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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Pages 53-75

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From page 53...
... C H A P T E R 5 Defining and Evaluating Lane Departure Crash Surrogate Thresholds Using Naturalistic Driving Study Data Lane departure crashes are the best measure of safety. Naturalistic driving studies, however, even the fully deployed SHRP 2 field driving study, will have limited cases of lane departure crashes.
From page 54...
... 54safety surrogates are believed to have some relationship to safety, although a demonstrated relationship rarely exists. Additionally, when safety surrogates are used in studies, there is no attempt to define the relationship between the safety surrogate and crashes.
From page 55...
... 55measure that has been used is time to collision (TTC) , where at TTC = 0 the subject vehicle and another vehicle/object collide, resulting in a crash.
From page 56...
... 56TTLD was defined as the time until an outer tire edge crosses the lane line. Mammar et al.
From page 57...
... 57Source: Szabo and Wilson, 2004. Figure 5.3.
From page 58...
... 58crash types, such as broadside or rear-end, can be defined by a time or distance metric (time or distance collision) because the hazard, collision with another vehicle, is clear.
From page 59...
... 59Category Hazard Surrogate Metric Normal driving Lateral drift Lane encroachment Shoulder encroachment Lane departure crash Table 5.1. Summary of Lane Departure Categories None Crossing lane line Sideswipe with adjacent or opposing vehicle Head-on collision Crossing lane line onto shoulder (left or right side)
From page 60...
... 60TTLD can also be calculated and used as the surrogate measure. • Lower boundary: Lower boundary is the point where normal driving ends, which will need to be determined in the full-scale study.
From page 61...
... 61another vehicle. The main hazard for an encroachment into an oncoming lane is a head-on or opposing-direction sideswipe crash.
From page 62...
... 62lane and control their vehicle when braking on wet surfaces (AASHTO, 2004)
From page 63...
... 63Figure 5.12. Threshold for normal steering.
From page 64...
... 64unless the damage exceeds some value. The VTTI driving study found that out of 82 minor nonproperty-damage contact collisions, only 15 were reported to the police (Dingus et al., 2006)
From page 65...
... 65Source: UMTRI RDCW data set. Figure 5.17.
From page 66...
... 66Source: Dingus et al., 2006. Figure 5.19.
From page 70...
... 70a large number of lane departure incidents, they could be used as a starting point to set threshold values for flagging lane departures. However, as indicated, there were not enough samples of incidents to determine what threshold values should be set.
From page 71...
... 71NightDay -1.5 -1.0 -0.5 0.0 0.5 1.0 La ne O ff se t Figure 5.28. Vehicle offset for daytime versus nighttime driving on tangent sections.Dr12 Dr14 Dr16 Dr17 Dr18 Dr24 Dr6 Dr8 -1.5 -1.0 -0.5 0.0 0.5 1.0 La ne O ff se t Figure 5.29.
From page 72...
... 72Dr28 Dr35 Dr48 Dr51 Dr59 Dr60 Dr64 Dr85 -1.5 -1.0 -0.5 0.0 0.5 1.0 La ne O ff se t2 Figure 5.30. Vehicle offset for Drivers 28, 35, 48, 51, 59, 60, 64, and 85 for tangent sections.between driving on a tangent and on a left- or right-hand curve, between nighttime and daytime driving, and between individual drivers.
From page 73...
... 73Source: VTTI data set. Figure 5.31.
From page 74...
... 74Source: AASHTO, 2001. © American Association of State Highway and Transportation Officials (AASHTO)
From page 75...
... 75One of the main methods to assess rollover risk is to use the static stability factor (SSF)

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