Street-network Sprawl in Nagaoka, 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.

Nagaoka: city in Niigata, 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 Nagaoka, Japan on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Nagaoka as of 2014, the overall level of street-network sprawl is 0.5, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.44, 0.61, 0.98 and 1.44. In each period, new street development in Nagaoka steadily grows more disconnected than in the last.

Quantity of street network construction: The street network in Nagaoka spans a total of 442 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 0.44, which is very 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 0.44, 0.46, 0.46 and 0.5. Overall, the SNDi of the aggregate street network has risen: the street network in Nagaoka has become more disconnected.

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

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

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

How do development practices in Nagaoka fare in comparison to others in Japan? Most recently in 2001-2014, street construction in Nagaoka was the 60th-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 Nagaoka has become more disconnected. Nagaoka ranked 102nd in 1975, 89th in 1976-1990, 86th in 1991-2000 and 60th in 2001-2014.

Nagaoka and Niigata follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these rose steadily.

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

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

To date, Nagaoka is the 100th-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 Nagaoka has become more disconnected. Nagaoka ranked 102nd in 1975, 102nd in 1976-1990, 102nd in 1991-2000 and 100th in 2001-2014.

As of 2015, Nagaoka had a built-up area of 17.34 square kilometers, and a population of 55971 people.

These are some other cities with approximately the same population: