Street-network Sprawl in N'Djamena, Chad

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.

N'Djamena: city in Ville de N'Djamena, Chad

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 N'Djamena, Chad on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in N'Djamena as of 2014, the overall level of street-network sprawl is 0.17, which is very well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are -0.11, 0.07, 0.41 and 0.17. Street construction in N'Djamena 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 N'Djamena spans a total of 2529 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 0.17, which is very 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 -0.11, -0.03, 0.17 and 0.17. The aggregate street network in N'Djamena increased in disconnectivity initially,but the trend has turned around after 2000.

N'Djamena and Ville de N'Djamena do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in N'Djamena peaked in 1991-2000, while the SNDi of street constructions in Ville de N'Djamena rose steadily.

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

N'Djamena and Chad do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in N'Djamena peaked in 1991-2000, while the SNDi of street constructions in Chad peaked in 1976-1990.

How do development practices in N'Djamena fare in comparison to others in Chad? Most recently in 2001-2014, street construction in N'Djamena was the 11th-most disconnected out of the 26 cities in Chad. Its position in the ranks since 1975 has fallen; relative to other cities in Chad, street construction in N'Djamena has become more connected. N'Djamena ranked 5th in 1975, 7th in 1976-1990, 8th in 1991-2000 and 11th in 2001-2014.

N'Djamena and Ville de N'Djamena do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in N'Djamena peaked in 1991-2000, while the SNDi of street constructions in Ville de N'Djamena rose steadily.

To date, N'Djamena is the 1st-most disconnected out of the 1 cities in Ville de N'Djamena. Its position in the ranks since 1975 has not changed. N'Djamena ranked 1st in 1975, 1st in 1976-1990, 1st in 1991-2000 and 1st in 2001-2014.

N'Djamena and Chad do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in N'Djamena peaked in 1991-2000, while the SNDi of street constructions in Chad rose steadily.

To date, N'Djamena is the 13th-most disconnected out of the 26 cities in Chad. Its position in the ranks since 1975 has fallen; relative to other cities in Chad, the street network in N'Djamena has become more connected. N'Djamena ranked 5th in 1975, 10th in 1976-1990, 10th in 1991-2000 and 13th in 2001-2014.

As of 2015, N'Djamena had a built-up area of 83.45 square kilometers, and a population of 1775331 people.

These are some other cities with approximately the same population: