Street-network Sprawl in North-West, Botswana

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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:

• nodal degree
• dendricity, the tree-likeness of the street network
• circuity, the ratio of the distance by road to the straight-line distance of two locations on the street network
• sinuosity, the curviness of a street

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:

• Global trends toward urban street-network sprawl
• A global assessment of street-network sprawl

To see the state of street-network sprawl across the globe, visit the sprawlmap.

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North-West: region in Botswana

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 North-West, Botswana on the sprawlmap

How have North-West's street networks changed over time?

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in North-West as of 2014, the overall level of street-network sprawl is 2.73, 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 1.35, 1.76, 2.49 and 3.54. In each period, new street development in North-West steadily grows more disconnected than in the last.

Quantity of street network construction: The street network in North-West spans a total of 1861 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 3.54, 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 1.35, 1.72, 2.09 and 2.73. Overall, the SNDi of the aggregate street network has risen: the street network in North-West has become more disconnected.

North-West in context: Street-network sprawl of new development

The level of street-network sprawl in new development in North-West rose steadily. To get a sense of how street development has changed in North-West, we can consider one of its most populous cities: Maun. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Maun was at its lowest in 1976-1990.

How do development practices in North-West fare in comparison to others in Botswana? Most recently in 2001-2014, street construction in North-West was the 2nd-most disconnected out of the 7 regions in Botswana. Its position in the ranks since 1975 has risen; relative to other regions in Botswana, street construction in North-West has become more disconnected. North-West ranked 3rd in 1975, 6th in 1976-1990, 5th in 1991-2000 and 2nd in 2001-2014.

North-West in context: Aggregate street-network sprawl

As of 2014, the city with the most disconnected street network in North-West is Maun with an SNDi of 1.81, which is relatively well-connected. Conversely, the most connected city is Maun with an SNDi of 1.81, which is relatively well-connected. See trends for these cities: Maun, Maun

The level of street-network sprawl in the aggregate network in North-West rose steadily. To get a sense of how the aggregate street network has changed in North-West, we can consider one of its most populous cities: Maun. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in the aggregate network in Maun was at its lowest in 1976-1990.

To date, North-West is the 4th-most disconnected out of the 7 regions in Botswana. Its position in the ranks since 1975 has fallen; relative to other regions in Botswana, the street network in North-West has become more connected. North-West ranked 3rd in 1975, 6th in 1976-1990, 6th in 1991-2000 and 4th in 2001-2014.

Cities in North-West

• Maun