The impact of any transit system on the urban environment is related to two areas-one, the metropolitan area; the other, along the routes near the transit stations. In the metropolitan area, the macrolevel, we find a series of social or economic impacts. Some of these can be quantified, such as savings in time and costs, but others cannot, such as facilitating decentralization, providing accessibility to employment for the disadvantaged and to educational, cultural and recreational activities, and alleviating air pollution. At the microlevel, the impact is on the development around the transit stations, due to the change in accessibility. However, this development will not be an asset to the community unless it is well done. Finally, to have a really improved urban environment, we must consider our social institutions. We must pull together our many programs into one effective program for rebuilding and managing our cities.