Street-network Sprawl in Christchurch, New Zealand

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.

Christchurch: city in Canterbury, New Zealand

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 Christchurch, New Zealand on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Christchurch as of 2014, the overall level of street-network sprawl is 2.56, which is in the 40th to 60th percentile of disconnectedness.

Trends in street network construction: The SNDis of street construction for the respective time periods are 2.5, nan, 4.35 and 3.54. Data was not available in 1976-1990.

Quantity of street network construction: The street network in Christchurch spans a total of 1171 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 2.5, which is in the 40th to 60th percentile of disconnectedness.

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 2.5, 2.5, 2.53 and 2.56. Overall, the SNDi of the aggregate street network has risen: the street network in Christchurch has become more disconnected.

Christchurch and Canterbury do not follow the same trend in the disconnectivity of their street network constructions. There was not enough data from the city, as well as the Canterbury's street network construction.

How do development practices in Christchurch fare in comparison to others in Canterbury? Most recently in 2001-2014, street construction in Christchurch was the 1st-most disconnected out of the 1 cities in Canterbury. Its position in the ranks since 1975 has not changed. Christchurch ranked 1st in 1975, 1st in 1991-2000 and 1st in 2001-2014. There was no ranking in 1976-1990 due to unavailable data.

Christchurch and New Zealand do not follow the same trend in the disconnectivity of their street network constructions. There was not enough data from the city, as well as the New Zealand's street network construction.

How do development practices in Christchurch fare in comparison to others in New Zealand? Most recently in 2001-2014, street construction in Christchurch was the 5th-most disconnected out of the 8 cities in New Zealand. Its position in the ranks since 1975 has not changed. Christchurch ranked 7th in 1975, 5th in 1991-2000 and 5th in 2001-2014. There was no ranking in 1976-1990 due to unavailable data.

Christchurch and Canterbury do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Christchurch rose steadily, while the SNDi of street constructions in Canterbury rose steadily.

To date, Christchurch is the 1st-most disconnected out of the 1 cities in Canterbury. Its position in the ranks since 1975 has not changed. Christchurch ranked 1st in 1975, 1st in 1976-1990, 1st in 1991-2000 and 1st in 2001-2014.

Christchurch and New Zealand do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Christchurch rose steadily, while the SNDi of street constructions in New Zealand rose steadily.

To date, Christchurch is the 7th-most disconnected out of the 8 cities in New Zealand. Its position in the ranks since 1975 has not changed. Christchurch ranked 7th in 1975, 7th in 1976-1990, 7th in 1991-2000 and 7th in 2001-2014.

As of 2015, Christchurch had a built-up area of 80.56 square kilometers, and a population of 260085 people.

These are some other cities with approximately the same population: