The DOT last month unveiled a host of possibilities for upgrading and improving I-380 in the Cedar Rapids area. Here’s a summary of the design ideas for the interchanges. The most notable point is that all of the smaller interchanges have a “diverging diamond” as an option. However, the overview document says “there is currently no funding in place for design or construction of recommended concepts.”
All of the PDF links below WILL expire at some point. This is merely explaining that information in text form. Working south to north:
Exit 13, Wright Brothers Boulevard (airport exit): Regular diamond, diverging diamond, six-ramp
- Flyover ramp for NB 380 to WB 30, instead of the existing loop, which itself would have a sub-exit to 6th Street SW (old US 218/IA 965). This carries the US 218 traffic, so I like that idea.
- Do nothing except expand the number of lanes on NB 380 through the interchange.
- Flyover ramp from EB 30 to NB 380.
- Long flyover ramp from WB 30 to SB 380, passing over both J Street SW and the ramps to/from NB 380 from WB 30. Then another flyover ramp from NB 380 to WB 30 that would split from the EB exit, and another flyover from EB 30 to NB 380 that joins the first ramp mentioned.
- Extend 12th Street NE into a northbound on/southbound off partial interchange where I-380 turns north again.
- Create a giant bypass of downtown between 1st Avenue and H Avenue. The entire thing would be a bridge over the Cedar River and nearby lake. I’m sure it would be extremely expensive and I don’t know how something like that would be signed.
- Relocate both curves around the downtown segment, replacing the 5-in-1 bridge and shortening the route. This would also include the 12th Street NE extension.
- Separate the Diagonal Drive and 1st Avenue exits, create a single “downtown” exit with 6th and 7th streets NE (removing the 8th Street interchange), and extend NE 12th Street.
Exits 23/24/24A/24B, 42nd Street, Collins Road, and Blairs Ferry Road: Page 1, Page 2
- Create an independent exit ramp for SB 380 to Collins Road, plus an independent entrance ramp for traffic heading north from Collins Road. This would eliminate the exit number issue evident in the header, because SB traffic for all three streets must exit at the same time. The volleyball interchange at Collins Road (IA 100) would remain.
- Spike the volleyball interchange at Collins Road in favor of a single bridge across the interstate that intersects the ramp roads. In addition, create an at-grade intersection for Collins Road and Center Point Road. Blairs Ferry Road, meanwhile, would get a diverging diamond.
- Kill the volleyball interchange at Collins Road (again) but build a SPUI at that intersection, and also have an at-grade intersection with Center Point Road. Each road would get its own extended exit and entrance ramps (one who enters NB I-380 from 42nd Street, for example, would cross over the exit ramp for NB 380 to Collins Road).
Exit 25, Boyson Road: All include a reconstruction of the intersection with Center Point Road.
- Five-ramp interchange (loop WB Boyson to SB 380).
- Folded diamond interchange — I think. The existing NB off/SB on ramps aren’t marked for removal on the map, but the new lane markings don’t show those roads.
- SPUI
NEW Exit 26, Tower Terrace Road: Normal diamond, five-ramp (WB Tower Terrace to SB 380), diverging diamond, SPUI. The new exit here is related to the significant growth of Hiawatha and Robins.
Exit 28, County Road E34: Normal diamond, six-ramp, diamond with roundabouts (EWW!), diverging diamond.
As mentioned in the lead-in, some of these may happen, or none of them will happen, or all of them could come up a decade down the road.