Street-network Sprawl in Amaigbo, 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.

Amaigbo: city in Imo, 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 Amaigbo, Nigeria on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Amaigbo as of 2014, the overall level of street-network sprawl is 2.42, which is in the 40th to 60th percentile of disconnectedness.

Trends in street network construction: The SNDis of street construction for the respective time periods are 1.4, 2.36, 2.38 and 2.57. In each period, new street development in Amaigbo steadily grows more disconnected than in the last. 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 0.19.

Quantity of street network construction: The street network in Amaigbo spans a total of 2505 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 2.36, which is in the 40th to 60th percentile of disconnectedness.

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 1.4, 2.34, 2.34 and 2.42. Overall, the SNDi of the aggregate street network has risen: the street network in Amaigbo has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.93 points, but between 1991-2000 and 2001-2014, it rose by just 0.08.

Amaigbo and Imo do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Amaigbo rose steadily, while the SNDi of street constructions in Imo followed a zig-zag trend with an overall increase.

How do development practices in Amaigbo fare in comparison to others in Imo? Most recently in 2001-2014, street construction in Amaigbo was the 5th-most disconnected out of the 10 cities in Imo. Its position in the ranks since 1975 has fallen; relative to other cities in Imo, street construction in Amaigbo has become more connected. Amaigbo ranked 4th in 1975, 5th in 1976-1990, 3rd in 1991-2000 and 5th in 2001-2014.

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

How do development practices in Amaigbo fare in comparison to others in Nigeria? Most recently in 2001-2014, street construction in Amaigbo was the 196th-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 Amaigbo has become more connected. Amaigbo ranked 120th in 1975, 145th in 1976-1990, 146th in 1991-2000 and 196th in 2001-2014.

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

To date, Amaigbo is the 6th-most disconnected out of the 10 cities in Imo. Its position in the ranks since 1975 has fallen; relative to other cities in Imo, the street network in Amaigbo has become more connected. Amaigbo ranked 4th in 1975, 6th in 1976-1990, 6th in 1991-2000 and 6th in 2001-2014.

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

To date, Amaigbo is the 167th-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 Amaigbo has become more connected. Amaigbo ranked 120th in 1975, 126th in 1976-1990, 141st in 1991-2000 and 167th in 2001-2014.

As of 2015, Amaigbo had a built-up area of 61.44 square kilometers, and a population of 1713470 people.

These are some other cities with approximately the same population: