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19 Figure 3.7. VTTI Mask Head Tracker: Calibrated eyes forward (left); calibrated eyes on speedometer (right). tially reduce reliance on a human data reductionist to open cantly enhance understanding of the actions, conditions, and each trip file to perform visual verification of the participant. behaviors that led to the crash. In addition, the comparison of crash investigation data, police accident reports (PARs), and Crash Investigation DAS data will provide interesting insights into the reliability of these different sources of crash information. Data from crash investigations provide an important comple- Given that more than 1,000 crashes of all severity levels (as ment and extension of the naturalistic driving data that will well as perhaps an order of magnitude more of number of near be collected as part of the NDS. While the data captured by crashes) are expected during this study (see Table 3.9), not all the instrumented vehicle will be extensive, it is expected that crashes recorded during the study are expected to be investi- they will not be a complete record of every detail of a crash, gated because of several constraints, including cost and, since so the methodology recommended here is designed to collect many crashes are expected to be minor, the lack of crash site the additional data needed in a way that is both feasible and information. Crash investigations will only be carried out for effective. Data from the crash investigations should signifi- crashes that meet certain criteria of interest. Such criteria may Table 3.9. Crashes and Near Crashes in the SHRP 2 Naturalistic Driving Study Estimated by Three Methods (Based on 1,950 DASs for 2 Years) Based on the 100-Car Study, Modified Based on Crash Rates Crash/Incident Severity 100-Car Study by Fatality Rate from GESa and NHTSb Police reported 624 363 230 Nonreported, reportable 975 566 360 Nonpolice reported: low-g contact or tire strike 1,599 929 590 Total crashes 3,198 1,859 1,180 Near crashes 29,679 17,247 10,952 a General Estimates System. b National Household Travel Survey, 2001 (FHWA 2010).

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20 be altered as the study proceeds, but they could include such Participant interview (using an instrument provided by the factors as the following: S06 contractor)--as soon as feasible postcrash to determine the following: Severity (e.g., airbag(s) deployed or injuries sustained); Predrive factors: Crash type (e.g., intersection-related or lane change/ Recent sleep patterns; ran-off-road); Fatigue levels; Driver age (e.g., teen driver or older driver); Emotional states; and Land use (e.g., rural versus urban); and Stress levels. Advanced technology vehicle (e.g., equipped with crash Driving factors: warning/avoidance technology). Weather; Traffic; and The rates based on the 100-Car Study (Dingus et al. 2006) Obstructions. (see the first data column in Table 3.9) simply and directly Crash factors. extrapolate the crash rates observed in the 100-Car Study to Aerial view (as available, for example, from Google Earth the size and scope of the current study. These estimates were or Google Street View). then modified on the basis of the ratio of the relatively high Vehicle photos (can be taken by data retrieval technicians)-- fatality rates for Washington, D.C. (the site of the 100-Car front, back, sides. Study) and that of the United States overall (see the second 37 Crashes categorization (Najm et al. 2007). data column in Table 3.9). Fatal crashes were selected, since General Estimates System (GES) crash estimates are not avail- Considering data privacy and IRB issues, the only people to able for a particular locality, such as the Washington, D.C., be interviewed in all crash investigations will be the consented and northern Virginia area. According to Fatality Analysis drivers (and possibly other consented passengers) participat- Reporting System data, Washington, D.C., had a fatality rate ing in the SHRP 2 NDS. Note that all the crash data noted above of 29.15 per 100,000 registered vehicles in 2003 compared can be gathered remotely or with already-existing personnel. with the latest available national rate of 16.05 per 100,000 reg- A detailed list of data elements to be collected has been istered vehicles in 2006 (NHTSA 2010; NHTSA 2007). This selected to be consistent with common data elements in the analysis assumes that the relative traffic fatality rates between National Center for Statistics and Analysis national crash Washington, D.C., and that of the United States overall can data, either by adopting the structure or by structuring indi- also be used to roughly approximate the relative crash and vidual data elements so that they can be mapped into the near-crash rates. The numbers in the third data column in national data. Investigations will include documentation and Table 3.9 are derived from GES and 2001 National Household data collection as related to precrash driver assessment, inter- Travel Survey (FHWA 2010) estimates. views, the crash site, and vehicle examination (as available). Near crashes have been operationally defined by VTTI The type of precrash and postcrash assessment information researchers (Dingus et al. 2006) as any circumstance that to be collected will be similar to the recent National Motor requires a rapid, evasive maneuver by the subject vehicle, Vehicle Crash Causation Survey (NMVCCS) conducted by or any other vehicle, pedestrian, cyclist, or animal to avoid a NHTSA (2008). crash. A rapid, evasive maneuver is defined as steering, brak- On the basis of the criteria of severity, type (e.g., run-off- ing, accelerating, or any combination of control inputs that road or intersection related), or some condition of uniqueness, approaches the limits of the vehicle's capabilities. However, the S06 contractor will notify the S07 contractor to dispatch an there is nothing prohibiting other researchers from defining the experienced investigator to visit the site within 48 hours (but concept as they see fit. not while police/emergency medical service [EMS] personnel In most cases, S06 personnel will be notified of a crash by are actively working the crash scene) to produce or retrieve the DAS via cellular communication channels. Included in the the following additional information: communications process will be key details about the crash, A detailed description of the crash etiology; including a snippet of video covering the time just before and Crash site documentation and description (using software immediately after the crash. S06 personnel will then assess such as Easy Street Draw); those data against the crash severity criteria bulleted above to Crash-site photographs showing the approach to point of determine if the crash event warrants further investigation. impact for each involved vehicle and looking back from the If the crash is selected for further investigation, the S07 point of impact for each vehicle; and contractor will make an attempt to gather or retrieve the fol- Photos of physical evidence such as skid marks, gouges in lowing information: the roadway or median, and impact points. DAS data. Crash-site investigation is expected to be conducted by expe- PAR (as available from participant or public records). rienced crash-site/scene investigators.