There are four studies used in this work: 1) Idaho Falls Roadway Study 2) Caltrans 99 Highway Study, 3) GM Sulfate Dispersion Experiment, and 4) the Berkeley Freeway Experiment. In all cases, the data used from the studies consist of concentration measurements of Sulfur Hexafluoride (SF6) released as a tracer to simulate roadway emissions and meteorological measurements. Comparisons are made to the various source formulations in AERMOD, the EPA’s preferred Gaussian dispersion model. This dataset is not publicly accessible because: This is non-EPA data. It can be accessed through the following means: 1) Idaho Falls Roadway Study. The data will be posted to https://www.epa.gov/scram in the future. In the meantime, contact Clint Tillerson (EPA) by email: tillerson.clint@epa.gov. 2) Caltrans 99 Highway Study. The data is available in the CALINE4 manual (accessible here: https://www.weblakes.com/products/calroads/resources/docs/CALINE4.pdf). 3) GM Sulfate Dispersion Experiment. The data will be posted to https://www.epa.gov/scram in the future. In the meantime, contact Clint Tillerson (EPA) by email: tillerson.clint@epa.gov. 4) Berkeley Freeway Experiment. The data is available here: https://nap.nationalacademies.org/catalog/27183/assessing-air-pollution-dispersion-models-for-emissions-regulation. Format: The format of the data varies by study as described in the data dictionary. This dataset is associated with the following publication: Owen, C., D. Heist, M. Snyder, R. Miller, L. Kent, M. Buechlein, and E. Carr. Incorporation of RLINE into AERMOD: An update and evaluation for mobile source applications. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION. Air & Waste Management Association, Pittsburgh, PA, USA, 75(4): 304-321, (2025).