Street-network Sprawl in Bình Định, Vietnam

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.

Bình Định: region in Vietnam

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 Bình Định, Vietnam on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Bình Định as of 2014, the overall level of street-network sprawl is 2.78, 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 2.12, 3.42, 2.58 and 4.49. Disconnectivity in street construction in Bình Định 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 Bình Định spans a total of 3932 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 2.12, 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 2.12, 2.36, 2.39 and 2.78. Overall, the SNDi of the aggregate street network has risen: the street network in Bình Định has become more disconnected.

The level of street-network sprawl in new development in Bình Định followed a zig-zag trend with an overall increase. To get a sense of how street development has changed in Bình Định, we can consider three of its most populous cities: Quy Nhơn, Tam Quan and Phú Phong. Out of the three cities, Phú Phong does not follow the same trend as the region. The level of street-network sprawl in new development in Phú Phong peaked in 1976-1990.

How do development practices in Bình Định fare in comparison to others in Vietnam? Most recently in 2001-2014, street construction in Bình Định was the 12th-most disconnected out of the 59 regions in Vietnam. Its position in the ranks since 1975 has risen; relative to other regions in Vietnam, street construction in Bình Định has become more disconnected. Bình Định ranked 34th in 1975, 21st in 1976-1990, 44th in 1991-2000 and 12th in 2001-2014.

As of 2014, the city with the most disconnected street network in Bình Định is Tam Quan with an SNDi of 2.75, which is in the 40th to 60th percentile of disconnectedness. Conversely, the most connected city is Quy Nhơn with an SNDi of 1.44, which is relatively well-connected. See trends for these cities: Quy Nhơn, Tam Quan

The level of street-network sprawl in the aggregate network in Bình Định rose steadily. To get a sense of how the aggregate street network has changed in Bình Định, we can consider three of its most populous cities: Quy Nhơn, Tam Quan and Phú Phong. Out of the three cities, Tam Quan does not follow the same trend as the region. The level of street-network sprawl in the aggregate network in Tam Quan followed a zig-zag trend with an overall increase.

To date, Bình Định is the 45th-most disconnected out of the 59 regions in Vietnam. Its position in the ranks since 1975 has fallen; relative to other regions in Vietnam, the street network in Bình Định has become more connected. Bình Định ranked 34th in 1975, 40th in 1976-1990, 48th in 1991-2000 and 45th in 2001-2014.