Street-network Sprawl in Saint-Pierre, France

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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:

• nodal degree
• dendricity, the tree-likeness of the street network
• circuity, the ratio of the distance by road to the straight-line distance of two locations on the street network
• sinuosity, the curviness of a street

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:

• Global trends toward urban street-network sprawl
• A global assessment of street-network sprawl

To see the state of street-network sprawl across the globe, visit the sprawlmap.

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Saint-Pierre: region in France

View Saint-Pierre, France on the sprawlmap

How have Saint-Pierre's street networks changed over time?

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Saint-Pierre as of 2014, the overall level of street-network sprawl is 5.38, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 5.36, nan, nan and 6.16. Data was not available in 1976-1990 and 1991-2000.

Quantity of street network construction: The street network in Saint-Pierre spans a total of 2049 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 5.36, 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 5.36, 5.36, 5.36 and 5.38. Overall, the SNDi of the aggregate street network has risen: the street network in Saint-Pierre has become more disconnected.

Saint-Pierre in context: Street-network sprawl of new development

The level of street-network sprawl in new development in Saint-Pierre followed a zig-zag trend with an overall increase. To get a sense of how street development has changed in Saint-Pierre, we can consider one of its most populous cities: Le Tampon. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Le Tampon followed a zig-zag trend.

How do development practices in Saint-Pierre fare in comparison to others in France? Most recently in 2001-2014, street construction in Saint-Pierre was the 7th-most disconnected out of the 20 regions in France. Saint-Pierre ranked 2nd in 1975 and 7th in 2001-2014. There was no ranking in 1976-1990 and 1991-2000 due to unavailable data.

Saint-Pierre in context: Aggregate street-network sprawl

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

The level of street-network sprawl in the aggregate network in Saint-Pierre rose steadily. To get a sense of how the aggregate street network has changed in Saint-Pierre, we can consider one of its most populous cities: Le Tampon. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in the aggregate network in Le Tampon rose steadily.

To date, Saint-Pierre is the 4th-most disconnected out of the 20 regions in France. Its position in the ranks since 1975 has fallen; relative to other regions in France, the street network in Saint-Pierre has become more connected. Saint-Pierre ranked 2nd in 1975, 3rd in 1976-1990, 4th in 1991-2000 and 4th in 2001-2014.

Cities in Saint-Pierre

• Le Tampon