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.
Analyze the relationship between 'Amtrak' and 'Northeast corridor' within the context of the input sentence.
Options: platform, industry, business division, owner of