Street-network Sprawl in Changshu, 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.

Changshu: city in Jiangsu, 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 Changshu, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Changshu as of 2014, the overall level of street-network sprawl is 1.27, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 1.01, 1.49, 1.4 and 1.22. Street construction in Changshu increased in disconnectivity initially but has since improved. The streets constructed in 1976-1990 were the most disconnected.

Quantity of street network construction: The street network in Changshu spans a total of 834 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 1.22, 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 1.01, 1.24, 1.29 and 1.27. The aggregate street network in Changshu increased in disconnectivity initially,but the trend has turned around after 2000.

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

How do development practices in Changshu fare in comparison to others in Jiangsu? Most recently in 2001-2014, street construction in Changshu was the 65th-most disconnected out of the 87 cities in Jiangsu. Its position in the ranks since 1975 has fallen; relative to other cities in Jiangsu, street construction in Changshu has become more connected. Changshu ranked 50th in 1975, 50th in 1976-1990, 49th in 1991-2000 and 65th in 2001-2014.

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

How do development practices in Changshu fare in comparison to others in China? Most recently in 2001-2014, street construction in Changshu was the 939th-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 Changshu has become more connected. Changshu ranked 826th in 1975, 874th in 1976-1990, 661st in 1991-2000 and 939th in 2001-2014.

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

To date, Changshu is the 61st-most disconnected out of the 87 cities in Jiangsu. Its position in the ranks since 1975 has fallen; relative to other cities in Jiangsu, the street network in Changshu has become more connected. Changshu ranked 50th in 1975, 54th in 1976-1990, 53rd in 1991-2000 and 61st in 2001-2014.

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

To date, Changshu is the 1081st-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 Changshu has become more connected. Changshu ranked 826th in 1975, 1027th in 1976-1990, 1010th in 1991-2000 and 1081st in 2001-2014.

As of 2015, Changshu had a built-up area of 82.58 square kilometers, and a population of 812989 people.

These are some other cities with approximately the same population: