Street-network Sprawl in Surabaya, Indonesia

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.

Surabaya: city in Jawa Timur, Indonesia

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 Surabaya, Indonesia on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Surabaya as of 2014, the overall level of street-network sprawl is 4.39, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 3.3, 4.2, 4.29 and 5.31. In each period, new street development in Surabaya steadily grows more disconnected than in the last.

Quantity of street network construction: The street network in Surabaya spans a total of 14170 kilometers. It is dominated by roads constructed in 1976-1990. These roads have an SNDi of 4.2, 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 3.3, 4.12, 4.14 and 4.39. Overall, the SNDi of the aggregate street network has risen: the street network in Surabaya has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.82 points, but between 1991-2000 and 2001-2014, it rose by just 0.25.

Surabaya and Jawa Timur follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these rose steadily.

How do development practices in Surabaya fare in comparison to others in Jawa Timur? Most recently in 2001-2014, street construction in Surabaya was the 8th-most disconnected out of the 52 cities in Jawa Timur. Its position in the ranks since 1975 has not changed. Surabaya ranked 8th in 1975, 3rd in 1976-1990, 13th in 1991-2000 and 8th in 2001-2014.

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

How do development practices in Surabaya fare in comparison to others in Indonesia? Most recently in 2001-2014, street construction in Surabaya was the 95th-most disconnected out of the 363 cities in Indonesia. Its position in the ranks since 1975 has risen; relative to other cities in Indonesia, street construction in Surabaya has become more disconnected. Surabaya ranked 121st in 1975, 63rd in 1976-1990, 124th in 1991-2000 and 95th in 2001-2014.

Surabaya and Jawa Timur follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these rose steadily.

To date, Surabaya is the 4th-most disconnected out of the 52 cities in Jawa Timur. Its position in the ranks since 1975 has risen; relative to other cities in Jawa Timur, the street network in Surabaya has become more disconnected. Surabaya ranked 8th in 1975, 3rd in 1976-1990, 4th in 1991-2000 and 4th in 2001-2014.

Surabaya and Indonesia do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Surabaya rose steadily, while the SNDi of street constructions in Indonesia was at its lowest in 1976-1990.

To date, Surabaya is the 93rd-most disconnected out of the 363 cities in Indonesia. Its position in the ranks since 1975 has risen; relative to other cities in Indonesia, the street network in Surabaya has become more disconnected. Surabaya ranked 121st in 1975, 91st in 1976-1990, 98th in 1991-2000 and 93rd in 2001-2014.

As of 2015, Surabaya had a built-up area of 566.76 square kilometers, and a population of 8352589 people.

These are some other cities with approximately the same population: