Street-network Sprawl in Zamboanga del Norte, Philippines

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.

Zamboanga del Norte: region in Philippines

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 Zamboanga del Norte, Philippines on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Zamboanga del Norte as of 2014, the overall level of street-network sprawl is 5.37, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 5.67, 5.32, 5.62 and 6.32. The disconnectivity of new streets constructed in Zamboanga del Norte fell, then rose. In 1976-1990, new street layouts were the most connected.

Quantity of street network construction: The street network in Zamboanga del Norte spans a total of 6401 kilometers. The period with the greatest volume of street construction was 1976-1990. These roads have an SNDi of 5.32, 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 5.67, 5.31, 5.19 and 5.37. The SNDi of the aggregate street network in fell at first, but Zamboanga del Norte has worsened in disconnectivity since 2000.

The level of street-network sprawl in new development in Zamboanga del Norte was at its lowest in 1976-1990. To get a sense of how street development has changed in Zamboanga del Norte, we can consider one of its most populous cities: Dipolog. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Dipolog peaked in 1991-2000.

How do development practices in Zamboanga del Norte fare in comparison to others in Philippines? Most recently in 2001-2014, street construction in Zamboanga del Norte was the 15th-most disconnected out of the 51 regions in Philippines. Its position in the ranks since 1975 has fallen; relative to other regions in Philippines, street construction in Zamboanga del Norte has become more connected. Zamboanga del Norte ranked 6th in 1975, 16th in 1976-1990, 25th in 1991-2000 and 15th in 2001-2014.

As of 2014, the city with the most disconnected street network in Zamboanga del Norte is Dipolog with an SNDi of 1.91, which is relatively well-connected. Conversely, the most connected city is Dipolog with an SNDi of 1.91, which is relatively well-connected. See trends for these cities: Dipolog, Dipolog

The level of street-network sprawl in the aggregate network in Zamboanga del Norte was at its lowest in 1991-2000. To get a sense of how the aggregate street network has changed in Zamboanga del Norte, we can consider one of its most populous cities: Dipolog. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in the aggregate network in Dipolog rose steadily.

To date, Zamboanga del Norte is the 15th-most disconnected out of the 51 regions in Philippines. Its position in the ranks since 1975 has fallen; relative to other regions in Philippines, the street network in Zamboanga del Norte has become more connected. Zamboanga del Norte ranked 6th in 1975, 12th in 1976-1990, 15th in 1991-2000 and 15th in 2001-2014.