Street-network Sprawl in Sangarédi, Guinea


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.

Sangarédi: city in Boké, Guinea

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 Sangarédi, Guinea on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Sangarédi as of 2014, the overall level of street-network sprawl is 0.6, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 1.35, 0.08, 0.77 and 2.02. The disconnectivity of new streets constructed in Sangarédi fell, then rose. In 1976-1990, new street layouts were the most connected.

Quantity of street network construction: The street network in Sangarédi spans a total of 103 kilometers. It is dominated by roads constructed in 1991-2000. These roads have an SNDi of 0.77, 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 1.35, 0.26, 0.52 and 0.6. The SNDi of the aggregate street network in fell at first, but Sangarédi has worsened in disconnectivity since 1990.

Sangarédi and Boké follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these was at its lowest in 1976-1990.

How do development practices in Sangarédi fare in comparison to others in Boké? Most recently in 2001-2014, street construction in Sangarédi was the 3rd-most disconnected out of the 4 cities in Boké. Its position in the ranks since 1975 has not changed. Sangarédi ranked 3rd in 1975, 3rd in 1976-1990, 4th in 1991-2000 and 3rd in 2001-2014.

Sangarédi and Guinea do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Sangarédi was at its lowest in 1976-1990, while the SNDi of street constructions in Guinea rose steadily.

How do development practices in Sangarédi fare in comparison to others in Guinea? Most recently in 2001-2014, street construction in Sangarédi was the 14th-most disconnected out of the 18 cities in Guinea. Its position in the ranks since 1975 has fallen; relative to other cities in Guinea, street construction in Sangarédi has become more connected. Sangarédi ranked 12th in 1975, 14th in 1976-1990, 16th in 1991-2000 and 14th in 2001-2014.

Sangarédi and Boké follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these was at its lowest in 1976-1990.

To date, Sangarédi is the 4th-most disconnected out of the 4 cities in Boké. Its position in the ranks since 1975 has fallen; relative to other cities in Boké, the street network in Sangarédi has become more connected. Sangarédi ranked 3rd in 1975, 4th in 1976-1990, 4th in 1991-2000 and 4th in 2001-2014.

Sangarédi and Guinea do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Sangarédi was at its lowest in 1976-1990, while the SNDi of street constructions in Guinea rose steadily.

To date, Sangarédi is the 16th-most disconnected out of the 18 cities in Guinea. Its position in the ranks since 1975 has fallen; relative to other cities in Guinea, the street network in Sangarédi has become more connected. Sangarédi ranked 12th in 1975, 15th in 1976-1990, 16th in 1991-2000 and 16th in 2001-2014.

As of 2015, Sangarédi had a built-up area of 3.19 square kilometers, and a population of 88493 people.

These are some other cities with approximately the same population: