Should HOV exits have exit numbers?

[Duke87]

HOV Exits should have Exit Numbers matching the same exit route from the main line.  If there is no corresponding mainline exit, then the exit number should simply be based on the mileage of the route.  And "H" Designation might be helpful, but only if it does not meet with the exit from the main line, or connects to other HOV or Express lanes.

As a general design philosophy, there should never be a destination with an HOV exit but no general use exit, thus avoiding this problem. It may not always hurt but it certainly won't help congestion to force non-HOV traffic to potentially have to take a longer route to its destination. It also screws up GPS navigation when an exit may or may not be available to a given driver depending on how many people are in the car.

The opposite, however (general use exit but no HOV exit, HOV lanes are "express" lanes) is perfectly acceptable so long as drivers are made aware of the skipped exits before they enter the HOV lanes.

[NE2]

It's fairly popular to have HOV interchanges at different roads than normal interchanges. It probably improves traffic on the local roads.

[KEK Inc.]

It's actually rare for a non-freeway interchange to have the same HOV exit to the exact road. 

[1995hoo]

Setting aside the issue of numbers, I've always liked the idea of using different-colored guide signs over managed lanes, similar to the way Route 401 through Toronto uses blue signs over the Collector Lanes and green signs over the Express Lanes. Back in the 1970s and through most of the 1980s the reversible center carriageway on I-395 in Virginia (back then people didn't call it "HOV" yet, everyone called it the "express lanes") had overhead signs that were white-on-black but otherwise looked like standard guide signs (i.e., normal in all way but color). It made it apparent at a glance when a sign was for the express lanes.