Street-network Sprawl in P'yŏngan-namdo, North Korea

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.

P'yŏngan-namdo: region in North Korea

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 P'yŏngan-namdo, North Korea on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in P'yŏngan-namdo as of 2014, the overall level of street-network sprawl is 6.04, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 5.86, 6.98, 5.51 and 5.6. Disconnectivity in street construction in P'yŏngan-namdo 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 P'yŏngan-namdo spans a total of 6429 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 5.86, 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 5.86, 6.11, 6.09 and 6.04. The aggregate street network in P'yŏngan-namdo increased in disconnectivity initially,but the trend has turned around after 1990.

The level of street-network sprawl in new development in P'yŏngan-namdo followed a zig-zag trend with an overall decrease. To get a sense of how street development has changed in P'yŏngan-namdo, we can consider three of its most populous cities: Nampo, P'yŏngsŏng and Kangson. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Nampo followed a zig-zag trend. The level of street-network sprawl in new development in P'yŏngsŏng peaked in 1976-1990. The level of street-network sprawl in new development in Kangson followed a zig-zag trend with an overall decrease.

How do development practices in P'yŏngan-namdo fare in comparison to others in North Korea? Most recently in 2001-2014, street construction in P'yŏngan-namdo was the 11th-most disconnected out of the 13 regions in North Korea. Its position in the ranks since 1975 has fallen; relative to other regions in North Korea, street construction in P'yŏngan-namdo has become more connected. P'yŏngan-namdo ranked 3rd in 1975, 2nd in 1976-1990, 7th in 1991-2000 and 11th in 2001-2014.

As of 2014, the city with the most disconnected street network in P'yŏngan-namdo is Tokchon with an SNDi of 7.24, which is highly disconnected. Conversely, the most connected city is Mundok with an SNDi of -0.07, which is very well-connected. See trends for these cities: Mundok, Tokchon

The level of street-network sprawl in the aggregate network in P'yŏngan-namdo peaked in 1976-1990. To get a sense of how the aggregate street network has changed in P'yŏngan-namdo, we can consider three of its most populous cities: Nampo, P'yŏngsŏng and Kangson. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in the aggregate network in Nampo fell steadily. The level of street-network sprawl in the aggregate network in P'yŏngsŏng peaked in 1991-2000. The level of street-network sprawl in the aggregate network in Kangson peaked in 1976-1990.

To date, P'yŏngan-namdo is the 3rd-most disconnected out of the 13 regions in North Korea. Its position in the ranks since 1975 has not changed. P'yŏngan-namdo ranked 3rd in 1975, 3rd in 1976-1990, 3rd in 1991-2000 and 3rd in 2001-2014.