Potential negative impacts on biological systems near proposed transportation facilities have been a major focus of environmental studies concerned with ural system. Plants and animals interact in complex ecosystems, even in urban areas. The construction of a transportation facility can disrupt the equilibrium established between the components of these ecosystems. Consideration must therefore be given to the loss of or injury to important organisms both directly (e.g., through destruction of vegetation) or indirectly (e.g., through contamination of water sup- plies Ecosystem management, at least as considered in transportation planning. is a rel atively new concept (see, for example, [Herbstritt and Marble, 1996]). The U.S. DOT in 1995 develo guidance to statcs and urban areas as to liow ecosystem consider- ations should be incorporated into planning. As noted by Garrett and Bank [1995]: The ecosystem approach is characterized as a method for sustaining or restoring natural systems and their functions and values. It is goal driven, and is based on a collabora- tively developed vision of desired future conditions that integrates ecological. eco- nomic, and social factors.