Street-network Sprawl in Dianjiang, 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.

Dianjiang: city in Chongqing, 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 Dianjiang, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Dianjiang as of 2014, the overall level of street-network sprawl is 2.59, 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 0.98, 0.61, 2.32 and 3.5. The disconnectivity of new streets constructed in Dianjiang fell, then rose. In 1976-1990, new street layouts were the most connected.

Quantity of street network construction: The street network in Dianjiang spans a total of 149 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 3.5, 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 0.98, 0.89, 1.51 and 2.59. The SNDi of the aggregate street network in fell at first, but Dianjiang has worsened in disconnectivity since 1990.

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

How do development practices in Dianjiang fare in comparison to others in Chongqing? Most recently in 2001-2014, street construction in Dianjiang was the 15th-most disconnected out of the 38 cities in Chongqing. Its position in the ranks since 1975 has risen; relative to other cities in Chongqing, street construction in Dianjiang has become more disconnected. Dianjiang ranked 17th in 1975, 29th in 1976-1990, 16th in 1991-2000 and 15th in 2001-2014.

Dianjiang and China do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Dianjiang 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 Dianjiang fare in comparison to others in China? Most recently in 2001-2014, street construction in Dianjiang was the 271st-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 Dianjiang has become more disconnected. Dianjiang ranked 832nd in 1975, 1192nd in 1976-1990, 398th in 1991-2000 and 271st in 2001-2014.

Dianjiang and Chongqing do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Dianjiang was at its lowest in 1976-1990, while the SNDi of street constructions in Chongqing followed a zig-zag trend with an overall increase.

To date, Dianjiang is the 20th-most disconnected out of the 38 cities in Chongqing. Its position in the ranks since 1975 has fallen; relative to other cities in Chongqing, the street network in Dianjiang has become more connected. Dianjiang ranked 17th in 1975, 27th in 1976-1990, 26th in 1991-2000 and 20th in 2001-2014.

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

To date, Dianjiang is the 439th-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 Dianjiang has become more disconnected. Dianjiang ranked 832nd in 1975, 1183rd in 1976-1990, 894th in 1991-2000 and 439th in 2001-2014.

As of 2015, Dianjiang had a built-up area of 5.72 square kilometers, and a population of 187479 people.

These are some other cities with approximately the same population: