Street-network Sprawl in Tongbai, 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.

Tongbai: city in Henan, 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 Tongbai, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Tongbai as of 2014, the overall level of street-network sprawl is 1.13, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are nan, 1.47, 0.99 and 0.5. Data was not available in 1975.

Quantity of street network construction: The street network in Tongbai spans a total of 79 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, 1.47, 1.45 and 1.13. Data was not available in 1975.

Tongbai and Henan 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 Henan peaked in 1991-2000.

How do development practices in Tongbai fare in comparison to others in Henan? Most recently in 2001-2014, street construction in Tongbai was the 72nd-most disconnected out of the 118 cities in Henan. Its position in the ranks since 1975 has fallen; relative to other cities in Henan, street construction in Tongbai has become more connected. Tongbai ranked 35th in 1976-1990, 43rd in 1991-2000 and 72nd in 2001-2014. There was no ranking in 1975 due to unavailable data.

Tongbai 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 Tongbai fare in comparison to others in China? Most recently in 2001-2014, street construction in Tongbai was the 1171st-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 Tongbai has become more connected. Tongbai ranked 887th in 1976-1990, 793rd in 1991-2000 and 1171st in 2001-2014. There was no ranking in 1975 due to unavailable data.

Tongbai and Henan 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 Henan peaked in 1976-1990.

To date, Tongbai is the 48th-most disconnected out of the 118 cities in Henan. Its position in the ranks since 1975 has fallen; relative to other cities in Henan, the street network in Tongbai has become more connected. Tongbai ranked 32nd in 1976-1990, 35th in 1991-2000 and 48th in 2001-2014. There was no ranking in 1975 due to unavailable data.

Tongbai 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, Tongbai is the 1153rd-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 Tongbai has become more connected. Tongbai ranked 894th in 1976-1990, 928th in 1991-2000 and 1153rd in 2001-2014. There was no ranking in 1975 due to unavailable data.

As of 2015, Tongbai had a built-up area of 9.72 square kilometers, and a population of 69584 people.

These are some other cities with approximately the same population: