Street-network Sprawl in Kan'onji, 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.

Kan'onji: city in Kagawa, 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 Kan'onji, Japan on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Kan'onji as of 2014, the overall level of street-network sprawl is 0.89, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.73, 0.94, 3.16 and 3.33. In each period, new street development in Kan'onji steadily grows more disconnected than in the last. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.2 points, but between 1991-2000 and 2001-2014, it rose by just 0.17.

Quantity of street network construction: The street network in Kan'onji spans a total of 594 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 0.73, 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 0.73, 0.79, 0.81 and 0.89. Overall, the SNDi of the aggregate street network has risen: the street network in Kan'onji has become more disconnected.

Kan'onji and Kagawa do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Kan'onji rose steadily, while the SNDi of street constructions in Kagawa peaked in 1991-2000.

How do development practices in Kan'onji fare in comparison to others in Kagawa? Most recently in 2001-2014, street construction in Kan'onji was the 1st-most disconnected out of the 3 cities in Kagawa. Its position in the ranks since 1975 has risen; relative to other cities in Kagawa, street construction in Kan'onji has become more disconnected. Kan'onji ranked 3rd in 1975, 3rd in 1976-1990, 2nd in 1991-2000 and 1st in 2001-2014.

Kan'onji and Japan do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Kan'onji rose steadily, while the SNDi of street constructions in Japan peaked in 1991-2000.

How do development practices in Kan'onji fare in comparison to others in Japan? Most recently in 2001-2014, street construction in Kan'onji was the 20th-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 Kan'onji has become more disconnected. Kan'onji ranked 86th in 1975, 80th in 1976-1990, 35th in 1991-2000 and 20th in 2001-2014.

Kan'onji and Kagawa follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these rose steadily.

To date, Kan'onji is the 3rd-most disconnected out of the 3 cities in Kagawa. Its position in the ranks since 1975 has not changed. Kan'onji ranked 3rd in 1975, 3rd in 1976-1990, 3rd in 1991-2000 and 3rd in 2001-2014.

Kan'onji and Japan follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these rose steadily.

To date, Kan'onji is the 80th-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 Kan'onji has become more disconnected. Kan'onji ranked 86th in 1975, 85th in 1976-1990, 84th in 1991-2000 and 80th in 2001-2014.

As of 2015, Kan'onji had a built-up area of 35.88 square kilometers, and a population of 61400 people.

These are some other cities with approximately the same population: