Street-network Sprawl in Binhai, 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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Binhai: 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 Binhai, China on the sprawlmap

How have Binhai's street networks changed over time?

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Binhai as of 2014, the overall level of street-network sprawl is 2.12, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 2.29, 3.93, 1.65 and 1.83. Disconnectivity in street construction in Binhai 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 Binhai spans a total of 259 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 1.83, 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 2.29, 2.93, 2.42 and 2.12. The aggregate street network in Binhai increased in disconnectivity initially,but the trend has turned around after 1990.

Binhai in context: Street-network sprawl of new development

Binhai 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 Binhai fare in comparison to others in Jiangsu? Most recently in 2001-2014, street construction in Binhai was the 42nd-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 Binhai has become more connected. Binhai ranked 15th in 1975, 6th in 1976-1990, 40th in 1991-2000 and 42nd in 2001-2014.

Binhai 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.

Binhai in context: Aggregate street-network sprawl

Binhai 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, Binhai is the 29th-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 Binhai has become more connected. Binhai ranked 15th in 1975, 16th in 1976-1990, 20th in 1991-2000 and 29th in 2001-2014.

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

What about other similarly-populated cities?

As of 2015, Binhai had a built-up area of 30.67 square kilometers, and a population of 209832 people.

These are some other cities with approximately the same population:

• Hulunbuir, China
• Govardhan, India
• Kiel, Germany