Street-network Sprawl in 北塘, 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.

北塘: city in Tianjin, 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 北塘, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in 北塘 as of 2014, the overall level of street-network sprawl is 1.91, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.22, 2.35, 2.79 and 1.71. Street construction in 北塘 increased in disconnectivity initially but has since improved. The streets constructed in 1991-2000 were the most disconnected.

Quantity of street network construction: The street network in 北塘 spans a total of 422 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 1.71, 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 0.22, 2.27, 2.35 and 1.91. The aggregate street network in 北塘 increased in disconnectivity initially,but the trend has turned around after 2000.

北塘 and Tianjin follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these peaked in 1991-2000.

How do development practices in 北塘 fare in comparison to others in Tianjin? Most recently in 2001-2014, street construction in 北塘 was the 7th-most disconnected out of the 14 cities in Tianjin. Its position in the ranks since 1975 has risen; relative to other cities in Tianjin, street construction in 北塘 has become more disconnected. 北塘 ranked 9th in 1975, 5th in 1976-1990, 3rd in 1991-2000 and 7th in 2001-2014.

北塘 and China do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in 北塘 peaked in 1991-2000, while the SNDi of street constructions in China followed a zig-zag trend with an overall decrease.

How do development practices in 北塘 fare in comparison to others in China? Most recently in 2001-2014, street construction in 北塘 was the 777th-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 北塘 has become more disconnected. 北塘 ranked 1069th in 1975, 509th in 1976-1990, 282nd in 1991-2000 and 777th in 2001-2014.

北塘 and Tianjin do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in 北塘 peaked in 1991-2000, while the SNDi of street constructions in Tianjin rose steadily.

To date, 北塘 is the 8th-most disconnected out of the 14 cities in Tianjin. Its position in the ranks since 1975 has risen; relative to other cities in Tianjin, the street network in 北塘 has become more disconnected. 北塘 ranked 9th in 1975, 5th in 1976-1990, 5th in 1991-2000 and 8th in 2001-2014.

北塘 and China do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in 北塘 peaked in 1991-2000, while the SNDi of street constructions in China peaked in 1976-1990.

To date, 北塘 is the 737th-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 北塘 has become more disconnected. 北塘 ranked 1069th in 1975, 544th in 1976-1990, 505th in 1991-2000 and 737th in 2001-2014.

As of 2015, 北塘 had a built-up area of 12.54 square kilometers, and a population of 472642 people.

These are some other cities with approximately the same population: