Evaluation of Data Needs, Crash Surrogates, and Analysis Methods to Address Lane Departure Research Questions Using Naturalistic Driving Study Data (2011) / Chapter Skim
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A P P E N D I X A Methodology for Extraction of Data Elements from the UMTRI Naturalistic Driving Study Data SetThis appendix includes description of the methodology to extract variables necessary to answer lane departure research questions using the UMTRI naturalistic driving study data set. The focus of the analysis is lane departures on rural, two-lane roadways.
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110Image source: Esri. © 2010 i-cubed.
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111• LDWBoundaryRight and LDWBoundaryLeft: Represent the type of lane line to the left or right of the vehicle's present lane. This information was used by the UMTRI system to determine position and offset within a lane.
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112• OvrCurveSpd5 and OvrCurveSpd10: Percentage. These variables reflect aggressive driving.
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113Figure A.4. Box plots showing acceleration ranges for Drivers 28, 35, 48, 51, 59, 60, 64, 85.Posted Speed Limit Advisory Speed Over Over Over Driver 5 mph 10 mph 10 mph OvrAdv15 6 0.0% 0.0% NA NA 8 49.0% 7.0% NA NA 12 8.0% 0.0% 83.0% 11.0% 14 36.0% 5.3% NA NA 16 1.2% 0.0% 31.4% 14.1% 17 0.9% 0.0% 2.3% 0.0% 18 12.1% 6.0% 41.7% 27.1% 24 36.0% 3.0% 78.0% 12.0% 28 90.2% 81.8% 100.0% 45.4% 35 21.9% 2.1% 41.1% 16.0% 48 25.0% 3.0% 75.0% 47.0% 51 13.2% 0.0% NA NA 59 8.5% 0.0% 89.0% 7.5% 60 41.8% 15.0% 63.7% 25.0% 64 55.5% 11.1% 61.1% 28.4% 85 25.0% 3.0% 75.0% 47.0% Table A.2.
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114• Brake: Provided with the data set, this is a categorical variable that indicates whether the brake was engaged, where 0 = not engaged and 1 = engaged. • Engaged: Provided with the data set, this is a categorical variable that indicates whether cruise control was engaged, where 0 = off and 1 = on.
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115Source: UMTRI. Figure A.5.
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116to the right of the vehicle in the direction of travel divided by vehicle trace length. Driveway density was calculated as indicated above but not included as a variable in the analysis.
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117• OtherPassDensity: The number of vehicles traveling in the same direction that passed the subject vehicle was determined from the forward video. The density of vehicles passing the subject vehicle (v/m)
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118the two research questions, it was necessary to identify actual lane departures within the UMTRI data set so that this information could be used to begin identifying thresholds. This section describes how vehicle lane departure events were identified and extracted from the UMTRI data set.
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119Right wheel path is calculated using lane width, lane offset, and track width according to Equation A.5: where RWPk = right wheel path (in meters) is the location of the right wheel path relative to the right and left lane lines for time interval k, Wk = lane width (in m)
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121The angle of departure was calculated using Equation A.7: where Angle of departure (θ) = angle that the vehicle departed from its original straight-line wheel path (in degrees)
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