It looks like a weird situation with no exit, which appears to mean no point on US 12 and IN 912 is appropriate at the east end of IN 312. But if that's the case, should the east end of IN 312 be named something other than "US12"? I also assume that the intent here is that traffic that is on the frontage/outer roadways is not considered to be traveling on US 12 and IN 912.
I noticed because it was giving a weird-looking result in one of the new METAL algorithm visualizations.