Urban Density Index
This indicator is not an integral part of the SNAMUTS accessibility assessment, but rather a contextual measure to visualise the distribution of urban density (measured in residents and jobs per hectare) across the walkable activity node catchments in each SNAMUTS city. It was added to the standard range of SNAMUTS maps in 2022, starting with the Australasian and the majority of European cities, and will gradually be rolled out to cover the entire international sample.
The data contained in this index is (largely) compiled from figures that the statistical agencies of the relevant jurisdictions make publicly available, for example as part of regular releases of census outputs. SNAMUTS represents this data for the same catchment areas used in the calculation of residents and jobs within walking distance of activity nodes in the contour catchment, network coverage, betweenness and resilience indexes (generally defined as 800-metre radii around rail stations and ferry ports, and 400-metre linear corridors along tram and bus routes). Wherever the catchments of two or more activity nodes overlap in space, the overlap area is fully counted for each nodal catchment in order to determine the density figure.
Note that the density measure refers to gross urban density: in the denominator, it includes open spaces, public roads and other transport infrastructure (but not significant water bodies). The figures shown on the SNAMUTS maps can thus not be validly compared to site density (or net density) measures that only refer to private and/or developable land and are often used in zoning plans.
Note also that the average density figure given in the map legend only refers to those parts of the metropolitan area that are within walking distance of public transport at the SNAMUTS minimum standard, as defined in the network coverage index. In most cases, we would expect the average urban density for the entire metropolitan area to be lower (as public transport of this standard generally tends to concentrate on the higher-density components of the built-up-area).
Across our international sample, we can expect the standards of spatial granularity for the statistical units that form the base of this index to be anything but uniform, in some cases even between cities within the same country. Nor are the definitions of what constitutes a ‘resident’ or a ‘job’ without ambiguity – for example, in some jurisdictions these are counted exactly as found on a particular census day, in others this data originates from regular updates to council registers or business surveys. Both the spatial definitions as well as the survey methodologies may also change over time and import inevitable distortions into the data presented in this SNAMUTS index. A sensible degree of caution should thus be applied to any comparison of urban density figures between different cities in the sample, or year-on-year within the same city.
The data contained in this index is (largely) compiled from figures that the statistical agencies of the relevant jurisdictions make publicly available, for example as part of regular releases of census outputs. SNAMUTS represents this data for the same catchment areas used in the calculation of residents and jobs within walking distance of activity nodes in the contour catchment, network coverage, betweenness and resilience indexes (generally defined as 800-metre radii around rail stations and ferry ports, and 400-metre linear corridors along tram and bus routes). Wherever the catchments of two or more activity nodes overlap in space, the overlap area is fully counted for each nodal catchment in order to determine the density figure.
Note that the density measure refers to gross urban density: in the denominator, it includes open spaces, public roads and other transport infrastructure (but not significant water bodies). The figures shown on the SNAMUTS maps can thus not be validly compared to site density (or net density) measures that only refer to private and/or developable land and are often used in zoning plans.
Note also that the average density figure given in the map legend only refers to those parts of the metropolitan area that are within walking distance of public transport at the SNAMUTS minimum standard, as defined in the network coverage index. In most cases, we would expect the average urban density for the entire metropolitan area to be lower (as public transport of this standard generally tends to concentrate on the higher-density components of the built-up-area).
Across our international sample, we can expect the standards of spatial granularity for the statistical units that form the base of this index to be anything but uniform, in some cases even between cities within the same country. Nor are the definitions of what constitutes a ‘resident’ or a ‘job’ without ambiguity – for example, in some jurisdictions these are counted exactly as found on a particular census day, in others this data originates from regular updates to council registers or business surveys. Both the spatial definitions as well as the survey methodologies may also change over time and import inevitable distortions into the data presented in this SNAMUTS index. A sensible degree of caution should thus be applied to any comparison of urban density figures between different cities in the sample, or year-on-year within the same city.
