Exterior Noise Created by Vehicles Traveling over Rumble Strips

Rumble strips are raised or recessed patterns in or adjacent to the travel way that produce audible and vibratory warnings when traversed by vehicle tires and thus are used to alert drivers to lane departures and/or changes in the roadway environment. However, there are trade-offs between the potential operational and safety impacts of rumble strips on non-freeway facilities, such as the exterior noise created when vehicles travel over the rumble strips and its impact on adjacent residences and businesses. Researchers measured the exterior noise produced by two types of vehicles traveling over five types of rumble strip applications at two different speeds. Only 13 percent of the peak rumble strip noise levels were above the highest noise level measured for a commercial vehicle driving along the roadway not hitting the rumble strips. However, over half of the rumble strip conditions produced changes in the exterior noise greater than 4 decibels. In general, the increase in exterior noise was greater at 70 mph than at 55 mph and lower for the commercial vehicle than for the sedan. Button rumble strips produced the smallest increase in exterior noise, while milled and rolled rumble strips yielded the largest increase in exterior noise. For milled rumble strips, the amount of additional exterior noise increased as the rumble strip width increased and decreased as the rumble strip spacing increased. The change in the exterior noise level was also affected by the pavement type (chip seal versus hot-mix asphalt).