A roadway toxics dispersion study will be conducted during the month of October at the U.S. DOE's Idaho National Laboratory (INL) near Idaho Falls, ID. The Field Research Division of NOAA, in conjunction with the Atmospheric Modeling Division of the U.S. EPA, is conducting the experiment. The purpose of the study is to document the concentrations of an intentionally released atmospheric tracer behind a roadway sound barrier in various conditions of atmospheric stability. The results will augment those of a wind tunnel study conducted in a similar manner as this field study. The experiment is being conducted in the pristine environment of the INL to enable clear and easy interpretation of the data. Simultaneous tracer concentration measurements with bag and real-time samplers will be made downwind from two 78m line sources; one with a mock sound barrier and one without the barrier. Sonic anemometers will be employed to measure the barrier-induced turbulence. Supporting meteorological measurements will come from infrastructure already in place at the test site, including a radar wind profiler with RASS, a mini sodar, an eddy flux station, and nearby NOAA/INL Mesonet stations. The field experiment layout and preliminary results will be presented.