Street-network Sprawl in El Hamma, Tunisia

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.

El Hamma: city in Gabès, Tunisia

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 El Hamma, Tunisia on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in El Hamma as of 2014, the overall level of street-network sprawl is 0.61, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.45, 0.75, nan and 0.55. Data was not available in 1991-2000.

Quantity of street network construction: The street network in El Hamma spans a total of 149 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 0.75, 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 0.45, 0.6, 0.62 and 0.61. The aggregate street network in El Hamma increased in disconnectivity initially,but the trend has turned around after 2000.

El Hamma and Gabès do not follow the same trend in the disconnectivity of their street network constructions. There was not enough data from the city, while the SNDi of street constructions in Gabès followed a zig-zag trend with an overall decrease.

How do development practices in El Hamma fare in comparison to others in Gabès? Most recently in 2001-2014, street construction in El Hamma was the 1st-most disconnected out of the 2 cities in Gabès. Its position in the ranks since 1975 has not changed. El Hamma ranked 2nd in 1975, 2nd in 1976-1990 and 1st in 2001-2014. There was no ranking in 1991-2000 due to unavailable data.

El Hamma and Tunisia do not follow the same trend in the disconnectivity of their street network constructions. There was not enough data from the city, while the SNDi of street constructions in Tunisia rose steadily.

How do development practices in El Hamma fare in comparison to others in Tunisia? Most recently in 2001-2014, street construction in El Hamma was the 20th-most disconnected out of the 26 cities in Tunisia. Its position in the ranks since 1975 has fallen; relative to other cities in Tunisia, street construction in El Hamma has become more connected. El Hamma ranked 18th in 1975, 22nd in 1976-1990 and 20th in 2001-2014. There was no ranking in 1991-2000 due to unavailable data.

El Hamma and Gabès do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in El Hamma peaked in 1991-2000, while the SNDi of street constructions in Gabès followed a zig-zag trend with an overall decrease.

To date, El Hamma is the 2nd-most disconnected out of the 2 cities in Gabès. Its position in the ranks since 1975 has not changed. El Hamma ranked 2nd in 1975, 2nd in 1976-1990, 2nd in 1991-2000 and 2nd in 2001-2014.

El Hamma and Tunisia do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in El Hamma peaked in 1991-2000, while the SNDi of street constructions in Tunisia rose steadily.

To date, El Hamma is the 21st-most disconnected out of the 26 cities in Tunisia. Its position in the ranks since 1975 has fallen; relative to other cities in Tunisia, the street network in El Hamma has become more connected. El Hamma ranked 18th in 1975, 20th in 1976-1990, 20th in 1991-2000 and 21st in 2001-2014.

As of 2015, El Hamma had a built-up area of 5.66 square kilometers, and a population of 62277 people.

These are some other cities with approximately the same population: