Street-network Sprawl in Dechang, 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.

Dechang: 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 Dechang, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Dechang as of 2014, the overall level of street-network sprawl is 2.48, 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 2.42, 2.56, 2.16 and 2.53. Disconnectivity in street construction in Dechang follows a zig-zag trend. In 1991-2000, street construction was most disconnected, while construction was most connected in 1976-1990.

Quantity of street network construction: The street network in Dechang spans a total of 82 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 2.56, 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 2.42, 2.56, 2.49 and 2.48. The aggregate street network in Dechang increased in disconnectivity initially,but the trend has turned around after 1990.

Dechang and Sichuan do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Dechang 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 Dechang fare in comparison to others in Sichuan? Most recently in 2001-2014, street construction in Dechang was the 40th-most disconnected out of the 102 cities in Sichuan. Its position in the ranks since 1975 has fallen; relative to other cities in Sichuan, street construction in Dechang has become more connected. Dechang ranked 36th in 1975, 33rd in 1976-1990, 28th in 1991-2000 and 40th in 2001-2014.

Dechang 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 Dechang fare in comparison to others in China? Most recently in 2001-2014, street construction in Dechang was the 505th-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 Dechang has become more connected. Dechang ranked 384th in 1975, 442nd in 1976-1990, 437th in 1991-2000 and 505th in 2001-2014.

Dechang and Sichuan do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Dechang peaked in 1976-1990, while the SNDi of street constructions in Sichuan was at its lowest in 1991-2000.

To date, Dechang is the 41st-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 Dechang has become more connected. Dechang ranked 36th in 1975, 39th in 1976-1990, 37th in 1991-2000 and 41st in 2001-2014.

Dechang and China follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these peaked in 1976-1990.

To date, Dechang is the 485th-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 Dechang has become more connected. Dechang ranked 384th in 1975, 421st in 1976-1990, 441st in 1991-2000 and 485th in 2001-2014.

As of 2015, Dechang had a built-up area of 3.93 square kilometers, and a population of 53374 people.

These are some other cities with approximately the same population: