At the end of this month, construction will begin on the IA 21 interchange with future four-lane US 30. The space is pretty flat, so to build up land for an overpass (as with US 218), IA 21 will have to be closed for an extended amount of time.
The DOT press release says “until fall 2023” but I assume that closure can go all the way to Thanksgiving. The detour (PDF) runs through Keystone and uses old IA 131 between Belle Plaine and 30. That means there will be more left-turning traffic than usual at two intersections.
The interchange will likely open to a four-lane on the west first, since the Tama County four-lane now extends to literally just over the hill from the intersection. The 12-mile segment from just east of 21 to just west of US 218 will be the last link of a four-lane 30 from Ogden to Lisbon that began more than half a century ago.