Street-network Sprawl in Dazhu, 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.

Dazhu: city in Sichuan, 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 Dazhu, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Dazhu as of 2014, the overall level of street-network sprawl is 3.9, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 3.51, 3.66, 2.43 and 5.15. Disconnectivity in street construction in Dazhu follows a zig-zag trend. In 1991-2000, street construction was most disconnected, while construction was most connected in 2001-2014.

Quantity of street network construction: The street network in Dazhu spans a total of 218 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 5.15, 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 3.51, 3.6, 3.3 and 3.9. Disconnectivity in Dazhu's street network follows a zig-zag trend. In 1991-2000, the city was most disconnected; while it was most connected in 2001-2014.

Dazhu and Sichuan do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Dazhu followed a zig-zag trend with an overall increase, while the SNDi of street constructions in Sichuan was at its lowest in 1991-2000.

How do development practices in Dazhu fare in comparison to others in Sichuan? Most recently in 2001-2014, street construction in Dazhu was the 13th-most disconnected out of the 102 cities in Sichuan. Its position in the ranks since 1975 has risen; relative to other cities in Sichuan, street construction in Dazhu has become more disconnected. Dazhu ranked 14th in 1975, 15th in 1976-1990, 24th in 1991-2000 and 13th in 2001-2014.

Dazhu 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 Dazhu fare in comparison to others in China? Most recently in 2001-2014, street construction in Dazhu was the 92nd-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 Dazhu has become more disconnected. Dazhu ranked 156th in 1975, 184th in 1976-1990, 367th in 1991-2000 and 92nd in 2001-2014.

Dazhu and Sichuan do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Dazhu followed a zig-zag trend with an overall increase, while the SNDi of street constructions in Sichuan was at its lowest in 1991-2000.

To date, Dazhu is the 21st-most disconnected out of the 102 cities in Sichuan. Its position in the ranks since 1975 has fallen; relative to other cities in Sichuan, the street network in Dazhu has become more connected. Dazhu ranked 14th in 1975, 18th in 1976-1990, 22nd in 1991-2000 and 21st in 2001-2014.

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

To date, Dazhu is the 112th-most disconnected out of the 1651 cities in China. Its position in the ranks since 1975 has risen; relative to other cities in China, the street network in Dazhu has become more disconnected. Dazhu ranked 156th in 1975, 157th in 1976-1990, 189th in 1991-2000 and 112th in 2001-2014.

As of 2015, Dazhu had a built-up area of 5.62 square kilometers, and a population of 181539 people.

These are some other cities with approximately the same population: