Street-network Sprawl in Wau, South Sudan

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.

Wau: city in West Bahr-al-Ghazal, South Sudan

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 Wau, South Sudan on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Wau as of 2014, the overall level of street-network sprawl is 0.79, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.25, 0.09, 1.16 and 2.25. The disconnectivity of new streets constructed in Wau fell, then rose. In 1976-1990, new street layouts were the most connected.

Quantity of street network construction: The street network in Wau spans a total of 510 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 0.25, 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 0.25, 0.21, 0.34 and 0.79. The SNDi of the aggregate street network in fell at first, but Wau has worsened in disconnectivity since 1990.

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

How do development practices in Wau fare in comparison to others in West Bahr-al-Ghazal? Most recently in 2001-2014, street construction in Wau was the 2nd-most disconnected out of the 2 cities in West Bahr-al-Ghazal. Its position in the ranks since 1975 has fallen; relative to other cities in West Bahr-al-Ghazal, street construction in Wau has become more connected. Wau ranked 1st in 1975, 1st in 1976-1990, 1st in 1991-2000 and 2nd in 2001-2014.

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

How do development practices in Wau fare in comparison to others in South Sudan? Most recently in 2001-2014, street construction in Wau was the 13th-most disconnected out of the 26 cities in South Sudan. Its position in the ranks since 1975 has fallen; relative to other cities in South Sudan, street construction in Wau has become more connected. Wau ranked 5th in 1975, 7th in 1976-1990, 4th in 1991-2000 and 13th in 2001-2014.

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

To date, Wau is the 2nd-most disconnected out of the 2 cities in West Bahr-al-Ghazal. Its position in the ranks since 1975 has fallen; relative to other cities in West Bahr-al-Ghazal, the street network in Wau has become more connected. Wau ranked 1st in 1975, 1st in 1976-1990, 1st in 1991-2000 and 2nd in 2001-2014.

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

To date, Wau is the 17th-most disconnected out of the 26 cities in South Sudan. Its position in the ranks since 1975 has fallen; relative to other cities in South Sudan, the street network in Wau has become more connected. Wau ranked 5th in 1975, 9th in 1976-1990, 11th in 1991-2000 and 17th in 2001-2014.

As of 2015, Wau had a built-up area of 14.37 square kilometers, and a population of 235262 people.

These are some other cities with approximately the same population: