Street-network Sprawl in `Asir, Saudi Arabia

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.

`Asir: region in Saudi Arabia

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 `Asir, Saudi Arabia on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in `Asir as of 2014, the overall level of street-network sprawl is 3.03, which is in the 40th to 60th percentile of disconnectedness.

Trends in street network construction: The SNDis of street construction for the respective time periods are 6.25, 2.31, 3.04 and 2.83. Disconnectivity in street construction in `Asir follows a zig-zag trend. In 1976-1990, street construction was most disconnected, while construction was most connected in 1975.

Quantity of street network construction: The street network in `Asir spans a total of 3383 kilometers. The period with the greatest volume of street construction was 1991-2000. These roads have an SNDi of 3.04, which is in the 40th to 60th percentile of disconnectedness.

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 6.25, 3.09, 3.04 and 3.03. Overall, the SNDi of the aggregate street network has fallen: the street network in `Asir has become more connected.

The level of street-network sprawl in new development in `Asir followed a zig-zag trend with an overall decrease. To get a sense of how street development has changed in `Asir, we can consider three of its most populous cities: Khamis Mushait, Abha and Muhayil. Out of the three cities, Abha and Muhayil do not follow the same trend as the region. The level of street-network sprawl in new development in Abha was at its lowest in 1976-1990. The level of street-network sprawl in new development in Muhayil followed a zig-zag trend.

How do development practices in `Asir fare in comparison to others in Saudi Arabia? Most recently in 2001-2014, street construction in `Asir was the 7th-most disconnected out of the 12 regions in Saudi Arabia. Its position in the ranks since 1975 has fallen; relative to other regions in Saudi Arabia, street construction in `Asir has become more connected. `Asir ranked 1st in 1975, 5th in 1976-1990, 5th in 1991-2000 and 7th in 2001-2014.

As of 2014, the city with the most disconnected street network in `Asir is King Faisal Military City with an SNDi of 2.8, which is in the 40th to 60th percentile of disconnectedness. Conversely, the most connected city is Bisha with an SNDi of 1.22, which is relatively well-connected. See trends for these cities: Bisha, King Faisal Military City

The level of street-network sprawl in the aggregate network in `Asir fell steadily. To get a sense of how the aggregate street network has changed in `Asir, we can consider three of its most populous cities: Khamis Mushait, Abha and Muhayil. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in the aggregate network in Khamis Mushait was at its lowest in 1976-1990. The level of street-network sprawl in the aggregate network in Abha was at its lowest in 1976-1990. The level of street-network sprawl in the aggregate network in Muhayil followed a zig-zag trend.

To date, `Asir is the 1st-most disconnected out of the 12 regions in Saudi Arabia. Its position in the ranks since 1975 has not changed. `Asir ranked 1st in 1975, 1st in 1976-1990, 1st in 1991-2000 and 1st in 2001-2014.