Protection of the natural and human environment is a primary responsibility of government agencies responsible for the development, operation, and maintenance of the nation's transportation system. Ongoing research and development is one key to assuring that transportation agencies have the best and most current information, processes, and tools they need to successfully meet their environmental responsibilities. Every 5 years the Transportation Research Board (TRB) conducts a Transportation Environmental Research Needs (ERN) Conference to select and draft top-priority statements of environmental research needs. The most recent of these conferences was held in March 2002, this time with a multimodal perspective. This Proceedings contains the top research needs identified at the conference, along with background papers. These are organized into chapters for each of the following 15 topic areas: o Air Quality o Community Impacts, Environmental Justice, and Public Involvement o Context-Sensitive Design, Including Aesthetics and Visual Quality o Cultural Resources o Energy and Alternative Fuels o Environmental Information Management o Environmental Streamlining and Stewardship o Integrated Environmental Decision Making o Land Use and Transportation o Noise o Sustainability, Including Climate Change: Cause and Effects o Transportation, Human Health, and Physical Activity o Waste Management and Environmental Management o Water Quality and Hydrology o Wetlands, Wildlife, and Ecosystems