(a) Plan.—In consultation with the States on the main line of the Northeast Corridor, the Secretary of Transportation shall develop a plan not later than September 30, 1993, to eliminate all highway at-grade crossings of the main line by not later than December 31, 1997. 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's Share of Costs.—Amtrak shall pay 20 percent of the cost of eliminating each highway at-grade crossing under the plan.