AERMOD-RLINE: An air quality model algorithm for roadways.

Abstract

The U.S. Environmental Protection Agency (EPA) Office of Research and Development (ORD) developed the stand-alone Gaussian dispersion R-LINE model for roadway applications including roadway specific complexities, such as noise barriers and depressions. This model has since been incorporated into EPA's preferred near-field dispersion model, AERMOD, as the RLINE source type. The 2024 proposed updates to EPA's Guideline on Air Quality Models include RLINE as an additional regulatory option for roadway applications. This article outlines the journey of the stand-alone R-LINE model from research and development, through the integration into AERMOD, testing, evaluation, formulation and refinement process, and proposal for regulatory adoption. Additionally, future research and development priorities for the RLINE source type are outlined.