Street-network Sprawl in Comilla, Bangladesh

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.

Comilla: city in Chittagong, Bangladesh

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 Comilla, Bangladesh on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Comilla as of 2014, the overall level of street-network sprawl is 5.52, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 4.38, 5.36, 5.77 and 5.42. Street construction in Comilla 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 Comilla spans a total of 1917 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 5.42, 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 4.38, 5.13, 5.56 and 5.52. The aggregate street network in Comilla increased in disconnectivity initially,but the trend has turned around after 2000.

Comilla and Chittagong follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these peaked in 1991-2000.

How do development practices in Comilla fare in comparison to others in Chittagong? Most recently in 2001-2014, street construction in Comilla was the 6th-most disconnected out of the 21 cities in Chittagong. Its position in the ranks since 1975 has risen; relative to other cities in Chittagong, street construction in Comilla has become more disconnected. Comilla ranked 8th in 1975, 8th in 1976-1990, 5th in 1991-2000 and 6th in 2001-2014.

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

How do development practices in Comilla fare in comparison to others in Bangladesh? Most recently in 2001-2014, street construction in Comilla was the 30th-most disconnected out of the 157 cities in Bangladesh. Its position in the ranks since 1975 has fallen; relative to other cities in Bangladesh, street construction in Comilla has become more connected. Comilla ranked 19th in 1975, 18th in 1976-1990, 20th in 1991-2000 and 30th in 2001-2014.

Comilla and Chittagong do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Comilla peaked in 1991-2000, while the SNDi of street constructions in Chittagong peaked in 1976-1990.

To date, Comilla is the 9th-most disconnected out of the 21 cities in Chittagong. Its position in the ranks since 1975 has fallen; relative to other cities in Chittagong, the street network in Comilla has become more connected. Comilla ranked 8th in 1975, 11th in 1976-1990, 9th in 1991-2000 and 9th in 2001-2014.

Comilla and Bangladesh do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Comilla peaked in 1991-2000, while the SNDi of street constructions in Bangladesh rose steadily.

To date, Comilla is the 28th-most disconnected out of the 157 cities in Bangladesh. Its position in the ranks since 1975 has fallen; relative to other cities in Bangladesh, the street network in Comilla has become more connected. Comilla ranked 19th in 1975, 22nd in 1976-1990, 21st in 1991-2000 and 28th in 2001-2014.

As of 2015, Comilla had a built-up area of 423.98 square kilometers, and a population of 6167651 people.

These are some other cities with approximately the same population: