COES has four subcommittees:
Each subcommittee supports COES by providing policy support related to their topic areas, increasing the capacity of members to deliver environmentally sound transportation projects, programs, and services, and create the knowledge foundation on which to base state-of-the-art impact analysis and mitigation planning, for current and future issues.
Together, these subcommittees monitor and actively participate in the development and consistent application of environmental laws, regulations, and guidance. They support the goals and guide/support the work of the Center for Environmental Excellence by AASHTO, the Environmental Technical Assistance Program (ETAP), and the Transportation Systems Security and Resilience (TSSR) Technical Assistance Program. In accordance with the current Subcommittee Research Road Maps, they continue to identify and prioritize environmental/transportation research and support priority research selection and funding.