Street-network Sprawl in Midlands, Zimbabwe

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.

Midlands: region in Zimbabwe

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 Midlands, Zimbabwe on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Midlands as of 2014, the overall level of street-network sprawl is 2.79, which is in the 40th to 60th percentile of disconnectedness.

Trends in street network construction: The SNDis of street construction for the respective time periods are 2.32, 2.33, 3.4 and 3.53. In each period, new street development in Midlands steadily grows more disconnected than in the last.

Quantity of street network construction: The street network in Midlands spans a total of 3957 kilometers. The period with the greatest volume of street construction was 2001-2014. These roads have an SNDi of 3.53, 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 2.32, 2.33, 2.6 and 2.79. Overall, the SNDi of the aggregate street network has risen: the street network in Midlands has become more disconnected.

The level of street-network sprawl in new development in Midlands rose steadily. To get a sense of how street development has changed in Midlands, we can consider three of its most populous cities: Gweru, Kwekwe and Mbizo. Out of the three cities, Kwekwe and Mbizo do not follow the same trend as the region. The level of street-network sprawl in new development in Kwekwe followed a zig-zag trend with an overall increase. The level of street-network sprawl in new development in Mbizo followed a zig-zag trend.

How do development practices in Midlands fare in comparison to others in Zimbabwe? Most recently in 2001-2014, street construction in Midlands was the 6th-most disconnected out of the 8 regions in Zimbabwe. Its position in the ranks since 1975 has fallen; relative to other regions in Zimbabwe, street construction in Midlands has become more connected. Midlands ranked 5th in 1975, 7th in 1976-1990, 6th in 1991-2000 and 6th in 2001-2014.

As of 2014, the city with the most disconnected street network in Midlands is Mbizo with an SNDi of 2.83, which is in the 40th to 60th percentile of disconnectedness. Conversely, the most connected city is Kwekwe with an SNDi of 1.47, which is relatively well-connected. See trends for these cities: Kwekwe, Mbizo

The level of street-network sprawl in the aggregate network in Midlands rose steadily. To get a sense of how the aggregate street network has changed in Midlands, we can consider three of its most populous cities: Gweru, Kwekwe and Mbizo. Out of the three cities, Kwekwe and Mbizo do not follow the same trend as the region. The level of street-network sprawl in the aggregate network in Kwekwe followed a zig-zag trend with an overall increase. The level of street-network sprawl in the aggregate network in Mbizo followed a zig-zag trend.

To date, Midlands is the 7th-most disconnected out of the 8 regions in Zimbabwe. Its position in the ranks since 1975 has fallen; relative to other regions in Zimbabwe, the street network in Midlands has become more connected. Midlands ranked 5th in 1975, 7th in 1976-1990, 7th in 1991-2000 and 7th in 2001-2014.