Street-network Sprawl in Karachi, Pakistan

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.

Karachi: city in Sind, Pakistan

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 Karachi, Pakistan on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Karachi as of 2014, the overall level of street-network sprawl is 1.9, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 1.76, 2.02, 2.4 and 2.3. Street construction in Karachi 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 Karachi spans a total of 7405 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 1.76, which is relatively well-connected.

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 1.76, 1.83, 1.87 and 1.9. Overall, the SNDi of the aggregate street network has risen: the street network in Karachi has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.07 points, but between 1991-2000 and 2001-2014, it rose by just 0.02.

Karachi and Sind 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 Karachi fare in comparison to others in Sind? Most recently in 2001-2014, street construction in Karachi was the 13th-most disconnected out of the 36 cities in Sind. Its position in the ranks since 1975 has fallen; relative to other cities in Sind, street construction in Karachi has become more connected. Karachi ranked 10th in 1975, 12th in 1976-1990, 4th in 1991-2000 and 13th in 2001-2014.

Karachi and Pakistan 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 Karachi fare in comparison to others in Pakistan? Most recently in 2001-2014, street construction in Karachi was the 87th-most disconnected out of the 198 cities in Pakistan. Its position in the ranks since 1975 has fallen; relative to other cities in Pakistan, street construction in Karachi has become more connected. Karachi ranked 85th in 1975, 103rd in 1976-1990, 61st in 1991-2000 and 87th in 2001-2014.

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

To date, Karachi is the 15th-most disconnected out of the 36 cities in Sind. Its position in the ranks since 1975 has fallen; relative to other cities in Sind, the street network in Karachi has become more connected. Karachi ranked 10th in 1975, 14th in 1976-1990, 14th in 1991-2000 and 15th in 2001-2014.

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

To date, Karachi is the 129th-most disconnected out of the 198 cities in Pakistan. Its position in the ranks since 1975 has fallen; relative to other cities in Pakistan, the street network in Karachi has become more connected. Karachi ranked 85th in 1975, 121st in 1976-1990, 122nd in 1991-2000 and 129th in 2001-2014.

As of 2015, Karachi had a built-up area of 336.81 square kilometers, and a population of 13150694 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.