Utilize the input text as a context reference, choose the right relationship between Northeast corridor and Amtrak from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

Gardner told lawmakers that it would cost Amtrak $1 billion per year just to keep its Northeast corridor infrastructure in a state of good repair, and would cost another $4 billion per year to complete its backlog of projects on the 457-mile corridor, a span that includes numerous century-old bridges and a 142-year-old tunnel.

Answer: operator