Street-network Sprawl in 中江县, 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.

中江县: 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 中江县, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in 中江县 as of 2014, the overall level of street-network sprawl is 1.97, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 1.42, 1.73, 0.97 and 2.39. Disconnectivity in street construction in 中江县 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 中江县 spans a total of 240 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 2.39, 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 1.42, 1.63, 1.42 and 1.97. Disconnectivity in 中江县's street network follows a zig-zag trend. In 1975, the city was most disconnected; while it was most connected in 2001-2014.

中江县 and Sichuan do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in 中江县 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 中江县 fare in comparison to others in Sichuan? Most recently in 2001-2014, street construction in 中江县 was the 42nd-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 中江县 has become more disconnected. 中江县 ranked 57th in 1975, 45th in 1976-1990, 50th in 1991-2000 and 42nd in 2001-2014.

中江县 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 中江县 fare in comparison to others in China? Most recently in 2001-2014, street construction in 中江县 was the 543rd-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 中江县 has become more disconnected. 中江县 ranked 682nd in 1975, 769th in 1976-1990, 805th in 1991-2000 and 543rd in 2001-2014.

中江县 and Sichuan do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in 中江县 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, 中江县 is the 58th-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 中江县 has become more connected. 中江县 ranked 57th in 1975, 58th in 1976-1990, 66th in 1991-2000 and 58th in 2001-2014.

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

To date, 中江县 is the 713th-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 中江县 has become more connected. 中江县 ranked 682nd in 1975, 824th in 1976-1990, 945th in 1991-2000 and 713th in 2001-2014.

As of 2015, 中江县 had a built-up area of 11.18 square kilometers, and a population of 177643 people.

These are some other cities with approximately the same population: