Street-network Sprawl in Suzhou, 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.

Suzhou: city in Anhui, 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 Suzhou, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Suzhou as of 2014, the overall level of street-network sprawl is 1.69, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 2.38, 1.57, 2.36 and 1.94. Disconnectivity in street construction in Suzhou follows a zig-zag trend. In 1976-1990, street construction was most disconnected, while construction was most connected in 1975.

Quantity of street network construction: The street network in Suzhou spans a total of 396 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 1.57, 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 2.38, 1.58, 1.63 and 1.69. The SNDi of the aggregate street network in fell at first, but Suzhou has worsened in disconnectivity since 1990.

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

How do development practices in Suzhou fare in comparison to others in Anhui? Most recently in 2001-2014, street construction in Suzhou was the 16th-most disconnected out of the 65 cities in Anhui. Its position in the ranks since 1975 has fallen; relative to other cities in Anhui, street construction in Suzhou has become more connected. Suzhou ranked 10th in 1975, 25th in 1976-1990, 6th in 1991-2000 and 16th in 2001-2014.

Suzhou and China do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Suzhou 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 Suzhou fare in comparison to others in China? Most recently in 2001-2014, street construction in Suzhou was the 683rd-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 Suzhou has become more connected. Suzhou ranked 396th in 1975, 834th in 1976-1990, 384th in 1991-2000 and 683rd in 2001-2014.

Suzhou and Anhui do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Suzhou was at its lowest in 1976-1990, while the SNDi of street constructions in Anhui fell steadily.

To date, Suzhou is the 18th-most disconnected out of the 65 cities in Anhui. Its position in the ranks since 1975 has fallen; relative to other cities in Anhui, the street network in Suzhou has become more connected. Suzhou ranked 10th in 1975, 21st in 1976-1990, 20th in 1991-2000 and 18th in 2001-2014.

Suzhou and China do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Suzhou was at its lowest in 1976-1990, while the SNDi of street constructions in China peaked in 1976-1990.

To date, Suzhou is the 860th-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 Suzhou has become more connected. Suzhou ranked 396th in 1975, 841st in 1976-1990, 835th in 1991-2000 and 860th in 2001-2014.

As of 2015, Suzhou had a built-up area of 43.68 square kilometers, and a population of 428504 people.

These are some other cities with approximately the same population: