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70 A p p e n d i x C Research Question Analyses
71 Table C.1. How Do Dynamic Driver Characteristics, as Observed Through Driver Performance Measures, Influence Crash Likelihood? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static Can driving control performance for various states be categorized more simply (i.e., good and bad, or risky and nonrisky)? UMTRI Driving control performance measures Can various driver states (e.g., drowsy, aggressive, distracted, engaged) be identified from naturalistic driving data? UMTRI Driver state How do driver behavior and response influ- ence subsequent events and outcomes after a vehicle initially leaves the roadway? CTRE Driver distraction, aggressiveness, driver status What is the relationship between measures obtained from pretest assessment batteries (e.g., a life stress test) and the frequency of engagement in distracting behaviors while driving? VTTI Does there appear to be any correlation between willingness to engage in distracting behaviors and life stress sources, personality characteristics, or ability to focus attention? VTTI Pretest batteries (life stress test) Willingness to engage in distracting activities How often and under what circumstances do drivers drive while fatigued? VTTI Fatigued driving What are the individual differences, both between and within drivers, related to fatigue? Fatigue sensors? VTTI Driver fatigue Age How often and under what circumstances do drivers drive while under the influence of alcohol? VTTI Alcohol use What are the individual differences, both between and within drivers, related to alcohol use? Passive alcohol sensors? VTTI Alcohol use Individual differences Crash What are the differences in demographic data, test battery results, and performance-based measures between attentive and inattentive drivers? VTTI Many How might knowledge of demographic differ- ences in attentive and inattentive drivers be used to mitigate the potential negative con- sequences of inattentive driving behaviors? VTTI Could information concerning demographic differences in attentive and inattentive drivers be used to improve driver education courses or traffic schools? VTTI
72Table C.2. What Impacts Do Roadway Countermeasures Have on Lane-Keeping Performance? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static Are drivers more likely to lane keep on roadways with edge-line rumble strips? CTRE Roadway attributes, number of lanes, type of pavement surface, lane width, shoulder type and width Lane position (lane departures) How do lane-edge markings affect lane keeping? VTTI Lane-edge markings Lane departure What is the influence of rumble strips in measured lane-keeping performance? VTTI Rumble strips Lane departure Are centerline rumble strips ben- eficial in improving lane-keeping performance? VTTI Rumble strips Lane departure Would centerline rumble strips be effective in preventing head-on collisions? VTTI Centerline rumble strips Head-on collisions What is the influence of special curve warning markings (e.g., on- pavement markings)? VTTI Curve warning markers Lane departure What are the potential impacts of rumble strips on nonfreeways? VTTI Rumble strips Lane departure Would rumble strips be effective without the paved shoulder? VTTI Rumble strips, paved shoulder Lane departure (continued on next page)
73 Does rumble strip noise reduce the deviation from the lane, or does it function as an alarm to improve subsequent alertness and lane keeping after encountering the rumble strip? VTTI Alertness Noise from rumble strips Lane departure Do rumble strips reduce the fre- quency and duration of lane devia- tions, making successful recovery more likely, and/or does a lane departure over a rumble strip improve subsequent lane keeping and decrease the frequency of lane departures? VTTI Rumble strips Lane departure How does the driverâs positioning of the vehicle affect lane keeping, and how is this related to the effi- cacy of edge marking and rumble strips? VTTI Driver lane position maintained Edge markings and rumble strips Lane departure Are drivers less likely to pass with centerline rumble strips? VTTI Centerline rumble strips Lane departure How likely are drivers to overcorrect or countersteer away from edge rumble strips so that they avoid a road departure but encroach into an adjacent lane? CTRE Vehicle head- ing; lateral and lon- gitudinal acceleration; pitch, yaw, and roll rates; speed Roadway attributes, number of lanes, type of pavement surface, lane width, shoulder type, shoulder width Lane position (lane departures) Table C.2. What Impacts Do Roadway Countermeasures Have on Lane-Keeping Performance? (continued) Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static
74 Table C.3. How Does Driver Distraction Influence Crash Likelihood? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static Is driving-control-performance pattern different for the same driver when distracted or not distracted (e.g., on cell phone or not on cell phone)? UMTRI How do driver distractions affect involvement in ROR collisions? VTTI Distraction What is the role of inattention in collision risk at intersections? VTTI Inattention Crash risks in intersections What is the role of driver inattention in rear-end crashes (i.e., striking a vehicle in the travel lane)? VTTI Inattention Rear-end crashes To what degree does the lead vehicle driver (i.e., the driver in the instrumented vehicle) contribute to the crash as a result of driver inattention? VTTI Inattention for lead vehicle driver Crashes What is the role of driver inattention as it relates to crashes involving pedestrians, objects, or animals in the travel lane? VTTI Inattention Crashes with pedestrians, objects, or animals What is the role of inattention (i.e., as a result of second- ary task) in lane-change or merge crashes? VTTI Secondary tasks, inattention Lane-change or merge crashes What is the role of inattention in head-on crashes? VTTI Inattention Head-on collisions What is the role of inattention (i.e., as a result of focusing on a secondary task) in backing crashes? VTTI Secondary tasks, inattention Backing crashes
75 Table C.4. How Do Aggressive Driving Behaviors Influence Crash Likelihood? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What is the relative contribution of aggressive driving to inappropriate gap acceptance? VTTI Aggressive driving Inappropriate gap acceptance What is the relative contribution of aggressive driving to red light running? VTTI Aggressive driving Red light running What is the role of aggressive driving in rear-end crashes (i.e., striking a vehicle in the travel lane)? VTTI Aggressive driving Rear-end crashes To what degree does the lead vehicle driver (i.e., the driver in the instrumented vehicle) contribute to the crash as a result of aggressive driving? VTTI Aggressive driving Lead vehicle contri- bution to crashes What is the role of aggressive driving as it relates to crashes involving pedestrians, objects, or animals in the travel lane? VTTI Aggressive driving Crashes with pedes- trians, objects, or animals What is the role of aggressive driving (e.g., approach speed, gap with lead vehicle when change is initiated) in lane-change or merge crashes? VTTI Aggressive driving Lane-change or merge crashes What is the role of aggressive driving (e.g., speeding, being in a hurry) to backing crashes? VTTI Aggressive driving Backing crashes What is the influence of aggression or aggressive driving on lane keeping? VTTI Aggressive driving Lane departure What is the influence of aggression or aggressive driving on ROR events? VTTI Aggressive driving ROR crashes How does aggressive driving behavior affect crash risks? VTTI Aggressive driving Crash risks What is the role of aggressive driving in passing-maneuver errors? VTTI Aggressive driving Passing maneuver crashes How does aggressive driving behavior affect near-crash risks? VTTI Aggressive driving Near crash, crash Why do aggressive driving behaviors occur, and how do they relate to ROR crashes and near crashes? VTTI Aggressive driving ROR crashes, near crashes
76 Table C.5. How Does Driver Fatigue Influence the Likelihood and Type of Crashes? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What is the role of driver fatigue in rear-end crashes (i.e., striking a vehicle in the travel lane)? VTTI Fatigue Rear-end crashes To what degree does the lead vehicle driver (i.e., the driver in the instrumented vehicle) contribute to the crash as a result of driver fatigue? VTTI Fatigue Lead vehicle contribution to crash What is the role of driver fatigue as it relates to crashes involving pedestrians, objects, or animals in the travel lane? VTTI Fatigue Crashes with pedestrians, objects, or animals What is the role of driver fatigue in head-on crashes? VTTI Fatigue Head-on crashes What is the role of driver fatigue in lane-change or merge crashes? VTTI Fatigue Lane-change or merge crashes What is the role of driver fatigue in backing crashes? VTTI Fatigue Backing crashes
77 Table C.6. How Do Advanced Driver Support Systems Influence Crash Likelihood? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static Are drivers less likely to lose control with antilock braking systems? CTRE Make and model, any known deficiencies How do drivers react in a ROR crash or near crash in terms of precrash maneu- vers (with or without a crash-warning system)? VTTI Warning system Driver behavior response time How do crash-avoidance systems, including electronic stability control (ESC), affect driver behavior in ROR or rear-end crash scenarios? VTTI Crash-avoidance systems Driver behavior in ROR or rear-end crashes Can ACC help reduce ROR crashes? VTTI ACC ROR crashes What are the benefits of CWS deployed in the fleet when a striking vehicle is in the travel lane? VTTI CWS Safety benefits What are the benefits of other vehicle countermeasures (e.g., brake assist) in the fleet? VTTI Other vehicle countermeasures Safety benefits Do vehicle CWS contribute to crashes? VTTI CWS Crashes Do other types of vehicle counter- measures, such as brake assist, lead to struck secondary crashes? VTTI Vehicle countermeasures Secondary crashes Given that most objects, pedestrians, and animals produce no radar signature, is there any indication that reliance on CWS is a detriment? VTTI Reliance on CWS CWS Detriment on safety Are there benefits to enhanced vision sys- tems at night (e.g., infrared headlamps or differing types of head lighting) in determining the presence of pedestri- ans or objects in the travel lane? VTTI Enhanced vision systems Ability to see pedes- trians or objects in lane Are there any forward CWS benefits related to head-on crashes? VTTI Forward CWS Head-on crashes What are the potential benefits of other vehicle countermeasures (e.g., brake assist) in the fleet related to head-on crashes? VTTI Other vehicle countermeasures Head-on crashes (continued on next page)
78 What are the benefits of lane-change aids and CWS? VTTI Lane-change aids Benefits to safety How does ACC use (compared with cruise control) affect speed compliance? VTTI ACC Driver speed compliance How does ACC use affect eyes-off-the- road time (i.e., drivers allowing themselves to be more distracted)? VTTI ACC Eyes-off-the-road time Where do drivers look when they receive these alerts or activate these systems? VTTI Glance behavior Warning system None How and how fast do drivers respond when they receive these alerts or acti- vate these systems? VTTI Warning system Response time Do these alerts and/or systems offer a safety benefit for impaired or drowsy drivers? VTTI Impaired/ fatigued Alerts Safety benefits What are the potential benefits of radar and ABS in reducing the incidence and severity of automobile accidents? VTTI Radar and ABS Reducing crash severity and incidents How do crash-avoidance systems, including ESC, affect driver behavior in ROR or rear-end crash scenarios? VTTI ESC Driver behavior in ROR or rear-end crashes How can the effectiveness of back-up warning algorithms be tested? VTTI Are back-up warning systems of differ- ent types (e.g., cameras) beneficial? What aspects make them beneficial or detrimental? VTTI Back-up warning systems Beneficial What is the driver response, in terms of immediate control input and subse- quent speed selection, to in-vehicle CWS warnings? VTTI CWS warning Driver response Table C.6. How Do Advanced Driver Support Systems Influence Crash Likelihood? (continued) Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static
79 Table C.7. What Is the Influence of Driver Impairment on Crashes and Driver Errors? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What is the relative contribution of impairment to inap- propriate gap acceptance? VTTI Impairment Inappropriate gap acceptance What is the relative contribution of impairment to red light running? VTTI Impairment Red light running What is the role of driver impairment in rear-end crashes (i.e., striking a vehicle in the travel lane)? VTTI Impairment Rear-end crashes To what degree does the lead vehicle driver (i.e., the driver in the instrumented vehicle) contribute to the crash as a result of other driver impairment? VTTI Impairment Lead vehicle contribution What is the role of other driver impairment as it relates to crashes involving pedestrians, objects, or animals in the travel lane? VTTI Impairment Crashes with pedes- trians, objects, or animals What is the role of other driver impairment in head-on crashes? VTTI Impairment Head-on crashes What is the role of other driver impairment in lane- change or merge crashes? VTTI Impairment Lane-change or merge crashes What is the role of other driver impairment in backing crashes? VTTI Impairment Backing crashes
80 Table C.8. How Does the Turn-Lane Configuration Influence Behavior and Crash Risks? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What are the safety effects of protected and unprotected turn lanes? VTTI Protected turn lanes Lane departure How do turn lanes change the pattern of conflict at intersections? VTTI Turn lanes Pattern of conflicts Do offset left-turn lanes (bays) affect turn behavior (e.g., gap acceptance and the decision to turn)? VTTI Offset turn lanes Driver turn behav- ior (e.g., gap acceptance and decision to turn) How much do left-turn lanes and/or signal phases reduce collision risk? VTTI Turn lanes or signal phases Crash risks How much do left-turn lanes reduce colli- sion risk, with and without left-turn signal phases? VTTI Left-turn lanes with and without signal phases Crash risks How much do right-turn lanes reduce colli- sion risk, with and without right-turn signal phases? VTTI Right-turn lanes Crash risks How much do right-turn lanes and/or signal phases reduce collision risk? VTTI Right-turn lanes with and without signal phases Crash risks
81 Table C.9a. What Variables or Pre-Event Factors Are the Most Effective Crash Surrogate Measures? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static For a given crash type, are any conflicts directly informative about crashes in the sense that they are generated from similar sets of background conditions? UofMN Gap-selection events Conflict types, back- ground variables Back- ground variables Crash type Which noncrash incidents can be used as crash surrogates to assess risk for road-departure crashes? CTRE Pitch and roll angle rates, lateral and longitudinal acceleration, speed, distance vehicle encroaches into adja- cent lane or shoulder Road- departure crashes Do naturalistic driving data con- tain measurable episodes of disturbed control? (Broad research question.) UMTRI Disturbed control Do objective measures of dis- turbed control from naturalistic driving data, together with high- way geometric factors, off- highway factors, and environ- mental factors, satisfy the criteria for crash surrogates, i.e., are they related to actual crashes? (Broad research question.) UMTRI Disturbed control Highway features Environ- mental factors If so, are these conflicts more frequent, as frequent, or less frequent than actual crashes? UofMN Gap-selection events Crash types and con- flict types Once a road departure occurs, what is the next most common sequence of incidents and out- comes (e.g., safe recovery and return to roadway, minor conflict with safe return, near miss with safe return, property damage accident, or injury accident)? CTRE Lateral and longitudinal acceleration, speed, distance vehicle encroaches into adja- cent lane or shoulder Pitch and roll angles and rates Once a road departure occurs, what kinematic variables can be used to define the different outcomes (e.g., road-departure crash, near crash, conflict, or incident)? CTRE Longitudinal and lateral acceleration, speed, distance vehicle encroaches into adja- cent lane or shoulder Pitch and roll angles and rates What measures exist in natural- istic driving data that directly measure disturbed control? UMTRI Disturbed control
82Table C.9b. What Explanatory Factors Are Associated with Crashes or Crash Surrogates, and What Analytical Models Can Be Developed to Predict Crashes or Crash Surrogates? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What kinematic mea- sures of driving con- trol performance are available in the natu- ralistic driving data, and what are the levels of accuracy in those measures? UMTRI What kinematic vari- ables can be used to determine when a road departure is likely or imminent? CTRE Lateral and longitudinal accelera- tion, vehicle heading Lane width Position of other vehicles Lane position (lane departures) How can severity- related factors con- ditioned on an event having occurred be most effectively examined? PSU Conversing with passengers, internal dis- tractions, wire- less devices, talking, eating, distractions from the vehicle, loss of control, aggressive, risky driving, life stressors, improper speed behavior Number of years driving, driving experience, miles driven, history of violations and crashes, edu- cation, gen- der, annual mileage, and other predis- posing factors Vehicle age Congested flow Over road edge, curve Dawn/dusk; lighting conditions; wet, icy, or snowy Severity level: crashes, near crashes, incidents Are other driving con- trol metrics neces- sary (in addition to vehicle kinematic measures) to identify disturbed control? UMTRI Vehicle kinematics Are there measures of driving control per- formance in exist- ing FOT data that depend on highway factors in a way that is consistent with single-vehicle road- departure crash frequencies? UMTRI Driving control performance measures (continued on next page)
83 Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What factors are associated with unconditional event occurrences? PSU Aggression, risky driving, life stress Gender, driving experience, miles driven, education, history of driv- ing violations, past crashes Vehicle age Crashes What is the nature of the relationship between crashes, near crashes, inci- dents, and pre-event maneuvers and precipitating fac- tors, driver factors, contributing factors, and environmental factors? PSU Pre-event maneuvers Driver factors Environmen- tal factors Crashes, near crashes, incidents (and their surrogates) For a given crash type and data source, is it possible to identify a plausible struc- tural model? If so is the data source sufficiently rich to support estimation of the values taken on by the model variables for crashes and interesting non- crashes? UofMN Speed, reaction times, evasive actions Vehicle speed, accelera- tion (longi- tudinal and lateral) Opposing traffic Vehicle trajectory If it is not possible to identify and validate plausible models, what additional data would be needed to support the estima- tion of the values for crashes and interest- ing noncrashes? UofMN Gap-selection events Opposing driverâs eva- sive ac tions (braking, steering, or a combination) Table C.9b. What Explanatory Factors Are Associated with Crashes or Crash Surrogates, and What Analytical Models Can Be Developed to Predict Crashes or Crash Surrogates? (continued) (continued on next page)
84 Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What hierarchical structure (statistically speaking), if any, exists in the manner in which these rela- tionships need to be explored? PSU Dula Danger- ous Driving Inventory component score (e.g., aggressive or reckless driv- ing, negative emotion), life stress inven- tory score, driving experi- ence, improper speed, driver distraction (e.g., wire- less devices, vehicle related, passenger related, talk- ing, singing, daydreaming, internal dis- traction, din- ing, other) Surface condi- tions (wet, snowy, or icy), traffic density not free flowing, alignment or curve, light- ing (dusk/ dawn) Environ- mental conditions Do single-vehicle road-departure crashes occur only under conditions of disturbed control? (Broad research question.) UMTRI Disturbed control ROR crashes Table C.9b. What Explanatory Factors Are Associated with Crashes or Crash Surrogates, and What Analytical Models Can Be Developed to Predict Crashes or Crash Surrogates? (continued) (continued on next page)
85 Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static Can satisfactory crash risk predictions be made based on vehicle, driver, and highway factors available from natu- ralistic driving data (e.g., via extreme value theory), or do additional roadside and environmental factors need to be introduced? UMTRI Does coupling road- side factors to natu- ralistic driving data improve correlation with actual crashes? UMTRI What kinds of elucida- tive evidence emerge from the analysis of roadway departure crashes in terms of the relationship between crashes, near crashes, and incidents with situ- ational factors, and what (statistical) hierarchical structure exists within these relationships? Table C.9b. What Explanatory Factors Are Associated with Crashes or Crash Surrogates, and What Analytical Models Can Be Developed to Predict Crashes or Crash Surrogates? (continued)
86Table C.10. How Do Roadway Features Influence Crash Likelihood? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What statistical tests are available to determine if measures of driving control performance in naturalistic data and single-vehicle crashes depend on geometric fea- tures in a consistent way? UMTRI Driving control performance measures Roadway geometric features Single-vehicle crashes (ROR, lane departure) What key driver, roadway, and environmental fac- tors affect lane keeping that may result in a road departure? CTRE Lateral and longitudinal accelera- tion, vehicle heading Lane width Position of other vehicles Lane position (lane departures) What is the influence of life events and factors on ROR events? VTTI Life events ROR crashes What combination of driver, vehicle, traffic, environ- mental, and roadway factors leads to rear-end crashes (i.e., striking a vehicle in the travel lane)? VTTI Driver factors Roadway factors Environmental conditions What environmental fac- tors influence whether a vehicle actually departs the roadway once a road departure is precipitated? CTRE Wiper use Weather conditions, outside temperature Lane position (lane departures) To what extent do road- way features influence whether a vehicle actually departs the roadway once a roadway departure is precipitated? CTRE Vehicle head- ing; lateral and lon- gitudinal acceleration; pitch, yaw, and roll rates; speed GIMS database (roadway attributes: number of lanes, type of pavement surface, lane width, shoulder type, shoulder width) Lane position (lane departures) How frequently do road departures occur given a specific set of roadway variables? CTRE Vehicle head- ing; lateral and lon- gitudinal accelera- tion; pitch, yaw, and roll rates; speed GIMS database (roadway attributes: number of lanes, type of pavement surface, lane width, shoulder type, shoulder width) Lane position (lane departures) (continued on next page)
87 Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static Are any specific highway features (e.g., isolated horizontal curves, sharp horizontal curves, sequences of horizontal curves, combinations of horizontal and verti- cal curves) associated with single-vehicle road- departure crashes and specific driving control performance measures? UMTRI Driving control performance measures Isolated, sharp, and the sequence of curves; combina- tions of horizontal and vertical curves Single-vehicle crashes (ROR, lane departures) How is the occurrence of ROR events under dif- ferent driving conditions and roadway geometries related to ROR causal factors and driver inputs during ROR maneuvers? VTTI Roadway geometries Driving conditions Rate of ROR crashes How are ROR crashes affected by different roadway geometries (e.g., shoulder width and speed limits)? VTTI Roadway geometries ROR crashes How are ROR crashes and near crashes affected by different roadway features (e.g., shoulder width, sig- nage, and delineators)? VTTI Roadway features ROR crashes What is the influence of roundabouts on pedes- trian crashes? VTTI Roundabouts Pedestrian crashes Are there methods of iden- tifying potentially danger- ous intersections before the occurrence of high collision rates? VTTI Intersections What is the role of curves and grades in lane-change or merge crashes? VTTI Curves or grades Lane-change or merge crashes What is the role of length and type of ramps (e.g., weave) in lane-change or merge crashes? VTTI Length of ramps Lane-change or merge crashes Table C.10. How Do Roadway Features Influence Crash Likelihood? (continued)
88Table C.11. How Do Signage, Lighting Conditions, and Other Traffic ControlâRelated Countermeasures Influence Crash Likelihood and Driver Performance? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static Are road departures less likely when pavement markings are more visible? CTRE Vehicle heading; lateral and longitudinal acceleration; Pitch, yaw, and roll rates; speed GIMS database (roadway attributes: number of lanes, pave- ment types, shoulder width) Lane position (lane departures) Does roadway lighting result in fewer nighttime road departures? CTRE Lighting conditions Lighting con- ditions, time of day Lane position (lane departures) Does signage have any impact on frequency of road departures (e.g., large chevrons may alert drivers to an adverse horizontal curve)? CTRE Vehicle heading; lateral and longitudinal acceleration; pitch, yaw, and roll rates; speed GIMS database (roadway attributes: number of lanes, type of pavement surface, lane width, shoul- der type, shoulder width) Lane position (lane departures) How does signage influence braking behavior at intersections? VTTI Signage Excessive braking Would there be any safety benefits of alternative signal-control strategies? Adaptive signal-control timing? Alter- native signal timing? VTTI Alternative signal control strategies Safety benefits How do traffic control variables influence braking behavior at intersections? VTTI Traffic control variables Excessive braking How do traffic control variables influ- ence speed behavior at intersections? VTTI Traffic control variables Speeding How do traffic control variables influ- ence compliance with traffic controls at intersections? VTTI Traffic control variables Compliance with traffic controls What are the effects of in-pavement warning lights at pedestrian crossings? VTTI In-pavement warning lights Pedestrian safety (continued on next page)
89 Table C.11. How Do Signage, Lighting Conditions, and Other Traffic ControlâRelated Countermeasures Influence Crash Likelihood and Driver Performance? (continued) Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What is the influence of closed-loop signal systems? VTTI Closed loop signal system What is the safety effect of offset, split, and cycle time for fixed-time signals? VTTI Offset, split, and cycle time Safety effect (crash reduction) What is the safety effect of detector placement and signal-timing param- eters for semiactuated signals? VTTI Detector placement and signal timing Safety effect (crash reduction) What are the safety effects of different- sized signal heads (8 in. versus 12 in.), number of signals per approach lane (is one necessary for each lane?), and signal placement (overhead versus nearside)? VTTI Different-sized signal heads Safety effect (crash reduction) How does operating speed affect deceleration for traffic signals? VTTI Operating speed Deceleration How do drivers react to different inter- section signal installations (phasing and timing operations)? Do certain types appear better? VTTI Signalized intersections Driversâ reactions What is the effectiveness of various counter measures (e.g., strobe lights to red lights) to reduce intersection- related crashes? VTTI Intersection- related crashes Could new technology, such as auto- mated all-red signal extension systems, infrastructure to inform drivers of acceptable gaps in traffic, or dilemma-zone detection at high speed intersections, reduce inter- section crashes? VTTI What are the effects of protected left- turn phasing at high-speed rural intersections? VTTI Protected left- turn phasing How do traffic control variables influence gap acceptance at intersections? VTTI Traffic control variables Gap acceptance (continued on next page)
90 Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static How does signage influence gap acceptance at intersections? VTTI Signage Gap acceptance What is the prevalence of straight crossing path traffic signal violations? VTTI Prevalence of signal violations Do traffic control device counter- measures (e.g., signal phase related) lead to struck secondary crashes? VTTI TCD counter- measures Secondary crashes What are the benefits of roadway light- ing, and under what circumstances does roadway lighting increase driversâ ability to see pedestrians, animals, or objects in the travel lane? VTTI Roadway lighting Ability to see pedestrians, animals, and objects What are the benefits of reflectors and reflective clothing, and under what circumstances do these items improve driversâ ability to see pedestrians, animals, or objects in the travel lane? VTTI Reflectors and reflective clothing Ability to see pedestrians, animals, and objects How long does it take for drivers to respond to speed limit reductions? VTTI Speed limit reductions Response times Are drivers influenced by speed reduc- tion signs and if so, how? Do drivers travel at higher speeds on secondary streets and highways after long- distance travel on freeways? VTTI Speed reductions signs Driver behavior Table C.11. How Do Signage, Lighting Conditions, and Other Traffic ControlâRelated Countermeasures Influence Crash Likelihood and Driver Performance? (continued)
91 Table C.12. How Do Static Driver Characteristics Influence Driver Performance and Crash Likelihood? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What can be done to reduce the number of crashes and fatalities for older drivers? VTTI Age Crashes What is the influence of gender on ROR crashes? VTTI Gender ROR crashes What is the influence of age on ROR crashes? VTTI Age ROR crashes What is the influence of personality (as measured by MyersâBriggs or other assessment) on ROR crashes? VTTI Personality factors ROR crashes What is the influence of driving confidence (self- report) on ROR crashes? VTTI Driving confidence ROR crashes What is the influence of useful field of view on ROR crashes? VTTI Useful field of view ROR crashes Do demographics play a role in ROR crashes? VTTI Demographic data ROR crashes
92Table C.13. How Do Static Driver Characteristics, as Observed Through Driver Performance Measures, Influence Crash Likelihood? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static In terms of elucidative evidence, what types of behavioral correlates emerge? For example, are attitudinal measurements indicative of revealed behavior in terms of head- way maintenance and speed reductions? PSU Behavioral correlates, headway maintenance, speed Are attitudinal (e.g., predis- posing) measurements indicative of revealed behavior in terms of head- way distance and speed reduction? PSU Attitudinal (e.g., predisposing) measurements Headway distance, speed reduction Is there a difference in the driving control performance of good and bad drivers (or risky and nonrisky drivers) at locations with geometric features associated with high single-vehicle crash frequency? UMTRI How does within- and between-subject variation in lane keeping compare (i.e., to what extent does one driver consistently perform better than another driver)? VTTI Within- and between- subject variability Lane departures How can performance dif- ferences be quantified (e.g., as differences in the frequency and amplitude of steering and braking actions; or in terms of frequency, duration, or amount of lane departure, time to departure, or other measures)? VTTI Performance differences Are all drivers equally exposed to road departures? VTTI Driver exposure Road departures (continued on next page)
93 Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static How do driver testing scores serve as predictors to driving performance, in particular, to lane keeping? VTTI Driver test scores Driving performance Does the relative risk of dif- ferent intersection maneu- vers vary with driver age and gender? VTTI Age, gender Intersection maneuvers Do older drivers make fewer left turns or accept larger gaps? VTTI Age Gap acceptance, left-turn frequencies Do older drivers make fewer right turns or accept larger gaps? VTTI Age, gender Right turn or larger gap frequencies What is the role of driver fac- tors in the risk associated with inappropriate gap acceptance with crossing traffic? VTTI Driver factors Gap acceptance What is the role of driver fac- tors in the risk associated with red light running and inappropriate gap accep- tance situations? VTTI Driver factors Red light running, gap acceptance How do drivers of various age categories judge and select a gap in traffic flow to enter or cross a street or highway? VTTI Driver age Judgment of gaps in traffic What are the intra- and inter- individual differences in braking and crash- avoidance skill? VTTI Individual differences Crash-avoidance skills What are the intra- and inter- individual differences in willingness to pass and skill in passing? VTTI Individual differences Willingness to pass and skill in passing What are the intra- and interindividual differences in lane-change or merge behavior and skill? VTTI Individual differences Lane-change or merge behavior and skill (continued on next page) Table C.13. How Do Static Driver Characteristics, as Observed Through Driver Performance Measures, Influence Crash Likelihood? (continued)
94Table C.13. How Do Static Driver Characteristics, as Observed Through Driver Performance Measures, Influence Crash Likelihood? (continued) Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What are the intra- and inter- individual differences in backing behavior and skill? VTTI Individual differences Backing behavior and skill What is the influence of gender on lane keeping? VTTI Gender Lane departure What is the influence of age on lane keeping? VTTI Age Lane departure What is the influence of personality (as measured by MyersâBriggs or other assessment) on lane keeping? VTTI Personality factors Lane departure What is the influence of driving confidence (self report) on lane keeping? VTTI Driving confidence Lane departure What is the influence of risk- taking propensity on lane keeping? VTTI Risk-taking propensity Lane departure, ROR crashes What is the influence of expe- rience and previous motor vehicle accidents on lane keeping? VTTI Experience and previous crashes Lane departure What is the influence of life events and factors on lane keeping? VTTI Life events Lane departure What is the influence of experience and previous motor vehicle accidents on ROR crashes? VTTI ROR crashes Do demographics influence lane keeping? VTTI Demographic data Lane departure How do differences in age, gender, and other driver traits influence variations in driving behavior? VTTI Age gender Driving behavior How do drivers of various age categories use the available acceleration lanes when entering freeways? VTTI Age Use of acceleration lanes (continued on next page)
95 Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What is the level of compli- ance by drivers of various age categories to stop signs, traffic signals, advi- sory speeds on curves, speed limits, and stopping for pedestrians? VTTI Age Compliance to traffic signals and signs How do drivers adjust their behavior (relative to expected adjustments) in response to high-risk situa- tions? Such situations may be environmental (e.g., night, slick roads from rain and snow, or fog) or personal (e.g., fatigue or alcohol intoxication). VTTI High-risk personal factors High-risk environmental factors Behavior adjustments What is the relationship between driversâ involve- ment in crashes, near crashes, and incidents and driversâ age, driving knowledge, vision, driving experience, and vehicle familiarity? VTTI Vehicle familiarity Age, knowl- edge, vision, experience Crash involvement How do exposure differences across subgroups vary in terms of amount of travel and environment? VTTI Amount of travel How does the driving expe- rience vary in different regions of the country and for different drivers? VTTI Different drivers Regions of the country Driving experience What driving styles exist across the country and within different driving conditions? VTTI Driving conditions Regions of the country Driving styles What are exposure differ- ences in terms of road types, speed selection, and miles traveled across driver age and gender subgroups? VTTI Speed selection Miles traveled Road types Exposure differences (continued on next page) Table C.13. How Do Static Driver Characteristics, as Observed Through Driver Performance Measures, Influence Crash Likelihood? (continued)
96 Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static How often, for what length of time, and in what pat- tern do drivers look away from the forward roadway? What are the individual differences among and between drivers? VTTI Individual differences Visual scan patterns Can attitudes toward risk tak- ing (or other behaviors or beliefs) versus driving style (i.e., errors, inattention, or distraction) be character- ized demographically? VTTI Demographic data Characterization of attitudes toward risk taking, beliefs versus driving style, distractions What are the behavioral char- acteristics, especially in terms of driving style and visual search, which dis- tinguish the youngest and oldest drivers from drivers aged 25â65 years? VTTI Age Driving behavior characteristics How are a specific driving behavior and crash risk affected by both perma- nent descriptors (e.g., age, gender, driving experience, and crash record) and transitory descriptors (e.g., fatigue, other impairment, and distraction)? VTTI Many Crash How do safe and unsafe drivers differ in demographic data, test battery results, and performance-based mea- sures? What are the crash rate and history of violations before the study for these safe and unsafe drivers? (Some drivers may not be honest in reporting this driving history information.) VTTI Demographic data Categorization of safe and unsafe drivers What is the relationship between various risky driving behaviors and com- binations of risky driving behaviors between low-risk and high-risk drivers? VTTI Risky driving behaviors Categorization of low- and high- risk drivers Table C.13. How Do Static Driver Characteristics, as Observed Through Driver Performance Measures, Influence Crash Likelihood? (continued)
97 Table C.14. What Are the Relationships Between Driver Behavior, Performance, Crash Types, Crash Likelihood, and Population-Attributable Risk for Each Factor Contributing to Crashes? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static In order to use conflict data to predict crash probability, it is necessary to know how the selected evasive action varies as a function of background conditions. For a given crash type and data set, is it possible to identify and validate plausible mod- els for this relationship? UofMN Driver gap selection Opposing driverâs evasive actions In terms of elucidative evidence, what types of behavioral correlates emerge? PSU What exposure variables are available and which are the best measures to use in the analytical models? Pos- sible exposure variables include traffic volume, traf- fic density, driver subpopu- lations (i.e., crash risk for teenage drivers compared with older drivers), and miles of travel. CTRE Driver age AADT Number of licensed drivers in state Number of licensed drivers in state What driver actions and behaviors are present in the seconds preceding and during ROR crashes? VTTI Driver actions and behaviors ROR crashes Can ROR countermeasures be effectively designed to reduce crashes? VTTI ROR crash counter- measures Reduction in crashes At what point can the inter- section safety effective- ness of automated speed enforcement on roads with posted speed limits be considered credible? VTTI (continued on next page)
98 What is the role of illegal maneuvers in collision risk at intersections? VTTI Illegal maneuvers Gap acceptance What driver actions occur in the seconds preceding and during intersection crashes and near crashes? VTTI Driver actions What is driversâ situational awareness just before crashes (e.g., at multiple- vehicle accidents at inter- sections)? VTTI Driversâ situational awareness What is the role of driver fac- tors in the risk associated with red light running and inappropriate gap accep- tance situations? VTTI Driver factors Red light running What is the relative risk of dif- ferent maneuvers at inter- sections? VTTI Driving maneuvers Relative risks in intersections Having defined appropriate exposure measures for each intersection maneu- ver, what is the relative risk of the different maneuvers? VTTI Relative risks of driving maneuvers How does risk assessment vary based on driver behavior and intersection design? VTTI Driver behavior Intersection design Risk assessment What effect does the inter- section environment have on driversâ decision- making processes? VTTI Intersection design Decision- making process How does the public percep- tion of the attitude of law enforcement on highway safety affect intersection crashes? VTTI Public perception Intersection crashes Is there greater risk for left turns? VTTI Risk of left turns Table C.14. What Are the Relationships Between Driver Behavior, Performance, Crash Types, Crash Likelihood, and Population-Attributable Risk for Each Factor Contributing to Crashes? (continued) Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static (continued on next page)
99 What is the role of driver fac- tors in the risk associated with inappropriate gap acceptance with opposing traffic on left turns? VTTI Driver factors Gap acceptance What is the role of driver fac- tors in the risk associated with inappropriate gap acceptance with opposing traffic on right turns? VTTI Driver factors Gap acceptance What is the relative contribu- tion of decision errors to inappropriate gap acceptance? VTTI Decision errors Gap acceptance What is the relative contribu- tion of illegal maneuvers to inappropriate gap acceptance? VTTI Illegal maneuvers Gap acceptance What is the relative contribu- tion of decision errors to red light running? VTTI Decision errors Red light running What is the role of driver fac- tors in the risk associated with red light running? VTTI Driver factors Risk of red light running What is the relative contribu- tion of illegal maneuvers to red light running? VTTI Illegal maneuvers Red light running For willful straight crossing path signal violations, what is the nature (e.g., position and speed) of the crossing traffic? VTTI Crossing traffic Signal violations What is the role of follow- ing distance in rear-end crashes (i.e., striking a vehicle in the travel lane)? VTTI Following distance Rear-end crashes (continued on next page) Table C.14. What Are the Relationships Between Driver Behavior, Performance, Crash Types, Crash Likelihood, and Population-Attributable Risk for Each Factor Contributing to Crashes? (continued) Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static
100 To what degree does the lead vehicle driver (i.e., the driver in the instrumented vehicle) contribute to the crash as a result of the following distance? VTTI Following distance Lead vehicle Crash What is the role of following distance as it relates to crashes involving pedestri- ans, objects, or animals in the travel lane? VTTI Following distance Crashes with pedestrians, objects, or animals What is the role of sight dis- tance in passing maneuver errors? VTTI Sight distance Sight distance Passing maneuver errors How many times do drivers pass against road markings (e.g., double yellow)? VTTI Driver behavior Road markings Passing against road markings How many times do drivers misjudge the speed or gap of approaching vehicles? VTTI Driver mis- judgment Gap acceptance How many times do drivers misjudge car acceleration or time available? VTTI Driver mis- judgment Frequency of misjudg- ments What is the role of inadequate mirror check in lane- change or merge crashes? VTTI Inadequate mirror checking Lane-change or merge crashes What is the role of no blind spot check in lane-change or merge crashes? VTTI No blind spot checking Lane-change or merge crashes What is the role of inadequate gap in lane-change or merge crashes? VTTI Inadequate gaps Lane-change or merge crashes What is the role of failure to match speed in lane- change or merge crashes? VTTI Failure to match speed Lane-change or merge crashes What is the role of failure to recognize speed differential in lane-change or merge crashes? VTTI Failure to recognize speed differentials Lane-change or merge crashes Table C.14. What Are the Relationships Between Driver Behavior, Performance, Crash Types, Crash Likelihood, and Population-Attributable Risk for Each Factor Contributing to Crashes? (continued) Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static (continued on next page)
101 What is the role of sight distance in lane-change or merge crashes? VTTI Sight distance Sight distance Lane-change or merge crashes What is the role of failure to visually verify (i.e., over- the-shoulder check)? VTTI Failure to visually verify What is the role of inadequate mirror check to backing crashes? VTTI Inadequate mirror checking Backing crashes What is the role of failure to clear windows or improve visibility to backing crashes? VTTI Failure to clear windows, improve visibility Backing crashes What is the influence of fac- tors such as backing while turning? VTTI Backing while turning What mechanisms of occu- pant injury exist that have been unrecognized or underemphasized? VTTI Mechanism of occu- pant injury What baselines can be mea- sured in frequencies, risk exposure, or behaviors against which design improvements can be compared? VTTI Design improve- ments Frequen- cies, risk exposures, behaviors How does driver interac- tion with vehicle systems change over extended peri- ods (e.g., 1 year)? VTTI Driver interaction Change over first year What steering and brake inputs occur in the seconds preceding collisions? VTTI Actions and behavior ROR crashes What is the influence of use- ful field of view on lane keeping? VTTI Useful field of view Lane departure What is the driver reaction time and control input selection for safety-critical events? VTTI Driver reaction Safety-critical events (continued on next page) Table C.14. What Are the Relationships Between Driver Behavior, Performance, Crash Types, Crash Likelihood, and Population-Attributable Risk for Each Factor Contributing to Crashes? (continued) Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static
102 What is the error/accident involvement in crashes, near crashes, and inci- dents, and how can the driver behavior that con- tributed to the involvement be assessed? VTTI Driver error/ accident involvement Crashes, near crashes What are the response times, deceleration, braking behavior, and turn-signal use of following drivers in response to vehicles that enter the forward driving path? VTTI Vehicle entering driving path Response times How can braking and signal- ing behaviors with respect to striking and struck drivers be assessed and analyzed? VTTI Striking, struck vehicles Braking behav- ior and signaling behavior How can potential patterns in driving performanceâbased measures (e.g., high longi- tudinal decelerations, high lateral accelerations) be assessed and analyzed? VTTI Driving patterns What new methodologies for assessing the role of human factors in accident causa- tion can be developed? VTTI What driver behaviors (e.g., bracing, postural adjust- ments) arise immediately before a crash? VTTI Driver behavior (bracing) What is the role of following distance in lane-change or merge crashes? VTTI Following distance Lane-change or merge crashes Table C.14. What Are the Relationships Between Driver Behavior, Performance, Crash Types, Crash Likelihood, and Population-Attributable Risk for Each Factor Contributing to Crashes? (continued) Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static (continued on next page)
103 What types of accidents occur when drivers are paying attention? VTTI Paying attention Crashes In what circumstances do distracted drivers have accidents (e.g., are these more likely within the influ- ence area of intersections or in stop-and-go traffic, but less likely on freeways)? VTTI Circumstances Crashes How can differences between struck and striking vehicles with regard to sampling behavior for rear-view and side-view mirrors be assessed and analyzed? VTTI Struck, striking vehicles Struck, striking vehicles Rear- and side- view mirror sampling behavior Does a driverâs familiarity with a road influence his or her driving behavior? VTTI Familiarity with road Driving behavior How do differences in vehicle types influence variations in driving behavior? VTTI Vehicle types Driving behavior What factors initiate or influ- ence the sequence of events resulting in a motor vehicle accident? VTTI Driver factors Sequence of errors How does the availability or lack of sight distance affect how a driver travels over a crest, around a horizontal curve, or through an inter- section? VTTI Sight distance Sight distance Driver performance In a crash or near crash did the driver perceive but mis- judge the available gap, or did the driver not perceive the oncoming vehicle? VTTI Table C.14. What Are the Relationships Between Driver Behavior, Performance, Crash Types, Crash Likelihood, and Population-Attributable Risk for Each Factor Contributing to Crashes? (continued) Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static
104 Table C.15. How Do Individual Differences (e.g., Age, Gender, or Speed Selection) Influence Lane-Keeping Performance? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What are the individual differences in lane-keeping performance? VTTI Individual differences Lane departure What is the role of speed relative to the posted speed limit in lane-keeping performance? VTTI Speed selection Posted speed limit Lane departure Does lane keeping vary with vehicle type or driver age and gender? VTTI Driver age Vehicle type Lane departure How do driver age and gender, grade, curve, speed, rumble strips, and other factors relate to lane-keeping performance? VTTI Driver age, gender Grade, curve, rumble strips Lane departure How does driver behavior (speeding) affect lane keeping? VTTI Driver behavior Lane departure
105 Table C.16. How Do Traffic and Traffic Volume Influence Intersection Negotiation, Lane-Keeping Performance, and Crashes? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors Dynamic Static Dynamic Static Dynamic Static Dynamic Static Outcome Is the illustrative hierarchy of relationships generalizable to other nonintersection crash types such as leading-vehicle crashes? PSU Does risk of lane departure vary by road type and traffic volume? VTTI Road type and traffic volume Lane departure How will increased traffic volume on U.S. roadways affect driver involvement in ROR crashes? VTTI Traffic volume ROR crashes What is the influence of surrounding traffic on lane keeping? VTTI Surrounding traffic Lane departure Does opposing traffic affect lane position or lane-keeping performance? VTTI Opposing traffic Lane departure What is the influence of adjacent traffic or opposing traffic on lane keeping? VTTI Adjacent traffic Lane departure What is the influence of leading vehicles on lane keeping? VTTI Leading vehi- cles Lane departure What lane-changing behavior of nearby vehicles may contribute to crash and near- crash events? VTTI Lane changing of other vehicles Crash and near-crash events How can a consideration of traffic volume for each of the turning maneuvers, which may play a role in all aspects of intersection risk, be incorporated into the analysis? VTTI Traffic volume Intersection crashes What is the relationship of traffic density and type of traffic-control devices to crash occurrence at intersections? VTTI Traffic density Traffic control devices Intersection crashes How does the pattern of conflicts and collision risk vary with traffic volume? VTTI Traffic volume Pattern of conflicts How does traffic volume influence left-turn maneuvers at intersections? VTTI Traffic volume Left maneuvers How does traffic volume influence right-turn maneuvers at intersections? VTTI Traffic volume Left-hand turn crashes What is the role of the amount and location of traffic in lane-change or merge crashes? VTTI Traffic amount and location Lane-change or merge crash risks What combinations of factors (including closure speed) affect left-turn risk? VTTI Oncoming vehicles Left-turn crashes What combinations of factors (including closure speed) affect right-turn risk? VTTI Oncoming vehicles Right-turn crashes
106 Table C.17. Do Vehicle Characteristics Influence Crash Likelihoods or Driver Behaviors? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors Dynamic Static Dynamic Static Dynamic Static Dynamic Static Outcome Are sport utility vehicles more likely to be involved in an overturn than other passenger vehicles? CTRE Make and model, any known deficiencies Are vehicle kinematic measures sufficient to identify disturbed control for risk measures in single-vehicle departure crashes? UMTRI How do vehicle characteristics (e.g., size, brak- ing capabilities, and center of gravity) affect subsequent events and outcome after a vehicle initially leaves the roadway? CTRE Make and model, any known deficiencies How do circumstances of low friction (e.g., OBD II, traction control, and wheel slip) affect driver behavior and crash or near-crash risk at intersections? VTTI Low friction Driver behavior Does driver behavior or performance relate to vehicle design (e.g., weight, center of mass, greenhouse geometry, and instrument panel design)? VTTI Driver behavior Vehicle design What lifestyle or driving behaviors (e.g., gas use, brake behavior, and trip distances) reveal opportunities for fuel economy or alternative- fuel vehicle designs? VTTI Driving behavior Lifestyle Fuel economy or alternative vehicle designs What are the kinematic conditions, in terms of range, range rate, vehicle speed, and deceleration, at the onset of a hard braking maneuver? VTTI Kinematic conditions Hard braking maneuver How does driver behavior change by vehicle type (e.g., truck or SUV)? VTTI Vehicle type Driver behavior
107 Table C.18. What Are the Interrelationships of Environmental, Road, and Driver Factors with Nondriving-Related Activities (i.e., Technology, OEM, or Nomadic Devices)? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What is the relative risk of an activityâs duration on driver behavior when using technology-related tasks? VTTI Technology related Relative risk of activities duration What is the relative risk of an activityâs duration on driver behavior when using OEM system tasks? VTTI OEM system tasks Relative risk of activities duration What is the relative risk of an activityâs duration on driver behavior when using nomadic devices? VTTI Nomadic device Relative risk of activities duration What is the relative risk of the road geometry (e.g., curves, straightaways, and hills) on driver behavior when using technology-related tasks? VTTI Technology related Relative risk of road geometry What is the relative risk of the road geometry (e.g., curves, straightaways, and hills) on driver behavior when using OEM system tasks? VTTI OEM system tasks Relative risk of road geometry What is the relative risk of the road geometry (e.g., curves, straightaways, and hills) on driver behavior when using nomadic devices? VTTI Nomadic device Relative risk of road geometry What is the relative risk of time of day on driver behavior when using technology-related tasks? VTTI Technology related Relative risk of time of day What is the relative risk of time of day on driver behavior when using OEM system tasks? VTTI OEM system tasks Relative risk of time of day What is the relative risk of time of day on driver behavior when using nomadic devices? VTTI Nomadic device Relative risk of time of day What is the relative risk of traffic density on driver behavior when using technology-related tasks? VTTI Technology related Relative risk of traffic density What is the relative risk of traffic density on driver behavior when using OEM system tasks? VTTI OEM system tasks Relative risk of traffic density What is the relative risk of traffic density on driver behavior when using nomadic devices? VTTI Nomadic device Relative risk of traffic density What is the relative risk of pedestrian or cyclist density on driver behavior when using technology-related tasks? VTTI Technology related Relative risk of pedestrian or cyclist density (continued on next page)
108 What is the relative risk of pedestrian or cyclist density on driver behavior when using OEM system tasks? VTTI OEM system tasks Relative risk of pedestrian or cyclist density What is the relative risk of pedestrian or cyclist density on driver behavior when using nomadic devices? VTTI Nomadic devices Relative risk of pedestrian or cyclist density What is the relative risk of weather conditions on driver behavior when using technology-related tasks? VTTI Technology related Relative risk of weather conditions What is the relative risk of weather conditions on driver behavior when using OEM system tasks? VTTI OEM system tasks Relative risk of weather conditions What is the relative risk of weather conditions on driver behavior when using nomadic devices? VTTI Nomadic devices Relative risk of weather conditions What is the relative risk of various sources of currently available and future devices (e.g., nomadic or in-vehicle devices such as iPhones or mobile offices)? VTTI Nomadic devices Relative risk of new devices Table C.18. What Are the Interrelationships of Environmental, Road, and Driver Factors with Nondriving-Related Activities (i.e., Technology, OEM, or Nomadic Devices)? (continued) Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static
109 Table C.19. How Does Seatbelt Use Vary with Different Levels of Enforcement and in Different Jurisdictions? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static How does seatbelt use vary between states with and without primary seatbelt laws? For example, do different types of seatbelt laws result in variations of seatbelt use in the presence of passengers or during day and night hours? VTTI Passengers Time of day Laws Seatbelt use What is the effect on seatbelt use of a change in seatbelt law from a secondary to a primary source? VTTI Laws Seatbelt use
110 Table C.20. General or Very High-Level Questions Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeActual Research Question Source Dynamic Static Dynamic Static Dynamic Static Dynamic Static What driver, vehicle, operational, roadway, and environmental factors increase inad- vertent lane departures? Specific factors of interest (* denotes highest-priority factors): driver fatigue, speed limit, alcohol level, driver distraction, driver gender, shoulder width, shoulder type (paved or unpaved), clear zone cross slope, weather, day or night, *driver age, *vehicle speed, *lane width, edge drop presence, *lane line pres- ence and nighttime visibility, *rumble strip presence, *curvature. VTTI Distractions Driver factors Roadway factors Environmental conditions What percentage of roadway-departure crashes start as rear-end crash scenarios? VTTI What combination of driver, vehicle, traffic, environmental, and roadway factors leads to rear-end crashes in which there is a struck vehicle in the same travel lane? VTTI Driver factors Vehicle factors Roadway factors Environmental conditions Relationship between ROR crashes and lane depar- tures What combination of driver, vehicle, traffic, environmental, and roadway factors leads to crashes involving pedestrians, animals, or objects in the travel lane? VTTI Driver factors Vehicle factors Roadway factors Environmental conditions Rear-end crashes What combination of driver, vehicle, traffic, environmental, and roadway factors leads to head-on crashes? VTTI Driver factors Vehicle factors Roadway factors Environmental conditions Crashes What combination of driver, vehicle, traffic, environmental, and roadway factors leads to lane-change or merge crashes? VTTI Driver factors Vehicle factors Roadway factors Environmental conditions Crashes with pedestrians, animals, or objects What combination of driver, vehicle, traffic, environmental, and roadway factors leads to backing crashes? VTTI Driver factors Vehicle factors Roadway factors Environmental conditions Head-on crashes How do various factors work together to affect collisions, and how do exposure data for noncrash populations and accurate pre- crash data weigh into this scenario? VTTI (continued on next page)
111 Table C.20. General or Very High-Level Questions (continued) Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeActual Research Question Source Dynamic Static Dynamic Static Dynamic Static Dynamic Static How are a specific driving behavior and crash risk affected by both permanent descriptors (e.g., curvature, road surface, lane width, and sight distance) and transitory descrip- tors (e.g., weather, light conditions, traffic flow, and adjacent vehicles)? VTTI What effect do various countermeasures have on crash and near-crash incidents? VTTI Where do drivers position their vehicles in the travel lane on two-lane, two-way roads (using a simply painted centerline and gravel shoulders as baseline), and is this position influenced by factors such as opposing traf- fic volumes, centerline rumble strips, shoul- der treatments, curbs, and weather? VTTI Opposing traffic Centerline rumble strips, shoulders Weather conditions What is the interrelationship of driver factors and behavior with roadway design and traffic conditions on the risk of collision and causalities? VTTI Driver factors Roadway design and traffic conditions How cost-effective are various counter- measures? VTTI Position of vehicle in lane What is the relative frequency of these fac- tors and their causal contribution within a defined accident and driving population? VTTI Risk of crashes What is the feasibility and research potential of linking GIS and GPS data to investigate ROR crashes? VTTI What defined events may be recorded through naturalistic driving studies so that these events may be understood? VTTI Relative frequencies of crashes For the purpose of accident prediction mod- eling, how can driversâ failures to perceive oncoming vehicles be classified, and what are the baseline estimates of the frequency of such events? VTTI What opportunities for crash counter- measures exist that have been unrecognized or underemphasized? VTTI Defined naturalistic events (continued on next page)
112 Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeActual Research Question Source Dynamic Static Dynamic Static Dynamic Static Dynamic Static How can crash data from the 100-car natural- istic driving study be used to investigate the potential role of specific crash-avoidance systems in preventing near crashes and actual crashes? VTTI How do drivers process multiple sources of information? VTTI How do drivers make decisions? VTTI What types of driver distraction episodes can be identified and understood? VTTI Distractions What problems emerge from an examina- tion of naturalistic driving data on driver distraction that would be amendable to countermeasures? VTTI Table C.20. General or Very High-Level Questions (continued)
113 Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static Can the analysis of data from southeast Michigan be applied or recreated in another region, such as Virginia? UMTRI Can roadside factors (e.g., locations of poles, trees, bridge abutments, and side slopes) be coupled to natu- ralistic driving data? UMTRI Locations of poles, trees, bridge abutments, side slopes Can general descriptors of roadside environments be used in this coupling (e.g., tree density or proportion of side slope steeper than 4:1), or does the location of roadside obstacles need to be more specified? UMTRI Tree density, proportion of side slopes Could naturalistic driving data be used to validate simulators? VTTI Driving simulator validation Can a cognitive model be developed that could assess how specific factors influence specific driving tasks or events (e.g., gap acceptance or ROR events)? VTTI How can human factors design standards be imple- mented in roadway design to minimize errors associ- ated with gap acceptance or other driving behaviors? VTTI Table C.21. How Else Can Naturalistic Driving Data Be Used? (continued on next page)
114 Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What is the incidence of drowsiness and the condi- tions under which drowsi- ness arises? VTTI Drowsiness conditions Incidents of drowsiness How can lane-change events be classified according to subject vehicle, role, event severity, precrash or event maneuvers, causal or contributing factors, evasive maneuvers, and state variables? VTTI Vehicle role Lane-change events How can taxonomy develop- ment and group identifica- tion concepts be used to define and identify problem driver types and actions (specifically, alcohol- impaired drivers and the driving performance mis- takes made by particular types of alcohol-impaired drivers under certain condi- tions), and how can this process lead to recom- mendations for dealing with particular classes of drivers? VTTI Can a design driver be defined, and relative to that concept can crash causes be identified? VTTI Table C.21. How Else Can Naturalistic Driving Data Be Used? (continued)
115 Table C.22. How Does the Speed That Drivers Select Influence Other Driver Behaviors or Actions? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static Do drivers adjust their headway distance in response to level of operating speed, traffic volumes, weather conditions, road conditions, and visibility? VTTI Driving behavior Traffic conditions Weather conditions Headway distance maintained How does pavement roughness affect speed (i.e., how much will milled pavement slow drivers down)? VTTI Pavement roughness Speed Do drivers drive faster and/or wander less in the lane on curves with better delineation (brighter lane markings, RPMs, chevrons, post-mounted delineators) than on curves with poorer delineation? VTTI Lane markings, delineations Driving behavior (drive faster, wander less) How do drivers select speed? VTTI Speed selection Is a subset of drivers responsi- ble for the majority of speed- ing, or do all drivers speed occasionally? VTTI Individual differences Responsi- bility for speeding Do drivers travel at slower speeds and with longer head- ways, and to what degree, in rain, snow, or fog? VTTI Snow, fog Headway distance and speed maintained Does speed increase with cell phone usage? VTTI Cell phone usage Speeding Do drivers travel at slower speeds and within what range when pedestrians (especially children) and bicyclists are present? VTTI Pedestrians and bicyclists Driver speed selection What factors (e.g., roadway geometry, roadside features, intersections, driveways, weather, traffic volume, or day versus night) influence a driverâs choice of operat- ing speed, and how does the speed change? VTTI Driver factors Vehicle factors Roadway factors Environmental conditions Speed changes
116 Table C.23. How Do Roadway Features Influence Driver Performance and Behavior? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static How much impact does pave- ment surface condition have on driversâ ability to safely recover within their own lane once a road departure is likely? CTRE Surface conditions Lane position (lane departures) What is the influence of super elevation on lane keeping and departure? VTTI Super elevations Lane departure How do lane keeping and road departure on curves and grades compare with straight and flat road segments? VTTI Curves versus straights Lane departures What are the effects of closely associated versus isolated curves with the same geomet- ric characteristics, such as spirals, and other compound curves on lane keeping? VTTI Roadway geometries Lane departures What are the potential effects of improved roadway delineation? VTTI Roadway delineation Crashes How do rumble strips change driver behavior? VTTI Rumble strips Are current design guidelines for roadway design (e.g., curva- ture of roadway) appropriate for the aging population? VTTI Age Roadway design guidelines How does risk assessment vary based on driver performance and highway design or other features in roadway departure? VTTI Driver performance Highway design Risk assessment How does roadway design influ- ence compliance with traffic controls at intersections? VTTI Roadway design Compliance with traffic signals What is the effect of remov- ing access (e.g., commercial driveways) near high-volume signalized intersections? VTTI Removing access roads near high- volume inter- sections Crashes (continued on next page)
117 What effect do access points near the intersection have? VTTI Access points near intersections Crashes How does sight distance affect safety at intersections? At roundabouts? Of pedestrians? VTTI Sight distance Sight distance Safety at inter- sections, round- abouts, with pedestrians How does roadway design influence speed behavior at intersections? VTTI Roadway design Speeding How does roadway design influence braking behavior at intersections? VTTI Roadway design Excessive braking How does roadway design influence gap acceptance at intersections? VTTI Roadway design Gap acceptance What is the influence of factors such as backing on a slope? VTTI Backing ability Slope in road surface Crashes How do differences in roadway geometry influence variations in driving behavior? VTTI Roadway geometries Driving behavior What road features (e.g., gen- erally gentle curvature with the exception of one curve) and curve features (e.g., tight radius but high posted speed, wide shoulders) result in high lateral acceleration? VTTI Geometric features, curve features Large lateral accelerations What is the effect of glare from opposing vehicles and road- way lighting of differing levels on driver behavior and performance? VTTI Glare Roadway lighting Driver behavior How does the length of an accel- eration lane and traffic volume affect how long drivers take to merge or change lanes? VTTI Traffic volume, length of acceleration lanes Traffic volume Time course of lane change or merge At what point on the ramp do drivers typically merge? VTTI Table C.23. How Do Roadway Features Influence Driver Performance and Behavior? (continued) Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static
118 Table C.24. How Do the Number and Type of Passengers Influence the Driverâs Behavior? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static How do driving behavior and crash and near-crash risk change when one or more passengers are present? VTTI Passengers Driver behavior How does a driverâs behavior change with and without particular passengers, such as peers, parents, or children, in the vehicle? VTTI Passengers Driver behavior Does teen driver behavior change based on the presence of other teens in the vehicle? VTTI Teen passengers Teen driving behavior
119 Table C.25. How Does Driver Fatigue Affect Driver Performance? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static How does fatigue influence speed behavior at intersections? VTTI Fatigue Speeding How does fatigue influence braking behavior at intersections? VTTI Fatigue Excessive braking How does fatigue influence compliance with traffic controls at intersections? VTTI Fatigue Compliance with controls How does fatigue influence gap acceptance at intersections? VTTI Fatigue Gap acceptance
120 Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static How do driver factors such as inattention or fatigue affect lane keeping? VTTI Inattention or fatigue Lane keeping How does signage influ- ence inattention at intersections? VTTI Signage Inattention at intersections How do traffic control vari- ables influence inattention at intersections? VTTI Traffic controls Driver inattention How does roadway design influence inattention at intersections? VTTI Roadway design Inattention at intersections How does fatigue influ- ence inattention at intersections? VTTI Fatigue Inattention at intersections What is the role of inatten- tion in intersection errors and conflicts? VTTI Inattention Intersection errors or conflicts How does distraction influ- ence braking behavior at intersections? VTTI Distraction Excessive braking How does distraction influ- ence speed behavior at intersections? VTTI Distraction Speeding Does driver distraction influence compliance with traffic controls at intersections? VTTI Distraction How does distraction influ- ence compliance with traffic controls at inter- sections? VTTI Distraction To what degree do differ- ent types of distractions influence inattention at intersections? VTTI Distractions Inattention at intersections What is the relative contri- bution of inattention to inappropriate gap acceptance? VTTI Inattention Inappropriate gap acceptance (continued on next page) Table C.26. How Does Inattention Affect Driver Behavior and Performance?
121 Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static How does distraction influ- ence gap acceptance at intersections? VTTI Distraction What is the relative contribu- tion of inattention to red light running? VTTI Inattention Red light running How do drivers come to use and understand advanced in-vehicle safety systems, and are the full benefits of the system being realized by individual drivers? VTTI In-vehicle systems What is the frequency and type of in-vehicle activity related to the use of OEM system tasks? VTTI OEM systems What is the level of expo- sure for OEM system tasks? VTTI OEM systems What types of technology- related tasks do drivers engage in while driving, and at what frequency? VTTI Technology- related tasks What nontechnology- related tasks do drivers engage in while driving? VTTI Non- technology- related tasks What in-vehicle activities do drivers engage in using nomadic or non- OEM devices? VTTI Nomadic devices What external distractions (e.g., billboards, variable messaging signs, pedes- trians, animals, objects, and other traffic) influ- ence driving behavior? VTTI Distraction Table C.26. How Does Inattention Affect Driver Behavior and Performance? (continued) (continued on next page)
122 Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What is the level of expo- sure for technology- related tasks? VTTI Technology- related tasks What is the level of exposure for nomadic devices? VTTI Nomadic devices What is the level of exposure for external distractions? VTTI How frequently do drivers interact with infotainment or nomadic devices (e.g., iPod)? VTTI Nomadic devices Is the frequency of use for infotainment or nomadic devices affected by road type and/or traffic volume? VTTI Road type and traffic volume Is the frequency of use for infotainment or nomadic devices affected by lead vehicles? VTTI Nomadic devices Lead vehicles How long are the inter- actions of use for infotain- ment or nomadic devices? VTTI Nomadic devices What are the eyeglance patterns before, during, and after inter actions of use for infotainment or nomadic devices? VTTI Nomadic devices Is there a difference in fre- quency or duration of the interactions across differ- ent infotainment units? VTTI Nomadic devices How often are these interactions associated with crash or near-crash events? Is this association dependent on the dura- tion of the interaction? VTTI Nomadic devices (continued on next page) Table C.26. How Does Inattention Affect Driver Behavior and Performance? (continued)
123 Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static Does the use of nomadic devices outside of the vehicleâs infotainment system (e.g., iPod or MP3 player) degrade driving performance more than typical vehicle infotainment system use? If such degrada- tion exists, is it alleviated by integration of the nomadic device with the infotainment system? VTTI Nomadic devices To what extent does the use of vehicle-based or nomadic devices reduce drowsy driving (e.g., listening to music versus listening to talk radio ver- sus driving without listen- ing to anything; or talking on a cell phone versus talking with a passenger versus driving without conversation)? VTTI Drowsy driving Nomadic devices What are the effects of learning to use new infotainment devices on driving performance? VTTI Learning Nomadic devices What percentage of time do drivers look at mirrors, in-vehicle or nomadic devices, signs, and exter- nal distractions? VTTI Gaze patterns What factors (e.g., age, try- ing circumstances, traffic volume, or controlled access versus arterial) determine the amount of distracted driving that people engage in? VTTI Distracted driving Age What types of driver dis- traction lead to serious consequences? VTTI Distraction Table C.26. How Does Inattention Affect Driver Behavior and Performance? (continued) (continued on next page)
124 Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static How well are drivers able to divert their attention from nondriving voluntary distractions (e.g., cell phones, use of the sound system, eating, or con- versing with passengers)? VTTI Distraction In-vehicle systems Does driving performance differ between drivers who are engaged in a distraction task and drivers who are attend- ing to driving? Are some safety surrogate mea- sures more sensitive to driving performance differences when driving distracted than other safety surrogate measures? VTTI Distraction Individual differences What percentage of the time do drivers spend engaged in distracted behavior, traveling specified speeds over the speed limit, traveling through stop- controlled or signalized intersections, driving in various lighting condi- tions, driving in rain, or driving through construc- tion zones? VTTI Distraction Speeding Intersection, construc- tion zones Various lighting conditions, raining Exposure to various driving conditions What do drivers do to cause distraction and when do they do it? VTTI Behavioral causes of distractions, distractions Do drivers reserve tech- nology-related tasks (e.g., speaking on a cell phone or tuning a radio) for times when the driv- ing situation is relatively simple? VTTI Distractions (continued on next page) Table C.26. How Does Inattention Affect Driver Behavior and Performance? (continued)
125 Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static How often and in what cir- cumstances do drivers check the speedometer and rearview mirrors? VTTI Driving circumstances What is the relative risk of eyes off the forward roadway? VTTI Do eyes off the forward roadway significantly affect safety and/or driving performance? VTTI How do drivers adapt their level of attention and direction of gaze in response to expected and unexpected changes in driving demands? VTTI Expected and unexpected changes in driving demands How can normative driver inattention be characterized? VTTI Normative driver inattention What is the relative risk of driving while engaging in a task that results in inattention? VTTI Is the relative risk different for different types of secondary tasks? VTTI What are the environmental conditions associated with driver choice of engagement in second- ary tasks or driving while fatigued? VTTI Secondary tasks, inattention, or fatigue Environ- mental conditions What are the relative risks of driving inattention while encountering these envi- ronmental conditions? VTTI Table C.26. How Does Inattention Affect Driver Behavior and Performance? (continued)
126Table C.27. What Nonsafety-Related but Useful Information Can Be Obtained from These Data? Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static What spatially referenced crash and highway data exist in the regions where the driving took place, and what gaps exist in the data? UMTRI Can closure data or oncom- ing vehicle presence (with estimate of speed) be obtained? VTTI Oncoming vehicles Can driver interfaces be compared? VTTI Interfaces Are OnStar data task dependentâe.g., phone vs. wayfinding? VTTI OnStar What useful data could be obtained from studies that track driver use and inter- action with a given system? VTTI System What new infotainment devices are being used in vehicles? VTTI Can new or novel uses for existing (or traditional) infotainment devices be detected? VTTI Nomadic devices How often do drivers activate the antilock braking system (ABS)? VTTI ABS How often do drivers activate predictive brake assist (PBA)? VTTI PBA How often do drivers activate electronic stability control (ESC)? VTTI ESC How often do drivers receive forward collision warning (FCW) alerts? How often are these alerts a nuisance? VTTI (continued on next page)
127 How often do drivers receive lane-keeping alerts? How often are those alerts a nuisance? VTTI Lane- keeping alerts What are the traffic and envi- ronmental characteristics for activation of these systems and alerts? VTTI Traffic characteristics Environmental conditions How often are different alerts presented for the same situation? VTTI Alert types What is the driver response to these multiple alerts? VTTI Alert types How effective is less- expensive methodology in answering research ques- tions? For example, does showing photographs or videos of curves to drivers and asking them to esti- mate an appropriate speed effectively predict the speed selected by drivers in the naturalistic study? VTTI How do drivers look but not see? VTTI What are the prevalence, types, and frequency of driver inattention in which drivers engage during their daily commuting? VTTI Inattention Table C.27. What Nonsafety-Related but Useful Information Can Be Obtained from These Data? (continued) Actual Research Question Source Driver Factors Vehicle Factors Roadway Factors Environmental Factors OutcomeDynamic Static Dynamic Static Dynamic Static Dynamic Static
