Street-network Sprawl in Youyang, 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.

Youyang: city in Chongqing, 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 Youyang, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Youyang as of 2014, the overall level of street-network sprawl is 1.88, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.5, 1.34, -0.13 and 2.86. Disconnectivity in street construction in Youyang 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 Youyang spans a total of 75 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 2.86, 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 0.5, 1.13, 0.99 and 1.88. Disconnectivity in Youyang's street network follows a zig-zag trend. In 1975, the city was most disconnected; while it was most connected in 2001-2014.

Youyang and Chongqing 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 Youyang fare in comparison to others in Chongqing? Most recently in 2001-2014, street construction in Youyang was the 20th-most disconnected out of the 38 cities in Chongqing. Its position in the ranks since 1975 has fallen; relative to other cities in Chongqing, street construction in Youyang has become more connected. Youyang ranked 19th in 1975, 23rd in 1976-1990, 33rd in 1991-2000 and 20th in 2001-2014.

Youyang 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 Youyang fare in comparison to others in China? Most recently in 2001-2014, street construction in Youyang was the 417th-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 Youyang has become more disconnected. Youyang ranked 996th in 1975, 940th in 1976-1990, 1110th in 1991-2000 and 417th in 2001-2014.

Youyang and Chongqing follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these followed a zig-zag trend with an overall increase.

To date, Youyang is the 28th-most disconnected out of the 38 cities in Chongqing. Its position in the ranks since 1975 has fallen; relative to other cities in Chongqing, the street network in Youyang has become more connected. Youyang ranked 19th in 1975, 26th in 1976-1990, 31st in 1991-2000 and 28th in 2001-2014.

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

To date, Youyang is the 766th-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 Youyang has become more disconnected. Youyang ranked 996th in 1975, 1071st in 1976-1990, 1156th in 1991-2000 and 766th in 2001-2014.

As of 2015, Youyang had a built-up area of 2.42 square kilometers, and a population of 51936 people.

These are some other cities with approximately the same population: