How can the future growth of settlements in the third world (Africa) be sustainable and planned?

The recent UN-HABITAT (2008) report on rate of urbanization said that the number of people of living in urban areas will more than double its 2007 level of 373.4 Million by 2030. Unlike in the developed western world where the urbanization process is taking place within a planned environment, in Africa the cities are growing without any plan or pattern. Slums are in the increase all over the cities of Africa with its attendant consequences of crime, poverty and health problems which has the capacity to truncate any global effort to make our earth a better and safer place. We must therefore address the root causes of unplanned growth and institutionalize community planning so that each community within and outside the cities of Africa and other developing countries would see the beauty of planning so that the towns are not only planned but provision are made for conservation and environmental protection.