Street-network Sprawl in Islands, China

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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:

• nodal degree
• dendricity, the tree-likeness of the street network
• circuity, the ratio of the distance by road to the straight-line distance of two locations on the street network
• sinuosity, the curviness of a street

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:

• Global trends toward urban street-network sprawl
• A global assessment of street-network sprawl

To see the state of street-network sprawl across the globe, visit the sprawlmap.

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Islands: region in China

View Islands, China on the sprawlmap

How have Islands's street networks changed over time?

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Islands as of 2014, the overall level of street-network sprawl is 2.31, 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 3.1, 2.19, 2.14 and nan. Data was not available in 2001-2014.

Quantity of street network construction: The street network in Islands spans a total of 193 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 2.19, 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 3.1, 2.37, 2.3 and 2.31. The SNDi of the aggregate street network in fell at first, but Islands has worsened in disconnectivity since 2000.

Islands in context: Street-network sprawl of new development

The level of street-network sprawl in new development in Islands followed a zig-zag trend. To get a sense of how street development has changed in Islands, we can consider one of its most populous cities: Tung Chung. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Tung Chung followed a zig-zag trend.

How do development practices in Islands fare in comparison to others in China? out of the 34 regions in China. Its position in the ranks since 1975 has fallen; relative to other regions in China, street construction in Islands has become more connected. Islands ranked 17th in 1975, 31st in 1976-1990 and 30th in 1991-2000. There was no ranking in 2001-2014 due to unavailable data.

Islands in context: Aggregate street-network sprawl

As of 2014, the city with the most disconnected street network in Islands is Tung Chung with an SNDi of 1.44, which is relatively well-connected. Conversely, the most connected city is Tung Chung with an SNDi of 1.44, which is relatively well-connected. See trends for these cities: Tung Chung, Tung Chung

The level of street-network sprawl in the aggregate network in Islands was at its lowest in 1991-2000. To get a sense of how the aggregate street network has changed in Islands, we can consider one of its most populous cities: Tung Chung. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in the aggregate network in Tung Chung followed a zig-zag trend.

To date, Islands is the 28th-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 Islands has become more connected. Islands ranked 17th in 1975, 28th in 1976-1990, 28th in 1991-2000 and 28th in 2001-2014.

Cities in Islands

• Tung Chung