For purposes of this chapter:

that actually separate the vehicular roadway from the railroad tracks, and all approaches, ramps, connections, drainage, and other construction required to make the grade separation operable and to effect the separation of grades. A grade separation project may include provision for separation of nonmotorized traffic from the vehicular roadway and the railroad tracks. If a separation of nonmotorized traffic is not to be included in a project, there shall be an affirmative finding that the separation of nonmotorized traffic is not in the public interest. On any project where there is only one railroad track in existence, the project shall be built so as to provide for expansion to two tracks when the Director of Transportation determines that the project is on an existing or potential major railroad passenger corridor. The project may consist of: