Rationale and Definition:

Having sufficient public space allows cities and regions to function efficiently and equitably.¹  It provides the rights of way required for streets and infrastructure (and their connectivity) as well as the green space necessary for recreation and the provision of ecosystem services. At the same time, the positive outcomes of public space are not limited to infrastructure development and environmental sustainability. Access to open public space not only improves quality of life but also constitutes a first step towards civic empowerment and greater access to institutional and political spaces. Well-designed and maintained streets and public spaces can help lower rates of crime and violence, make space for formal and informal economic activities and avail services and opportunities to a diversity of users, including particularly marginalized ones.

By contrast, a reduced amount of public space impacts negatively on life in a city. The private sector generally has little incentive to provide public space and wider urban connectivity, so the role of local governments in defending the commons is critical. However, many local governments are relinquishing this role. As a result, much rapid urbanization is proceeding in an uncontrolled manner, yielding settlement patterns with dangerously low proportions of public space. Even the planned areas of new cities have sizably reduced allocations of land for public space, with an average of 15% of land allocated to streets. In unplanned areas the situation is considerably worse, with an average of only 2%.² Such areas are totally unable to accommodate safe pedestrian and vehicular rights of way; land for critical infrastructure such as water, sewerage, and waste collection; and green spaces that can facilitate social cohesion and critical ecological functioning.

The generally accepted minimum standard for public space in urban areas (defined by those achieving a minimum density of 150 inhabitants per hectare, the minimum threshold for a viable public transport system) is 45%. This is broken down into 30% for streets and sidewalks and 15% for green space.³ Total city space refers to the administrative/jurisdictional spatial extent of a municipality. This is strongly reinforced by the metric of street connectivity. If the average number of intersections per square kilometer is too few, the corresponding distance between intersections will be too far to incentivize walking; if it is too many, the average block size will be too small to be economically viable for development. As a result, the generally accepted target range for street connectivity is between 80-120 intersections per square kilometer.⁴ At an optimal level of 100 intersections per km2 (e.g. a grid of 10 by 10 streets) with each street occupying an average width of 15m (minimum for one vehicular lane each direction, street side parking and sidewalks), a city’s streets would occupy approximately 28% of its total area. This cross-verifies the recommended proportion of 30% for street area.

Disaggregation:

This indicator can easily be disaggregated into paved (streets) and green portions of total public space; it can also be disaggregated into public and private portions of total green space; lastly, it can be disaggregated by neighborhood, city and region.

Comments and Limitations:

With sufficient data, this indicator allows for comparing and aggregating progress across cities towards the achievement of an optimal quantity of land allocated to public space.

Preliminary Assessment of Current Data Availability by Friends of the Chair:

TBD

Primary Data Source:

High resolution satellite imagery (e.g. from US Geological Survey/NASA Landsat data or European Community’s Joint Research Center Global Human Settlement Layer), open public space maps (most municipalities have legal documents delineating publicly owned land) and/or GIS data.

Potential lead agency or agencies:

UN-Habitat, World Bank.