Street-network Sprawl in São Sebastião, Brazil

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.

São Sebastião: city in Distrito Federal, Brazil

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 São Sebastião, Brazil on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in São Sebastião as of 2014, the overall level of street-network sprawl is 2.16, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 3.68, 1.77, 1.41 and 5.96. The disconnectivity of new streets constructed in São Sebastião fell, then rose. In 1991-2000, new street layouts were the most connected.

Quantity of street network construction: The street network in São Sebastião spans a total of 191 kilometers. It is dominated by roads constructed in 1991-2000. These roads have an SNDi of 1.41, which is relatively well-connected.

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 3.68, 1.88, 1.55 and 2.16. The SNDi of the aggregate street network in fell at first, but São Sebastião has worsened in disconnectivity since 2000.

São Sebastião and Distrito Federal do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in São Sebastião was at its lowest in 1991-2000, while the SNDi of street constructions in Distrito Federal followed a zig-zag trend with an overall increase.

How do development practices in São Sebastião fare in comparison to others in Distrito Federal? Most recently in 2001-2014, street construction in São Sebastião was the 2nd-most disconnected out of the 9 cities in Distrito Federal. Its position in the ranks since 1975 has not changed. São Sebastião ranked 2nd in 1975, 7th in 1976-1990, 6th in 1991-2000 and 2nd in 2001-2014.

São Sebastião and Brazil do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in São Sebastião was at its lowest in 1991-2000, while the SNDi of street constructions in Brazil rose steadily.

How do development practices in São Sebastião fare in comparison to others in Brazil? Most recently in 2001-2014, street construction in São Sebastião was the 37th-most disconnected out of the 348 cities in Brazil. Its position in the ranks since 1975 has fallen; relative to other cities in Brazil, street construction in São Sebastião has become more connected. São Sebastião ranked 25th in 1975, 123rd in 1976-1990, 228th in 1991-2000 and 37th in 2001-2014.

São Sebastião and Distrito Federal do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in São Sebastião was at its lowest in 1991-2000, while the SNDi of street constructions in Distrito Federal followed a zig-zag trend with an overall increase.

To date, São Sebastião is the 6th-most disconnected out of the 9 cities in Distrito Federal. Its position in the ranks since 1975 has fallen; relative to other cities in Distrito Federal, the street network in São Sebastião has become more connected. São Sebastião ranked 2nd in 1975, 6th in 1976-1990, 6th in 1991-2000 and 6th in 2001-2014.

São Sebastião and Brazil do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in São Sebastião was at its lowest in 1991-2000, while the SNDi of street constructions in Brazil rose steadily.

To date, São Sebastião is the 110th-most disconnected out of the 348 cities in Brazil. Its position in the ranks since 1975 has fallen; relative to other cities in Brazil, the street network in São Sebastião has become more connected. São Sebastião ranked 25th in 1975, 113th in 1976-1990, 154th in 1991-2000 and 110th in 2001-2014.

As of 2015, São Sebastião had a built-up area of 4.68 square kilometers, and a population of 82546 people.

These are some other cities with approximately the same population: