Applicability of Biodiversity Impact Assessment Methodologies to Transportation Projects

Abstract

Human activities often adversely affect natural landscapes or ecosystems. Natural landscapes typically consist of habitats differing in size, shape, structure, and composition. These components create biodiversity, which is broadly defined as the variety of the world’s organisms. Impacts on biodiversity—including direct impacts from development, secondary impacts, and impacts from active consumption—are increasing as the human population continues to grow. Impact on biodiversity is emerging as a concern of environmental groups. Highway construction may contribute to biodiversity loss because transportation corridors tend to disrupt normal patterns in the landscape. Transportation agencies, such as the Pennsylvania Department of Transportation, are interested in evaluating the need to analyze the effects on habitat fragmentation and biodiversity caused by roadway construction projects. Evaluation of such effects is a relatively new issue. There are currently no regulatory requirements to perform these types of evaluations. Therefore, the opportunity exists to develop rational and practical guidance to use on transportation projects. Even though no formal guidance exists, a number of similar methods in use could be modified for analyzing and quantifying impacts on biodiversity caused by highway projects. The decision whether to assess biodiversity for a project depends on the existing environment and the types of impacts the project will have on that environment. Whether mitigation of these biodiversity impacts should occur depends on the overall impacts on all resources by the proposed project. Much work still needs to be done in the development of an acceptable method for assessing the potential impacts of transportation projects on biodiversity. The general state analysis should be molded into an acceptable method for use by state departments of transportation. This method would need support in the form of a new mandate for implementation under the National Environmental Policy Act.