92 Ill. Adm. Code 1500.130
Subsidiary Passenger Tracks
Section 1500
Section 1500.130 Subsidiary
Passenger Tracks
a) Except as to ladder tracks the distance between the centerline
of any two subsidiary passenger tracks shall be not less than 13 feet.
b) Any pair of subsidiary tracks used solely for passenger
service may have centers less than 13 feet provided the centerline of any
track, adjacent to either side of such pair of tracks is located not less than
13 feet from the side of the track.