Street-network Sprawl in Dosso, Niger

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.

Dosso: region in Niger

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 Dosso, Niger on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Dosso as of 2014, the overall level of street-network sprawl is 1.31, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.02, 1.31, 1.24 and 1.62. Disconnectivity in street construction in Dosso follows a zig-zag trend. In 1975, street construction was most disconnected, while construction was most connected in 2001-2014.

Quantity of street network construction: The street network in Dosso spans a total of 3791 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 1.62, 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 0.02, 0.97, 1.08 and 1.31. Overall, the SNDi of the aggregate street network has risen: the street network in Dosso has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.96 points, but between 1991-2000 and 2001-2014, it rose by just 0.24.

The level of street-network sprawl in new development in Dosso followed a zig-zag trend with an overall increase. To get a sense of how street development has changed in Dosso, we can consider three of its most populous cities: Dosso, Gaya and Dogondoutchi. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Dosso rose steadily. The level of street-network sprawl in new development in Gaya was at its lowest in 1991-2000. The level of street-network sprawl in new development in Dogondoutchi was at its lowest in 1991-2000.

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

As of 2014, the city with the most disconnected street network in Dosso is Dosso with an SNDi of 0.49, which is relatively well-connected. Conversely, the most connected city is Dogondoutchi with an SNDi of -0.03, which is very well-connected. See trends for these cities: Dogondoutchi, Dosso

The level of street-network sprawl in the aggregate network in Dosso rose steadily. To get a sense of how the aggregate street network has changed in Dosso, we can consider three of its most populous cities: Dosso, Gaya and Dogondoutchi. Out of the three cities, Gaya and Dogondoutchi do not follow the same trend as the region. The level of street-network sprawl in the aggregate network in Gaya was at its lowest in 1991-2000. The level of street-network sprawl in the aggregate network in Dogondoutchi was at its lowest in 1991-2000.

To date, Dosso is the 6th-most disconnected out of the 8 regions in Niger. Its position in the ranks since 1975 has risen; relative to other regions in Niger, the street network in Dosso has become more disconnected. Dosso ranked 7th in 1975, 5th in 1976-1990, 6th in 1991-2000 and 6th in 2001-2014.