Street-network Sprawl in Takhar, Afghanistan

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.

Takhar: region in Afghanistan

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 Takhar, Afghanistan on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Takhar as of 2014, the overall level of street-network sprawl is 7.51, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 8.56, 5.92, 9.7 and 5.79. Disconnectivity in street construction in Takhar follows a zig-zag trend. In 2001-2014, street construction was most disconnected, while construction was most connected in 1991-2000.

Quantity of street network construction: The street network in Takhar spans a total of 149 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 8.56, 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 8.56, 8.04, 8.2 and 7.51. Disconnectivity in Takhar's street network follows a zig-zag trend. In 2001-2014, the region was most disconnected; while it was most connected in 1975.

The level of street-network sprawl in new development in Takhar followed a zig-zag trend with an overall decrease. To get a sense of how street development has changed in Takhar, we can consider three of its most populous cities: Taloqan, Rustaq and Chayab. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Taloqan followed a zig-zag trend with an overall decrease. The level of street-network sprawl in new development in Rustaq followed a zig-zag trend. The level of street-network sprawl in new development in Chayab followed a zig-zag trend.

How do development practices in Takhar fare in comparison to others in Afghanistan? Most recently in 2001-2014, street construction in Takhar was the 6th-most disconnected out of the 25 regions in Afghanistan. Its position in the ranks since 1975 has fallen; relative to other regions in Afghanistan, street construction in Takhar has become more connected. Takhar ranked 2nd in 1975, 3rd in 1976-1990, 1st in 1991-2000 and 6th in 2001-2014.

As of 2014, the city with the most disconnected street network in Takhar is Chayab with an SNDi of 10.36, which is highly disconnected. Conversely, the most connected city is Taloqan with an SNDi of 4.61, which is highly disconnected. See trends for these cities: Taloqan, Chayab

The level of street-network sprawl in the aggregate network in Takhar followed a zig-zag trend with an overall decrease. To get a sense of how the aggregate street network has changed in Takhar, we can consider three of its most populous cities: Taloqan, Rustaq and Chayab. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in the aggregate network in Taloqan was at its lowest in 1976-1990. The level of street-network sprawl in the aggregate network in Rustaq rose steadily. The level of street-network sprawl in the aggregate network in Chayab followed a zig-zag trend.

To date, Takhar is the 4th-most disconnected out of the 25 regions in Afghanistan. Its position in the ranks since 1975 has fallen; relative to other regions in Afghanistan, the street network in Takhar has become more connected. Takhar ranked 2nd in 1975, 2nd in 1976-1990, 3rd in 1991-2000 and 4th in 2001-2014.