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From page 118... ... To determine optimum dimensions for both shoulder and centerline rumble strips for a range of operating conditions, a ﬁeld experiment was conducted where noise data were collected and statistical models developed to predict noise responses within the passenger compartment of a passenger car while it traversed various rumble strip patterns. The remainder of this section is organized as follows: Field Data Acquisition Methodology, Field Data Collection, Analysis Methodology, and Analysis Results. Read the entire page →
From page 119... ... The decision was made to include only passenger cars in this experiment primarily because the crash data suggest that passenger cars (and light trucks) are involved in the majority of crashes that could be remedied by shoulder and centerline rumble strips. Read the entire page →
From page 120... ... Raw data collected by data acquisition system. etoNstinUeciveDdleifataD CPemaneliF tsetfotratstadedroceRCPraeY tsetfotratstadedroceRCPhtnoM tsetfotratstadedroceRCPyaD tsetfotratstadedroceRCPruoH tsetfotratstadedroceRCPetuniM tsetfotratstadedroceRmm.mmddSPGedutitaL Longitude GPS ddmm.mm Recorded at start of test Vehicle speed GPS miles/hour Recorded at start of test Angle of departure GPS degrees Maximum difference in heading from start of test Ambient sound level SLM dBA Average over first 0.5 seconds Maximum sound level SLM dBA Maximum value during test Duration of sound event SLM seconds Time when sound level is above mean plus 1.5 standard deviations Dominant frequency of sound event MIC Hz FFT peak frequency File Yr Mo Day Hr Min Lat Lon pilot_east1 2006 10 12 9 18 4048.97 7754.65 Speed Ang_Dep Amb_SL Max_SL Dur Freq 59.67 4.10 66.22 79.83 1.05 172.20 Table 77. Read the entire page →
From page 121... ... Steeper angles were not possible because either shoulder widths were not wide enough or roadside hardware were adjacent to the shoulder, thus preventing maneuvers at larger angles. In many cases, left-side encroachments over centerline rumble strips were limited to 5 degrees 122 0 1 2 3 4 5 6 7 8 9 10 60 70 80 Time [sec] Read the entire page →
From page 122... ... , location (latitude and longitude) , travel speed, angle of departure, ambient and maximum sound levels, and duration and frequency of rumble strip noise generated in the vehicle. Read the entire page →
From page 123... ... The sound level difference was computed as the difference between the maximum sound level generated as the test vehicle traversed the rumble strip pattern minus the ambient sound generated in the passenger compartment of the test vehicle prior to encroaching the rumble strips. Separate models for the maximum and ambient sound levels were not speciﬁed because the sound level distributions obtained on the travel lane (ambient sound) Read the entire page →
From page 124... ... 67.12 90.02 79.41 4.08 Sound level difference (dBA) 2.63 26.26 15.98 4.32 Location indicator 1: shoulder rumble strips ; 0: centerline rumble strips 0 1 0.44 0.50 Pavement type indicator 1: concrete; 0: asphalt 0 1 0.08 0.27 Rumble strip type indicator 1: milled 0: rolled 0 1 0.86 0.35 Pavement condition indicator 1: wet surface 0: dry surface 0 1 0.20 0.40 Vehicle travel speed (mph) Read the entire page →
From page 125... ... • Rumble strips encountered on the shoulder by the rightside tires of a passenger car are associated with lower sound level differences when compared to centerline rumble strips encountered by the left-side tires of a passenger car. • A one unit increase in the vehicle angle of departure (degrees) Read the entire page →
From page 126... ... • Milled rumble strips are associated with a higher sound level difference when compared to rolled rumble strips. • A concrete pavement surface is associated with a lower sound level difference when compared to an asphalt pavement surface. Read the entire page →
From page 127... ... ) indicating that rumble strips with narrower widths produce greater sound level differences. Read the entire page →
From page 128... ... the condition of the rumble strips in the varying states (i.e., whether the rumble strips were recently installed or had been in place for several years) Read the entire page →
From page 129... ... Because the policy will be for freeways, the shoulders will be relatively wide, and in most cases bicycles will not be permitted on the roadways; thus the length dimension of the rumble strip can be determined independent of the shoulder width and bicycle considerations. Also, because bicycles are not permitted on freeways in most states, the rumble strips can be designed for the higher ranges of desirable maximum sound level difference. Read the entire page →
From page 130... ... 2: Designing Shoulder Rumble Strip Dimensions for Rural Two-Lane Roads Suppose a transportation agency wants to establish a policy for the design of milled shoulder rumble strips on rural twolane roads. In establishing such a policy, the agency will need to consider the following: • Bicyclists; • Narrower shoulders; • Sharper curves; • Intermediate and high speeds (e.g., 45 to 55 mph [70 to 88 km/h] Read the entire page →
From page 131... ... 3: Designing Centerline Rumble Strip Dimensions for Rural Two-Lane Roads Suppose a transportation agency wants to establish a policy for the design of milled centerline rumble strips on rural two-lane roads. In establishing such a policy, the agency will need to consider the following: • Sharper curves; • Intermediate and high speeds (e.g., 45 to 55 mph [70 to 88 km/h] Read the entire page →
From page 132... ... (8) that it is desirable to develop rumble strip patterns that generate sound level differences in the range from 10 to 15 dBA (i.e., 10 dBA ≤ SLDiff ≤ 15 dBA) Read the entire page →
From page 133... ... do not include all four primary rumble strip dimensions. • The predictive models include other independent variables such as vehicle speed, angle of departure, pavement type, and pavement condition, which logically explain some of the variability in the sound levels generated by rumble strips above the ambient level. Read the entire page →

From page 118...

... To determine optimum dimensions for both shoulder and centerline rumble strips for a range of operating conditions, a ﬁeld experiment was conducted where noise data were collected and statistical models developed to predict noise responses within the passenger compartment of a passenger car while it traversed various rumble strip patterns. The remainder of this section is organized as follows: Field Data Acquisition Methodology, Field Data Collection, Analysis Methodology, and Analysis Results.