My understanding is they are very cheap to install relatively speaking. All lanes should really have them, they are really useful even for regular driving. For example if you have to cross a shoulder line or center line it can give the driver a better idea of exactly where the line and their vehicle is. They also help find the shoulder or center line if some snow is covering the paint. If pulling over all the way onto the shoulder, you know when you are completely out the lane after the second set of vibrations.