Street-network Sprawl in Solwezi, Zambia

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.

Solwezi: city in North-Western, Zambia

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 Solwezi, Zambia on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Solwezi as of 2014, the overall level of street-network sprawl is 2.34, 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 1.32, 1.27, 0.71 and 3.5. The disconnectivity of new streets constructed in Solwezi fell, then rose. In 1991-2000, new street layouts were the most connected.

Quantity of street network construction: The street network in Solwezi spans a total of 159 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 3.5, 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 1.32, 1.27, 1.19 and 2.34. The SNDi of the aggregate street network in fell at first, but Solwezi has worsened in disconnectivity since 2000.

Solwezi and North-Western do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Solwezi was at its lowest in 1991-2000, while the SNDi of street constructions in North-Western was at its lowest in 1976-1990.

How do development practices in Solwezi fare in comparison to others in North-Western? Most recently in 2001-2014, street construction in Solwezi was the 2nd-most disconnected out of the 3 cities in North-Western. Its position in the ranks since 1975 has not changed. Solwezi ranked 2nd in 1975, 2nd in 1976-1990, 2nd in 1991-2000 and 2nd in 2001-2014.

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

How do development practices in Solwezi fare in comparison to others in Zambia? Most recently in 2001-2014, street construction in Solwezi was the 8th-most disconnected out of the 38 cities in Zambia. Its position in the ranks since 1975 has risen; relative to other cities in Zambia, street construction in Solwezi has become more disconnected. Solwezi ranked 21st in 1975, 27th in 1976-1990, 27th in 1991-2000 and 8th in 2001-2014.

Solwezi and North-Western do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Solwezi was at its lowest in 1991-2000, while the SNDi of street constructions in North-Western was at its lowest in 1976-1990.

To date, Solwezi is the 3rd-most disconnected out of the 3 cities in North-Western. Its position in the ranks since 1975 has fallen; relative to other cities in North-Western, the street network in Solwezi has become more connected. Solwezi ranked 2nd in 1975, 3rd in 1976-1990, 3rd in 1991-2000 and 3rd in 2001-2014.

Solwezi and Zambia do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Solwezi was at its lowest in 1991-2000, while the SNDi of street constructions in Zambia rose steadily.

To date, Solwezi is the 15th-most disconnected out of the 38 cities in Zambia. Its position in the ranks since 1975 has risen; relative to other cities in Zambia, the street network in Solwezi has become more disconnected. Solwezi ranked 21st in 1975, 26th in 1976-1990, 28th in 1991-2000 and 15th in 2001-2014.

As of 2015, Solwezi had a built-up area of 12.48 square kilometers, and a population of 111818 people.

These are some other cities with approximately the same population: