lane assist on my tom tom gps will switch to show lanes when you are on interstate highways going by exits. So if for example you are in a 3 lane road and getting off, it will show 3 lanes and an arrow flashing on the off ramp. Or if there are 2 exit lanes, arrows will flash in both lanes. If you are going straight through the arrows will flash in the straight lanes when you go by an exit. It was great going through the spaghetti bowl in Las Vegas.