Street-network Sprawl in Sachsen, Germany

---

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:

• nodal degree
• dendricity, the tree-likeness of the street network
• circuity, the ratio of the distance by road to the straight-line distance of two locations on the street network
• sinuosity, the curviness of a street

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:

• Global trends toward urban street-network sprawl
• A global assessment of street-network sprawl

To see the state of street-network sprawl across the globe, visit the sprawlmap.

---

Sachsen: region in Germany

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 Sachsen, Germany on the sprawlmap

How have Sachsen's street networks changed over time?

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Sachsen as of 2014, the overall level of street-network sprawl is 2.09, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 1.73, 2.59, 2.95 and 3.23. In each period, new street development in Sachsen steadily grows more disconnected than in the last. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.86 points, but between 1991-2000 and 2001-2014, it rose by just 0.28.

Quantity of street network construction: The street network in Sachsen spans a total of 39151 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 1.73, 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 1.73, 2.0, 2.05 and 2.09. Overall, the SNDi of the aggregate street network has risen: the street network in Sachsen has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.27 points, but between 1991-2000 and 2001-2014, it rose by just 0.04.

Sachsen in context: Street-network sprawl of new development

The level of street-network sprawl in new development in Sachsen rose steadily. To get a sense of how street development has changed in Sachsen, we can consider three of its most populous cities: Dresden, Leipzig and Chemnitz. Out of the three cities, Leipzig does not follow the same trend as the region. The level of street-network sprawl in new development in Leipzig peaked in 1991-2000.

How do development practices in Sachsen fare in comparison to others in Germany? Most recently in 2001-2014, street construction in Sachsen was the 10th-most disconnected out of the 16 regions in Germany. Its position in the ranks since 1975 has risen; relative to other regions in Germany, street construction in Sachsen has become more disconnected. Sachsen ranked 13th in 1975, 13th in 1976-1990, 12th in 1991-2000 and 10th in 2001-2014.

Sachsen in context: Aggregate street-network sprawl

As of 2014, the city with the most disconnected street network in Sachsen is Görlitz with an SNDi of 1.35, which is relatively well-connected. Conversely, the most connected city is Leipzig with an SNDi of 0.81, which is relatively well-connected. See trends for these cities: Leipzig, Görlitz

The level of street-network sprawl in the aggregate network in Sachsen rose steadily. To get a sense of how the aggregate street network has changed in Sachsen, we can consider three of its most populous cities: Dresden, Leipzig and Chemnitz. Disconnectivity in the most populous cities in Sachsen follow the same region trend.

To date, Sachsen is the 13th-most disconnected out of the 16 regions in Germany. Its position in the ranks since 1975 has not changed. Sachsen ranked 13th in 1975, 13th in 1976-1990, 13th in 1991-2000 and 13th in 2001-2014.

Cities in Sachsen

• Leipzig
• Zwickau
• Chemnitz
• Dresden
• Görlitz