National Transit Frontline Workforce Training Act of 2020 This bill directs the Department of Transportation to establish a national transit frontline workforce training center to meet the needs of the rural and urban transit system frontline workforce through standards-based training relating to relevant maintenance and operations occupations. It must also evaluate, and provide a grant to, a nonprofit organization with demonstrated capacity to develop and provide transit career ladder programs through labor-management partnerships and apprenticeships on a nationwide basis to carry out the duties of the center. The center must develop and carry out training and educational programs for public transportation employees serving in the frontline workforce, including programs relating to (1) developing consensus national training standards for key frontline occupations with demonstrated skill gaps; (2) developing national systems of qualification and apprenticeship for transit maintenance and operations occupations; and (3) establishing local, regional, and statewide transit training partnerships.