Street-network Sprawl in Gifu, Japan

---

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:

• nodal degree
• dendricity, the tree-likeness of the street network
• circuity, the ratio of the distance by road to the straight-line distance of two locations on the street network
• sinuosity, the curviness of a street

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:

• Global trends toward urban street-network sprawl
• A global assessment of street-network sprawl

To see the state of street-network sprawl across the globe, visit the sprawlmap.

---

Gifu: region in Japan

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 Gifu, Japan on the sprawlmap

How have Gifu's street networks changed over time?

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Gifu as of 2014, the overall level of street-network sprawl is 1.16, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.94, 0.94, 3.49 and 2.99. Street construction in Gifu 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 Gifu spans a total of 25510 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 0.94, 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 0.94, 0.94, 1.07 and 1.16. Overall, the SNDi of the aggregate street network has risen: the street network in Gifu has become more disconnected.

Gifu in context: Street-network sprawl of new development

The level of street-network sprawl in new development in Gifu peaked in 1991-2000. To get a sense of how street development has changed in Gifu, we can consider two of its most populous cities: Kani and Tajimi. Out of the two cities, Kani does not follow the same trend as the region. The level of street-network sprawl in new development in Kani was at its lowest in 1991-2000.

How do development practices in Gifu fare in comparison to others in Japan? Most recently in 2001-2014, street construction in Gifu was the 18th-most disconnected out of the 44 regions in Japan. Its position in the ranks since 1975 has risen; relative to other regions in Japan, street construction in Gifu has become more disconnected. Gifu ranked 38th in 1975, 43rd in 1976-1990, 9th in 1991-2000 and 18th in 2001-2014.

Gifu in context: Aggregate street-network sprawl

As of 2014, the city with the most disconnected street network in Gifu is Tajimi with an SNDi of 2.2, which is relatively well-connected. Conversely, the most connected city is Kani with an SNDi of 1.03, which is relatively well-connected. See trends for these cities: Kani, Tajimi

The level of street-network sprawl in the aggregate network in Gifu rose steadily. To get a sense of how the aggregate street network has changed in Gifu, we can consider two of its most populous cities: Kani and Tajimi. Out of the two cities, Kani does not follow the same trend as the region. The level of street-network sprawl in the aggregate network in Kani was at its lowest in 1991-2000.

To date, Gifu is the 37th-most disconnected out of the 44 regions in Japan. Its position in the ranks since 1975 has risen; relative to other regions in Japan, the street network in Gifu has become more disconnected. Gifu ranked 38th in 1975, 39th in 1976-1990, 39th in 1991-2000 and 37th in 2001-2014.

Cities in Gifu

• Kani
• Tajimi