A press release from the Iowa DOT says C57 at US 218 south of Janesville will soon close for a year and a half for construction of an interchange. It’s the second interchange to be programmed in the area as traffic on the Avenue of the Saints has steadily increased, making intersections more dangerous. Because new 218 was built paralleling the railroad, railroad tracks will also have to be relocated and C57 will have an overpass there, as these maps from August 2013 show.
This interchange is years in coming, as these 2011 and 2013 articles from the Waterloo Courier show. This summer will mark the 20th anniversary of the opening of four-lane 218 between C57 and IA 57, completing four-lane links from Waverly to US 20 via both US 218 and IA 58. You can see the end of construction in this aerial photo from March 31, 1994.
When the interchange is completed and surrounding intersections are blocked off, US 218 will be a full controlled-access freeway from downtown Waterloo to the north side of Janesville.