Street-network Sprawl in Ganyu, 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.

Ganyu: city in Jiangsu, 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 Ganyu, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Ganyu as of 2014, the overall level of street-network sprawl is 1.61, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 2.19, 2.36, 0.36 and 0.85. Disconnectivity in street construction in Ganyu 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 Ganyu spans a total of 295 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 0.85, which is relatively well-connected.

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 2.19, 2.25, 2.12 and 1.61. The aggregate street network in Ganyu increased in disconnectivity initially,but the trend has turned around after 1990.

Ganyu and Jiangsu 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 decrease.

How do development practices in Ganyu fare in comparison to others in Jiangsu? Most recently in 2001-2014, street construction in Ganyu was the 75th-most disconnected out of the 87 cities in Jiangsu. Its position in the ranks since 1975 has fallen; relative to other cities in Jiangsu, street construction in Ganyu has become more connected. Ganyu ranked 21st in 1975, 29th in 1976-1990, 68th in 1991-2000 and 75th in 2001-2014.

Ganyu 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 decrease.

How do development practices in Ganyu fare in comparison to others in China? Most recently in 2001-2014, street construction in Ganyu was the 1056th-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 Ganyu has become more connected. Ganyu ranked 437th in 1975, 504th in 1976-1990, 991st in 1991-2000 and 1056th in 2001-2014.

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

To date, Ganyu is the 46th-most disconnected out of the 87 cities in Jiangsu. Its position in the ranks since 1975 has fallen; relative to other cities in Jiangsu, the street network in Ganyu has become more connected. Ganyu ranked 21st in 1975, 27th in 1976-1990, 26th in 1991-2000 and 46th in 2001-2014.

Ganyu 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, Ganyu is the 897th-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 Ganyu has become more connected. Ganyu ranked 437th in 1975, 555th in 1976-1990, 606th in 1991-2000 and 897th in 2001-2014.

As of 2015, Ganyu had a built-up area of 40.55 square kilometers, and a population of 199916 people.

These are some other cities with approximately the same population: