Street-network Sprawl in Hexian, 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.

Hexian: 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 Hexian, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Hexian as of 2014, the overall level of street-network sprawl is 0.66, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.54, 0.76, 0.78 and -0.29. Street construction in Hexian increased in disconnectivity initially but has since improved. The streets constructed in 1991-2000 were the most disconnected.

Quantity of street network construction: The street network in Hexian spans a total of 63 kilometers. The period with the greatest volume of street construction was 1975. These roads have an SNDi of 0.54, 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 0.54, 0.69, 0.71 and 0.66. The aggregate street network in Hexian increased in disconnectivity initially,but the trend has turned around after 2000.

Hexian and Anhui do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Hexian peaked in 1991-2000, while the SNDi of street constructions in Anhui fell steadily.

How do development practices in Hexian fare in comparison to others in Anhui? Most recently in 2001-2014, street construction in Hexian was the 57th-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 Hexian has become more connected. Hexian ranked 30th in 1975, 44th in 1976-1990, 26th in 1991-2000 and 57th in 2001-2014.

Hexian and China do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Hexian peaked in 1991-2000, while the SNDi of street constructions in China followed a zig-zag trend with an overall decrease.

How do development practices in Hexian fare in comparison to others in China? Most recently in 2001-2014, street construction in Hexian was the 1324th-most disconnected out of the 1651 cities in China. Its position in the ranks since 1975 has fallen; relative to other cities in China, street construction in Hexian has become more connected. Hexian ranked 983rd in 1975, 1150th in 1976-1990, 867th in 1991-2000 and 1324th in 2001-2014.

Hexian and Anhui do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Hexian peaked in 1991-2000, while the SNDi of street constructions in Anhui fell steadily.

To date, Hexian is the 44th-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 Hexian has become more connected. Hexian ranked 30th in 1975, 45th in 1976-1990, 39th in 1991-2000 and 44th in 2001-2014.

Hexian and China do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Hexian peaked in 1991-2000, while the SNDi of street constructions in China peaked in 1976-1990.

To date, Hexian is the 1385th-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 Hexian has become more connected. Hexian ranked 983rd in 1975, 1283rd in 1976-1990, 1282nd in 1991-2000 and 1385th in 2001-2014.

As of 2015, Hexian had a built-up area of 10.92 square kilometers, and a population of 102267 people.

These are some other cities with approximately the same population: