Evaluating In-Vehicle Sound and Vibration During Incursions on Sinusoidal Rumble Strips

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Transportation Research Record

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Rumble strips (RS) are a countermeasure used to reduce roadway-departure crashes by providing audible and haptic alerts to the driver when a vehicle is departing the roadway. This study evaluated the feasibility of using sinusoidal RS as a substitute for more traditional rounded RS. A van, a passenger car, and a heavy vehicle were equipped with sound and vibration sensors to measure the interior noise and haptic feedback of each RS design. A set of typical conditions (with interior climate control fan and radio turned on) were also tested. Data from 75 RS strikes were analyzed. Experimental results demonstrated that the rounded RS doubled interior noise for the passenger car and van (11.3 dBA, 10.0 dBA) but the sinusoidal RS also generated a clearly noticeable interior alert for the passenger car and van (5.8 dBA, 4.6 dBA). The haptic alert provided an increase over the human perception threshold of vibration for all vehicles. The sinusoidal RS interior alert was detectable and within the acceptable range, but not clearly noticeable (5 dBA) when the climate control and radio were active. Alert levels for the rounded RS were >10 dBA, doubling the amount of interior noise for all ambient factor groups (11.2–14.4 dBA).

Roadway-departure crashes accounted for 18,275 fatal crashes in 2017 across the United States. Many of these crashes are on rural highways. Rumble strips (RS) are a proven safety countermeasure that alerts drivers to a roadway-departure through noise and vibration caused by milled grooves or raised striping on the roadway. Shoulder rumble strips (SRS) have been shown to reduce fatal rural highway roadway-departure crashes by 33%. Similarly, centerline rumble strips (CLRS) have been shown to reduce lane-departure crashes by 30%.

While RS are a proven safety countermeasure, they are also associated with highway noise concerns, especially from people living near roadways where they are installed. Long-term exposure to road noise has been shown to have negative health impacts, including disturbed sleep, annoyance, learning impairment, and hypertension ischemic heart disease. A new RS design that uses a shallower sinusoidal pattern has been shown to reduce roadside noise. However, the interior alert, or the noise and vibration generated from an incursion with the RS, must also be sufficient for the RS to remain an effective countermeasure. If the interior alert is adequate, sinusoidal RS could be installed in more locations where noise concerns have prevented their use. RS have a low cost per life saved ($320,000 per life), so extending the application of this countermeasure has the potential to reduce roadway-departure crashes.

The objective of this study is to evaluate the feasibility of using sinusoidal RS as a substitute for rounded milled RS on roadway segments with roadway-departure crash problems. In-vehicle noises and vibrations are quantitively and empirically compared between sinusoidal and rounded RS to indicate whether the sinusoidal pattern can potentially be used as a substitute for the rounded pattern. Thus, highway safety would be improved by reducing the rates of roadway-departure crashes and associated fatalities and injuries, while nearby residences would not experience as much roadside noise.


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