Street-network Sprawl in Thanh Hóa, 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.

Thanh Hóa: 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 Thanh Hóa, Vietnam on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Thanh Hóa as of 2014, the overall level of street-network sprawl is 2.93, 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 -0.49, 2.67, 2.77 and 4.32. In each period, new street development in Thanh Hóa steadily grows more disconnected than in the last. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 3.16 points, but between 1991-2000 and 2001-2014, it rose by just 1.55.

Quantity of street network construction: The street network in Thanh Hóa spans a total of 2704 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 2.67, 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 -0.49, 2.55, 2.52 and 2.93. Disconnectivity in Thanh Hóa'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 Thanh Hóa rose steadily. To get a sense of how street development has changed in Thanh Hóa, we can consider three of its most populous cities: Thanh Hóa, Nga Sơn and Thọ Xuân. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Thanh Hóa followed a zig-zag trend. The level of street-network sprawl in new development in Nga Sơn followed a zig-zag trend. The level of street-network sprawl in new development in Thọ Xuân followed a zig-zag trend.

How do development practices in Thanh Hóa fare in comparison to others in Vietnam? Most recently in 2001-2014, street construction in Thanh Hóa was the 17th-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 Thanh Hóa has become more disconnected. Thanh Hóa ranked 56th in 1975, 35th in 1976-1990, 40th in 1991-2000 and 17th in 2001-2014.

As of 2014, the city with the most disconnected street network in Thanh Hóa is Nga Sơn with an SNDi of 6.98, which is highly disconnected. Conversely, the most connected city is Thanh Hóa with an SNDi of 1.52, which is relatively well-connected. See trends for these cities: Thanh Hóa, Nga Sơn

The level of street-network sprawl in the aggregate network in Thanh Hóa followed a zig-zag trend with an overall increase. To get a sense of how the aggregate street network has changed in Thanh Hóa, we can consider three of its most populous cities: Thanh Hóa, Nga Sơn and Thọ Xuân. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in the aggregate network in Thanh Hóa followed a zig-zag trend. The level of street-network sprawl in the aggregate network in Nga Sơn followed a zig-zag trend. The level of street-network sprawl in the aggregate network in Thọ Xuân followed a zig-zag trend.

To date, Thanh Hóa is the 41st-most disconnected out of the 59 regions in Vietnam. Its position in the ranks since 1975 has risen; relative to other regions in Vietnam, the street network in Thanh Hóa has become more disconnected. Thanh Hóa ranked 56th in 1975, 34th in 1976-1990, 42nd in 1991-2000 and 41st in 2001-2014.