Street-network Sprawl in Central and Western, 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.

Central and Western: region in China

View Central and Western, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Central and Western as of 2014, the overall level of street-network sprawl is 0.07, which is very well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.06, 0.23, -0.42 and 8.49. Disconnectivity in street construction in Central and Western 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 Central and Western spans a total of 148 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 0.06, which is very 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 0.06, 0.11, 0.07 and 0.07. Disconnectivity in Central and Western's street network follows a zig-zag trend. In 1975, the region was most disconnected; while it was most connected in 1976-1990.

The level of street-network sprawl in new development in Central and Western followed a zig-zag trend with an overall increase. To get a sense of how street development has changed in Central and Western, we can consider one of its most populous cities: Hong Kong. Disconnectivity in the most populous cities in Central and Western follow the same region trend.

How do development practices in Central and Western fare in comparison to others in China? Most recently in 2001-2014, street construction in Central and Western was the 1st-most disconnected out of the 34 regions in China. Its position in the ranks since 1975 has risen; relative to other regions in China, street construction in Central and Western has become more disconnected. Central and Western ranked 33rd in 1975, 34th in 1976-1990, 34th in 1991-2000 and 1st in 2001-2014.

As of 2014, the city with the most disconnected street network in Central and Western is Hong Kong with an SNDi of 1.04, which is relatively well-connected. Conversely, the most connected city is Hong Kong with an SNDi of 1.04, which is relatively well-connected. See trends for these cities: Hong Kong, Hong Kong

The level of street-network sprawl in the aggregate network in Central and Western followed a zig-zag trend with an overall increase. To get a sense of how the aggregate street network has changed in Central and Western, we can consider one of its most populous cities: Hong Kong. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in the aggregate network in Hong Kong rose steadily.

To date, Central and Western is the 34th-most disconnected out of the 34 regions in China. Its position in the ranks since 1975 has fallen; relative to other regions in China, the street network in Central and Western has become more connected. Central and Western ranked 33rd in 1975, 34th in 1976-1990, 34th in 1991-2000 and 34th in 2001-2014.