High Occupancy Vehicles (HOV) Lane are marked on highways by a diamond shape in the center of the lane. HOV lanes may also be special lanes separated by a barrier or solid double white lines.
During heavy traffic periods, HOV lanes are reserved for buses, vanpools, carpools, other high occupancy vehicles, motorcycles, and certain clean special fuel vehicles. Road signs show the minimum number of passengers a vehicle must carry (excluding motorcycles and clean fuel vehicles) to use the HOV lanes and the times that HOV restrictions are in effect. If the lanes are separated by a barrier, they are reversible. This means that during certain times of the day, traffic flows one way.
During other times of the day, traffic flows in the opposite direction. A diamond-shaped marking may also indicate that the lane is reserved for use as a bus lane.