Street-network Sprawl in Negros Oriental, 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:

• 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.

---

Negros Oriental: 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 Negros Oriental, Philippines on the sprawlmap

How have Negros Oriental's street networks changed over time?

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Negros Oriental as of 2014, the overall level of street-network sprawl is 4.7, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 2.73, 4.55, 7.01 and 5.66. Street construction in Negros Oriental 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 Negros Oriental spans a total of 4862 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 5.66, 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 2.73, 3.91, 4.48 and 4.7. Overall, the SNDi of the aggregate street network has risen: the street network in Negros Oriental has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 1.19 points, but between 1991-2000 and 2001-2014, it rose by just 0.22.

Negros Oriental in context: Street-network sprawl of new development

The level of street-network sprawl in new development in Negros Oriental peaked in 1991-2000. To get a sense of how street development has changed in Negros Oriental, we can consider one of its most populous cities: Dumaguete. Disconnectivity in the most populous cities in Negros Oriental follow the same region trend.

How do development practices in Negros Oriental fare in comparison to others in Philippines? Most recently in 2001-2014, street construction in Negros Oriental was the 32nd-most disconnected out of the 51 regions in Philippines. Its position in the ranks since 1975 has risen; relative to other regions in Philippines, street construction in Negros Oriental has become more disconnected. Negros Oriental ranked 40th in 1975, 28th in 1976-1990, 8th in 1991-2000 and 32nd in 2001-2014.

Negros Oriental in context: Aggregate street-network sprawl

As of 2014, the city with the most disconnected street network in Negros Oriental is Dumaguete with an SNDi of 4.3, which is highly disconnected. Conversely, the most connected city is Dumaguete with an SNDi of 4.3, which is highly disconnected. See trends for these cities: Dumaguete, Dumaguete

The level of street-network sprawl in the aggregate network in Negros Oriental rose steadily. To get a sense of how the aggregate street network has changed in Negros Oriental, we can consider one of its most populous cities: Dumaguete. Disconnectivity in the most populous cities in Negros Oriental follow the same region trend.

To date, Negros Oriental is the 29th-most disconnected out of the 51 regions in Philippines. Its position in the ranks since 1975 has risen; relative to other regions in Philippines, the street network in Negros Oriental has become more disconnected. Negros Oriental ranked 40th in 1975, 32nd in 1976-1990, 29th in 1991-2000 and 29th in 2001-2014.

Cities in Negros Oriental

• Dumaguete