Street-network Sprawl in France

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.

France

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 France on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in France as of 2014, the overall level of street-network sprawl is 5.47, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 5.44, nan, nan and 6.28. Data was not available in 1976-1990 and 1991-2000.

Quantity of street network construction: The street network in France spans a total of 5828 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 5.44, 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 5.44, 5.44, 5.44 and 5.47. Overall, the SNDi of the aggregate street network has risen: the street network in France has become more disconnected.

The level of street-network sprawl in new development in France followed a zig-zag trend with an overall increase. To get a sense of how street development has changed in France, we can consider three of its most populous regions: Île-de-France, Provence-Alpes-Côte d'Azur and Auvergne-Rhône-Alpes. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Île-de-France peaked in 1976-1990. The level of street-network sprawl in new development in Provence-Alpes-Côte d'Azur peaked in 1991-2000. The level of street-network sprawl in new development in Auvergne-Rhône-Alpes peaked in 1991-2000.

How do development practices in France fare in comparison to others in the world? Most recently in 2001-2014, street construction in France was the 10th-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 France has become more disconnected. France ranked 49th in 1975, 13th in 1976-1990, 20th in 1991-2000 and 10th in 2001-2014.

The largest city in France is Paris, with a population of 9711700 people. Taking into account the entire (i.e. aggregate) street network in Paris as of 2014, the overall level of street-network sprawl is 1.58, which is relatively well-connected. The level of street-network sprawl in new development in Paris peaked in 1976-1990.

As of 2014, the city with the most disconnected street network in France is Le Tampon with an SNDi of 5.53, which is highly disconnected. Conversely, the most connected city is Le Havre with an SNDi of 1.17, which is relatively well-connected. See trends for these cities: Le Havre, Le Tampon

The level of street-network sprawl in the aggregate network in France rose steadily. To get a sense of how the aggregate street network has changed in France, we can consider three of its most populous regions: Île-de-France, Provence-Alpes-Côte d'Azur and Auvergne-Rhône-Alpes. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in the aggregate network in Île-de-France rose steadily. The level of street-network sprawl in the aggregate network in Provence-Alpes-Côte d'Azur rose steadily. The level of street-network sprawl in the aggregate network in Auvergne-Rhône-Alpes rose steadily.

To date, France is the 24th-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, the street network in France has become more disconnected. France ranked 49th in 1975, 29th in 1976-1990, 24th in 1991-2000 and 24th in 2001-2014.

The largest city in France is Paris, with a population of 9711700 people. Taking into account the entire (i.e. aggregate) street network in Paris as of 2014, the overall level of street-network sprawl is 1.58, which is relatively well-connected. The level of street-network sprawl in the aggregate network in Paris rose steadily.