Street-network Sprawl in Bilbao, Spain

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.

Bilbao: city in País Vasco, Spain

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 Bilbao, Spain on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Bilbao as of 2014, the overall level of street-network sprawl is 1.94, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 1.85, 2.23, 2.11 and 3.3. Disconnectivity in street construction in Bilbao follows a zig-zag trend. In 1975, street construction was most disconnected, while construction was most connected in 2001-2014.

Quantity of street network construction: The street network in Bilbao spans a total of 1521 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 1.85, 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 1.85, 1.9, 1.9 and 1.94. Overall, the SNDi of the aggregate street network has risen: the street network in Bilbao has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.05 points, but between 1991-2000 and 2001-2014, it rose by just 0.04.

Bilbao and País Vasco do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Bilbao followed a zig-zag trend with an overall increase, while the SNDi of street constructions in País Vasco rose steadily.

How do development practices in Bilbao fare in comparison to others in País Vasco? Most recently in 2001-2014, street construction in Bilbao was the 3rd-most disconnected out of the 4 cities in País Vasco. Its position in the ranks since 1975 has fallen; relative to other cities in País Vasco, street construction in Bilbao has become more connected. Bilbao ranked 2nd in 1975, 3rd in 1976-1990, 3rd in 1991-2000 and 3rd in 2001-2014.

Bilbao and Spain do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Bilbao followed a zig-zag trend with an overall increase, while the SNDi of street constructions in Spain peaked in 1991-2000.

How do development practices in Bilbao fare in comparison to others in Spain? Most recently in 2001-2014, street construction in Bilbao was the 12th-most disconnected out of the 72 cities in Spain. Its position in the ranks since 1975 has fallen; relative to other cities in Spain, street construction in Bilbao has become more connected. Bilbao ranked 10th in 1975, 19th in 1976-1990, 32nd in 1991-2000 and 12th in 2001-2014.

Bilbao and País Vasco follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these rose steadily.

To date, Bilbao is the 2nd-most disconnected out of the 4 cities in País Vasco. Its position in the ranks since 1975 has not changed. Bilbao ranked 2nd in 1975, 2nd in 1976-1990, 2nd in 1991-2000 and 2nd in 2001-2014.

Bilbao and Spain follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these rose steadily.

To date, Bilbao is the 11th-most disconnected out of the 72 cities in Spain. Its position in the ranks since 1975 has fallen; relative to other cities in Spain, the street network in Bilbao has become more connected. Bilbao ranked 10th in 1975, 12th in 1976-1990, 12th in 1991-2000 and 11th in 2001-2014.

As of 2015, Bilbao had a built-up area of 48.16 square kilometers, and a population of 778581 people.

These are some other cities with approximately the same population: