Street-network Sprawl in New Jersey, United States

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.

New Jersey: region in United States

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 New Jersey, United States on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in New Jersey as of 2014, the overall level of street-network sprawl is 3.51, which is highly disconnected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 2.71, 4.69, 5.77 and 5.1. Street construction in New Jersey 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 New Jersey spans a total of 75789 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 2.71, 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 2.71, 3.19, 3.31 and 3.51. Overall, the SNDi of the aggregate street network has risen: the street network in New Jersey has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.48 points, but between 1991-2000 and 2001-2014, it rose by just 0.19.

The level of street-network sprawl in new development in New Jersey peaked in 1991-2000. To get a sense of how street development has changed in New Jersey, we can consider three of its most populous cities: Brick, Trenton and Toms River. Out of the three cities, Trenton and Toms River do not follow the same trend as the region. The level of street-network sprawl in new development in Trenton peaked in 1976-1990. The level of street-network sprawl in new development in Toms River rose steadily.

How do development practices in New Jersey fare in comparison to others in United States? Most recently in 2001-2014, street construction in New Jersey was the 31st-most disconnected out of the 46 regions in United States. Its position in the ranks since 1975 has fallen; relative to other regions in United States, street construction in New Jersey has become more connected. New Jersey ranked 29th in 1975, 22nd in 1976-1990, 22nd in 1991-2000 and 31st in 2001-2014.

As of 2014, the city with the most disconnected street network in New Jersey is Dover with an SNDi of 4.2, which is highly disconnected. Conversely, the most connected city is Atlantic City with an SNDi of 0.63, which is relatively well-connected. See trends for these cities: Atlantic City, Dover

The level of street-network sprawl in the aggregate network in New Jersey rose steadily. To get a sense of how the aggregate street network has changed in New Jersey, we can consider three of its most populous cities: Brick, Trenton and Toms River. Disconnectivity in the most populous cities in New Jersey follow the same region trend.

To date, New Jersey is the 28th-most disconnected out of the 46 regions in United States. Its position in the ranks since 1975 has risen; relative to other regions in United States, the street network in New Jersey has become more disconnected. New Jersey ranked 29th in 1975, 27th in 1976-1990, 29th in 1991-2000 and 28th in 2001-2014.