Street-network Sprawl in Okwuzu, 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.

Okwuzu: city in Rivers, 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 Okwuzu, Nigeria on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Okwuzu as of 2014, the overall level of street-network sprawl is 1.63, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.99, 1.52, 3.84 and 4.13. In each period, new street development in Okwuzu steadily grows more disconnected than in the last. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.53 points, but between 1991-2000 and 2001-2014, it rose by just 0.3.

Quantity of street network construction: The street network in Okwuzu spans a total of 40 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 1.52, which is relatively 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 0.99, 1.45, 1.53 and 1.63. Overall, the SNDi of the aggregate street network has risen: the street network in Okwuzu has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.46 points, but between 1991-2000 and 2001-2014, it rose by just 0.1.

Okwuzu and Rivers follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these rose steadily.

How do development practices in Okwuzu fare in comparison to others in Rivers? Most recently in 2001-2014, street construction in Okwuzu was the 9th-most disconnected out of the 15 cities in Rivers. Its position in the ranks since 1975 has risen; relative to other cities in Rivers, street construction in Okwuzu has become more disconnected. Okwuzu ranked 11th in 1975, 13th in 1976-1990, 10th in 1991-2000 and 9th in 2001-2014.

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

How do development practices in Okwuzu fare in comparison to others in Nigeria? Most recently in 2001-2014, street construction in Okwuzu was the 117th-most disconnected out of the 411 cities in Nigeria. Its position in the ranks since 1975 has risen; relative to other cities in Nigeria, street construction in Okwuzu has become more disconnected. Okwuzu ranked 145th in 1975, 194th in 1976-1990, 98th in 1991-2000 and 117th in 2001-2014.

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

To date, Okwuzu is the 13th-most disconnected out of the 15 cities in Rivers. Its position in the ranks since 1975 has fallen; relative to other cities in Rivers, the street network in Okwuzu has become more connected. Okwuzu ranked 11th in 1975, 13th in 1976-1990, 13th in 1991-2000 and 13th in 2001-2014.

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

To date, Okwuzu is the 227th-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 Okwuzu has become more connected. Okwuzu ranked 145th in 1975, 184th in 1976-1990, 195th in 1991-2000 and 227th in 2001-2014.

As of 2015, Okwuzu had a built-up area of 3.06 square kilometers, and a population of 54640 people.

These are some other cities with approximately the same population: