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Posts Tagged ‘Marchetti Constant

“The city, however, does not tell its past, but contains it like the lines of a hand”*…

 

city

As transportation got faster, cities got bigger: The borders of Ancient Rome, Medieval Paris, Victorian London, early 20th century Chicago, and modern-day Atlanta

 

In 1994, Cesare Marchetti, an Italian physicist, described an idea that has come to be known as the Marchetti Constant. In general, he declared, people have always been willing to commute for about a half-hour, one way, from their homes each day.

This principle has profound implications for urban life. The value of land is governed by its accessibility—which is to say, by the reasonable speed of transport to reach it.

Even if there is a vast amount of land available in the country, that land has no value in an urban context, unless transportation makes it quickly accessible to the urban core. And that pattern has repeated itself, again and again, as new mobility modes have appeared. This means that the physical size of cities is a function of the speed of the transportation technologies that are available. And, as speed increases, cities can occupy more land, bringing down the price of land, and therefore of housing, in newly accessed territory.

Modern Atlanta may bear little resemblance to the cities of past millennia, but its current residents share something fundamental with urbanites of the distant past: The average one-way commute time in American metropolitan areas today is about 26 minutes. That figure varies from city to city, and from person to person: Some places have significant numbers of workers who enjoy or endure particularly short or long commutes; some people are willing to travel for much longer than 30 minutes. But the endurance of the Marchetti Constant has profound implications for urban life. It means that the average speed of our transportation technologies does more than anything to shape the physical structure of our cities…

From ancient Rome to modern Atlanta, the shape of cities has been defined by the technologies that allow commuters to get to work in about 30 minutes: “The One Weird Rule That Explains Urban Sprawl.”

* Italo Calvino

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As we whistle “Heigh Ho,” we might recall that in Britain on this date in 1752 absolutely nothing happened.  There was no “September 3” (nor September 4-13) in Britain that year, as 1752 was the year that Britain converted from the Julian to the Gregorian calendar, which required an adjustment of 11 days.  Thus, that year British calendars went from Wednesday, September 2 directly to Thursday, September 14.

Most historians believe that persistent stories of riots in England at the time, demanding “give us our eleven days,” are an urban legend, fueled in part by an over-enthusiastic take on Hogarth’s 1755 painting “An Election Entertainment”:

source

 

Written by LW

September 3, 2019 at 1:01 am

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