Street-network Sprawl in Victoria, 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.

Victoria: region in 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 Victoria, Australia on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Victoria as of 2014, the overall level of street-network sprawl is 3.27, which is in the 40th to 60th percentile of disconnectedness.

Trends in street network construction: The SNDis of street construction for the respective time periods are 2.52, 4.28, 4.77 and 4.08. Street construction in Victoria 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 Victoria spans a total of 71650 kilometers. The period with the greatest volume of street construction was 1975. These roads have an SNDi of 2.52, which is in the 40th to 60th percentile of disconnectedness.

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 2.52, 3.1, 3.17 and 3.27. Overall, the SNDi of the aggregate street network has risen: the street network in Victoria has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.58 points, but between 1991-2000 and 2001-2014, it rose by just 0.1.

The level of street-network sprawl in new development in Victoria peaked in 1991-2000. To get a sense of how street development has changed in Victoria, we can consider three of its most populous cities: Melbourne, Werribee and Geelong. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Melbourne peaked in 1976-1990. The level of street-network sprawl in new development in Werribee peaked in 1976-1990. The level of street-network sprawl in new development in Geelong rose steadily.

How do development practices in Victoria fare in comparison to others in Australia? Most recently in 2001-2014, street construction in Victoria was the 5th-most disconnected out of the 7 regions in Australia. Its position in the ranks since 1975 has not changed. Victoria ranked 5th in 1975, 5th in 1976-1990, 5th in 1991-2000 and 5th in 2001-2014.

As of 2014, the city with the most disconnected street network in Victoria is Werribee with an SNDi of 3.38, which is highly disconnected. Conversely, the most connected city is Ballarat with an SNDi of 1.74, which is relatively well-connected. See trends for these cities: Ballarat, Werribee

The level of street-network sprawl in the aggregate network in Victoria rose steadily. To get a sense of how the aggregate street network has changed in Victoria, we can consider three of its most populous cities: Melbourne, Werribee and Geelong. Out of the three cities, Werribee does not follow the same trend as the region. The level of street-network sprawl in the aggregate network in Werribee peaked in 1976-1990.

To date, Victoria is the 5th-most disconnected out of the 7 regions in Australia. Its position in the ranks since 1975 has not changed. Victoria ranked 5th in 1975, 5th in 1976-1990, 5th in 1991-2000 and 5th in 2001-2014.