Street-network Sprawl in Chittagong, 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.

Chittagong: region in 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 Chittagong, Bangladesh on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Chittagong as of 2014, the overall level of street-network sprawl is 6.16, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 6.19, 6.23, 6.47 and 6.41. Street construction in Chittagong 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 Chittagong spans a total of 20808 kilometers. The period with the greatest volume of street construction was 1976-1990. These roads have an SNDi of 6.23, 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 6.19, 6.23, 6.18 and 6.16. The aggregate street network in Chittagong increased in disconnectivity initially,but the trend has turned around after 1990.

The level of street-network sprawl in new development in Chittagong peaked in 1991-2000. To get a sense of how street development has changed in Chittagong, we can consider three of its most populous cities: Comilla, Chattogram and Noakhali. Out of the three cities, Chattogram and Noakhali do not follow the same trend as the region. The level of street-network sprawl in new development in Chattogram was at its lowest in 1976-1990. The level of street-network sprawl in new development in Noakhali peaked in 1976-1990.

How do development practices in Chittagong fare in comparison to others in Bangladesh? Most recently in 2001-2014, street construction in Chittagong was the 3rd-most disconnected out of the 8 regions in Bangladesh. Its position in the ranks since 1975 has fallen; relative to other regions in Bangladesh, street construction in Chittagong has become more connected. Chittagong ranked 1st in 1975, 1st in 1976-1990, 2nd in 1991-2000 and 3rd in 2001-2014.

As of 2014, the city with the most disconnected street network in Chittagong is আলীখালী with an SNDi of 11.14, which is highly disconnected. Conversely, the most connected city is সন্দ্বীপ with an SNDi of 0.43, which is very well-connected. See trends for these cities: সন্দ্বীপ, আলীখালী

The level of street-network sprawl in the aggregate network in Chittagong peaked in 1976-1990. To get a sense of how the aggregate street network has changed in Chittagong, we can consider three of its most populous cities: Comilla, Chattogram and Noakhali. Out of the three cities, Comilla and Chattogram do not follow the same trend as the region. The level of street-network sprawl in the aggregate network in Comilla peaked in 1991-2000. The level of street-network sprawl in the aggregate network in Chattogram was at its lowest in 1976-1990.

To date, Chittagong is the 3rd-most disconnected out of the 8 regions in Bangladesh. Its position in the ranks since 1975 has fallen; relative to other regions in Bangladesh, the street network in Chittagong has become more connected. Chittagong ranked 1st in 1975, 1st in 1976-1990, 1st in 1991-2000 and 3rd in 2001-2014.