Street-network Sprawl in Yihuang, 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.

Yihuang: city in Jiangxi, 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 Yihuang, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Yihuang as of 2014, the overall level of street-network sprawl is 2.16, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 1.89, 2.92, -0.03 and 1.25. Disconnectivity in street construction in Yihuang follows a zig-zag trend. In 1991-2000, street construction was most disconnected, while construction was most connected in 1976-1990.

Quantity of street network construction: The street network in Yihuang spans a total of 68 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 2.92, which is in the 40th to 60th percentile of disconnectedness.

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 1.89, 3.16, 2.65 and 2.16. The aggregate street network in Yihuang increased in disconnectivity initially,but the trend has turned around after 1990.

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

How do development practices in Yihuang fare in comparison to others in Jiangxi? Most recently in 2001-2014, street construction in Yihuang was the 47th-most disconnected out of the 74 cities in Jiangxi. Its position in the ranks since 1975 has fallen; relative to other cities in Jiangxi, street construction in Yihuang has become more connected. Yihuang ranked 27th in 1975, 21st in 1976-1990, 49th in 1991-2000 and 47th in 2001-2014.

Yihuang and China follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these followed a zig-zag trend with an overall decrease.

How do development practices in Yihuang fare in comparison to others in China? Most recently in 2001-2014, street construction in Yihuang was the 921st-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 Yihuang has become more connected. Yihuang ranked 531st in 1975, 331st in 1976-1990, 1095th in 1991-2000 and 921st in 2001-2014.

Yihuang and Jiangxi follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these peaked in 1976-1990.

To date, Yihuang is the 33rd-most disconnected out of the 74 cities in Jiangxi. Its position in the ranks since 1975 has fallen; relative to other cities in Jiangxi, the street network in Yihuang has become more connected. Yihuang ranked 27th in 1975, 13th in 1976-1990, 20th in 1991-2000 and 33rd in 2001-2014.

Yihuang and China follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these peaked in 1976-1990.

To date, Yihuang is the 632nd-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 Yihuang has become more connected. Yihuang ranked 531st in 1975, 239th in 1976-1990, 381st in 1991-2000 and 632nd in 2001-2014.

As of 2015, Yihuang had a built-up area of 2.48 square kilometers, and a population of 50767 people.

These are some other cities with approximately the same population: