Street-network Sprawl in Quảng Bình, 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.

Quảng Bình: 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 Quảng Bình, Vietnam on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Quảng Bình as of 2014, the overall level of street-network sprawl is 2.38, 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 2.13, 5.02, 2.08 and 3.87. Disconnectivity in street construction in Quảng Bình follows a zig-zag trend. In 1991-2000, street construction was most disconnected, while construction was most connected in 1976-1990.

Quantity of street network construction: The street network in Quảng Bình spans a total of 2133 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 2.13, 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 2.13, 2.29, 2.27 and 2.38. Disconnectivity in Quảng Bình's street network follows a zig-zag trend. In 1975, the region was most disconnected; while it was most connected in 2001-2014.

The level of street-network sprawl in new development in Quảng Bình followed a zig-zag trend with an overall increase. To get a sense of how street development has changed in Quảng Bình, we can consider one of its most populous cities: Hoàn Lão. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Hoàn Lão followed a zig-zag trend.

How do development practices in Quảng Bình fare in comparison to others in Vietnam? Most recently in 2001-2014, street construction in Quảng Bình was the 30th-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 Quảng Bình has become more disconnected. Quảng Bình ranked 33rd in 1975, 3rd in 1976-1990, 55th in 1991-2000 and 30th in 2001-2014.

As of 2014, the city with the most disconnected street network in Quảng Bình is Hoàn Lão with an SNDi of 0.38, which is very well-connected. Conversely, the most connected city is Hoàn Lão with an SNDi of 0.38, which is very well-connected. See trends for these cities: Hoàn Lão, Hoàn Lão

The level of street-network sprawl in the aggregate network in Quảng Bình followed a zig-zag trend with an overall increase. To get a sense of how the aggregate street network has changed in Quảng Bình, we can consider one of its most populous cities: Hoàn Lão. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in the aggregate network in Hoàn Lão fell steadily.

To date, Quảng Bình is the 52nd-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 Quảng Bình has become more connected. Quảng Bình ranked 33rd in 1975, 45th in 1976-1990, 50th in 1991-2000 and 52nd in 2001-2014.