Street-network Sprawl in Nampula, Mozambique

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.

Nampula: region in Mozambique

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 Nampula, Mozambique on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Nampula as of 2014, the overall level of street-network sprawl is 3.52, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 3.33, 3.17, 3.18 and 3.99. The disconnectivity of new streets constructed in Nampula fell, then rose. In 1976-1990, new street layouts were the most connected.

Quantity of street network construction: The street network in Nampula spans a total of 9091 kilometers. It is dominated by roads constructed in 2001-2014. These roads have an SNDi of 3.99, 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 3.33, 3.28, 3.26 and 3.52. The SNDi of the aggregate street network in fell at first, but Nampula has worsened in disconnectivity since 2000.

The level of street-network sprawl in new development in Nampula was at its lowest in 1976-1990. To get a sense of how street development has changed in Nampula, we can consider three of its most populous cities: Nampula, Nacala and Moma. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in new development in Nampula followed a zig-zag trend with an overall increase. The level of street-network sprawl in new development in Nacala followed a zig-zag trend. The level of street-network sprawl in new development in Moma followed a zig-zag trend.

How do development practices in Nampula fare in comparison to others in Mozambique? Most recently in 2001-2014, street construction in Nampula was the 1st-most disconnected out of the 10 regions in Mozambique. Its position in the ranks since 1975 has risen; relative to other regions in Mozambique, street construction in Nampula has become more disconnected. Nampula ranked 3rd in 1975, 4th in 1976-1990, 3rd in 1991-2000 and 1st in 2001-2014.

As of 2014, the city with the most disconnected street network in Nampula is Nampula with an SNDi of 4.2, which is highly disconnected. Conversely, the most connected city is Lulúti with an SNDi of -0.43, which is very well-connected. See trends for these cities: Lulúti, Nampula

The level of street-network sprawl in the aggregate network in Nampula was at its lowest in 1991-2000. To get a sense of how the aggregate street network has changed in Nampula, we can consider three of its most populous cities: Nampula, Nacala and Moma. None of the most populous cities follow the same trend as the region. The level of street-network sprawl in the aggregate network in Nampula followed a zig-zag trend with an overall increase. The level of street-network sprawl in the aggregate network in Nacala rose steadily. The level of street-network sprawl in the aggregate network in Moma rose steadily.

To date, Nampula is the 2nd-most disconnected out of the 10 regions in Mozambique. Its position in the ranks since 1975 has risen; relative to other regions in Mozambique, the street network in Nampula has become more disconnected. Nampula ranked 3rd in 1975, 2nd in 1976-1990, 3rd in 1991-2000 and 2nd in 2001-2014.