Street-network Sprawl in Duyun, 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.

Duyun: city in Guizhou, 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 Duyun, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Duyun as of 2014, the overall level of street-network sprawl is 2.24, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 2.32, 2.42, nan and 0.01. Data was not available in 1991-2000.

Quantity of street network construction: The street network in Duyun spans a total of 247 kilometers. The period with the greatest volume of street construction was 1975. These roads have an SNDi of 2.32, 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 2.32, 2.32, 2.33 and 2.24. Disconnectivity in Duyun's street network follows a zig-zag trend. In 2001-2014, the city was most disconnected; while it was most connected in 1991-2000.

Duyun and Guizhou do not follow the same trend in the disconnectivity of their street network constructions. There was not enough data from the city, while the SNDi of street constructions in Guizhou peaked in 1991-2000.

How do development practices in Duyun fare in comparison to others in Guizhou? Most recently in 2001-2014, street construction in Duyun was the 32nd-most disconnected out of the 42 cities in Guizhou. Its position in the ranks since 1975 has fallen; relative to other cities in Guizhou, street construction in Duyun has become more connected. Duyun ranked 10th in 1975, 14th in 1976-1990 and 32nd in 2001-2014. There was no ranking in 1991-2000 due to unavailable data.

Duyun and China do not follow the same trend in the disconnectivity of their street network constructions. There was not enough data from the city, while the SNDi of street constructions in China followed a zig-zag trend with an overall decrease.

How do development practices in Duyun fare in comparison to others in China? Most recently in 2001-2014, street construction in Duyun was the 1287th-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 Duyun has become more connected. Duyun ranked 415th in 1975, 483rd in 1976-1990 and 1287th in 2001-2014. There was no ranking in 1991-2000 due to unavailable data.

Duyun and Guizhou do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Duyun followed a zig-zag trend with an overall decrease, while the SNDi of street constructions in Guizhou peaked in 1991-2000.

To date, Duyun is the 26th-most disconnected out of the 42 cities in Guizhou. Its position in the ranks since 1975 has fallen; relative to other cities in Guizhou, the street network in Duyun has become more connected. Duyun ranked 10th in 1975, 16th in 1976-1990, 20th in 1991-2000 and 26th in 2001-2014.

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

To date, Duyun is the 602nd-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 Duyun has become more connected. Duyun ranked 415th in 1975, 522nd in 1976-1990, 513th in 1991-2000 and 602nd in 2001-2014.

As of 2015, Duyun had a built-up area of 11.8 square kilometers, and a population of 194563 people.

These are some other cities with approximately the same population: