Well I'm back from the PIM in Wauwatosa. I had some good conversations with WisDOT people. Lots of stuff to cover, so I'll just start rattling it off.
First of all, no surprise that WisDOT is apparently not getting much cooperation with the folks south of the border, so this seriously jeopardizes the extension of one of the Chicagoland interstates. Apparently, some folks are zeroing in on I-55 because that's the only one that Illinois is even remotely considering going along with. And even then, they are not very enthusiastic about it. It seems unlikely that WisDOT will have the cooperation of their flatlander counterparts to submit simultaneous applications to AASHTO this fall.
There was one display with the following possible numbers on it:
41 (starts @ Mitchell Interchange)
47 (starts @ Mitchell Interchange)
594 (starts @ Zoo Interchange)
643 (starts @ Hale Interchange)
But it was mentioned that these were not the only ones under serious consideration; hence the buzz about 55. I think Mike mentioned this from an earlier PIM, but 57 and 65 are almost certainly out. It's going to be 55 or one of those ^^ I mentioned.
WisDOT is really high on getting a 2di for this corridor due in no small part to the 3di possibilities. But mostly because of the perceived importance of a 2di.
I can confirm that WisDOT will likely move US 41 on to an all-freeway alignment in Milwaukee along with the new interstate. They like the idea of matching US 41 and the new interstate throughout the length of the corridor.
I was told they are not considering dropping I-894 in favor of the new interstate at this time. So 894 may become a useless duplex or we might even have another triplemultiplex (who, me?) in Wisconsin between the Hale and Mitchell interchanges.
The WisDOT people I spoke to said the number most people in the general public want at these meetings is 41. I think they can see the grid and how nicely 41 fits between 39 and 43. Plus, it's already 41.
Basically, every proposed number violates AASHTO numbering convention in some way, so WisDOT is looking for the one they could most easily talk them into. And to that end, it was mentioned to me that WisDOT is interested in talking to folks from North Carolina about how they've been able to make AASHTO their bitch in recent decades (I'm paraphrasing, of course.) Especially with that I-74/US 74 thing.
Despite Wisconsin's long standing non-duplication of numbers whether they be state, US or Interstate (prior to WI-39/I-39), nobody from WisDOT seemed overly concerned about duplicating any state highway number as the new interstate even though there is a WI 47, 55 and 57 in this part of Wisconsin. So if they get I-55, they have no plans to renumber WI 55.