Street-network Sprawl in Georgia

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.

Georgia

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 Georgia on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Georgia as of 2014, the overall level of street-network sprawl is 4.65, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 4.22, 4.93, 5.9 and 6.13. In each period, new street development in Georgia steadily grows more disconnected than in the last. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.71 points, but between 1991-2000 and 2001-2014, it rose by just 0.23.

Quantity of street network construction: The street network in Georgia spans a total of 40891 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 4.22, 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 4.22, 4.49, 4.58 and 4.65. Overall, the SNDi of the aggregate street network has risen: the street network in Georgia has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.27 points, but between 1991-2000 and 2001-2014, it rose by just 0.07.

The level of street-network sprawl in new development in Georgia rose steadily. To get a sense of how street development has changed in Georgia, we can consider three of its most populous regions: Tbilisi, Ajaria and Imereti. Out of the three regions, Ajaria and Imereti do not follow the same trend as the country. The level of street-network sprawl in new development in Ajaria followed a zig-zag trend with an overall increase. The level of street-network sprawl in new development in Imereti peaked in 1991-2000.

How do development practices in Georgia fare in comparison to others in the world? Most recently in 2001-2014, street construction in Georgia was the 27th-most disconnected out of the 155 countries in the world. Its position in the ranks since 1975 has risen; relative to other countries in the world, street construction in Georgia has become more disconnected. Georgia ranked 34th in 1975, 27th in 1976-1990, 25th in 1991-2000 and 27th in 2001-2014.

The largest city in Georgia is Tbilisi, with a population of 1077800 people. Taking into account the entire (i.e. aggregate) street network in Tbilisi as of 2014, the overall level of street-network sprawl is 3.06, which is in the 40th to 60th percentile of disconnectedness. The level of street-network sprawl in new development in Tbilisi followed a zig-zag trend with an overall increase.

As of 2014, the city with the most disconnected street network in Georgia is Batumi with an SNDi of 3.07, which is in the 40th to 60th percentile of disconnectedness. Conversely, the most connected city is Rustavi with an SNDi of 1.82, which is relatively well-connected. See trends for these cities: Rustavi, Batumi

The level of street-network sprawl in the aggregate network in Georgia rose steadily. To get a sense of how the aggregate street network has changed in Georgia, we can consider three of its most populous regions: Tbilisi, Ajaria and Imereti. Disconnectivity in the most populous cities in Georgia follow the same country trend.

To date, Georgia is the 34th-most disconnected out of the 155 countries in the world. Its position in the ranks since 1975 has not changed. Georgia ranked 34th in 1975, 31st in 1976-1990, 33rd in 1991-2000 and 34th in 2001-2014.

The largest city in Georgia is Tbilisi, with a population of 1077800 people. Taking into account the entire (i.e. aggregate) street network in Tbilisi as of 2014, the overall level of street-network sprawl is 3.06, which is in the 40th to 60th percentile of disconnectedness. The level of street-network sprawl in the aggregate network in Tbilisi rose steadily.