A rumble strip is a raised or corrugated section of a roadway which is designed as a highway safety feature. If drivers cross the rumble strip, it will produce a strong vibration and a lot of noise, alerting the driver to the fact that he or she may be doing something dangerous. Rumble strips are common along long, boring highways which might breed driver distraction, and they may be used on curvy roads, as well. Studies on rumble strips have suggested that they do save lives, greatly decreasing the accident rate on dangerous parts of the road.
There are three types of rumble strips. The first is a Shoulder Rumble Strip (SRS), which is located along the shoulder of a road. An SRS lets drivers know that they have strayed from the boundaries of the road, putting themselves at risk of crashing or spinning out on the dirt or gravel shoulder. A Centerline Rumble Strip (CRS) is located in the middle of the road. When drivers cross a CRS, it indicates that they are in a lane of opposing traffic, which could potentially be very dangerous. Finally, Roadway Rumble Strips (RRSs) are used in the middle of a lane to notify drivers about changes in driving conditions, and to encourage them to slow down.
Most commonly, a rumble strip is created by heavily grooving the pavement, creating a corrugated surface which will jar a car when its wheels pass over it. The rumble strip is often embedded into the pavement, so that plows can remove snow and ice from the road. In other cases, a rumble strip is made with elevations in the roadway, such as Botts' dots.
The first rumble strip was installed on New Jersey's Garden State Parkway in 1952. Realizing the potential applications of the device, highway departments in many other states followed suit. Rumble strips have become ubiquitous across the United States, especially in notoriously dangerous areas.
Inattentive driving can be caused by a number of things. Someone may be sleepy, distracted by children in the car, or trying to accomplish a task such as changing the radio station or shaving. As a result of their lack of focus, inattentive drivers may swerve off the road, start traveling too quickly, or drift into oncoming traffic. Rumble strips serve to literally shake the driver up, forcing him or her back into his lane.
There are other uses for rumble strips as well. On extremely curvy roads, going over the rumble strip suggests that the driver is going too fast, and therefore taking turns too wide. In fog and poor weather conditions, drivers can use rumble strips as guides to keep their cars in the proper lane, although they should ideally pull over if they are having a great deal of difficulty seeing.