Street-network Sprawl in Tan An, 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.

Tan An: city in Long An, 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 Tan An, Vietnam on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Tan An as of 2014, the overall level of street-network sprawl is 2.36, 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 0.77, 3.02, 4.45 and 1.47. Street construction in Tan An 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 Tan An spans a total of 228 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 3.02, 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 0.77, 2.77, 2.86 and 2.36. The aggregate street network in Tan An increased in disconnectivity initially,but the trend has turned around after 2000.

Tan An and Long An do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Tan An peaked in 1991-2000, while the SNDi of street constructions in Long An followed a zig-zag trend with an overall increase.

How do development practices in Tan An fare in comparison to others in Long An? Most recently in 2001-2014, street construction in Tan An was the 2nd-most disconnected out of the 2 cities in Long An. Its position in the ranks since 1975 has not changed. Tan An ranked 2nd in 1975, 2nd in 1976-1990, 2nd in 1991-2000 and 2nd in 2001-2014.

Tan An and Vietnam do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Tan An peaked in 1991-2000, while the SNDi of street constructions in Vietnam rose steadily.

How do development practices in Tan An fare in comparison to others in Vietnam? Most recently in 2001-2014, street construction in Tan An was the 86th-most disconnected out of the 129 cities in Vietnam. Its position in the ranks since 1975 has fallen; relative to other cities in Vietnam, street construction in Tan An has become more connected. Tan An ranked 72nd in 1975, 33rd in 1976-1990, 16th in 1991-2000 and 86th in 2001-2014.

Tan An and Long An do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Tan An peaked in 1991-2000, while the SNDi of street constructions in Long An peaked in 1976-1990.

To date, Tan An is the 2nd-most disconnected out of the 2 cities in Long An. Its position in the ranks since 1975 has not changed. Tan An ranked 2nd in 1975, 2nd in 1976-1990, 2nd in 1991-2000 and 2nd in 2001-2014.

Tan An and Vietnam do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Tan An peaked in 1991-2000, while the SNDi of street constructions in Vietnam rose steadily.

To date, Tan An is the 61st-most disconnected out of the 129 cities in Vietnam. Its position in the ranks since 1975 has risen; relative to other cities in Vietnam, the street network in Tan An has become more disconnected. Tan An ranked 72nd in 1975, 39th in 1976-1990, 38th in 1991-2000 and 61st in 2001-2014.

As of 2015, Tan An had a built-up area of 9.25 square kilometers, and a population of 153640 people.

These are some other cities with approximately the same population: