Street-network Sprawl in Bristol, United Kingdom

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.

Bristol: city in England, United Kingdom

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 Bristol, United Kingdom on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Bristol as of 2014, the overall level of street-network sprawl is 2.68, 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 2.52, 3.58, 3.69 and 3.6. Street construction in Bristol 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 Bristol spans a total of 1944 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 2.52, 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 2.52, 2.65, 2.67 and 2.68. Overall, the SNDi of the aggregate street network has risen: the street network in Bristol has become more disconnected. This increase has slowed: between 1975 and 1976-1990, SNDi rose by 0.12 points, but between 1991-2000 and 2001-2014, it rose by just 0.01.

Bristol and England follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these peaked in 1991-2000.

How do development practices in Bristol fare in comparison to others in England? Most recently in 2001-2014, street construction in Bristol was the 81st-most disconnected out of the 117 cities in England. Its position in the ranks since 1975 has risen; relative to other cities in England, street construction in Bristol has become more disconnected. Bristol ranked 109th in 1975, 113th in 1976-1990, 98th in 1991-2000 and 81st in 2001-2014.

Bristol and United Kingdom follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these peaked in 1991-2000.

How do development practices in Bristol fare in comparison to others in United Kingdom? Most recently in 2001-2014, street construction in Bristol was the 95th-most disconnected out of the 138 cities in United Kingdom. Its position in the ranks since 1975 has risen; relative to other cities in United Kingdom, street construction in Bristol has become more disconnected. Bristol ranked 130th in 1975, 134th in 1976-1990, 115th in 1991-2000 and 95th in 2001-2014.

Bristol and England do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Bristol rose steadily, while the SNDi of street constructions in England peaked in 1991-2000.

To date, Bristol is the 110th-most disconnected out of the 117 cities in England. Its position in the ranks since 1975 has fallen; relative to other cities in England, the street network in Bristol has become more connected. Bristol ranked 109th in 1975, 109th in 1976-1990, 110th in 1991-2000 and 110th in 2001-2014.

Bristol and United Kingdom do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Bristol rose steadily, while the SNDi of street constructions in United Kingdom peaked in 1991-2000.

To date, Bristol is the 130th-most disconnected out of the 138 cities in United Kingdom. Its position in the ranks since 1975 has not changed. Bristol ranked 130th in 1975, 130th in 1976-1990, 131st in 1991-2000 and 130th in 2001-2014.

As of 2015, Bristol had a built-up area of 104.91 square kilometers, and a population of 603350 people.

These are some other cities with approximately the same population: