Street-network Sprawl in Siwan, India

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.

Siwan: city in Bihar, India

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 Siwan, India on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Siwan as of 2014, the overall level of street-network sprawl is 0.82, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are -0.53, 0.82, -0.14 and 3.72. Disconnectivity in street construction in Siwan 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 Siwan spans a total of 70 kilometers. The period with the greatest volume of street construction was 2001-2014. These roads have an SNDi of 3.72, 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 -0.53, 0.35, 0.27 and 0.82. Disconnectivity in Siwan's street network follows a zig-zag trend. In 1975, the city was most disconnected; while it was most connected in 2001-2014.

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

How do development practices in Siwan fare in comparison to others in Bihar? Most recently in 2001-2014, street construction in Siwan was the 23rd-most disconnected out of the 120 cities in Bihar. Its position in the ranks since 1975 has risen; relative to other cities in Bihar, street construction in Siwan has become more disconnected. Siwan ranked 39th in 1975, 67th in 1976-1990, 42nd in 1991-2000 and 23rd in 2001-2014.

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

How do development practices in Siwan fare in comparison to others in India? Most recently in 2001-2014, street construction in Siwan was the 502nd-most disconnected out of the 1716 cities in India. Its position in the ranks since 1975 has risen; relative to other cities in India, street construction in Siwan has become more disconnected. Siwan ranked 832nd in 1975, 990th in 1976-1990, 968th in 1991-2000 and 502nd in 2001-2014.

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

To date, Siwan is the 82nd-most disconnected out of the 120 cities in Bihar. Its position in the ranks since 1975 has fallen; relative to other cities in Bihar, the street network in Siwan has become more connected. Siwan ranked 39th in 1975, 80th in 1976-1990, 89th in 1991-2000 and 82nd in 2001-2014.

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

To date, Siwan is the 1351st-most disconnected out of the 1716 cities in India. Its position in the ranks since 1975 has fallen; relative to other cities in India, the street network in Siwan has become more connected. Siwan ranked 832nd in 1975, 1211th in 1976-1990, 1352nd in 1991-2000 and 1351st in 2001-2014.

As of 2015, Siwan had a built-up area of 2.61 square kilometers, and a population of 317528 people.

These are some other cities with approximately the same population: