Street-network Sprawl in Hong Kong, China

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.

Hong Kong: city in Central and Western, China

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 Hong Kong, China on the sprawlmap

Most recent snapshot: Taking into account the entire (i.e. aggregate) street network in Hong Kong as of 2014, the overall level of street-network sprawl is 1.04, which is relatively well-connected.

Trends in street network construction: The SNDis of street construction for the respective time periods are 0.91, 1.58, 1.24 and 2.97. Disconnectivity in street construction in Hong Kong follows a zig-zag trend. In 1975, street construction was most disconnected, while construction was most connected in 2001-2014.

Quantity of street network construction: The street network in Hong Kong spans a total of 2280 kilometers. It is dominated by roads constructed prior to 1975. These roads have an SNDi of 0.91, 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 0.91, 1.03, 1.03 and 1.04. Overall, the SNDi of the aggregate street network has risen: the street network in Hong Kong 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.

Hong Kong and Central and Western follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these followed a zig-zag trend with an overall increase.

How do development practices in Hong Kong fare in comparison to others in Central and Western? Most recently in 2001-2014, street construction in Hong Kong was the 1st-most disconnected out of the 1 cities in Central and Western. Its position in the ranks since 1975 has not changed. Hong Kong ranked 1st in 1975, 1st in 1976-1990, 1st in 1991-2000 and 1st in 2001-2014.

Hong Kong and China follow the same trend in the disconnectivity of their street network constructions. The SNDi for both of these followed a zig-zag trend with an overall increase.

How do development practices in Hong Kong fare in comparison to others in China? Most recently in 2001-2014, street construction in Hong Kong was the 391st-most disconnected out of the 1651 cities in China. Its position in the ranks since 1975 has risen; relative to other cities in China, street construction in Hong Kong has become more disconnected. Hong Kong ranked 858th in 1975, 829th in 1976-1990, 701st in 1991-2000 and 391st in 2001-2014.

Hong Kong and Central and Western do not follow the same trend in the disconnectivity of their aggregate street networks. The SNDi in Hong Kong rose steadily, while the SNDi of street constructions in Central and Western followed a zig-zag trend with an overall increase.

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

Hong Kong and China follow the same trend in the disconnectivity of their aggregate street networks. The SNDi for both of these rose steadily.

To date, Hong Kong is the 1194th-most disconnected out of the 1651 cities in China. Its position in the ranks since 1975 has fallen; relative to other cities in China, the street network in Hong Kong has become more connected. Hong Kong ranked 858th in 1975, 1122nd in 1976-1990, 1136th in 1991-2000 and 1194th in 2001-2014.

As of 2015, Hong Kong had a built-up area of 127.06 square kilometers, and a population of 5707660 people.

These are some other cities with approximately the same population:

For some related information about population, urban extent and density, and roads, visit the Atlas of Urban Expansion.