Street-network Sprawl in Al Bahr al Ahmar, Egypt

---

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:

• nodal degree
• dendricity, the tree-likeness of the street network
• circuity, the ratio of the distance by road to the straight-line distance of two locations on the street network
• sinuosity, the curviness of a street

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:

• Global trends toward urban street-network sprawl
• A global assessment of street-network sprawl

To see the state of street-network sprawl across the globe, visit the sprawlmap.

---

Al Bahr al Ahmar: region in Egypt

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 Al Bahr al Ahmar, Egypt on the sprawlmap

How have Al Bahr al Ahmar's street networks changed over time?

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Al Bahr al Ahmar as of 2014, the overall level of street-network sprawl is 3.24, 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 1.85, 5.38, 4.94 and 2.16. Street construction in Al Bahr al Ahmar increased in disconnectivity initially but has since improved. The streets constructed in 1976-1990 were the most disconnected.

Quantity of street network construction: The street network in Al Bahr al Ahmar spans a total of 1042 kilometers. The period with the greatest volume of street construction was 1991-2000. These roads have an SNDi of 4.94, which is highly disconnected.

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 1.85, 2.88, 3.65 and 3.24. The aggregate street network in Al Bahr al Ahmar increased in disconnectivity initially,but the trend has turned around after 2000.

Al Bahr al Ahmar in context: Street-network sprawl of new development

The level of street-network sprawl in new development in Al Bahr al Ahmar peaked in 1976-1990. To get a sense of how street development has changed in Al Bahr al Ahmar, we can consider one of its most populous cities: Hurghada. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Hurghada peaked in 1991-2000.

How do development practices in Al Bahr al Ahmar fare in comparison to others in Egypt? Most recently in 2001-2014, street construction in Al Bahr al Ahmar was the 22nd-most disconnected out of the 25 regions in Egypt. Its position in the ranks since 1975 has fallen; relative to other regions in Egypt, street construction in Al Bahr al Ahmar has become more connected. Al Bahr al Ahmar ranked 21st in 1975, 4th in 1976-1990, 8th in 1991-2000 and 22nd in 2001-2014.

Al Bahr al Ahmar in context: Aggregate street-network sprawl

As of 2014, the city with the most disconnected street network in Al Bahr al Ahmar is Hurghada with an SNDi of 1.76, which is relatively well-connected. Conversely, the most connected city is Hurghada with an SNDi of 1.76, which is relatively well-connected. See trends for these cities: Hurghada, Hurghada

The level of street-network sprawl in the aggregate network in Al Bahr al Ahmar peaked in 1991-2000. To get a sense of how the aggregate street network has changed in Al Bahr al Ahmar, we can consider one of its most populous cities: Hurghada. Disconnectivity in the most populous cities in Al Bahr al Ahmar follow the same region trend.

To date, Al Bahr al Ahmar is the 15th-most disconnected out of the 25 regions in Egypt. Its position in the ranks since 1975 has risen; relative to other regions in Egypt, the street network in Al Bahr al Ahmar has become more disconnected. Al Bahr al Ahmar ranked 21st in 1975, 15th in 1976-1990, 10th in 1991-2000 and 15th in 2001-2014.

Cities in Al Bahr al Ahmar

• Hurghada