Street-network Sprawl in Rwanda

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.

Rwanda

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 Rwanda on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Rwanda as of 2014, the overall level of street-network sprawl is 3.7, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 3.01, 3.65, 3.69 and 3.63. Street construction in Rwanda 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 Rwanda spans a total of 71844 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 3.63, 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 3.01, 3.63, 3.71 and 3.7. The aggregate street network in Rwanda increased in disconnectivity initially,but the trend has turned around after 2000.

The level of street-network sprawl in new development in Rwanda peaked in 1991-2000. To get a sense of how street development has changed in Rwanda, we can consider three of its most populous regions: Umujyi wa Kigali, Amajyepfo and Amajyaruguru. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Umujyi wa Kigali followed a zig-zag trend with an overall decrease. The level of street-network sprawl in new development in Amajyepfo was at its lowest in 1976-1990. The level of street-network sprawl in new development in Amajyaruguru followed a zig-zag trend with an overall decrease.

How do development practices in Rwanda fare in comparison to others in the world? Most recently in 2001-2014, street construction in Rwanda was the 108th-most disconnected out of the 155 countries in the world. Its position in the ranks since 1975 has fallen; relative to other countries in the world, street construction in Rwanda has become more connected. Rwanda ranked 66th in 1975, 62nd in 1976-1990, 97th in 1991-2000 and 108th in 2001-2014.

The largest city in Rwanda is Kigali, with a population of 1114800 people. Taking into account the entire (i.e. aggregate) street network in Kigali as of 2014, the overall level of street-network sprawl is 3.39, which is highly disconnected. The level of street-network sprawl in new development in Kigali followed a zig-zag trend with an overall decrease.

As of 2014, the city with the most disconnected street network in Rwanda is Kigali with an SNDi of 3.39, which is highly disconnected. Conversely, the most connected city is Nyundo with an SNDi of 1.37, which is relatively well-connected. See trends for these cities: Nyundo, Kigali

The level of street-network sprawl in the aggregate network in Rwanda peaked in 1991-2000. To get a sense of how the aggregate street network has changed in Rwanda, we can consider three of its most populous regions: Umujyi wa Kigali, Amajyepfo and Amajyaruguru. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in the aggregate network in Umujyi wa Kigali was at its lowest in 1976-1990. The level of street-network sprawl in the aggregate network in Amajyepfo was at its lowest in 1976-1990. The level of street-network sprawl in the aggregate network in Amajyaruguru followed a zig-zag trend with an overall decrease.

To date, Rwanda is the 64th-most disconnected out of the 155 countries in the world. Its position in the ranks since 1975 has risen; relative to other countries in the world, the street network in Rwanda has become more disconnected. Rwanda ranked 66th in 1975, 55th in 1976-1990, 58th in 1991-2000 and 64th in 2001-2014.

The largest city in Rwanda is Kigali, with a population of 1114800 people. Taking into account the entire (i.e. aggregate) street network in Kigali as of 2014, the overall level of street-network sprawl is 3.39, which is highly disconnected. The level of street-network sprawl in the aggregate network in Kigali was at its lowest in 1976-1990.