Street-network Sprawl in Lenasia South, 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.

Lenasia South: 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 Lenasia South, South Africa on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Lenasia South as of 2014, the overall level of street-network sprawl is 4.16, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 4.8, 3.79, 3.4 and 4.29. The disconnectivity of new streets constructed in Lenasia South fell, then rose. In 1991-2000, new street layouts were the most connected.

Quantity of street network construction: The street network in Lenasia South spans a total of 348 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 4.8, 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 4.8, 4.33, 4.17 and 4.16. Overall, the SNDi of the aggregate street network has fallen: the street network in Lenasia South has become more connected.

Lenasia South and Gauteng do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Lenasia South was at its lowest in 1991-2000, while the SNDi of street constructions in Gauteng rose steadily.

How do development practices in Lenasia South fare in comparison to others in Gauteng? Most recently in 2001-2014, street construction in Lenasia South was the 8th-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 Lenasia South has become more connected. Lenasia South ranked 2nd in 1975, 6th in 1976-1990, 13th in 1991-2000 and 8th in 2001-2014.

Lenasia South and South Africa do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Lenasia South was at its lowest in 1991-2000, while the SNDi of street constructions in South Africa followed a zig-zag trend with an overall increase.

How do development practices in Lenasia South fare in comparison to others in South Africa? Most recently in 2001-2014, street construction in Lenasia South was the 28th-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 Lenasia South has become more connected. Lenasia South ranked 4th in 1975, 26th in 1976-1990, 46th in 1991-2000 and 28th in 2001-2014.

Lenasia South and Gauteng do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Lenasia South fell steadily, while the SNDi of street constructions in Gauteng rose steadily.

To date, Lenasia South is the 3rd-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 Lenasia South has become more connected. Lenasia South ranked 2nd in 1975, 4th in 1976-1990, 4th in 1991-2000 and 3rd in 2001-2014.

Lenasia South and South Africa do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Lenasia South fell steadily, while the SNDi of street constructions in South Africa rose steadily.

To date, Lenasia South is the 15th-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 Lenasia South has become more connected. Lenasia South ranked 4th in 1975, 13th in 1976-1990, 15th in 1991-2000 and 15th in 2001-2014.

As of 2015, Lenasia South had a built-up area of 5.92 square kilometers, and a population of 114723 people.

These are some other cities with approximately the same population: