Street-network Sprawl in Iraq

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.

Iraq

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 Iraq on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Iraq as of 2014, the overall level of street-network sprawl is 2.39, 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 2.41, 2.03, 2.43 and 2.77. The disconnectivity of new streets constructed in Iraq fell, then rose. In 1976-1990, new street layouts were the most connected.

Quantity of street network construction: The street network in Iraq spans a total of 95514 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 2.77, 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 2.41, 2.09, 2.13 and 2.39. The SNDi of the aggregate street network in fell at first, but Iraq has worsened in disconnectivity since 1990.

The level of street-network sprawl in new development in Iraq was at its lowest in 1976-1990. To get a sense of how street development has changed in Iraq, we can consider three of its most populous regions: Baghdad, Ninawa and Al-Basrah. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Baghdad rose steadily. The level of street-network sprawl in new development in Ninawa rose steadily. The level of street-network sprawl in new development in Al-Basrah followed a zig-zag trend with an overall increase.

How do development practices in Iraq fare in comparison to others in the world? Most recently in 2001-2014, street construction in Iraq was the 134th-most disconnected out of the 155 countries in the world. Its position in the ranks since 1975 has fallen; relative to other countries in the world, street construction in Iraq has become more connected. Iraq ranked 95th in 1975, 128th in 1976-1990, 135th in 1991-2000 and 134th in 2001-2014.

The largest city in Iraq is Baghdad, with a population of 5367300 people. Taking into account the entire (i.e. aggregate) street network in Baghdad as of 2014, the overall level of street-network sprawl is 2.14, which is relatively well-connected. The level of street-network sprawl in new development in Baghdad rose steadily.

As of 2014, the city with the most disconnected street network in Iraq is Qaryat Qabr al Abd with an SNDi of 4.65, which is highly disconnected. Conversely, the most connected city is Al Baaj with an SNDi of -0.73, which is very well-connected. See trends for these cities: Al Baaj, Qaryat Qabr al Abd

The level of street-network sprawl in the aggregate network in Iraq was at its lowest in 1976-1990. To get a sense of how the aggregate street network has changed in Iraq, we can consider three of its most populous regions: Baghdad, Ninawa and Al-Basrah. Out of the three regions, Baghdad and Ninawa do not follow the same trend as the country. The level of street-network sprawl in the aggregate network in Baghdad rose steadily. The level of street-network sprawl in the aggregate network in Ninawa rose steadily.

To date, Iraq is the 120th-most disconnected out of the 155 countries in the world. Its position in the ranks since 1975 has fallen; relative to other countries in the world, the street network in Iraq has become more connected. Iraq ranked 95th in 1975, 123rd in 1976-1990, 128th in 1991-2000 and 120th in 2001-2014.

The largest city in Iraq is Baghdad, with a population of 5367300 people. Taking into account the entire (i.e. aggregate) street network in Baghdad as of 2014, the overall level of street-network sprawl is 2.14, which is relatively well-connected. The level of street-network sprawl in the aggregate network in Baghdad rose steadily.