the environment and the climate.
The concept of mobility is about focusing not on getting people to move as efficiently as possible, but on achieving best accessibilty to their destinations. Thanks to this, sometimes movement can be completely given up and a given need may be fulfilled locally.
Thinking by “mobility” rather than “transport” stems from the growing understanding of paradoxes related to the development of transport systems, such as the study by Martin Mogridge, who showed that road expansion leads to further congestion, which in the long term leads to stability of the state with traffic jams at peak hours. This property is called the Lewis-Mogridge Law.
An important element of research on ineffectiveness of infrastructure expansion is also the work of the American economist Anthony Downs, which has begun in 1962, when he published a law stating that during rush hours, traffic on highways leading to cities increases to the maximum capacity, hence the expansion of roads does not lead to reduction of traffic jams. Further developments of these studies led to the formulation of the Downs-Thomson paradox, stating that investments in the road network deteriorate traffic conditions by reducing the attractiveness of public transport. Directing more funds for investments and maintenance of the road network causes correspondingly lower outlays being incurred for the development and operation of public rail and road transport. This law applies to regions where “the majority of rush hour traffic is carried by dedicated public transport systems”, as then in a relatively short period of time people may choose road transport if its competitiveness improves.
In 1994, the Italian physicist Cesare Marchetti, working in Austria – dealing mainly with system analysis and previously with nuclear energy – published an article in which, based on earlier works by the American scientist Yacov Zahavi and examples from around the world, he stated that the budget and the amount of time spent by commuters is constant and amounts to an average of, respectively, 13% of income and an hour a day, while the improvement of transport infrastructure only leads to longer travel distances. This time is sometimes called the Marchetti constant.
1. A. Downs, Stuck in Traffic: Coping with Peak-Hour Traffic Congestion. The Brookings Institution, Washington, 1992.
2. Y. Zahavi, Traveltime budgets and mobility in urban areas.US Department of Transportation, Washington 1974.
3. C. Marchetti, Anthropological Invariants in Travel Behavior. „Technological forecasting and social change” 47, 1994, s. 75-88.
4. M. J. H. Mogridge, Travel in towns: jam yesterday, jam today and jam tomorrow? Macmillan Press, London, 1990.
5. A. Downs, The Law of Peak-Hour Expressway Congestion. „Traffic Quarterly” 16, 1962, s. 393-409.