Street-network Sprawl in Tabriz, Iran

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.

Tabriz: city in East Azarbaijan, Iran

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 Tabriz, Iran on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Tabriz as of 2014, the overall level of street-network sprawl is 3.14, 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 3.47, 3.07, 2.4 and 3.95. The disconnectivity of new streets constructed in Tabriz fell, then rose. In 1991-2000, new street layouts were the most connected.

Quantity of street network construction: The street network in Tabriz spans a total of 2840 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 3.07, 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 3.47, 3.15, 3.09 and 3.14. The SNDi of the aggregate street network in fell at first, but Tabriz has worsened in disconnectivity since 2000.

Tabriz and East Azarbaijan do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Tabriz was at its lowest in 1991-2000, while the SNDi of street constructions in East Azarbaijan was at its lowest in 1976-1990.

How do development practices in Tabriz fare in comparison to others in East Azarbaijan? Most recently in 2001-2014, street construction in Tabriz was the 4th-most disconnected out of the 8 cities in East Azarbaijan. Its position in the ranks since 1975 has not changed. Tabriz ranked 4th in 1975, 4th in 1976-1990, 6th in 1991-2000 and 4th in 2001-2014.

Tabriz and Iran do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Tabriz was at its lowest in 1991-2000, while the SNDi of street constructions in Iran was at its lowest in 1976-1990.

How do development practices in Tabriz fare in comparison to others in Iran? Most recently in 2001-2014, street construction in Tabriz was the 44th-most disconnected out of the 181 cities in Iran. Its position in the ranks since 1975 has fallen; relative to other cities in Iran, street construction in Tabriz has become more connected. Tabriz ranked 36th in 1975, 30th in 1976-1990, 83rd in 1991-2000 and 44th in 2001-2014.

Tabriz and East Azarbaijan do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Tabriz was at its lowest in 1991-2000, while the SNDi of street constructions in East Azarbaijan was at its lowest in 1976-1990.

To date, Tabriz is the 4th-most disconnected out of the 8 cities in East Azarbaijan. Its position in the ranks since 1975 has not changed. Tabriz ranked 4th in 1975, 4th in 1976-1990, 4th in 1991-2000 and 4th in 2001-2014.

Tabriz and Iran do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Tabriz was at its lowest in 1991-2000, while the SNDi of street constructions in Iran was at its lowest in 1976-1990.

To date, Tabriz is the 41st-most disconnected out of the 181 cities in Iran. Its position in the ranks since 1975 has fallen; relative to other cities in Iran, the street network in Tabriz has become more connected. Tabriz ranked 36th in 1975, 29th in 1976-1990, 35th in 1991-2000 and 41st in 2001-2014.

As of 2015, Tabriz had a built-up area of 127.8 square kilometers, and a population of 1511358 people.

These are some other cities with approximately the same population: