Street-network Sprawl in Petaluma, United States

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.

Petaluma: city in California, United States

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 Petaluma, United States on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Petaluma as of 2014, the overall level of street-network sprawl is 3.64, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 3.4, 4.01, 4.37 and 3.63. Street construction in Petaluma increased in disconnectivity initially but has since improved. The streets constructed in 1991-2000 were the most disconnected.

Quantity of street network construction: The street network in Petaluma spans a total of 381 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 3.4, 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 3.4, 3.61, 3.64 and 3.64. The aggregate street network in Petaluma increased in disconnectivity initially,but the trend has turned around after 2000.

Petaluma and California follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these peaked in 1991-2000.

How do development practices in Petaluma fare in comparison to others in California? Most recently in 2001-2014, street construction in Petaluma was the 41st-most disconnected out of the 48 cities in California. Its position in the ranks since 1975 has fallen; relative to other cities in California, street construction in Petaluma has become more connected. Petaluma ranked 17th in 1975, 37th in 1976-1990, 29th in 1991-2000 and 41st in 2001-2014.

Petaluma and United States follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these peaked in 1991-2000.

How do development practices in Petaluma fare in comparison to others in United States? Most recently in 2001-2014, street construction in Petaluma was the 264th-most disconnected out of the 315 cities in United States. Its position in the ranks since 1975 has fallen; relative to other cities in United States, street construction in Petaluma has become more connected. Petaluma ranked 71st in 1975, 195th in 1976-1990, 227th in 1991-2000 and 264th in 2001-2014.

Petaluma and California do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Petaluma peaked in 1991-2000, while the SNDi of street constructions in California rose steadily.

To date, Petaluma is the 30th-most disconnected out of the 48 cities in California. Its position in the ranks since 1975 has fallen; relative to other cities in California, the street network in Petaluma has become more connected. Petaluma ranked 17th in 1975, 28th in 1976-1990, 28th in 1991-2000 and 30th in 2001-2014.

Petaluma and United States do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Petaluma peaked in 1991-2000, while the SNDi of street constructions in United States rose steadily.

To date, Petaluma is the 105th-most disconnected out of the 315 cities in United States. Its position in the ranks since 1975 has fallen; relative to other cities in United States, the street network in Petaluma has become more connected. Petaluma ranked 71st in 1975, 93rd in 1976-1990, 98th in 1991-2000 and 105th in 2001-2014.

As of 2015, Petaluma had a built-up area of 26.19 square kilometers, and a population of 55779 people.

These are some other cities with approximately the same population: