; (6) to determine best practices for the construction and maintenance of hydrogen pipelines; (7) to determine the reduction in carbon intensity at various levels of hydrogen blending into the natural gas network; and (8) to establish a framework for the measurement, reporting, and management of hydrogen leaks. 3. Supporting hydrogen infrastructure and regional development of hydrogen (a) Definitions In this section: (1) Board-regulated rates The term Board-regulated rates means rates regulated by the Surface Transportation Board. (2) Commission-regulated rates The term Commission-regulated rates means rates regulated by the Federal Energy Regulatory Commission. (3) Common carrier The term common carrier means a transportation infrastructure operator or owner that— (A) publishes a publicly available tariff containing the just and reasonable rates, terms, and conditions of nondiscriminatory service; and (B) holds itself out to provide transportation services to the public for a fee. (4) Eligible activity The term eligible activity means an activity described in subsection (g)(2) relating to, or carried out in connection with, an eligible project. (5) Eligible entity The term eligible entity means a corporation, partnership, joint venture, trust, non-Federal governmental entity, agency, or instrumentality, or other entity. (6) Eligible project (A) In general Subject to subparagraph (B), the term eligible project means an infrastructure project for hydrogen transportation, storage, or delivery, including pipeline, shipping, rail, refueling, or other infrastructure, or associated equipment, as the Secretary determines to be appropriate. (B) Inclusion of pipeline projects The term eligible project includes a pipeline project only if the project is for— (i) the construction of 1 or more new pipelines that are capable of handling pure hydrogen; or (ii) the retrofitting of 1 or more existing natural gas pipelines— (I) to transport a blend of hydrogen and natural gas