Looks like the Iowa DOT plans to replace the left exit from EB I-80 to NB I-35 with a flyover and replace a couple of the other ramps by 2023. There's going to be a meeting about this on October 26.
http://www.kcci.com/article/iowa-dot-unveils-multimillion-dollar-changes-to-50-year-old-mixmaster/13031535
Not a bad idea to replace that ramp. I hated that left exit, mostly during rush hour times.
I was wondering if they were planning something like that, especially since they're replacing the overpass immediately to the west.
The public meeting materials are available at the following link for anyone interested.
http://www.news.iowadot.gov/pim/2017/10/interstate-3580235-interchange-polk-county-oct-26.html