Street-network Sprawl in Asaba, 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.

Asaba: city in Delta, 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 Asaba, Nigeria on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Asaba as of 2014, the overall level of street-network sprawl is 2.92, 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 3.04, 4.23, 2.76 and 2.81. Disconnectivity in street construction in Asaba follows a zig-zag trend. In 1991-2000, street construction was most disconnected, while construction was most connected in 1976-1990.

Quantity of street network construction: The street network in Asaba spans a total of 753 kilometers. It is dominated by roads constructed in 1991-2000. These roads have an SNDi of 2.76, 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 3.04, 3.35, 2.95 and 2.92. The aggregate street network in Asaba increased in disconnectivity initially,but the trend has turned around after 1990.

Asaba and Delta follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these followed a zig-zag trend with an overall decrease.

How do development practices in Asaba fare in comparison to others in Delta? Most recently in 2001-2014, street construction in Asaba was the 13th-most disconnected out of the 16 cities in Delta. Its position in the ranks since 1975 has fallen; relative to other cities in Delta, street construction in Asaba has become more connected. Asaba ranked 6th in 1975, 4th in 1976-1990, 12th in 1991-2000 and 13th in 2001-2014.

Asaba and Nigeria do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Asaba followed a zig-zag trend with an overall decrease, while the SNDi of street constructions in Nigeria peaked in 1991-2000.

How do development practices in Asaba fare in comparison to others in Nigeria? Most recently in 2001-2014, street construction in Asaba was the 183rd-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 Asaba has become more connected. Asaba ranked 44th in 1975, 46th in 1976-1990, 136th in 1991-2000 and 183rd in 2001-2014.

Asaba and Delta do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Asaba peaked in 1976-1990, while the SNDi of street constructions in Delta followed a zig-zag trend with an overall increase.

To date, Asaba is the 12th-most disconnected out of the 16 cities in Delta. Its position in the ranks since 1975 has fallen; relative to other cities in Delta, the street network in Asaba has become more connected. Asaba ranked 6th in 1975, 5th in 1976-1990, 9th in 1991-2000 and 12th in 2001-2014.

Asaba and Nigeria do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Asaba peaked in 1976-1990, while the SNDi of street constructions in Nigeria rose steadily.

To date, Asaba is the 133rd-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 Asaba has become more connected. Asaba ranked 44th in 1975, 58th in 1976-1990, 94th in 1991-2000 and 133rd in 2001-2014.

As of 2015, Asaba had a built-up area of 30.83 square kilometers, and a population of 278618 people.

These are some other cities with approximately the same population: