Street-network Sprawl in Changning, 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.

Changning: city in Sichuan, 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 Changning, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Changning as of 2014, the overall level of street-network sprawl is 2.48, 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 2.77, nan, 4.2 and 1.74. Data was not available in 1976-1990.

Quantity of street network construction: The street network in Changning spans a total of 59 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 1.74, 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 2.77, 3.02, 3.51 and 2.48. The aggregate street network in Changning increased in disconnectivity initially,but the trend has turned around after 2000.

Changning and Sichuan 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 Sichuan was at its lowest in 1991-2000.

How do development practices in Changning fare in comparison to others in Sichuan? Most recently in 2001-2014, street construction in Changning was the 56th-most disconnected out of the 102 cities in Sichuan. Its position in the ranks since 1975 has fallen; relative to other cities in Sichuan, street construction in Changning has become more connected. Changning ranked 29th in 1975, 6th in 1991-2000 and 56th in 2001-2014. There was no ranking in 1976-1990 due to unavailable data.

Changning 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 Changning fare in comparison to others in China? Most recently in 2001-2014, street construction in Changning was the 767th-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 Changning has become more connected. Changning ranked 289th in 1975, 103rd in 1991-2000 and 767th in 2001-2014. There was no ranking in 1976-1990 due to unavailable data.

Changning and Sichuan do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Changning peaked in 1991-2000, while the SNDi of street constructions in Sichuan was at its lowest in 1991-2000.

To date, Changning is the 42nd-most disconnected out of the 102 cities in Sichuan. Its position in the ranks since 1975 has fallen; relative to other cities in Sichuan, the street network in Changning has become more connected. Changning ranked 29th in 1975, 24th in 1976-1990, 16th in 1991-2000 and 42nd in 2001-2014.

Changning and China do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Changning peaked in 1991-2000, while the SNDi of street constructions in China peaked in 1976-1990.

To date, Changning is the 486th-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 Changning has become more connected. Changning ranked 289th in 1975, 280th in 1976-1990, 155th in 1991-2000 and 486th in 2001-2014.

As of 2015, Changning had a built-up area of 2.9 square kilometers, and a population of 66884 people.

These are some other cities with approximately the same population: