Street-network Sprawl in Zhangzi, 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.

Zhangzi: city in Shanxi, 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 Zhangzi, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Zhangzi as of 2014, the overall level of street-network sprawl is 2.08, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 1.44, 3.03, 2.31 and 1.4. Street construction in Zhangzi 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 Zhangzi spans a total of 57 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 1.4, 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 1.44, 2.1, 2.13 and 2.08. The aggregate street network in Zhangzi increased in disconnectivity initially,but the trend has turned around after 2000.

Zhangzi and Shanxi follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these peaked in 1976-1990.

How do development practices in Zhangzi fare in comparison to others in Shanxi? Most recently in 2001-2014, street construction in Zhangzi was the 35th-most disconnected out of the 74 cities in Shanxi. Its position in the ranks since 1975 has fallen; relative to other cities in Shanxi, street construction in Zhangzi has become more connected. Zhangzi ranked 31st in 1975, 15th in 1976-1990, 17th in 1991-2000 and 35th in 2001-2014.

Zhangzi and China do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Zhangzi 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 Zhangzi fare in comparison to others in China? Most recently in 2001-2014, street construction in Zhangzi was the 886th-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 Zhangzi has become more connected. Zhangzi ranked 678th in 1975, 300th in 1976-1990, 402nd in 1991-2000 and 886th in 2001-2014.

Zhangzi and Shanxi do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Zhangzi peaked in 1991-2000, while the SNDi of street constructions in Shanxi rose steadily.

To date, Zhangzi is the 26th-most disconnected out of the 74 cities in Shanxi. Its position in the ranks since 1975 has risen; relative to other cities in Shanxi, the street network in Zhangzi has become more disconnected. Zhangzi ranked 31st in 1975, 26th in 1976-1990, 24th in 1991-2000 and 26th in 2001-2014.

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

To date, Zhangzi is the 664th-most disconnected out of the 1651 cities in China. Its position in the ranks since 1975 has risen; relative to other cities in China, the street network in Zhangzi has become more disconnected. Zhangzi ranked 678th in 1975, 615th in 1976-1990, 600th in 1991-2000 and 664th in 2001-2014.

As of 2015, Zhangzi had a built-up area of 5.48 square kilometers, and a population of 73393 people.

These are some other cities with approximately the same population: