Marchetti's Constant
Marchetti's Constant describes a persistent commuting-time budget: improvements in travel speed tend to expand the reachable city rather than permanently return time to its residents.
Boston, Lisbon and London supposedly share a commuting constraint not only with cities a century ago, but with settlements 10,000 years ago: average travel to work keeps returning to roughly the same time budget.
E1Speed enlarges the map
Faster transport changes what counts as a tolerable distance. Instead of preserving the old city footprint and shortening every journey, the city can spread outward as people and destinations reorganize around the additional reach. The technology improves distance per unit of time; development then consumes that gain by putting more distance inside the familiar commuting budget.
E1An average is not a destiny
The supplied evidence states a striking cross-city average, not an inviolable rule for every resident or every journey. It also does not establish that transport speed alone determines urban form; treat the constant as a recurring constraint to investigate, not a precise prediction of your own commute.
E1Episodes that teach this
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Are You Living In The Wrong City? Best City To Live In
· explained at 1:21
11,670 views
"Marchetti's constant says that no matter what you do the average commute in your city will be 1 hour 30 minutes each way... true of Boston, Lisbon, London, true 100 years ago and 10,000 years ago."