August 2, 2016: These exits for IA 192 and 24th Street are becoming Exits 49 and 50, respectively, heading north on I-29, as the dual divided freeway project advances in Council Bluffs.
The two exits on the shared I-29/80 segment in Council Bluffs are getting new exit numbers tonight, according to an e-mail (and then press release) from the Iowa DOT. As part of the Council Bluffs interstate program expanding I-29/80 to dual sets of “express” and “local” lanes, the ramps come off part of the outer/local/I-29 lanes.
The 24th Street exit will be I-29 Exit 50 and South Expressway (former IA 192) will be Exit 49. I-80 Exit 3 won’t go away completely, though, because there will be an exit from westbound mainline I-80 to South Expressway before the I-29 lanes join the local. The east 29/80 interchange will be Exit 48 (NB 29 to EB 80) and Exit 3 (WB 80 to SB 29) but unnumbered heading west.
This “corrects” an anomaly in interstate exit numbering that happens twice in Iowa. Generally, the lower-numbered interstate is supposed to take precedence, which means that these two exits in Council Bluffs should have been I-29’s to begin with, and I-35/80 around Des Moines should use I-35’s exit numbering. This convention is why the Avenue of the Saints got remarked around Charles City when US 18 was rerouted, creating an official Mile 218H. One case where the rules were bent for a positive outcome is US 18/63, where the New Hampton bypass uses 63’s exit numbers because 63 is clearly the more important route.