((a)) ** .—** Subject to subsection (b) of this section, the Secretary of Transportation may exempt from the requirements of this chapter railroad equipment or equipment that will be operated on rails, when those requirements preclude the development or implementation of more efficient railroad transportation equipment or other transportation innovations under existing law.

((b)) ** .—** The Secretary may grant an exemption under subsection (a) of this section only on the basis of—

((1)) findings based on evidence developed at a hearing; or

((2)) an agreement between national railroad labor representatives and the developer of the new equipment or technology.