while spatial plans can condition the choices that firms and households make by determining where roads will be constructed and by indicating what land is open for development and what land is not these are coarse tools for shaping economic growth overly rigid spatial plans can limit prosperity while overly flexible plans lose the ability to manage the built environment and achieve environmental protection goals the logic of constructing a pole metropolitain is that the correct spatial unit for planning is an urban core or cores that lead economic growth in a surrounding more rural hinterland