Street-network Sprawl in Calabar, 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.

Calabar: city in Cross River, 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 Calabar, Nigeria on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Calabar as of 2014, the overall level of street-network sprawl is 4.33, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 3.42, 5.61, 5.47 and 5.56. Disconnectivity in street construction in Calabar follows a zig-zag trend. In 1975, street construction was most disconnected, while construction was most connected in 1976-1990.

Quantity of street network construction: The street network in Calabar spans a total of 827 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 3.42, 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 3.42, 3.72, 4.02 and 4.33. Overall, the SNDi of the aggregate street network has risen: the street network in Calabar has become more disconnected.

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

How do development practices in Calabar fare in comparison to others in Cross River? Most recently in 2001-2014, street construction in Calabar was the 1st-most disconnected out of the 6 cities in Cross River. Its position in the ranks since 1975 has not changed. Calabar ranked 1st in 1975, 1st in 1976-1990, 1st in 1991-2000 and 1st in 2001-2014.

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

How do development practices in Calabar fare in comparison to others in Nigeria? Most recently in 2001-2014, street construction in Calabar was the 57th-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 Calabar has become more connected. Calabar ranked 30th in 1975, 7th in 1976-1990, 34th in 1991-2000 and 57th in 2001-2014.

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

To date, Calabar is the 1st-most disconnected out of the 6 cities in Cross River. Its position in the ranks since 1975 has not changed. Calabar ranked 1st in 1975, 1st in 1976-1990, 1st in 1991-2000 and 1st in 2001-2014.

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

To date, Calabar is the 47th-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 Calabar has become more connected. Calabar ranked 30th in 1975, 39th in 1976-1990, 41st in 1991-2000 and 47th in 2001-2014.

As of 2015, Calabar had a built-up area of 30.46 square kilometers, and a population of 661593 people.

These are some other cities with approximately the same population: