(a) As to the costs of any railroad grade crossing or railroad grade separation project or maintenance:
(1) 25 percent of these costs shall be paid by the railroads that benefit from the crossing or separation; and
(2) 75 percent of these costs shall be paid by the Administration.
(b) If two or more railroads benefit from the crossing or separation, the railroads’ 25 percent share shall be apportioned among them as determined by the Administration.