Street-network Sprawl in Kolkata, 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.

Kolkata: city in West Bengal, 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 Kolkata, India on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Kolkata as of 2014, the overall level of street-network sprawl is 4.09, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 3.9, 4.68, 5.04 and 4.71. Street construction in Kolkata 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 Kolkata spans a total of 8926 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 3.9, 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 3.9, 4.07, 4.08 and 4.09. Overall, the SNDi of the aggregate street network has risen: the street network in Kolkata has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.17 points, but between 1991-2000 and 2001-2014, it rose by just 0.01.

Kolkata and West Bengal do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Kolkata peaked in 1991-2000, while the SNDi of street constructions in West Bengal rose steadily.

How do development practices in Kolkata fare in comparison to others in West Bengal? Most recently in 2001-2014, street construction in Kolkata was the 10th-most disconnected out of the 80 cities in West Bengal. Its position in the ranks since 1975 has fallen; relative to other cities in West Bengal, street construction in Kolkata has become more connected. Kolkata ranked 5th in 1975, 7th in 1976-1990, 5th in 1991-2000 and 10th in 2001-2014.

Kolkata and India do not follow the same trend in the disconnectivity of their street network constructions. The SNDi in Kolkata peaked in 1991-2000, while the SNDi of street constructions in India rose steadily.

How do development practices in Kolkata fare in comparison to others in India? Most recently in 2001-2014, street construction in Kolkata was the 302nd-most disconnected out of the 1716 cities in India. Its position in the ranks since 1975 has fallen; relative to other cities in India, street construction in Kolkata has become more connected. Kolkata ranked 177th in 1975, 134th in 1976-1990, 180th in 1991-2000 and 302nd in 2001-2014.

Kolkata and West Bengal follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these rose steadily.

To date, Kolkata is the 11th-most disconnected out of the 80 cities in West Bengal. Its position in the ranks since 1975 has fallen; relative to other cities in West Bengal, the street network in Kolkata has become more connected. Kolkata ranked 5th in 1975, 9th in 1976-1990, 8th in 1991-2000 and 11th in 2001-2014.

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

To date, Kolkata is the 296th-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 Kolkata has become more connected. Kolkata ranked 177th in 1975, 199th in 1976-1990, 229th in 1991-2000 and 296th in 2001-2014.

As of 2015, Kolkata had a built-up area of 1218.22 square kilometers, and a population of 21620289 people.

These are some other cities with approximately the same population:

For some related information about population, urban extent and density, and roads, visit the Atlas of Urban Expansion.