Street-network Sprawl in Tiantai, 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.

Tiantai: city in Zhejiang, 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 Tiantai, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Tiantai as of 2014, the overall level of street-network sprawl is 0.57, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are -0.37, 0.62, 0.63 and 0.68. In each period, new street development in Tiantai steadily grows more disconnected than in the last. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.99 points, but between 1991-2000 and 2001-2014, it rose by just 0.05.

Quantity of street network construction: The street network in Tiantai spans a total of 204 kilometers. The period with the greatest volume of street construction was 2001-2014. These roads have an SNDi of 0.68, 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 -0.37, 0.51, 0.55 and 0.57. Overall, the SNDi of the aggregate street network has risen: the street network in Tiantai has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.89 points, but between 1991-2000 and 2001-2014, it rose by just 0.02.

Tiantai and Zhejiang do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Tiantai rose steadily, while the SNDi of street constructions in Zhejiang peaked in 1976-1990.

How do development practices in Tiantai fare in comparison to others in Zhejiang? Most recently in 2001-2014, street construction in Tiantai was the 76th-most disconnected out of the 94 cities in Zhejiang. Its position in the ranks since 1975 has risen; relative to other cities in Zhejiang, street construction in Tiantai has become more disconnected. Tiantai ranked 79th in 1975, 81st in 1976-1990, 62nd in 1991-2000 and 76th in 2001-2014.

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

How do development practices in Tiantai fare in comparison to others in China? Most recently in 2001-2014, street construction in Tiantai was the 1121st-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 Tiantai has become more disconnected. Tiantai ranked 1185th in 1975, 1191st in 1976-1990, 911th in 1991-2000 and 1121st in 2001-2014.

Tiantai and Zhejiang do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Tiantai rose steadily, while the SNDi of street constructions in Zhejiang peaked in 1976-1990.

To date, Tiantai is the 88th-most disconnected out of the 94 cities in Zhejiang. Its position in the ranks since 1975 has fallen; relative to other cities in Zhejiang, the street network in Tiantai has become more connected. Tiantai ranked 79th in 1975, 86th in 1976-1990, 85th in 1991-2000 and 88th in 2001-2014.

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

To date, Tiantai is the 1410th-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 Tiantai has become more connected. Tiantai ranked 1185th in 1975, 1336th in 1976-1990, 1350th in 1991-2000 and 1410th in 2001-2014.

As of 2015, Tiantai had a built-up area of 12.82 square kilometers, and a population of 145704 people.

These are some other cities with approximately the same population: