I left River Forest in 1970. At the time, the Lake Street bridge was still double track, and still had boards and hangers for Chicago & West Towns Railway streetcar wire (C&WT went to buses in 1947). The C&NW bridge was double track, and the double track extended to the junction with the CGW/C&NW in Forest Park. The piers and abutments for the C&NW bridge show clearly that they had carried double track at one time. Looking at Street View it appears that the eastern span was retained, as cut off transverse I-beams can be seen on the west side below the plate girders, The pads to raise the bridge’s elevation are also clearly visible in photos from street level Making the Lake Street bridge single track was easy since it is a deck girder design, so it only involved moving the track to the center of the structure and raising it a foot or two. The other bridges (Chicago Ave., Oak St, Washington Blvd) are all double track through girder - none of them have full-height clearance for trucks. I don’t know what year the changes were made as I didn’t see the C&NW bridge between 1970 and 1990, and I wasn’t where I could see the track changes. I guess I assumed the changes were made along with the other changes for double stacks, like raising the Belt Railway bridge at Kenton.