It is interesting that this tower is still left because the Blomington Line to the east, and thus the diamond, has been abandoned long enough to turn it into the 606 Trail. And why do they still have the turnouts to the East?
The east/west line was originally the Chicago and Pacific. It was acquired by Chicago, Milwaukee & St. Paul in 1870s according to a comment by Bob Lalich that I have seen in another Facebook posting. That comment also indicated that C&P had the Chicago & Evanston route.