Street-network Sprawl in Durban, 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.

Durban: 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 Durban, South Africa on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Durban as of 2014, the overall level of street-network sprawl is 5.68, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 3.19, 5.8, 7.37 and 7.34. Street construction in Durban 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 Durban spans a total of 7126 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 5.8, 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 3.19, 5.34, 5.54 and 5.68. Overall, the SNDi of the aggregate street network has risen: the street network in Durban has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 2.15 points, but between 1991-2000 and 2001-2014, it rose by just 0.15.

Durban and KwaZulu-Natal do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Durban peaked in 1991-2000, while the SNDi of street constructions in KwaZulu-Natal rose steadily.

How do development practices in Durban fare in comparison to others in KwaZulu-Natal? Most recently in 2001-2014, street construction in Durban was the 4th-most disconnected out of the 9 cities in KwaZulu-Natal. Its position in the ranks since 1975 has risen; relative to other cities in KwaZulu-Natal, street construction in Durban has become more disconnected. Durban ranked 5th in 1975, 2nd in 1976-1990, 1st in 1991-2000 and 4th in 2001-2014.

Durban and South Africa do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Durban peaked 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 Durban fare in comparison to others in South Africa? Most recently in 2001-2014, street construction in Durban was the 8th-most disconnected out of the 77 cities in South Africa. Its position in the ranks since 1975 has risen; relative to other cities in South Africa, street construction in Durban has become more disconnected. Durban ranked 18th in 1975, 3rd in 1976-1990, 2nd in 1991-2000 and 8th in 2001-2014.

Durban and KwaZulu-Natal follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these rose steadily.

To date, Durban is the 2nd-most disconnected out of the 9 cities in KwaZulu-Natal. Its position in the ranks since 1975 has risen; relative to other cities in KwaZulu-Natal, the street network in Durban has become more disconnected. Durban ranked 5th in 1975, 2nd in 1976-1990, 2nd in 1991-2000 and 2nd in 2001-2014.

Durban and South Africa follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these rose steadily.

To date, Durban is the 4th-most disconnected out of the 77 cities in South Africa. Its position in the ranks since 1975 has risen; relative to other cities in South Africa, the street network in Durban has become more disconnected. Durban ranked 18th in 1975, 3rd in 1976-1990, 4th in 1991-2000 and 4th in 2001-2014.

As of 2015, Durban had a built-up area of 329.12 square kilometers, and a population of 2867061 people.

These are some other cities with approximately the same population: