Study using OpenStreetMap and mathematics reveals there are only four unique city topologies

October 8, 2014 by Bob Yirka report
The four groups. (Left) Average distribution of the shape factor F for each group found by the clustering algorithm. (Right) Typical street pattern for each group ( plotted at the same scale in order to observe differences both in shape and areas). Group 1 (top left): Buenos Aires—Group 2: Athens—Group 3: New Orleans—Group 4: Mogadishu. Credit: Journal of the Royal Society Interface, Published 8 October 2014 doi: 10.1098/rsif.2014.0924

(Phys.org) —A pair of researchers, a physicist and a mathematician, has used data from OpenStreetMap and mathematical analysis to come up with the idea that there are only four main types of city topologies. In their paper published in Journal of the Royal Society Interface, Rémi Louf and Marc Barthelemy describe how they used publicly available data to compare the topologies of 131 cities around the world and what their study has revealed.

The two researchers are proposing that all in the world can be represented by one of four topological types based on block sizes, shape and arrangement. The first is a medium-sized grid made up of blocks that are generally grouped as squares or rectangles. The second is where areas are dominated by fractions of smaller blocks that have a variety of shapes. The third is where a is made up of mostly blocks of medium size that have diverse shapes. And the fourth, they suggest are cities made up of what they describe as mosaic patches that are themselves made up of areas shaped like squares or rectangles. The given shape for a city can be described as a topological fingerprint, the two note, offering clues about its identity.

They also note that when cities are compared using their categories, the old adage that American and European cities tend to be laid out differently holds true, except when they don't. U.S. cities, the duo point out, are generally grid-like, reflecting their young age and preplanning, compared to most cities in Europe. European cities on the other hand, tend to have small city blocks laid out in a wide variety of shapes. But, there are some breaks from the mold—Boston, for example, the researchers note is more similar to European cities. They also note that New York City, with its five Burroughs, is more like several smaller cities from other places in the world, placed together—the Bronx, they say, is laid out in a fashion similar to Porto, Portugal.

Louf and Barthelemy suggest their work provides a quantitative comparison of city street patterns, which they claim allows for better understanding of how and why cities are shaped the way they are.

Explore further: Lego housing, automatic ambulances and car-free streets

More information: A typology of street patterns, Journal of the Royal Society Interface, Published 8 October 2014 DOI: 10.1098/rsif.2014.0924

Abstract
We propose a quantitative method to classify cities according to their street pattern. We use the conditional probability distribution of shape factor of blocks with a given area and define what could constitute the 'fingerprint' of a city. Using a simple hierarchical clustering method, these fingerprints can then serve as a basis for a typology of cities. We apply this method to a set of 131 cities in the world, and at an intermediate level of the dendrogram, we observe four large families of cities characterized by different abundances of blocks of a certain area and shape. At a lower level of the classification, we find that most European cities and American cities in our sample fall in their own sub-category, highlighting quantitatively the differences between the typical layouts of cities in both regions. We also show with the example of New York and its different boroughs, that the fingerprint of a city can be seen as the sum of the ones characterizing the different neighbourhoods inside a city. This method provides a quantitative comparison of urban street patterns, which could be helpful for a better understanding of the causes and mechanisms behind their distinct shapes.

Related Stories

Study shows links between city design and health

August 11, 2014

In a rare study of how street network design affects public health, researchers at the University of Colorado Denver and the University of Connecticut have discovered that older, more compact cities promote more walking and ...

Recommended for you

Metacognition training boosts gen chem exam scores

October 20, 2017

It's a lesson in scholastic humility: You waltz into an exam, confident that you've got a good enough grip on the class material to swing an 80 percent or so, maybe a 90 if some of the questions go your way.

Scientists see order in complex patterns of river deltas

October 19, 2017

River deltas, with their intricate networks of waterways, coastal barrier islands, wetlands and estuaries, often appear to have been formed by random processes, but scientists at the University of California, Irvine and other ...

Six degrees of separation: Why it is a small world after all

October 19, 2017

It's a small world after all - and now science has explained why. A study conducted by the University of Leicester and KU Leuven, Belgium, examined how small worlds emerge spontaneously in all kinds of networks, including ...

Ancient DNA offers new view on saber-toothed cats' past

October 19, 2017

Researchers who've analyzed the complete mitochondrial genomes from ancient samples representing two species of saber-toothed cats have a new take on the animals' history over the last 50,000 years. The data suggest that ...

4 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

nilbud
3 / 5 (2) Oct 08, 2014
Less than pointless
krundoloss
1 / 5 (3) Oct 08, 2014
They act like the city's shape just "happens". People build them. Go ask City planners why the cities are shaped the way they are. Cities start small and build up, and they are usually centered around resources like water, bedrock for building on, etc. Why do people study things like this? Who cares?
Tektrix
5 / 5 (3) Oct 08, 2014
. . . Why do people study things like this? Who cares?

Anyone who has complained about traffic controls, zoning laws, public access, or resource management obviously cares. And then there are those motivated by curiosity and the pursuit of knowledge- two things that sadly, many seem to lack. Which begs the question, why are you even visiting a science and technology-centric website if these things are abstruse and pointless to you?
krundoloss
not rated yet Oct 09, 2014
I guess there is some science there. But to me, it just seems like someone has grant money to burn and they are categorizing and quantifying things that, just don't need categorizing and quantifying. But to each his own I guess....

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.