Street-network Sprawl in Azaadville, South Africa

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.

Azaadville: city in Gauteng, South Africa

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 Azaadville, South Africa on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Azaadville as of 2014, the overall level of street-network sprawl is 3.28, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 3.82, 4.1, 2.86 and 2.96. Disconnectivity in street construction in Azaadville 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 Azaadville spans a total of 90 kilometers. It is dominated by roads constructed in 1991-2000. These roads have an SNDi of 2.86, 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 3.82, 4.06, 3.35 and 3.28. The aggregate street network in Azaadville increased in disconnectivity initially,but the trend has turned around after 1990.

Azaadville and Gauteng do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Azaadville followed a zig-zag trend with an overall decrease, while the SNDi of street constructions in Gauteng rose steadily.

How do development practices in Azaadville fare in comparison to others in Gauteng? Most recently in 2001-2014, street construction in Azaadville was the 14th-most disconnected out of the 19 cities in Gauteng. Its position in the ranks since 1975 has fallen; relative to other cities in Gauteng, street construction in Azaadville has become more connected. Azaadville ranked 5th in 1975, 5th in 1976-1990, 17th in 1991-2000 and 14th in 2001-2014.

Azaadville and South Africa 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 decrease.

How do development practices in Azaadville fare in comparison to others in South Africa? Most recently in 2001-2014, street construction in Azaadville was the 54th-most disconnected out of the 77 cities in South Africa. Its position in the ranks since 1975 has fallen; relative to other cities in South Africa, street construction in Azaadville has become more connected. Azaadville ranked 8th in 1975, 19th in 1976-1990, 59th in 1991-2000 and 54th in 2001-2014.

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

To date, Azaadville is the 12th-most disconnected out of the 19 cities in Gauteng. Its position in the ranks since 1975 has fallen; relative to other cities in Gauteng, the street network in Azaadville has become more connected. Azaadville ranked 5th in 1975, 5th in 1976-1990, 11th in 1991-2000 and 12th in 2001-2014.

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

To date, Azaadville is the 38th-most disconnected out of the 77 cities in South Africa. Its position in the ranks since 1975 has fallen; relative to other cities in South Africa, the street network in Azaadville has become more connected. Azaadville ranked 8th in 1975, 15th in 1976-1990, 35th in 1991-2000 and 38th in 2001-2014.

As of 2015, Azaadville had a built-up area of 2.58 square kilometers, and a population of 58102 people.

These are some other cities with approximately the same population: