Street-network Sprawl in Gaziantep, Turkey

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.

Gaziantep: region in Turkey

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 Gaziantep, Turkey on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Gaziantep as of 2014, the overall level of street-network sprawl is 1.03, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.61, 0.45, 1.72 and 2.35. The disconnectivity of new streets constructed in Gaziantep fell, then rose. In 1976-1990, new street layouts were the most connected.

Quantity of street network construction: The street network in Gaziantep spans a total of 7166 kilometers. The period with the greatest volume of street construction was 2001-2014. These roads have an SNDi of 2.35, 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 0.61, 0.5, 0.75 and 1.03. The SNDi of the aggregate street network in fell at first, but Gaziantep has worsened in disconnectivity since 1990.

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

How do development practices in Gaziantep fare in comparison to others in Turkey? Most recently in 2001-2014, street construction in Gaziantep was the 60th-most disconnected out of the 71 regions in Turkey. Its position in the ranks since 1975 has risen; relative to other regions in Turkey, street construction in Gaziantep has become more disconnected. Gaziantep ranked 69th in 1975, 70th in 1976-1990, 59th in 1991-2000 and 60th in 2001-2014.

As of 2014, the city with the most disconnected street network in Gaziantep is Aktoprak with an SNDi of 1.21, which is relatively well-connected. Conversely, the most connected city is Nizip with an SNDi of -0.0, which is very well-connected. See trends for these cities: Nizip, Aktoprak

The level of street-network sprawl in the aggregate network in Gaziantep was at its lowest in 1976-1990. To get a sense of how the aggregate street network has changed in Gaziantep, we can consider three of its most populous cities: Gaziantep, Aktoprak and Nizip. Out of the three cities, Aktoprak and Nizip do not follow the same trend as the region. The level of street-network sprawl in the aggregate network in Aktoprak peaked in 1976-1990. The level of street-network sprawl in the aggregate network in Nizip rose steadily.

To date, Gaziantep is the 68th-most disconnected out of the 71 regions in Turkey. Its position in the ranks since 1975 has risen; relative to other regions in Turkey, the street network in Gaziantep has become more disconnected. Gaziantep ranked 69th in 1975, 70th in 1976-1990, 69th in 1991-2000 and 68th in 2001-2014.