Street-network Sprawl in Osizweni, 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.

Osizweni: city in KwaZulu-Natal, 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 Osizweni, South Africa on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Osizweni as of 2014, the overall level of street-network sprawl is 1.91, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 1.45, 1.21, 3.21 and 2.59. Disconnectivity in street construction in Osizweni follows a zig-zag trend. In 1976-1990, street construction was most disconnected, while construction was most connected in 1991-2000.

Quantity of street network construction: The street network in Osizweni spans a total of 508 kilometers. The period with the greatest volume of street construction was 1975. These roads have an SNDi of 1.45, 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 1.45, 1.34, 1.9 and 1.91. The SNDi of the aggregate street network in fell at first, but Osizweni has worsened in disconnectivity since 1990.

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

How do development practices in Osizweni fare in comparison to others in KwaZulu-Natal? Most recently in 2001-2014, street construction in Osizweni was the 8th-most disconnected out of the 9 cities in KwaZulu-Natal. Its position in the ranks since 1975 has not changed. Osizweni ranked 8th in 1975, 9th in 1976-1990, 9th in 1991-2000 and 8th in 2001-2014.

Osizweni and South Africa do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Osizweni followed a zig-zag trend with an overall increase, while the SNDi of street constructions in South Africa followed a zig-zag trend with an overall increase.

How do development practices in Osizweni fare in comparison to others in South Africa? Most recently in 2001-2014, street construction in Osizweni was the 58th-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 Osizweni has become more connected. Osizweni ranked 55th in 1975, 74th in 1976-1990, 52nd in 1991-2000 and 58th in 2001-2014.

Osizweni and KwaZulu-Natal do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Osizweni was at its lowest in 1976-1990, while the SNDi of street constructions in KwaZulu-Natal rose steadily.

To date, Osizweni is the 9th-most disconnected out of the 9 cities in KwaZulu-Natal. Its position in the ranks since 1975 has fallen; relative to other cities in KwaZulu-Natal, the street network in Osizweni has become more connected. Osizweni ranked 8th in 1975, 9th in 1976-1990, 9th in 1991-2000 and 9th in 2001-2014.

Osizweni and South Africa do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Osizweni was at its lowest in 1976-1990, while the SNDi of street constructions in South Africa rose steadily.

To date, Osizweni is the 73rd-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 Osizweni has become more connected. Osizweni ranked 55th in 1975, 75th in 1976-1990, 73rd in 1991-2000 and 73rd in 2001-2014.

As of 2015, Osizweni had a built-up area of 21.48 square kilometers, and a population of 244237 people.

These are some other cities with approximately the same population: