Street-network Sprawl in Hà Nội, 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.

Hà Nội: 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 Hà Nội, Vietnam on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Hà Nội as of 2014, the overall level of street-network sprawl is 4.06, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 4.41, 4.09, 3.59 and 3.86. The disconnectivity of new streets constructed in Hà Nội fell, then rose. In 1991-2000, new street layouts were the most connected.

Quantity of street network construction: The street network in Hà Nội spans a total of 11954 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 4.09, 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 4.41, 4.11, 4.09 and 4.06. Overall, the SNDi of the aggregate street network has fallen: the street network in Hà Nội has become more connected.

The level of street-network sprawl in new development in Hà Nội was at its lowest in 1991-2000. To get a sense of how street development has changed in Hà Nội, we can consider three of its most populous cities: Hanoi, Phú Minh and Đại Nghĩa. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Hanoi followed a zig-zag trend with an overall decrease. The level of street-network sprawl in new development in Phú Minh followed a zig-zag trend. The level of street-network sprawl in new development in Đại Nghĩa peaked in 1976-1990.

How do development practices in Hà Nội fare in comparison to others in Vietnam? Most recently in 2001-2014, street construction in Hà Nội was the 31st-most disconnected out of the 59 regions in Vietnam. Its position in the ranks since 1975 has fallen; relative to other regions in Vietnam, street construction in Hà Nội has become more connected. Hà Nội ranked 7th in 1975, 14th in 1976-1990, 22nd in 1991-2000 and 31st in 2001-2014.

As of 2014, the city with the most disconnected street network in Hà Nội is Quốc Oai with an SNDi of 5.52, which is highly disconnected. Conversely, the most connected city is Tây Đằng with an SNDi of -1.37, which is very well-connected. See trends for these cities: Tây Đằng, Quốc Oai

The level of street-network sprawl in the aggregate network in Hà Nội fell steadily. To get a sense of how the aggregate street network has changed in Hà Nội, we can consider three of its most populous cities: Hanoi, Phú Minh and Đại Nghĩa. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in the aggregate network in Hanoi peaked in 1976-1990. The level of street-network sprawl in the aggregate network in Phú Minh followed a zig-zag trend with an overall decrease. The level of street-network sprawl in the aggregate network in Đại Nghĩa peaked in 1976-1990.

To date, Hà Nội is the 14th-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 Hà Nội has become more connected. Hà Nội ranked 7th in 1975, 11th in 1976-1990, 12th in 1991-2000 and 14th in 2001-2014.