Street-network Sprawl in Cixi, 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.

Cixi: city in Zhejiang, 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 Cixi, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Cixi as of 2014, the overall level of street-network sprawl is 1.82, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 1.65, 1.86, 1.9 and 1.85. Street construction in Cixi increased in disconnectivity initially but has since improved. The streets constructed in 1991-2000 were the most disconnected.

Quantity of street network construction: The street network in Cixi spans a total of 2099 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 1.86, 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 1.65, 1.8, 1.8 and 1.82. Overall, the SNDi of the aggregate street network has risen: the street network in Cixi has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.15 points, but between 1991-2000 and 2001-2014, it rose by just 0.02.

Cixi and Zhejiang do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Cixi peaked in 1991-2000, while the SNDi of street constructions in Zhejiang peaked in 1976-1990.

How do development practices in Cixi fare in comparison to others in Zhejiang? Most recently in 2001-2014, street construction in Cixi was the 47th-most disconnected out of the 94 cities in Zhejiang. Its position in the ranks since 1975 has fallen; relative to other cities in Zhejiang, street construction in Cixi has become more connected. Cixi ranked 40th in 1975, 49th in 1976-1990, 28th in 1991-2000 and 47th in 2001-2014.

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

How do development practices in Cixi fare in comparison to others in China? Most recently in 2001-2014, street construction in Cixi was the 726th-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 Cixi has become more connected. Cixi ranked 602nd in 1975, 715th in 1976-1990, 521st in 1991-2000 and 726th in 2001-2014.

Cixi and Zhejiang do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Cixi rose steadily, while the SNDi of street constructions in Zhejiang peaked in 1976-1990.

To date, Cixi is the 49th-most disconnected out of the 94 cities in Zhejiang. Its position in the ranks since 1975 has fallen; relative to other cities in Zhejiang, the street network in Cixi has become more connected. Cixi ranked 40th in 1975, 48th in 1976-1990, 46th in 1991-2000 and 49th in 2001-2014.

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

To date, Cixi is the 791st-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 Cixi has become more connected. Cixi ranked 602nd in 1975, 747th in 1976-1990, 749th in 1991-2000 and 791st in 2001-2014.

As of 2015, Cixi had a built-up area of 267.02 square kilometers, and a population of 1935628 people.

These are some other cities with approximately the same population: