Protected bike lanes are located within the road right-of-way, but are physically separated from motor-vehicle lanes by concrete curbs, planters, vehicle parking, etc. Some protected lanes allow for only one-way bicycle traffic, while others accommodate travel in both directions. (The direction of these lanes are irrespective of the direction of regular traffic. For example, a two-way street can have a one-way bike lane.) Similarly, contraflow bike lanes allow cyclists to travel in the opposite direction of motor vehicle traffic, either on one-way streets or on the opposite side of the road. These lanes can be protected or painted, but are always separated with a yellow line to signify the opposing direction of travel.