Marchetti's constant

Marchetti's constant is the average time spent by a person for commuting each day, which is approximately one hour. In fact, the term is a misnomer, because Marchetti himself attributes the "one hour" finding to Yacov Zahavi.

Italian physicist Cesare Marchetti posits that although forms of urban planning and transport may change, and although some live in villages and others in cities, people gradually adjust their lives to their conditions (including location of their homes relative to their workplace) such that the average travel time stays approximately constant. Ever since Neolithic times, people have kept the average time spent per day for travel the same, even though the distance may increase due to the advancements in the means of transportation.

A related concept is that of transportation analyst and engineer Yacov Zahavi, who also noticed that people seem to have a constant "travel time budget," that is, "a stable daily amount of time that people make available for travel." David Metz, former chief scientist at the Department of Transport, UK, cites data of average travel time in Britain drawn from the British National Travel Survey in support of Marchetti's and Zahavi's conclusions. The work casts doubt on the contention that investment in infrastructure saves travel time. Instead, it appears from Metz's figures that people invest travel time saved in travelling a longer distance, a particular example of Jevons paradox described by the Lewis–Mogridge Position.

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