Street-network Sprawl in Liyang, 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.

Liyang: city in Jiangsu, 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 Liyang, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Liyang as of 2014, the overall level of street-network sprawl is 0.71, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.22, 0.96, 0.41 and 1.4. Disconnectivity in street construction in Liyang follows a zig-zag trend. In 1975, street construction was most disconnected, while construction was most connected in 2001-2014.

Quantity of street network construction: The street network in Liyang spans a total of 344 kilometers. The period with the greatest volume of street construction was 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 0.22, 0.43, 0.41 and 0.71. Disconnectivity in Liyang's street network follows a zig-zag trend. In 1975, the city was most disconnected; while it was most connected in 2001-2014.

Liyang and Jiangsu 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 Liyang fare in comparison to others in Jiangsu? Most recently in 2001-2014, street construction in Liyang was the 58th-most disconnected out of the 87 cities in Jiangsu. Its position in the ranks since 1975 has risen; relative to other cities in Jiangsu, street construction in Liyang has become more disconnected. Liyang ranked 68th in 1975, 59th in 1976-1990, 66th in 1991-2000 and 58th in 2001-2014.

Liyang 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 Liyang fare in comparison to others in China? Most recently in 2001-2014, street construction in Liyang was the 885th-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 Liyang has become more disconnected. Liyang ranked 1070th in 1975, 1076th in 1976-1990, 977th in 1991-2000 and 885th in 2001-2014.

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

To date, Liyang is the 74th-most disconnected out of the 87 cities in Jiangsu. Its position in the ranks since 1975 has fallen; relative to other cities in Jiangsu, the street network in Liyang has become more connected. Liyang ranked 68th in 1975, 74th in 1976-1990, 72nd in 1991-2000 and 74th in 2001-2014.

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

To date, Liyang is the 1362nd-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 Liyang has become more connected. Liyang ranked 1070th in 1975, 1363rd in 1976-1990, 1400th in 1991-2000 and 1362nd in 2001-2014.

As of 2015, Liyang had a built-up area of 31.65 square kilometers, and a population of 258046 people.

These are some other cities with approximately the same population: