Street-network Sprawl in Yanshi, 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.

Yanshi: city in Henan, 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 Yanshi, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Yanshi as of 2014, the overall level of street-network sprawl is 1.6, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are -0.03, 1.55, 6.9 and 2.59. Street construction in Yanshi increased in disconnectivity initially but has since improved. The streets constructed in 1991-2000 were the most disconnected.

Quantity of street network construction: The street network in Yanshi spans a total of 151 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 1.55, 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 -0.03, 1.45, 1.57 and 1.6. Overall, the SNDi of the aggregate street network has risen: the street network in Yanshi has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 1.48 points, but between 1991-2000 and 2001-2014, it rose by just 0.03.

Yanshi and Henan follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these peaked in 1991-2000.

How do development practices in Yanshi fare in comparison to others in Henan? Most recently in 2001-2014, street construction in Yanshi was the 16th-most disconnected out of the 118 cities in Henan. Its position in the ranks since 1975 has risen; relative to other cities in Henan, street construction in Yanshi has become more disconnected. Yanshi ranked 52nd in 1975, 31st in 1976-1990, 1st in 1991-2000 and 16th in 2001-2014.

Yanshi and China do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Yanshi peaked 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 Yanshi fare in comparison to others in China? Most recently in 2001-2014, street construction in Yanshi was the 486th-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 Yanshi has become more disconnected. Yanshi ranked 1125th in 1975, 846th in 1976-1990, 19th in 1991-2000 and 486th in 2001-2014.

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

To date, Yanshi is the 27th-most disconnected out of the 118 cities in Henan. Its position in the ranks since 1975 has risen; relative to other cities in Henan, the street network in Yanshi has become more disconnected. Yanshi ranked 52nd in 1975, 33rd in 1976-1990, 31st in 1991-2000 and 27th in 2001-2014.

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

To date, Yanshi is the 904th-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 Yanshi has become more disconnected. Yanshi ranked 1125th in 1975, 904th in 1976-1990, 861st in 1991-2000 and 904th in 2001-2014.

As of 2015, Yanshi had a built-up area of 23.36 square kilometers, and a population of 148721 people.

These are some other cities with approximately the same population: