Will the Real I-670 Please Stand Up?

Navigation through any city of largish size can be confusing. Nearby Columbus, OH is no exception. Take I-670 for instance, which runs from the I-270 loop just south of Westerville on the east, crosses I-71 just north of downtown, and ends on I-70 west. It's a pretty slick little cut through for us when we need to get to I-70 going because we don't have to either a) go all the way around the loop, or b) go directly through downtown on I-70. However, if you want to exit on the north side of downtown, well, you'd better know what you're doing. The image to the left over there (click to enlarge) is where I-670 crosses I-71. You'll notice that I-670 exists in two places. If you are coming across I-670 from the east, or picking it up from I-71 southbound, you get one set of exits, but if you happen to pick it up from I-71 northbound, you'll miss them. Likewise, depending on where you try to pick up I-670 eastbound, you'll get either the north leg or the south one, which is waaaay confusing. I'd love to know who thought that was a good idea...