Street-network Sprawl in Zamboanga City, 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 City: city in Zamboanga del Sur, 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 City, Philippines on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Zamboanga City as of 2014, the overall level of street-network sprawl is 6.61, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 6.54, 7.11, 6.62 and 8.08. Disconnectivity in street construction in Zamboanga City follows a zig-zag trend. In 1975, street construction was most disconnected, while construction was most connected in 2001-2014.

Quantity of street network construction: The street network in Zamboanga City spans a total of 511 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 6.54, 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 6.54, 6.55, 6.55 and 6.61. Overall, the SNDi of the aggregate street network has risen: the street network in Zamboanga City has become more disconnected.

Zamboanga City and Zamboanga del Sur do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Zamboanga City followed a zig-zag trend with an overall increase, while the SNDi of street constructions in Zamboanga del Sur was at its lowest in 1976-1990.

How do development practices in Zamboanga City fare in comparison to others in Zamboanga del Sur? Most recently in 2001-2014, street construction in Zamboanga City was the 3rd-most disconnected out of the 3 cities in Zamboanga del Sur. Its position in the ranks since 1975 has fallen; relative to other cities in Zamboanga del Sur, street construction in Zamboanga City has become more connected. Zamboanga City ranked 1st in 1975, 1st in 1976-1990, 1st in 1991-2000 and 3rd in 2001-2014.

Zamboanga City and Philippines do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Zamboanga City followed a zig-zag trend with an overall increase, while the SNDi of street constructions in Philippines rose steadily.

How do development practices in Zamboanga City fare in comparison to others in Philippines? Most recently in 2001-2014, street construction in Zamboanga City was the 7th-most disconnected out of the 89 cities in Philippines. Its position in the ranks since 1975 has fallen; relative to other cities in Philippines, street construction in Zamboanga City has become more connected. Zamboanga City ranked 2nd in 1975, 2nd in 1976-1990, 17th in 1991-2000 and 7th in 2001-2014.

Zamboanga City and Zamboanga del Sur do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Zamboanga City rose steadily, while the SNDi of street constructions in Zamboanga del Sur followed a zig-zag trend with an overall decrease.

To date, Zamboanga City is the 1st-most disconnected out of the 3 cities in Zamboanga del Sur. Its position in the ranks since 1975 has not changed. Zamboanga City ranked 1st in 1975, 1st in 1976-1990, 1st in 1991-2000 and 1st in 2001-2014.

Zamboanga City and Philippines follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these rose steadily.

To date, Zamboanga City is the 2nd-most disconnected out of the 89 cities in Philippines. Its position in the ranks since 1975 has not changed. Zamboanga City ranked 2nd in 1975, 2nd in 1976-1990, 2nd in 1991-2000 and 2nd in 2001-2014.

As of 2015, Zamboanga City had a built-up area of 8.57 square kilometers, and a population of 498586 people.

These are some other cities with approximately the same population: