Street-network Sprawl in Kenya

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.

Kenya

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 Kenya on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Kenya as of 2014, the overall level of street-network sprawl is 4.31, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 4.61, 4.29, 5.34 and 3.86. Disconnectivity in street construction in Kenya follows a zig-zag trend. In 2001-2014, street construction was most disconnected, while construction was most connected in 1991-2000.

Quantity of street network construction: The street network in Kenya spans a total of 58544 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 3.86, 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 4.61, 4.37, 4.72 and 4.31. Disconnectivity in Kenya's street network follows a zig-zag trend. In 2001-2014, the country was most disconnected; while it was most connected in 1991-2000.

The level of street-network sprawl in new development in Kenya followed a zig-zag trend with an overall decrease. To get a sense of how street development has changed in Kenya, we can consider three of its most populous regions: Nairobi, Mombasa and Nakuru. Out of the three regions, Nairobi and Nakuru do not follow the same trend as the country. The level of street-network sprawl in new development in Nairobi peaked in 1991-2000. The level of street-network sprawl in new development in Nakuru was at its lowest in 1976-1990.

How do development practices in Kenya fare in comparison to others in the world? Most recently in 2001-2014, street construction in Kenya was the 102nd-most disconnected out of the 155 countries in the world. Its position in the ranks since 1975 has fallen; relative to other countries in the world, street construction in Kenya has become more connected. Kenya ranked 18th in 1975, 42nd in 1976-1990, 43rd in 1991-2000 and 102nd in 2001-2014.

The largest city in Kenya is Nairobi, with a population of 3986200 people. Taking into account the entire (i.e. aggregate) street network in Nairobi as of 2014, the overall level of street-network sprawl is 5.77, which is highly disconnected. The level of street-network sprawl in new development in Nairobi peaked in 1991-2000.

As of 2014, the city with the most disconnected street network in Kenya is Nairobi with an SNDi of 5.77, which is highly disconnected. Conversely, the most connected city is Hagadera Refugee Camp with an SNDi of -0.2, which is very well-connected. See trends for these cities: Hagadera Refugee Camp, Nairobi

The level of street-network sprawl in the aggregate network in Kenya followed a zig-zag trend with an overall decrease. To get a sense of how the aggregate street network has changed in Kenya, we can consider three of its most populous regions: Nairobi, Mombasa and Nakuru. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in the aggregate network in Nairobi rose steadily. The level of street-network sprawl in the aggregate network in Mombasa was at its lowest in 1976-1990. The level of street-network sprawl in the aggregate network in Nakuru was at its lowest in 1976-1990.

To date, Kenya is the 45th-most disconnected out of the 155 countries in the world. Its position in the ranks since 1975 has fallen; relative to other countries in the world, the street network in Kenya has become more connected. Kenya ranked 18th in 1975, 34th in 1976-1990, 31st in 1991-2000 and 45th in 2001-2014.

The largest city in Kenya is Nairobi, with a population of 3986200 people. Taking into account the entire (i.e. aggregate) street network in Nairobi as of 2014, the overall level of street-network sprawl is 5.77, which is highly disconnected. The level of street-network sprawl in the aggregate network in Nairobi peaked in 1991-2000.