Street-network Sprawl in Xi'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.

Xi'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 Xi'an, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Xi'an as of 2014, the overall level of street-network sprawl is 2.51, which is in the 40th to 60th percentile of disconnectedness.

Trends in street network construction: The SNDis of street construction for the respective time periods are 2.45, 3.08, 2.42 and 2.5. Disconnectivity in street construction in Xi'an follows a zig-zag trend. In 1991-2000, street construction was most disconnected, while construction was most connected in 1976-1990.

Quantity of street network construction: The street network in Xi'an spans a total of 4249 kilometers. The period with the greatest volume of street construction was 1975. These roads have an SNDi of 2.45, which is in the 40th to 60th percentile of disconnectedness.

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 2.45, 2.55, 2.51 and 2.51. The aggregate street network in Xi'an increased in disconnectivity initially,but the trend has turned around after 1990.

Xi'an and Shaanxi do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Xi'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 Xi'an fare in comparison to others in Shaanxi? Most recently in 2001-2014, street construction in Xi'an was the 17th-most disconnected out of the 60 cities in Shaanxi. Its position in the ranks since 1975 has not changed. Xi'an ranked 17th in 1975, 11th in 1976-1990, 10th in 1991-2000 and 17th in 2001-2014.

Xi'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 Xi'an fare in comparison to others in China? Most recently in 2001-2014, street construction in Xi'an was the 511th-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 Xi'an has become more connected. Xi'an ranked 369th in 1975, 288th in 1976-1990, 372nd in 1991-2000 and 511th in 2001-2014.

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

To date, Xi'an is the 19th-most disconnected out of the 60 cities in Shaanxi. Its position in the ranks since 1975 has fallen; relative to other cities in Shaanxi, the street network in Xi'an has become more connected. Xi'an ranked 17th in 1975, 14th in 1976-1990, 15th in 1991-2000 and 19th in 2001-2014.

Xi'an and China follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these peaked in 1976-1990.

To date, Xi'an is the 473rd-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 Xi'an has become more connected. Xi'an ranked 369th in 1975, 425th in 1976-1990, 434th in 1991-2000 and 473rd in 2001-2014.

As of 2015, Xi'an had a built-up area of 335.92 square kilometers, and a population of 5071323 people.

These are some other cities with approximately the same population: