Street-network Sprawl in Longxi, 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.

Longxi: city in Gansu, 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 Longxi, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Longxi as of 2014, the overall level of street-network sprawl is 3.58, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 3.59, 3.46, 2.68 and 3.76. The disconnectivity of new streets constructed in Longxi fell, then rose. In 1991-2000, new street layouts were the most connected.

Quantity of street network construction: The street network in Longxi spans a total of 248 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 3.76, 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 3.59, 3.51, 3.39 and 3.58. The SNDi of the aggregate street network in fell at first, but Longxi has worsened in disconnectivity since 2000.

Longxi and Gansu follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these was at its lowest in 1991-2000.

How do development practices in Longxi fare in comparison to others in Gansu? Most recently in 2001-2014, street construction in Longxi was the 7th-most disconnected out of the 34 cities in Gansu. Its position in the ranks since 1975 has risen; relative to other cities in Gansu, street construction in Longxi has become more disconnected. Longxi ranked 8th in 1975, 11th in 1976-1990, 9th in 1991-2000 and 7th in 2001-2014.

Longxi and China do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Longxi was at its lowest 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 Longxi fare in comparison to others in China? Most recently in 2001-2014, street construction in Longxi was the 228th-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 Longxi has become more connected. Longxi ranked 150th in 1975, 220th in 1976-1990, 309th in 1991-2000 and 228th in 2001-2014.

Longxi and Gansu do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Longxi was at its lowest in 1991-2000, while the SNDi of street constructions in Gansu fell steadily.

To date, Longxi is the 10th-most disconnected out of the 34 cities in Gansu. Its position in the ranks since 1975 has fallen; relative to other cities in Gansu, the street network in Longxi has become more connected. Longxi ranked 8th in 1975, 10th in 1976-1990, 10th in 1991-2000 and 10th in 2001-2014.

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

To date, Longxi is the 159th-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 Longxi has become more connected. Longxi ranked 150th in 1975, 169th in 1976-1990, 173rd in 1991-2000 and 159th in 2001-2014.

As of 2015, Longxi had a built-up area of 15.97 square kilometers, and a population of 147300 people.

These are some other cities with approximately the same population: