WRONG WAY CONCURRENCY

Since highways in the United States and Canada are usually signed with assigned cardinal directions based on their primary orientation, it is possible for a stretch of roadway shared between two highways to be signed with conflicting, even opposite, cardinal directions in a wrong-way concurrency. For example, near Wytheville, Virginia, there is a concurrency between I-77 (which runs primarily north–south, as it is signed) and Interstate 81 (which runs primarily northeast–southwest, but is also signed north–south).

Because of the way they intersect, the section of Interstate where they overlap has the two roads signed for opposite directions, leading to the town's nickname of "Which-Way-Ville". 

One might simultaneously be on I-77 northbound and I-81 southbound, while actually traveling due westbound.

[Note: I happened to be driving northbound on I-81 in Virginia for the first time last year. When we reached the point where I-81 and I-77 joined, SIRI told me to continue southbound on I-77, rather than continue northbound on I-81. I immediately assumed that I must have gotten into the wrong lane somewhere, but fortunately I continued on and eventually saw a sign that indicated I was on I-81 northbound. Coming back the opposite way a few days later, I was able to figure out what happened because there was a sign where I-81 and I-77 merged that indicated that I-77 northbound exit was 10 miles ahead].

There is more. U.S. Route 11 and U.S. Route 52 are in concurrency with each other and with the I-77/I-81 concurrency.

Since U.S. Routes 11 and 52 are in concurrency, but signed in opposite directions, these two routes also form a wrong way concurrency. Therefore, I-77, I-81, U.S. 11 and U.S. 52 form a double wrong-way concurrency. This is the only double wrong-way concurrency in the U.S.

Wait, think I am done yet? No way. How can U.S. 52 be signed north-south when it is an even numbered route and even numbered routes are east-west routes? The answer is that although U.S. 52 is an east-west route, the Virginia segment of Route 52 is signed such that U.S. 52 North corresponds to the general westward direction of the highway and vice-versa.

Confused? The pictures and diagram below may help.