I don't agree with the I-880 in Iowa. I find it much easier to just follow I-680 if I want an alternative to I-80.
Agreed, why split a functional loop route into two different numbers? I assert the routes do serve different purposes, but did that many people really get confused by this arrangement?
I imagine that when the average non-roadgeek in that area hears "I-680", they think only of the segment that forms a suburban bypass around Omaha's northwest quadrant. So when people are told to avoid flooding by using (or not using) "I-680", but the segment in question might actually be the rural portion way off to the northeast of Council Bluffs, it's easy to see where the confusion would arise. I think the new I-880 designation makes sense.
And in the far distant future...
* when I-880 is extended west into Nebraska, and then southward, to form an outer bypass around greater Omaha,
* and the I-680 designation is extended east through Crescent to form a more useful bypass of Council Bluffs,
...then the wisdom of this decision will become even more apparent
