Street-network Sprawl in Youxian, 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.

Youxian: 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 Youxian, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Youxian as of 2014, the overall level of street-network sprawl is 0.9, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.79, 1.35, 0.07 and 1.6. Disconnectivity in street construction in Youxian follows a zig-zag trend. In 1991-2000, street construction was most disconnected, while construction was most connected in 2001-2014.

Quantity of street network construction: The street network in Youxian spans a total of 94 kilometers. The period with the greatest volume of street construction was 1976-1990. These roads have an SNDi of 1.35, 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 0.79, 1.11, 0.84 and 0.9. Disconnectivity in Youxian's street network follows a zig-zag trend. In 1975, the city was most disconnected; while it was most connected in 1976-1990.

Youxian 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 Youxian fare in comparison to others in Hunan? Most recently in 2001-2014, street construction in Youxian was the 48th-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 Youxian has become more disconnected. Youxian ranked 62nd in 1975, 61st in 1976-1990, 60th in 1991-2000 and 48th in 2001-2014.

Youxian 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 Youxian fare in comparison to others in China? Most recently in 2001-2014, street construction in Youxian was the 819th-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 Youxian has become more disconnected. Youxian ranked 902nd in 1975, 933rd in 1976-1990, 1066th in 1991-2000 and 819th in 2001-2014.

Youxian and Hunan do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Youxian followed a zig-zag trend with an overall increase, while the SNDi of street constructions in Hunan peaked in 1976-1990.

To date, Youxian is the 82nd-most disconnected out of the 95 cities in Hunan. Its position in the ranks since 1975 has fallen; relative to other cities in Hunan, the street network in Youxian has become more connected. Youxian ranked 62nd in 1975, 71st in 1976-1990, 77th in 1991-2000 and 82nd in 2001-2014.

Youxian and China do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Youxian followed a zig-zag trend with an overall increase, while the SNDi of street constructions in China peaked in 1976-1990.

To date, Youxian is the 1268th-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 Youxian has become more connected. Youxian ranked 902nd in 1975, 1083rd in 1976-1990, 1226th in 1991-2000 and 1268th in 2001-2014.

As of 2015, Youxian had a built-up area of 7.5 square kilometers, and a population of 105471 people.

These are some other cities with approximately the same population: