Street-network Sprawl in Rockingham, Australia

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.

Rockingham: city in Western Australia, Australia

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 Rockingham, Australia on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Rockingham as of 2014, the overall level of street-network sprawl is 4.61, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 4.48, 6.22, 6.77 and 2.59. Street construction in Rockingham 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 Rockingham spans a total of 461 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 4.48, 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 4.48, 4.54, 4.67 and 4.61. The aggregate street network in Rockingham increased in disconnectivity initially,but the trend has turned around after 2000.

Rockingham and Western Australia 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 Rockingham fare in comparison to others in Western Australia? Most recently in 2001-2014, street construction in Rockingham was the 2nd-most disconnected out of the 3 cities in Western Australia. Its position in the ranks since 1975 has fallen; relative to other cities in Western Australia, street construction in Rockingham has become more connected. Rockingham ranked 1st in 1975, 1st in 1976-1990, 1st in 1991-2000 and 2nd in 2001-2014.

Rockingham and Australia 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 Rockingham fare in comparison to others in Australia? Most recently in 2001-2014, street construction in Rockingham was the 19th-most disconnected out of the 27 cities in Australia. Its position in the ranks since 1975 has fallen; relative to other cities in Australia, street construction in Rockingham has become more connected. Rockingham ranked 1st in 1975, 2nd in 1976-1990, 4th in 1991-2000 and 19th in 2001-2014.

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

To date, Rockingham is the 1st-most disconnected out of the 3 cities in Western Australia. Its position in the ranks since 1975 has not changed. Rockingham ranked 1st in 1975, 2nd in 1976-1990, 2nd in 1991-2000 and 1st in 2001-2014.

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

To date, Rockingham is the 2nd-most disconnected out of the 27 cities in Australia. Its position in the ranks since 1975 has fallen; relative to other cities in Australia, the street network in Rockingham has become more connected. Rockingham ranked 1st in 1975, 4th in 1976-1990, 3rd in 1991-2000 and 2nd in 2001-2014.

As of 2015, Rockingham had a built-up area of 28.49 square kilometers, and a population of 66695 people.

These are some other cities with approximately the same population: