The PROT-AML has the main functions of translating, in regional and spatial terms, the major development objectives formulated in the National Programme for Spatial Planning Policy (PNPOT) and in the National Strategic Reference Framework (NSRF). In operational terms, it establishes broad guidelines for planning and urban occupation for the metropolitan area, defines the networks of regional infrastructure and transport, the essential ecological structure of the urban system, constituting itself as a framework for the elaboration of municipal plans of land use management.

The procedure for amending the PROT-AML, adopted in 2002, appears in a context of political decision to launch investment strongly restructurer for the metropolitan territory, as is the case of the New Lisbon Airport, the New Crossing of the Tejo River, the High Speed Rail Network and new logistics platforms.

CEDRU joined a broad multidisciplinary team and is particularly involved in issues of urban system, housing and community facilities and in defining the territorial model. The intention with this new plan was to contribute to the strengthening of the metropolitan urban armour, promoting polycentrism at several scales, striving for an urban-functional balance between the two large territorial units: Great Lisbon and the Peninsula of Setúbal.