I'm in the Washington, DC region of the United States and believe that you are not really serving the commuters here if you do not take the HOV restrictions into account. Thus the ability to designate HOV roads and HOV vehicles is needed. However, many of the HOV restrictions here are for only a portion of the day. Thus, HOV needs to be a quality/characteristic of the road (like toll is) and it needs to be able to vary based on the time of day. In other words, you will need to able to designate the road as HOV from 6:00 AM to 9:00 AM. During that time only HOV type vehicles can use the road. Additionally, it matters how many occupants the vehicle has here. In other words, some restrictions are HOV-2 (restricted to vehicles with 2 or more occupants) and some restrictions are HOV-3 (restricted to vehicles with 3 or more occupants). So ideally, you would be able to designate between HOV types. But I believe that just a HOV designation would be useful, even if you could not distinguished between HOV types.
There is also much discussion about the recently opened HOT/Express lanes in the area. The lanes are available either if you meet the HOV requirement or if you pay a toll. Thus, it would be beneficial if you could designate a road as both toll and HOV and that would allow routing if you have avoid toll road off or if you select that you are HOV.




