Street-network Sprawl in Shiyan, 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.

Shiyan: city in Hubei, 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 Shiyan, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Shiyan as of 2014, the overall level of street-network sprawl is 4.6, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 5.04, 5.38, 5.27 and 3.31. Street construction in Shiyan increased in disconnectivity initially but has since improved. The streets constructed in 1976-1990 were the most disconnected.

Quantity of street network construction: The street network in Shiyan spans a total of 326 kilometers. The period with the greatest volume of street construction was 2001-2014. These roads have an SNDi of 3.31, which is highly disconnected.

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 5.04, 5.18, 5.18 and 4.6. The aggregate street network in Shiyan increased in disconnectivity initially,but the trend has turned around after 2000.

Shiyan and Hubei follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these peaked in 1976-1990.

How do development practices in Shiyan fare in comparison to others in Hubei? Most recently in 2001-2014, street construction in Shiyan was the 24th-most disconnected out of the 80 cities in Hubei. Its position in the ranks since 1975 has fallen; relative to other cities in Hubei, street construction in Shiyan has become more connected. Shiyan ranked 5th in 1975, 3rd in 1976-1990, 2nd in 1991-2000 and 24th in 2001-2014.

Shiyan and China do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Shiyan peaked in 1976-1990, while the SNDi of street constructions in China followed a zig-zag trend with an overall decrease.

How do development practices in Shiyan fare in comparison to others in China? Most recently in 2001-2014, street construction in Shiyan was the 315th-most disconnected out of the 1651 cities in China. Its position in the ranks since 1975 has fallen; relative to other cities in China, street construction in Shiyan has become more connected. Shiyan ranked 51st in 1975, 46th in 1976-1990, 52nd in 1991-2000 and 315th in 2001-2014.

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

To date, Shiyan is the 5th-most disconnected out of the 80 cities in Hubei. Its position in the ranks since 1975 has not changed. Shiyan ranked 5th in 1975, 3rd in 1976-1990, 4th in 1991-2000 and 5th in 2001-2014.

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

To date, Shiyan is the 60th-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 Shiyan has become more connected. Shiyan ranked 51st in 1975, 34th in 1976-1990, 32nd in 1991-2000 and 60th in 2001-2014.

As of 2015, Shiyan had a built-up area of 36.32 square kilometers, and a population of 525870 people.

These are some other cities with approximately the same population: