Abstract:The identification of critical research needs in land use, transportation, and air quality was the focus of the biennial summer meeting of the Transportation Research Board Committee on Transportation and Air Quality, held in Irvine, California, in July 1992. Participants convened to build on the fundamental findings of the committee's workshop on environmental research needs held in Denver, Colorado, in November 1991, at which attendees identified 10 categories of national air-quality-related research needs that they considered highest priority. The list of 10 served as a baseline from which summer meeting participants developed additional research project needs. The three-day summer meeting was organized in a presentation and discussion format. Technical sessions were held on the following topics: (a) mobile source emissions estimates; (b) transportation control measures and transportation demand management effectiveness analysis and monitoring; (c) land use, travel patterns, and air quality; (d) transportation demand modeling for air-quality plans and control strategy analysis; and (e) top-down approaches to obtaining data for air-quality analysis. After each technical session, meeting participants met in groups of 10 to 12 to discuss issues raised by the speakers and to develop a list of what they believed to be critical research needs associated with the session topic. This article reports the findings of the summer meeting.