This index is a data aggregation tool that proposes an original angle to assess the affordability of a specific location by gathering data on the cost of housing and transport/commuting. For example, poorer populations can often find themselves pushed out of newer, sustainable, transit-oriented housing developments in walkable neighbourhoods, particularly when the housing is centrally located. Prioritising the metropolitan scale in delivering housing and transport investment will help ensure a co-ordinated response to the need for economic efficiency, affordability and access to opportunity for all citizens. While regulatory barriers may drive up the cost of affordable housing development in the core, low access to transport in the periphery could drive up the total costs of housing transport for poorer households, who then get priced out of the core. An example of a strategic and practical partnership in this sense can be found in the New York and Connecticut Sustainable Communities Consortium, which offered a platform of co-ordination for housing and transport policy (Box 5.8). The initiative focused on downtown areas and/or economically challenged communities along the Metropolitan Transportation Agency Metro-North railroad system.