Street-network Sprawl in Aşgabat, Turkmenistan

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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.

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Aşgabat: region in Turkmenistan

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 Aşgabat, Turkmenistan on the sprawlmap

How have Aşgabat's street networks changed over time?

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Aşgabat as of 2014, the overall level of street-network sprawl is 1.83, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 1.94, 2.17, 1.1 and 1.77. Disconnectivity in street construction in Aşgabat follows a zig-zag trend. In 1991-2000, street construction was most disconnected, while construction was most connected in 1976-1990.

Quantity of street network construction: The street network in Aşgabat spans a total of 1020 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 1.94, 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 1.94, 2.02, 1.84 and 1.83. The aggregate street network in Aşgabat increased in disconnectivity initially,but the trend has turned around after 1990.

Aşgabat in context: Street-network sprawl of new development

The level of street-network sprawl in new development in Aşgabat followed a zig-zag trend with an overall decrease. To get a sense of how street development has changed in Aşgabat, we can consider one of its most populous cities: Ashgabat. Disconnectivity in the most populous cities in Aşgabat follow the same region trend.

How do development practices in Aşgabat fare in comparison to others in Turkmenistan? Most recently in 2001-2014, street construction in Aşgabat was the 6th-most disconnected out of the 6 regions in Turkmenistan. Its position in the ranks since 1975 has fallen; relative to other regions in Turkmenistan, street construction in Aşgabat has become more connected. Aşgabat ranked 4th in 1975, 6th in 1976-1990, 6th in 1991-2000 and 6th in 2001-2014.

Aşgabat in context: Aggregate street-network sprawl

As of 2014, the city with the most disconnected street network in Aşgabat is Ashgabat with an SNDi of 1.75, which is relatively well-connected. Conversely, the most connected city is Ashgabat with an SNDi of 1.75, which is relatively well-connected. See trends for these cities: Ashgabat, Ashgabat

The level of street-network sprawl in the aggregate network in Aşgabat peaked in 1976-1990. To get a sense of how the aggregate street network has changed in Aşgabat, we can consider one of its most populous cities: Ashgabat. Disconnectivity in the most populous cities in Aşgabat follow the same region trend.

To date, Aşgabat is the 6th-most disconnected out of the 6 regions in Turkmenistan. Its position in the ranks since 1975 has fallen; relative to other regions in Turkmenistan, the street network in Aşgabat has become more connected. Aşgabat ranked 4th in 1975, 5th in 1976-1990, 6th in 1991-2000 and 6th in 2001-2014.

Cities in Aşgabat

• Ashgabat