((a)) ** .—** In consultation with the States on the main line of the Northeast Corridor, the Secretary of Transportation shall develop a plan not later than , to eliminate all highway at-grade crossings of the main line by not later than . The plan may provide that eliminating a crossing is not required if—

((1)) impracticable or unnecessary; and

((2)) using the crossing is consistent with conditions the Secretary considers appropriate to ensure safety.

((b)) ** .—** Amtrak shall pay 20 percent of the cost of eliminating each highway at-grade crossing under the plan.