Street-network Sprawl in Xiangxiang, 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.

Xiangxiang: city in Hunan, 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 Xiangxiang, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Xiangxiang as of 2014, the overall level of street-network sprawl is 2.26, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 1.49, 4.71, 1.83 and 2.4. Disconnectivity in street construction in Xiangxiang follows a zig-zag trend. In 1975, street construction was most disconnected, while construction was most connected in 1976-1990.

Quantity of street network construction: The street network in Xiangxiang spans a total of 148 kilometers. The period with the greatest volume of street construction was 1975. These roads have an SNDi of 1.49, 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 1.49, 2.35, 2.26 and 2.26. The aggregate street network in Xiangxiang increased in disconnectivity initially,but the trend has turned around after 1990.

Xiangxiang and Hunan 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 increase.

How do development practices in Xiangxiang fare in comparison to others in Hunan? Most recently in 2001-2014, street construction in Xiangxiang was the 32nd-most disconnected out of the 95 cities in Hunan. Its position in the ranks since 1975 has risen; relative to other cities in Hunan, street construction in Xiangxiang has become more disconnected. Xiangxiang ranked 49th in 1975, 5th in 1976-1990, 29th in 1991-2000 and 32nd in 2001-2014.

Xiangxiang 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 increase.

How do development practices in Xiangxiang fare in comparison to others in China? Most recently in 2001-2014, street construction in Xiangxiang was the 541st-most disconnected out of the 1651 cities in China. Its position in the ranks since 1975 has risen; relative to other cities in China, street construction in Xiangxiang has become more disconnected. Xiangxiang ranked 658th in 1975, 77th in 1976-1990, 542nd in 1991-2000 and 541st in 2001-2014.

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

To date, Xiangxiang is the 42nd-most disconnected out of the 95 cities in Hunan. Its position in the ranks since 1975 has risen; relative to other cities in Hunan, the street network in Xiangxiang has become more disconnected. Xiangxiang ranked 49th in 1975, 38th in 1976-1990, 40th in 1991-2000 and 42nd in 2001-2014.

Xiangxiang 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, Xiangxiang is the 599th-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 Xiangxiang has become more disconnected. Xiangxiang ranked 658th in 1975, 509th in 1976-1990, 548th in 1991-2000 and 599th in 2001-2014.

As of 2015, Xiangxiang had a built-up area of 12.1 square kilometers, and a population of 167046 people.

These are some other cities with approximately the same population: