Street-network Sprawl in Sixian, 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.

Sixian: city in Anhui, 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 Sixian, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Sixian as of 2014, the overall level of street-network sprawl is 0.07, which is very well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are nan, 0.1, 1.99 and -0.41. Data was not available in 1975.

Quantity of street network construction: The street network in Sixian spans a total of 133 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of nan, which is highly disconnected.

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 nan, 0.06, 0.56 and 0.07. Data was not available in 1975.

Sixian and Anhui do not follow the same trend in the disconnectivity of their street network constructions. There was not enough data from the city, while the SNDi of street constructions in Anhui fell steadily.

How do development practices in Sixian fare in comparison to others in Anhui? Most recently in 2001-2014, street construction in Sixian was the 58th-most disconnected out of the 65 cities in Anhui. Its position in the ranks since 1975 has fallen; relative to other cities in Anhui, street construction in Sixian has become more connected. Sixian ranked 56th in 1976-1990, 12th in 1991-2000 and 58th in 2001-2014. There was no ranking in 1975 due to unavailable data.

Sixian and China do not follow the same trend in the disconnectivity of their street network constructions. There was not enough data from the city, while the SNDi of street constructions in China followed a zig-zag trend with an overall decrease.

How do development practices in Sixian fare in comparison to others in China? Most recently in 2001-2014, street construction in Sixian was the 1336th-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 Sixian has become more disconnected. Sixian ranked 1345th in 1976-1990, 493rd in 1991-2000 and 1336th in 2001-2014. There was no ranking in 1975 due to unavailable data.

Sixian and Anhui do not follow the same trend in the disconnectivity of their aggregate street networks. There was not enough data from the city, while the SNDi of street constructions in Anhui fell steadily.

To date, Sixian is the 61st-most disconnected out of the 65 cities in Anhui. Its position in the ranks since 1975 has fallen; relative to other cities in Anhui, the street network in Sixian has become more connected. Sixian ranked 58th in 1976-1990, 48th in 1991-2000 and 61st in 2001-2014. There was no ranking in 1975 due to unavailable data.

Sixian and China do not follow the same trend in the disconnectivity of their aggregate street networks. There was not enough data from the city, while the SNDi of street constructions in China peaked in 1976-1990.

To date, Sixian is the 1547th-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 Sixian has become more connected. Sixian ranked 1459th in 1976-1990, 1344th in 1991-2000 and 1547th in 2001-2014. There was no ranking in 1975 due to unavailable data.

As of 2015, Sixian had a built-up area of 16.51 square kilometers, and a population of 68867 people.

These are some other cities with approximately the same population: