Chicago L

[TrainNut]

I was reading a book this morning (it happens occasionally), and I saw a picture of the Chicago L. The picture was of a corner above the intersection of E Lake St. and N Wabash Ave. in the downtown loop. It appears that when traveling north, the track briefly curves to the right before making a 90 degree curve to the left creating an S curve. My best guess is that they did this because the radius was too tight but it seems like there could have been a better way. Upon looking around, it also appears this is the only curve to have been built this way. Does anybody have more information on this curve and why it was built like this? The operators have got to have a special name for this curve but I have been unable to find any information.
While none of the pictures I was able to find are from the right angle, I did manage to find a few that showed this curve however subtle they are. Simply for the sake of comparison, this is a normal curve...


The next two pictures show the S curve...
one from down low...


...and one from up high...


And just for the sake of interest, I found a couple more that are not related to the curve but interesting shots all the same....