Street-network Sprawl in Yirgalem, Ethiopia

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.

Yirgalem: city in Southern Nations, Nationalities and Peoples, Ethiopia

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 Yirgalem, Ethiopia on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Yirgalem as of 2014, the overall level of street-network sprawl is 0.25, which is very well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are nan, nan, -0.64 and 0.3. Data was not available in 1975 and 1976-1990.

Quantity of street network construction: The street network in Yirgalem spans a total of 78 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of nan, 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 nan, nan, -0.64 and 0.25. Data was not available in 1975 and 1976-1990.

Yirgalem and Southern Nations, Nationalities and Peoples do not follow the same trend in the disconnectivity of their street network constructions. There was not enough data from the city, while the SNDi of street constructions in Southern Nations, Nationalities and Peoples peaked in 1991-2000.

How do development practices in Yirgalem fare in comparison to others in Southern Nations, Nationalities and Peoples? Most recently in 2001-2014, street construction in Yirgalem was the 47th-most disconnected out of the 68 cities in Southern Nations, Nationalities and Peoples. Its position in the ranks since 1975 has fallen; relative to other cities in Southern Nations, Nationalities and Peoples, street construction in Yirgalem has become more connected. Yirgalem ranked 28th in 1991-2000 and 47th in 2001-2014. There was no ranking in 1975 and 1976-1990 due to unavailable data.

Yirgalem and Ethiopia do not follow the same trend in the disconnectivity of their street network constructions. There was not enough data from the city, while the SNDi of street constructions in Ethiopia followed a zig-zag trend with an overall increase.

How do development practices in Yirgalem fare in comparison to others in Ethiopia? Most recently in 2001-2014, street construction in Yirgalem was the 186th-most disconnected out of the 252 cities in Ethiopia. Its position in the ranks since 1975 has fallen; relative to other cities in Ethiopia, street construction in Yirgalem has become more connected. Yirgalem ranked 119th in 1991-2000 and 186th in 2001-2014. There was no ranking in 1975 and 1976-1990 due to unavailable data.

Yirgalem and Southern Nations, Nationalities and Peoples do not follow the same trend in the disconnectivity of their aggregate street networks. There was not enough data from the city, while the SNDi of street constructions in Southern Nations, Nationalities and Peoples peaked in 1991-2000.

To date, Yirgalem is the 50th-most disconnected out of the 68 cities in Southern Nations, Nationalities and Peoples. Its position in the ranks since 1975 has fallen; relative to other cities in Southern Nations, Nationalities and Peoples, the street network in Yirgalem has become more connected. Yirgalem ranked 31st in 1991-2000 and 50th in 2001-2014. There was no ranking in 1975 and 1976-1990 due to unavailable data.

Yirgalem and Ethiopia do not follow the same trend in the disconnectivity of their aggregate street networks. There was not enough data from the city, while the SNDi of street constructions in Ethiopia followed a zig-zag trend with an overall increase.

To date, Yirgalem is the 202nd-most disconnected out of the 252 cities in Ethiopia. Its position in the ranks since 1975 has fallen; relative to other cities in Ethiopia, the street network in Yirgalem has become more connected. Yirgalem ranked 137th in 1991-2000 and 202nd in 2001-2014. There was no ranking in 1975 and 1976-1990 due to unavailable data.

As of 2015, Yirgalem had a built-up area of 0.61 square kilometers, and a population of 307932 people.

These are some other cities with approximately the same population: