Street-network Sprawl in Erigavo, Somalia

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.

Erigavo: city in Sanaag, Somalia

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 Erigavo, Somalia on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Erigavo as of 2014, the overall level of street-network sprawl is 1.13, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.22, -0.64, -0.15 and 3.99. The disconnectivity of new streets constructed in Erigavo fell, then rose. In 1976-1990, new street layouts were the most connected.

Quantity of street network construction: The street network in Erigavo spans a total of 188 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of -0.64, which is very 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 0.22, -0.62, -0.57 and 1.13. The SNDi of the aggregate street network in fell at first, but Erigavo has worsened in disconnectivity since 1990.

Erigavo and Sanaag do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Erigavo was at its lowest in 1976-1990, while the SNDi of street constructions in Sanaag followed a zig-zag trend with an overall increase.

How do development practices in Erigavo fare in comparison to others in Sanaag? Most recently in 2001-2014, street construction in Erigavo was the 1st-most disconnected out of the 1 cities in Sanaag. Its position in the ranks since 1975 has not changed. Erigavo ranked 1st in 1975, 1st in 1976-1990, 1st in 1991-2000 and 1st in 2001-2014.

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

How do development practices in Erigavo fare in comparison to others in Somalia? Most recently in 2001-2014, street construction in Erigavo was the 2nd-most disconnected out of the 23 cities in Somalia. Its position in the ranks since 1975 has risen; relative to other cities in Somalia, street construction in Erigavo has become more disconnected. Erigavo ranked 8th in 1975, 17th in 1976-1990, 10th in 1991-2000 and 2nd in 2001-2014.

Erigavo and Sanaag do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Erigavo was at its lowest in 1976-1990, while the SNDi of street constructions in Sanaag peaked in 1976-1990.

To date, Erigavo is the 1st-most disconnected out of the 1 cities in Sanaag. Its position in the ranks since 1975 has not changed. Erigavo ranked 1st in 1975, 1st in 1976-1990, 1st in 1991-2000 and 1st in 2001-2014.

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

To date, Erigavo is the 7th-most disconnected out of the 23 cities in Somalia. Its position in the ranks since 1975 has risen; relative to other cities in Somalia, the street network in Erigavo has become more disconnected. Erigavo ranked 8th in 1975, 19th in 1976-1990, 19th in 1991-2000 and 7th in 2001-2014.

As of 2015, Erigavo had a built-up area of 1.69 square kilometers, and a population of 103984 people.

These are some other cities with approximately the same population: