Rumble strips are those notches along the lines on a roadway. If you drive over them, they make a loud noise that draws your attention.
According to the U.S. Department of Transportation, rumble strips can help prevent accidents where your vehicle either crosses the center line or the white line on the edge of the road.
Rumble strips can help to get your attention if you fall asleep or otherwise are not paying attention to the road before you end up in an accident situation. They not only cause a noise but also will vibrate your vehicle, which provides a two-step approach to ensuring you realize you have traveled out of your lane.
They also work well in situations when weather reduces visibility, such as fog or heavy rain or snow. Due to their design, rumble strips also provide a visible difference in the roadway, which can help you during adverse weather conditions.
When rumble strips are in the center of the road, they can help reduce the instances of head-on collisions. You will often find these located in areas where there is no passing. They are also usually outside the city limits as they do produce noise pollution.
Rumble strips on the outer lines of the roadway often run continuously down a road. They may only be put in where needed, though. They are helpful on narrow roads.
They may cause issues for bicyclists, so they may have periodic breaks to allow them to enter and leave the side of the road or the road crew may not install them in areas with a lot of bicycle traffic.