Street-network Sprawl in Ilesa, Nigeria

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.

Ilesa: city in Osun, Nigeria

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 Ilesa, Nigeria on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Ilesa as of 2014, the overall level of street-network sprawl is 4.23, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 3.44, 4.62, 6.19 and 5.9. Street construction in Ilesa 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 Ilesa spans a total of 658 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 3.44, 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 3.44, 3.5, 3.52 and 4.23. Overall, the SNDi of the aggregate street network has risen: the street network in Ilesa has become more disconnected.

Ilesa and Osun do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Ilesa peaked in 1991-2000, while the SNDi of street constructions in Osun rose steadily.

How do development practices in Ilesa fare in comparison to others in Osun? Most recently in 2001-2014, street construction in Ilesa was the 5th-most disconnected out of the 15 cities in Osun. Its position in the ranks since 1975 has not changed. Ilesa ranked 5th in 1975, 4th in 1976-1990, 2nd in 1991-2000 and 5th in 2001-2014.

Ilesa and Nigeria follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these peaked in 1991-2000.

How do development practices in Ilesa fare in comparison to others in Nigeria? Most recently in 2001-2014, street construction in Ilesa was the 42nd-most disconnected out of the 411 cities in Nigeria. Its position in the ranks since 1975 has fallen; relative to other cities in Nigeria, street construction in Ilesa has become more connected. Ilesa ranked 29th in 1975, 33rd in 1976-1990, 21st in 1991-2000 and 42nd in 2001-2014.

Ilesa and Osun follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these rose steadily.

To date, Ilesa is the 5th-most disconnected out of the 15 cities in Osun. Its position in the ranks since 1975 has not changed. Ilesa ranked 5th in 1975, 5th in 1976-1990, 6th in 1991-2000 and 5th in 2001-2014.

Ilesa and Nigeria follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these rose steadily.

To date, Ilesa is the 50th-most disconnected out of the 411 cities in Nigeria. Its position in the ranks since 1975 has fallen; relative to other cities in Nigeria, the street network in Ilesa has become more connected. Ilesa ranked 29th in 1975, 46th in 1976-1990, 60th in 1991-2000 and 50th in 2001-2014.

As of 2015, Ilesa had a built-up area of 29.62 square kilometers, and a population of 359019 people.

These are some other cities with approximately the same population: