Street-network Sprawl in Longhui, 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.

Longhui: 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 Longhui, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Longhui as of 2014, the overall level of street-network sprawl is 2.8, which is in the 40th to 60th percentile of disconnectedness.

Trends in street network construction: The SNDis of street construction for the respective time periods are 4.4, 1.4, 2.43 and 2.79. The disconnectivity of new streets constructed in Longhui fell, then rose. In 1976-1990, new street layouts were the most connected.

Quantity of street network construction: The street network in Longhui spans a total of 74 kilometers. It is dominated by roads constructed in 1991-2000. These roads have an SNDi of 2.43, 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 4.4, 3.12, 2.81 and 2.8. Overall, the SNDi of the aggregate street network has fallen: the street network in Longhui has become more connected.

Longhui and Hunan do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Longhui was at its lowest in 1976-1990, while the SNDi of street constructions in Hunan followed a zig-zag trend with an overall decrease.

How do development practices in Longhui fare in comparison to others in Hunan? Most recently in 2001-2014, street construction in Longhui was the 25th-most disconnected out of the 95 cities in Hunan. Its position in the ranks since 1975 has fallen; relative to other cities in Hunan, street construction in Longhui has become more connected. Longhui ranked 9th in 1975, 60th in 1976-1990, 19th in 1991-2000 and 25th in 2001-2014.

Longhui and China do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Longhui was at its lowest in 1976-1990, while the SNDi of street constructions in China followed a zig-zag trend with an overall decrease.

How do development practices in Longhui fare in comparison to others in China? Most recently in 2001-2014, street construction in Longhui was the 442nd-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 Longhui has become more connected. Longhui ranked 83rd in 1975, 912th in 1976-1990, 368th in 1991-2000 and 442nd in 2001-2014.

Longhui and Hunan do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Longhui fell steadily, while the SNDi of street constructions in Hunan peaked in 1976-1990.

To date, Longhui is the 26th-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 Longhui has become more connected. Longhui ranked 9th in 1975, 22nd in 1976-1990, 22nd in 1991-2000 and 26th in 2001-2014.

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

To date, Longhui is the 366th-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 Longhui has become more connected. Longhui ranked 83rd in 1975, 251st in 1976-1990, 328th in 1991-2000 and 366th in 2001-2014.

As of 2015, Longhui had a built-up area of 5.65 square kilometers, and a population of 92693 people.

These are some other cities with approximately the same population: