Street-network Sprawl in Zhanjiang, 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.

Zhanjiang: city in Guangdong, 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 Zhanjiang, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Zhanjiang as of 2014, the overall level of street-network sprawl is 1.29, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 1.83, 1.36, 0.59 and 1.54. The disconnectivity of new streets constructed in Zhanjiang fell, then rose. In 1991-2000, new street layouts were the most connected.

Quantity of street network construction: The street network in Zhanjiang spans a total of 673 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 1.36, 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 1.83, 1.39, 1.28 and 1.29. The SNDi of the aggregate street network in fell at first, but Zhanjiang has worsened in disconnectivity since 2000.

Zhanjiang and Guangdong follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these was at its lowest in 1991-2000.

How do development practices in Zhanjiang fare in comparison to others in Guangdong? Most recently in 2001-2014, street construction in Zhanjiang was the 64th-most disconnected out of the 109 cities in Guangdong. Its position in the ranks since 1975 has fallen; relative to other cities in Guangdong, street construction in Zhanjiang has become more connected. Zhanjiang ranked 41st in 1975, 77th in 1976-1990, 67th in 1991-2000 and 64th in 2001-2014.

Zhanjiang and China do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Zhanjiang was at its lowest 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 Zhanjiang fare in comparison to others in China? Most recently in 2001-2014, street construction in Zhanjiang was the 843rd-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 Zhanjiang has become more connected. Zhanjiang ranked 546th in 1975, 931st in 1976-1990, 931st in 1991-2000 and 843rd in 2001-2014.

Zhanjiang and Guangdong follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these was at its lowest in 1991-2000.

To date, Zhanjiang is the 84th-most disconnected out of the 109 cities in Guangdong. Its position in the ranks since 1975 has fallen; relative to other cities in Guangdong, the street network in Zhanjiang has become more connected. Zhanjiang ranked 41st in 1975, 78th in 1976-1990, 82nd in 1991-2000 and 84th in 2001-2014.

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

To date, Zhanjiang is the 1068th-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 Zhanjiang has become more connected. Zhanjiang ranked 546th in 1975, 941st in 1976-1990, 1018th in 1991-2000 and 1068th in 2001-2014.

As of 2015, Zhanjiang had a built-up area of 72.5 square kilometers, and a population of 967286 people.

These are some other cities with approximately the same population: