Reverse route numbers in one location

[roadfro]

That is still the most annoying thing I find about Interstate Concurrencies.  Why, does I-15 get priority over I-90 in Butte, even though 90 is the straight road, and I-15 gets on, then off, and all the exit numbers don't make sense for those driving on I-90?

It is fairly common practice among highway agencies. When highways of equal status overlap, the lower numbered route is usually considered the primary route for reference point (milepost) continuity, and thus, exit number continuity. (The MUTCD's only mention of overlaps is that an Interstate must take reference point continuity above an overlapping lower-class highway.)

[WNYroadgeek]

NY 36 and NY 63 intersect each other in York, and again in Dansville (both in Livingston County).
NY 13 and NY 31 intersect each other in Lenox (in Madison County).

[Charles2]

AL-14 and AL-41 junction in Selma.

[The High Plains Traveler]

CO-96 ends at CO-69 in Westcliffe.

[robbones]

Macon, MO US 63 & US 36 intersect each other.

[robbones]

West of Lansing, MI, there is I-69 and I-96.  They even share pavement for a short distance.

US 69 & US 96 in Beaumont, Texas shares pavement as well. IIRC this is the only instance where both numbers share pavement as a US and Interstate highway.

[hbelkins]

[hbelkins]