Street-network Sprawl in Shikoku-Chuo, Japan

What is Street-network sprawl?

Street-network Sprawl is a way to measure urban sprawl, worldwide, through the connectedness of the streets. Less sprawl means more connected, more walkable streets. Well-connected streets – like New York City’s grid – are more walkable and can be served by public transit.

The street network is permanent, and its connectivity affects the livability and environmental footprint of cities for decades and centuries to come. In places with more connected streets, residents drive less and walk more. A well-connected street network is associated with better outcomes for health, the environment, sustainable consumption, social integration, and equity.

We can quantify how connected street networks are with the Street Network Disconnectedness Index (SNDi).

SNDi -- our measure of street-network sprawl (disconnectedness)

The SNDi is a comprehensive measurement of “sprawl”. It captures:

A higher SNDi means less-connected streets – i.e., more sprawl. For the 10137 cities in our dataset, the average SNDi is 2.25, with half of the cities' SNDis falling between 1.08 and 3.25.

More information on the sprawl index can be found in these research papers:

To see the state of street-network sprawl across the globe, visit the sprawlmap.

Shikoku-Chuo: city in Ehime, Japan

What exactly constitutes the spatial extent of the city? For these aggregations, we used the Global Human Settlement Layer Urban Center Database (GHS-UCDB) to define the boundaries of the city. These cities -- or urban centers -- cover areas that are densely populated and built-up, and so may extend beyond the spatial borders of these cities that we may be familiar with. The GHS area is shaded in blue.

View Shikoku-Chuo, Japan on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Shikoku-Chuo as of 2014, the overall level of street-network sprawl is 0.88, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.7, 2.15, 5.13 and 0.79. Street construction in Shikoku-Chuo increased in disconnectivity initially but has since improved. The streets constructed in 1991-2000 were the most disconnected.

Quantity of street network construction: The street network in Shikoku-Chuo spans a total of 401 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 0.7, which is relatively well-connected.

Effect on the aggregate network: New construction in each period adds to the total stock of streets, but does not change streets that have already been built. Therefore, it has a limited effect on the street network as a whole. The SNDis of the aggregate street network in the respective time periods are 0.7, 0.83, 0.88 and 0.88. The aggregate street network in Shikoku-Chuo increased in disconnectivity initially,but the trend has turned around after 2000.

Shikoku-Chuo and Ehime follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these peaked in 1991-2000.

How do development practices in Shikoku-Chuo fare in comparison to others in Ehime? Most recently in 2001-2014, street construction in Shikoku-Chuo was the 3rd-most disconnected out of the 4 cities in Ehime. Its position in the ranks since 1975 has not changed. Shikoku-Chuo ranked 3rd in 1975, 4th in 1976-1990, 2nd in 1991-2000 and 3rd in 2001-2014.

Shikoku-Chuo and Japan follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these peaked in 1991-2000.

How do development practices in Shikoku-Chuo fare in comparison to others in Japan? Most recently in 2001-2014, street construction in Shikoku-Chuo was the 79th-most disconnected out of the 109 cities in Japan. Its position in the ranks since 1975 has risen; relative to other cities in Japan, street construction in Shikoku-Chuo has become more disconnected. Shikoku-Chuo ranked 87th in 1975, 41st in 1976-1990, 9th in 1991-2000 and 79th in 2001-2014.

Shikoku-Chuo and Ehime do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Shikoku-Chuo peaked in 1991-2000, while the SNDi of street constructions in Ehime rose steadily.

To date, Shikoku-Chuo is the 3rd-most disconnected out of the 4 cities in Ehime. Its position in the ranks since 1975 has not changed. Shikoku-Chuo ranked 3rd in 1975, 3rd in 1976-1990, 3rd in 1991-2000 and 3rd in 2001-2014.

Shikoku-Chuo and Japan do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Shikoku-Chuo peaked in 1991-2000, while the SNDi of street constructions in Japan rose steadily.

To date, Shikoku-Chuo is the 81st-most disconnected out of the 109 cities in Japan. Its position in the ranks since 1975 has risen; relative to other cities in Japan, the street network in Shikoku-Chuo has become more disconnected. Shikoku-Chuo ranked 87th in 1975, 82nd in 1976-1990, 80th in 1991-2000 and 81st in 2001-2014.

As of 2015, Shikoku-Chuo had a built-up area of 29.47 square kilometers, and a population of 62595 people.

These are some other cities with approximately the same population: