Street-network Sprawl in Yan'an, 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.

Yan'an: city in Shaanxi, 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 Yan'an, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Yan'an as of 2014, the overall level of street-network sprawl is 1.39, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are -1.23, -0.87, -1.39 and 6.07. Disconnectivity in street construction in Yan'an follows a zig-zag trend. In 1991-2000, street construction was most disconnected, while construction was most connected in 2001-2014.

Quantity of street network construction: The street network in Yan'an spans a total of 79 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 6.07, 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 -1.23, -1.09, -1.09 and 1.39. Disconnectivity in Yan'an's street network follows a zig-zag trend. In 1975, the city was most disconnected; while it was most connected in 2001-2014.

Yan'an and Shaanxi do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Yan'an followed a zig-zag trend with an overall increase, while the SNDi of street constructions in Shaanxi was at its lowest in 1976-1990.

How do development practices in Yan'an fare in comparison to others in Shaanxi? Most recently in 2001-2014, street construction in Yan'an was the 1st-most disconnected out of the 60 cities in Shaanxi. Its position in the ranks since 1975 has risen; relative to other cities in Shaanxi, street construction in Yan'an has become more disconnected. Yan'an ranked 48th in 1975, 55th in 1976-1990, 47th in 1991-2000 and 1st in 2001-2014.

Yan'an 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 increase.

How do development practices in Yan'an fare in comparison to others in China? Most recently in 2001-2014, street construction in Yan'an was the 45th-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 Yan'an has become more disconnected. Yan'an ranked 1285th in 1975, 1468th in 1976-1990, 1283rd in 1991-2000 and 45th in 2001-2014.

Yan'an and Shaanxi do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Yan'an followed a zig-zag trend with an overall increase, while the SNDi of street constructions in Shaanxi was at its lowest in 1991-2000.

To date, Yan'an is the 34th-most disconnected out of the 60 cities in Shaanxi. Its position in the ranks since 1975 has risen; relative to other cities in Shaanxi, the street network in Yan'an has become more disconnected. Yan'an ranked 48th in 1975, 59th in 1976-1990, 60th in 1991-2000 and 34th in 2001-2014.

Yan'an and China do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Yan'an followed a zig-zag trend with an overall increase, while the SNDi of street constructions in China peaked in 1976-1990.

To date, Yan'an is the 1012th-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 Yan'an has become more disconnected. Yan'an ranked 1285th in 1975, 1587th in 1976-1990, 1618th in 1991-2000 and 1012th in 2001-2014.

As of 2015, Yan'an had a built-up area of 8.43 square kilometers, and a population of 106625 people.

These are some other cities with approximately the same population: