When the long, long-awaited four-lane IA 58 was built through Cedar Falls, the south portion had at-grade intersections. At the time, it was defensible, because there was little development in the area vs. today, there was a budget issue, and the DOT had just had a protracted battle in Waterloo over the US 218 freeway/expressway status (it was built as a boulevard with wide median and at-grade intersections). It was also before the Avenue of the Saints really got going, and the corridor is now part of that.
But 20 years later, the road has become a victim of its own success, and is woefully underpowered and potentially dangerous. The biggest problem, aside from being unfunded for at least three more years, is that there is very little room to fit in upgrades. But the DOT is going to try.
Viking Road, in particular (above), had development 10 and three years ago on the east sides, and also has a nature trail. To solve this issue, the two least-land-intensive interchanges are on the table, a SPUI and diverging diamond, which so far have been used very sparingly in Iowa. Even so, it would have to be about the world’s tightest SPUI. (Also proposed is something called a “double roundabout,” which NO. JUST NO.)
There are plans for the other intersections as well. Greenhill Road, north of Viking, currently has space around for a standard diamond. South of Viking, there’s a proposed diamond at Performance Drive, which currently does not intersect 58 and serves the industrial park. That diamond could also be changed into two half-diamond interchanges with frontages roads between Performance and Viking. (But bending the road seems unnecessary.)
Then there’s the US 20 interchange, which again is underpowered for the traffic. The minimum change would be to add a southbound-to-eastbound ramp for IA 27/Avenue of the Saints, but there are also multiple concepts for using flyover ramp(s).
All of the plans are in the “Display 1” PDF available at the link near the top of this post.