A plan to transform the nation's busiest commuter rail line has reached a milestone.

The Federal Railroad Administration on Tuesday released a draft environmental impact statement that looks at three alternatives for the Northeast Corridor between now and 2040.

The 457-mile Northeast Corridor is the site of regular delays on Amtrak and regional lines, due to 100-year-old infrastructure and crowded tracks.

Among the more ambitious improvements in consideration are a high-speed rail between Washington, D.C. and Boston, a new rail line connecting Hartford, Connecticut to Providence, Rhode Island, and a rail tunnel from Long Island to Connecticut.

Federal officials will hold a series of public hearings in December and January before picking one of the alternatives next spring for a final environmental review.