Street-network Sprawl in Nord-Ouest, Haiti

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.

Nord-Ouest: region in Haiti

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 Nord-Ouest, Haiti on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Nord-Ouest as of 2014, the overall level of street-network sprawl is 4.42, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 5.41, 3.93, 7.04 and 3.92. Disconnectivity in street construction in Nord-Ouest 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 Nord-Ouest spans a total of 733 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 3.93, 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 5.41, 4.42, 4.52 and 4.42. Disconnectivity in Nord-Ouest's street network follows a zig-zag trend. In 1976-1990, the region was most disconnected; while it was most connected in 1975.

The level of street-network sprawl in new development in Nord-Ouest followed a zig-zag trend with an overall decrease. To get a sense of how street development has changed in Nord-Ouest, we can consider two of its most populous cities: Port-de-Paix and Saint-Louis-du-Nord. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Port-de-Paix followed a zig-zag trend. The level of street-network sprawl in new development in Saint-Louis-du-Nord followed a zig-zag trend.

How do development practices in Nord-Ouest fare in comparison to others in Haiti? Most recently in 2001-2014, street construction in Nord-Ouest was the 8th-most disconnected out of the 9 regions in Haiti. Its position in the ranks since 1975 has fallen; relative to other regions in Haiti, street construction in Nord-Ouest has become more connected. Nord-Ouest ranked 1st in 1975, 5th in 1976-1990, 3rd in 1991-2000 and 8th in 2001-2014.

As of 2014, the city with the most disconnected street network in Nord-Ouest is Saint-Louis-du-Nord with an SNDi of 6.65, which is highly disconnected. Conversely, the most connected city is Port-de-Paix with an SNDi of 3.03, which is in the 40th to 60th percentile of disconnectedness. See trends for these cities: Port-de-Paix, Saint-Louis-du-Nord

The level of street-network sprawl in the aggregate network in Nord-Ouest followed a zig-zag trend with an overall decrease. To get a sense of how the aggregate street network has changed in Nord-Ouest, we can consider two of its most populous cities: Port-de-Paix and Saint-Louis-du-Nord. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in the aggregate network in Port-de-Paix rose steadily. The level of street-network sprawl in the aggregate network in Saint-Louis-du-Nord rose steadily.

To date, Nord-Ouest is the 5th-most disconnected out of the 9 regions in Haiti. Its position in the ranks since 1975 has fallen; relative to other regions in Haiti, the street network in Nord-Ouest has become more connected. Nord-Ouest ranked 1st in 1975, 3rd in 1976-1990, 4th in 1991-2000 and 5th in 2001-2014.