"This report presents an evaluation of the current methods used to generate air emissions information from all freight transportation activities and discusses their suitability for purposes such as health and climate risk assessments, prioritization of emission reduction activities (e.g., through State Implementation Plans), and public education. The report is especially valuable for (1) its identification of the state of the practice, gaps, and strengths and limitations of current emissions data estimates and methods and (2) its conceptual model that offers a comprehensive representation of freight activity by all transportation modes and relationships between modes. This report will better inform the near-term needs of public and private stakeholders regarding the quality of emissions data and guide future research that links freight activities with air emissions."--pub. desc.