Helen Loeb

EMERGENCY BRAKING IN ADULTS VERSUS NOVICE TEEN DRIVERS: RESPONSE TO SIMULATED SUDDEN DRIVING EVENTS.

Motor vehicle crashes remain the leading cause of death of teens in the United States. Newly licensed drivers are the group most at risk for such crashes. The driving skills of teen drivers are new and still often untested; therefore, their ability to react properly in an emergency situation remains a subject for research. Because it is not possible to expose human subjects to critical life-threatening driving scenarios, researchers increasingly have been using driving simulators to assess driving skills. This paper summarizes the results of a driving scenario in a study that compared the driving performance of novice teen drivers (n = 21) 16 to 17 years old with 90 days of provisional licensure with that of experienced adult drivers (n = 17) 25 to 50 years old with at least 5 years of Pennsylvania licensure who drove at least 100 mi per week and had experienced no self-reported collisions in the previous 3 years. As part of a 30 to 35 mph simulated drive that encompassed the most common scenarios that result in serious crashes, participants were exposed to a sudden car event. As the participant drove on a suburban road, a car surged from a driveway hidden by a fence on the right-hand side of the road. To avoid the crash the participant had to brake hard and demonstrate dynamic control over both attentional and motor resources. The results showed significant differences between the experienced adult and the novice teen drivers in the amount of brake pressure applied. When placed in the same situation, the novice teens decelerated on average 50% less than the experienced adults (p < .01).

Simulated Driving Assessment (SDA) for teen drivers: results from a validation study

Background Driver error and inadequate skill are common critical reasons for novice teen driver crashes, yet few validated, standardised assessments of teen driving skills exist. The purpose of this study is to evaluate the construct and criterion validity of a newly developed Simulated Driving Assessment (SDA) for novice teen drivers. Methods The SDA’s 35 min simulated drive incorporates 22 variations of the most common teen driver crash configurations. Driving performance was compared for 21 inexperienced teens (age 16–17 years, provisional license ≤90 days) and 17 experienced adults (age 25–50 years, license ≥5 years, drove ≥100 miles per week, no collisions or moving violations ≤3 years). SDA driving performance (Error Score) was based on driving safety measures derived from simulator and eye-tracking data. Negative driving outcomes included simulated collisions or run-off-the-road incidents. A professional driving evaluator/instructor (DEI Score) reviewed videos of SDA performance. Results The SDA demonstrated construct validity: (1) teens had a higher Error Score than adults (30 vs 13, p=0.02); (2) For each additional error committed, the RR of a participants propensity for a simulated negative driving outcome increased by 8% (95% CI 1.05 to 1.10, p<0.01). The SDA-demonstrated criterion validity: Error Score was correlated with DEI Score (r=−0.66, p<0.001). Conclusions This study supports the concept of validated simulated driving tests like the SDA to assess novice driver skill in complex and hazardous driving scenarios. The SDA, as a standard protocol to evaluate teen driver performance, has the potential to facilitate screening and assessment of teen driving readiness and could be used to guide targeted skill training.

Comparison of Crash Rates and Rear-End Striking Crashes among Novice Teens and Experienced Adults Using the SHRP2 Naturalistic Driving Study

ABSTRACT Objective: Motor vehicle crashes are the leading cause of death for teens. Previous teen and adult crash rates have been based upon fatal crashes, police-reported crashes, and estimated miles driven. Large-scale naturalistic driving studies offer the opportunity to compute crash rates using a reliable methodology to capture crashes and driving exposure. The Strategic Highway Research Program 2 (SHRP2) Naturalistic Driving Study contains extensive real-world data on teen and adult driving. This article presents findings on the crash rates of novice teen and experienced adult drivers in naturalistic crashes. Methods: A subset from the SHRP2 database consisting of 539 crash events for novice teens (16–19 years, n = 549) and experienced adults (35–54 years, n = 591) was used. Onboard instrumentation such as scene cameras, accelerometers, and Global Positioning System logged time series data at 10 Hz. Scene videos were reviewed for all events to identify rear-end striking crashes. Dynamic variables such as acceleration and velocity were analyzed for rear-end striking events. Number of crashes, crash rates, rear-end striking crash severity, and rear-end striking impact velocity were compared between novice teens and experienced adults. Results: Video review of the SHRP2 crashes identified significantly more crashes (P < 0.01) and rear-end striking crashes (P < 0.01) among the teen group than among the adult group. This yielded crash rates of 30.0 crashes per million miles driven for novice teens compared to 5.3 crashes per million miles driven for experienced adults. The crash rate ratio for teens vs. adults was 5.7. The rear-end striking crash rate was 13.5 and 1.8 per million miles driven for novice teens and experienced adults, respectively. The rear-end striking crash rate ratio for teens vs. adults was 7.5. The rear-end striking crash severity measured by the accelerometers was greater (P < 0.05) for the teen group (1.8 ± 0.9 g; median = 1.6 g) than for the adult group (1.1 ± 0.4 g; median = 1.0 g), suggesting that teen crashes tend to be more serious than adult crashes. Increased rear-end striking impact velocity (P < 0.01) was also observed for novice teens (18.8 ± 13.2 mph; median = 18.9 mph) compared to experienced adults (3.3 ± 1.2 mph; median = 2.8 mph). Conclusion: To our knowledge, this is the first study to compare crash rates between teens and adults using a large-scale naturalistic driving database. Unlike previous crash rates, the reported rates reliably control for crash type and driving exposure. These results conform to previous findings that novice teens exhibit increased crash rates compared to experienced adults.

Analysis of near crashes among teen, young adult, and experienced adult drivers using the SHRP2 naturalistic driving study

ABSTRACT Objective: Motor vehicle crashes are the leading cause of death among young drivers. Though previous research has focused on crash events, near crashes offer additional data to help identify driver errors that could potentially lead to crashes as well as evasive maneuvers used to avoid them. The Strategic Highway Research Program 2 (SHRP2) Naturalistic Driving Study (NDS) contains extensive data on real-world driving and offers a reliable methodology to quantify and study near crashes. This article presents findings on near crashes and how they compare to crash events among teen, young adult, and experienced adult drivers. Methods: A subset from the SHRP2 database consisting of 1,653 near crashes for teen (16–19 years, n = 550), young adult (20–24 years, n = 748), and experienced adult (35–54 years, n = 591) drivers was used. Onboard instrumentation including scene cameras, accelerometers, and Global Positioning System logged time series data at 10 Hz. Scene videos were reviewed for all events to classify near crashes based on 7 types: rear-end, road departure, intersection, head-on, side-swipe, pedestrian/cyclist, and animal. Near crash rates, incident type, secondary tasks, and evasive maneuvers were compared across age groups and between crashes and near crashes. For rear-end near crashes, vehicle dynamic variables including near crash severity, headway distance, time headway, and time to collision at the time of braking were compared across age groups. Crashes and near crashes were combined to compare the frequency of critical events across age. Results: Teen drivers exhibited a significantly higher (P <.01) near crash rate than young adult and experienced adult drivers. The near crash rates were 81.6, 56.6, and 37.3 near crashes per million miles for teens, young adults, and experienced adults, respectively. Teens were also involved in significantly more rear-end (P <.01), road departure (P <.01), side-swipe (P <.01), and animal (P <.05) near crashes compared to young and experienced adults. Teens exhibited a significantly greater (P <.01) critical event rate of 102.2 critical events per million miles compared to 72.4 and 40.0 critical events per million miles for young adults and experienced adults, respectively; the critical event rate ratio was 2.6 and 1.8 for teens and young adults, respectively. Conclusions: To our knowledge, this is the first study to examine near crashes among teen, young adult, and experienced adult drivers using SHRP2 naturalistic data. Near crash and critical event rates significantly decreased with increasing age and driver experience. Overall, teens were more than twice as likely to be involved in critical events compared to experienced adults. These data can be used to develop more targeted driver training programs and help manufacturers design active safety systems based on the most common driving errors for vulnerable road users.

Open Source Computer Vision Solution for Head and Gaze Tracking in a Driving Simulator Environment

Inadequate situation awareness and response are increasingly recognized as prevalent critical errors that lead to young driver crashes. To identify and assess key indicators of young driver performance (including situation awareness), we previously developed and validated a Simulated Driving Assessment (SDA) in which drivers are safely and reproducibly exposed to a set of common and potentially serious crash scenarios. Many of the standardized safety measures can be calculated in near real-time from simulator variables. Assessment of situation awareness, however, largely relies on time-consuming data reduction and video coding. Therefore, the objective of this research was to develop a near realtime automated method for analyzing general direction and location of driver’s gaze in order to assess situation awareness. Head tracking was employed as a proxy and standard display of computer readable patterns at the corners of the simulator monitors created fixed locations within the simulator display. The analysis system algorithmically detected whether each unique pattern was in the driver’s field of view and computed a homography transformation from the camera view to each of the three screens. The homography transformation standardized the gaze tracking data streams for each of the simulator screens and generated corrected scene-view videos for manual validation. All software and immediate dependencies are open source. We verified that our automated procedure, called SimGaze: (1) produced comparable results to those produced by hand coding of well-calibrated videos and (2) worked in real time, reducing researcher time required for analysis and improving the simulator report.

Frontal and oblique crash tests of HIII 6-year-old child ATD using real-world, observed child passenger postures

ABSTRACT Objective: The aim of this study was to evaluate the consequences of frontal and oblique crashes when positioning a Hybrid III (HIII) 6-year-old child anthropometric test device (ATD) using observed child passenger postures from a naturalistic driving study (NDS). Methods: Five positions for booster-seated children aged 4–7 years were selected, including one reference position according to the FMVSS 213 ATD seating protocol and 4 based on real-world observed child passenger postures from an NDS including 2 user positions with forward tilting torso and 2 that combined both forward and lateral inboard tilting of the torso. Seventeen sled tests were conducted in a mid-sized vehicle body at 64 km/h (European New Car Assessment Programme [Euro NCAP] Offset Deformable Barrier [ODB] pulse), in full frontal and oblique (15°) crash directions. The rear-seated HIII 6-year-old child ATD was restrained on a high-back booster seat. In 10 tests, the booster seat was also attached with a top tether. In the oblique tests, the ATD was positioned on the far side. Three camera views and ATD responses (head, neck, and chest) were analyzed. Results: The shoulder belt slipped off the shoulder in all ATD positions in the oblique test configuration. In full frontal tests, the shoulder belt stayed on the shoulder in 3 out of 9 tests. Head acceleration and neck tension were decreased in the forward leaning positions; however, the total head excursion increased up to 210 mm compared to te reference position, due to belt slip-off and initial forward leaning position. Conclusions: These results suggest that real-world child passenger postures may contribute to shoulder belt slip-off and increased head excursion, thus increasing the risk of head injury. Restraint system development needs to include a wider range of sitting postures that children may choose, in addition to the specified postures of ATDs in seating test protocols, to ensure robust performance across diverse use cases. In addition, these tests revealed that the child ATD is limited in its ability to mimic real-world child passenger postures. There is a need to develop child human body models that may offer greater flexibility for these types of crash evaluations.

Stereo 3D tracking of infants in natural play conditions

This paper describes the design and implementation of a multiple view stereoscopic 3D vision system and a supporting infant tracker pipeline to track limb movement in natural play environments and identify potential metrics to quantify movement behavior. So far, human pose estimation and tracking with 3D cameras has been focused primarily on adults and cannot be directly extended to infants because of differences in visual features such as shapes, sizes and appearance. With rehabilitation in mind, we propose a portable, compact, markerless, low cost and high resolution 3D vision system and a tracking algorithm that exploits infant appearance attributes and depth information. This approach achieved a mean 3D tracking error of 8.21cm and a standard deviation of 8.75cm. We also identify two potential metrics for movement behavior analysis — approximate entropy and interaction events.

Automated recognition of rear seat occupants' head position using Kinect™ 3D point cloud

INTRODUCTION Child occupant safety in motor-vehicle crashes is evaluated using Anthropomorphic Test Devices (ATD) seated in optimal positions. However, child occupants often assume suboptimal positions during real-world driving trips. Head impact to the seat back has been identified as one important injury causation scenario for seat belt restrained, head-injured children (Bohman et al., 2011). There is therefore a need to understand the interaction of children with the Child Restraint System to optimize protection. METHOD Naturalistic driving studies (NDS) will improve understanding of out-of-position (OOP) trends. To quantify OOP positions, an NDS was conducted. Families used a study vehicle for two weeks during their everyday driving trips. The positions of rear-seated child occupants, representing 22 families, were evaluated. The study vehicle - instrumented with data acquisition systems, including Microsoft Kinect™ V1 - recorded rear seat occupants in 1120 driving 26 trips. Three novel analytical methods were used to analyze data. To assess skeletal tracking accuracy, analysts recorded occurrences where Kinect™ exhibited invalid head recognition among a randomly-selected subset (81 trips). Errors included incorrect target detection (e.g., vehicle headrest) or environmental interference (e.g., sunlight). When head data was present, Kinect™ was correct 41% of the time; two other algorithms - filtering for extreme motion, and background subtraction/head-based depth detection are described in this paper and preliminary results are presented. Accuracy estimates were not possible because of their experimental nature and the difficulty to use a ground truth for this large database. This NDS tested methods to quantify the frequency and magnitude of head positions for rear-seated child occupants utilizing Kinect™ motion-tracking. RESULTS This studys results informed recent ATD sled tests that replicated observed positions (most common and most extreme), and assessed the validity of child occupant protection on these typical CRS uses. SUMMARY Optimal protection in vehicles requires an understanding of how child occupants use the rear seat space. This study explored the feasibility of using Kinect™ to log positions of rear seated child occupants. Initial analysis used the Kinect™ systems skeleton recognition and two novel analytical algorithms to log head location. PRACTICAL APPLICATIONS This research will lead to further analysis leveraging Kinect™ raw data - and other NDS data - to quantify the frequency/magnitude of OOP situations, ATD sled tests that replicate observed positions, and advances in the design and testing of child occupant protection technology.