Street-network Sprawl in Nankang, China

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.

Nankang: city in Jiangxi, China

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 Nankang, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Nankang as of 2014, the overall level of street-network sprawl is 2.44, which is in the 40th to 60th percentile of disconnectedness.

Trends in street network construction: The SNDis of street construction for the respective time periods are 3.1, 1.48, 5.48 and 2.21. Disconnectivity in street construction in Nankang follows a zig-zag trend. In 1976-1990, street construction was most disconnected, while construction was most connected in 1991-2000.

Quantity of street network construction: The street network in Nankang spans a total of 130 kilometers. The period with the greatest volume of street construction was 1975. These roads have an SNDi of 3.1, which is in the 40th to 60th percentile of disconnectedness.

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 3.1, 2.38, 2.53 and 2.44. Disconnectivity in Nankang's street network follows a zig-zag trend. In 1976-1990, the city was most disconnected; while it was most connected in 1975.

Nankang and Jiangxi do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Nankang followed a zig-zag trend with an overall decrease, while the SNDi of street constructions in Jiangxi peaked in 1976-1990.

How do development practices in Nankang fare in comparison to others in Jiangxi? Most recently in 2001-2014, street construction in Nankang was the 26th-most disconnected out of the 74 cities in Jiangxi. Its position in the ranks since 1975 has fallen; relative to other cities in Jiangxi, street construction in Nankang has become more connected. Nankang ranked 11th in 1975, 46th in 1976-1990, 4th in 1991-2000 and 26th in 2001-2014.

Nankang and China do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Nankang followed a zig-zag trend with an overall decrease, while the SNDi of street constructions in China followed a zig-zag trend with an overall decrease.

How do development practices in Nankang fare in comparison to others in China? Most recently in 2001-2014, street construction in Nankang was the 594th-most disconnected out of the 1651 cities in China. Its position in the ranks since 1975 has fallen; relative to other cities in China, street construction in Nankang has become more connected. Nankang ranked 225th in 1975, 884th in 1976-1990, 46th in 1991-2000 and 594th in 2001-2014.

Nankang and Jiangxi do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Nankang followed a zig-zag trend with an overall decrease, while the SNDi of street constructions in Jiangxi peaked in 1976-1990.

To date, Nankang is the 25th-most disconnected out of the 74 cities in Jiangxi. Its position in the ranks since 1975 has fallen; relative to other cities in Jiangxi, the street network in Nankang has become more connected. Nankang ranked 11th in 1975, 27th in 1976-1990, 22nd in 1991-2000 and 25th in 2001-2014.

Nankang and China do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Nankang followed a zig-zag trend with an overall decrease, while the SNDi of street constructions in China peaked in 1976-1990.

To date, Nankang is the 507th-most disconnected out of the 1651 cities in China. Its position in the ranks since 1975 has fallen; relative to other cities in China, the street network in Nankang has become more connected. Nankang ranked 225th in 1975, 486th in 1976-1990, 427th in 1991-2000 and 507th in 2001-2014.

As of 2015, Nankang had a built-up area of 15.64 square kilometers, and a population of 181508 people.

These are some other cities with approximately the same population: