include measurable thresholds for determining proficiency. (3) International and inland navigation rules test (A) In general All personnel assigned, employed, or working in a vessel traffic service center with responsibilities that include communicating, interacting, or directing vessels within a vessel traffic service area, as determined under the national policy developed under subsection (a), shall be required to pass a United States international and inland navigation rules test developed by the Secretary. (B) Elements of test The Secretary shall determine the content and passing standard for the rules test developed under subparagraph (A). (C) Testing frequency The Secretary shall establish a frequency, not to exceed once every 5 years, for personnel described in subparagraph (A) to be required to pass the rules test developed under such subparagraph. (e) Research on vessel traffic (1) Vessel communication The Secretary shall conduct research, in consultation with subject matter experts identified by the Secretary, to develop more effective procedures for monitoring vessel communications on radio frequencies to identify and address unsafe situations in a vessel traffic service area. The Secretary shall consider data collected under subparagraphs (A) and (B) of subsection (c)(3). (2) Professional mariner representation (A) In general The Secretary shall conduct research, in consultation with local stakeholders and subject matter experts identified by the Secretary, to evaluate and determine the feasibility and benefits of representation by professional mariners on the vessel traffic service watchfloor at each vessel traffic service center. (B) Implementation The Secretary shall implement representation by professional mariners on the vessel traffic service watchfloor at those vessel traffic service centers for which it is determined feasible and beneficial pursuant to research conducted under subparagraph (A). (f) Working group (1) In general The Secretary shall establish a working group with regional