Determination of functional scenarios for intersection collisions.

INTRODUCTION: The National Highway Traffic Safety Administration (NHTSA) estimated that in 2019, intersection crashes accounted for $179 billion of economic damages and $639 billion in societal damages. Intersection advanced driver assist systems (I-ADASs) and automated driving systems (ADS) are designed and have been actively deployed to avoid or mitigate these intersection crash scenarios. Given the indeterminate parameter space for describing collision scenarios, evaluators, and designers are all challenged with condensing the possible intersection crash configurations into digestible, executable conditions for scenario-based simulation testing. The objective of this study is to identify functional intersection crash configurations for I-ADAS and ADS safety evaluation. METHODS: Real-world intersection crash characteristics are important considerations for scenario testing as these features can directly correlate to or influence causality, controllability, and potential injury severity. To identify functional intersection crash types, similar crash scenarios were grouped together by identified critical features using an unsupervised decision tree model. A key advantage of this approach was that the implemented cluster crash scenarios would be understandable and interpretable by users. Unsupervised decision trees work by generating uniformly distributed synthetic data with features from real data and classifying all the data as real or synthetic. Long, non-diverging branches were manually pruned to reduce overfitting and improve model performance. Feature importance values were computed based on how effective a given variable grouped the crashes together. DATA SOURCES: This analysis selected intersection cases that only involved two vehicles from the Crash Investigation Sampling System (CISS) spanning 2017 to 2020. Crash features such as road geometry, intersection signal, and vehicle configuration were important to consider for scenario generation. CISS contained the traffic device, device functionality, vehicle intended pre-event movement, road alignment, road profile, trafficway flow, number of lanes, and crash type for each crash case. Intersection geometry, intersecting road angle, each vehicles' legal moves, and the presence of a two-way-left-turn-lane (TWLTL), channelized roads, bike lanes, crosswalks, street parking, slip lanes, and visual obstructions were manually recorded from the scene diagram. RESULTS: The tree identified 44 functional intersection crash configurations after pruning. These clusters have five main sections: Straight-crossing path (SCP) crashes at 4-legged intersections, Left-Turn-Across-Path/Opposite Direction (LTAP/OD) crashes at 4-legged intersections, other crash types at 4-legged intersections, roundabout and multileg intersections, and 3-legged intersection crashes. The features that best split the data were TWLTL, lane travel direction violation, and traffic control device functionality. The largest cluster was SCP crashes at 4-legged, undivided intersections where the traffic control device was working and both vehicles did not violate the direction of their lane of travel. This cluster was adjacent to 32 vehicles in similar SCP crashes except a vehicle performed an unexpected maneuver based on their lane position. CONCLUSION: These 44 identified crash configurations could be useful in bolstering the robustness of I-ADAS and ADS intersection scenario testing as they are a compact representation of all the police reported intersection crashes where a vehicle was towed. Future studies could generate logical scenarios with distributions of initial conditions and behaviors from these clusters that could be used to evaluate an I-ADAS or ADS.

Passenger and heavy vehicle collisions with pedestrians: Assessment of injury mechanisms and risk.

OBJECTIVE: Automated Driving System (ADS) fleets are currently being deployed in several dense-urban operational design domains within the United States. In these dense-urban areas, pedestrians have historically comprised a significant portion, and sometimes the majority, of injury and fatal collisions. An expanded understanding of the injury risk in collision events involving pedestrians and human-driven vehicles can inform continued ADS development and safety benefits evaluation. There is no current systematic investigation of United States pedestrian collisions, so this study used reconstruction data from the German In-Depth Accident Study (GIDAS) to develop mechanistic injury risk models for pedestrians involved in collisions with vehicles. DATA SOURCE: The study queried the GIDAS database for cases from 1999 to 2021 involving passenger vehicle or heavy vehicle collisions with pedestrians. METHODS: We describe the injury patterns and frequencies for passenger vehicle-to-pedestrian and heavy vehicle-to-pedestrian collisions, where heavy vehicles included heavy trucks and buses. Injury risk functions were developed at the AIS2+, 3+, 4+ and 5+ levels for pedestrians involved in frontal collisions with passenger vehicles and separately for frontal collisions with heavy vehicles. Model predictors included mechanistic factors of collision speed, pedestrian age, sex, pedestrian height relative to vehicle bumper height, and vehicle acceleration before impact. Children (≤17 y.o.) and elderly (≥65 y.o.) pedestrians were included. We further conducted weighted and imputed analyses to understand the effects of missing data elements and of weighting towards the overall population of German pedestrian crashes. RESULTS: We identified 3,112 pedestrians involved in collisions with passenger vehicles, where 2,524 of those collisions were frontal vehicle strikes. Furthermore, we determined 154 pedestrians involved in collisions with heavy vehicles, where 87 of those identified collisions were frontal vehicle strikes. Children were found to be at higher risk of injury compared to young adults, and the highest risk of serious injuries (AIS 3+) existed for the oldest pedestrians in the dataset. Collisions with heavy vehicles were more likely to produce serious (AIS 3+) injuries at low speeds than collisions with passenger vehicles. Injury mechanisms differed between collisions with passenger vehicles and with heavy vehicles. The initial engagement caused 36% of pedestrians' most-severe injuries in passenger vehicle collisions, compared with 23% in heavy vehicles collisions. Conversely, the vehicle underside caused 6% of the most-severe injuries in passenger vehicle collisions and 20% in heavy vehicles collisions. SIGNIFICANCE: U.S. pedestrian fatalities have risen 59% since their recent recorded low in 2009. It is imperative that we understand and describe injury risk so that we can target effective strategies for injury and fatality reduction. This study builds on previous analyses by including the most modern vehicles, including children and elderly pedestrians, incorporating additional mechanistic predictors, broadening the scope of included crashes, and using multiple imputation and weighting to better estimate these effects relative to the entire population of German pedestrian collisions. This study is the first to investigate the risk of injury to pedestrians in collisions with heavy vehicles based on field data.

Combined quadriceps medial patellofemoral ligament reconstruction and osteochondral fixation offers good patient-reported outcomes and low rates of recurrent instability for osteochondral defects secondary to acute patella dislocation.

PURPOSE: Chondral injuries secondary to traumatic patella dislocation are common, and a subgroup of these are significant defects with fragments amenable to fixation. There is a paucity of published evidence assessing patients managed with combined acute patellofemoral stabilisation and osteochondral fixation. The purpose of this study is to report the outcomes of patients with osteochondral injuries secondary to acute traumatic patella dislocation treated with combined early fragment fixation and MPFL reconstruction using a quadriceps tendon turndown technique which has distinct advantages for this cohort, including preventing chondral overloading and non-violation of the patella bone. METHODS: Patients who underwent combined quadriceps tendon MPFL reconstruction and osteochondral fixation were included. Patient demographics, defect characteristics, complications and reoperations were evaluated. Patients were assessed with Lysholm, Kujala, KOOS-PF scores and satisfaction scale at follow up. Pre-operative MRI was assessed for presence of radiological risk factors for patella dislocation and post-operative MRI was used to assess cartilage quality with MOCART 2.0 score. RESULTS: A total of 19 patients (63.2% female) were included. The mean age was 17.4 ± 4.8 years and patients were followed up at a mean 15.8 ± 5.1 months post-surgery. The mean defect size was 2.4 cm2 ± 1.3 cm2, with the most common defect location being the patella (13/19; 68.4%) followed by the lateral femoral condyle (5/19; 26.3%). At final follow up, the overall mean Lysholm, Kujala, and KOOS-PF scores were 84.9 ± 11.1, 89.7 ± 5.8 and 80.6 ± 13.6, respectively. Seventeen patients (89.5%) were satisfied with their outcome. The mean MOCART 2.0 score at final follow-up was 72.5. One patient required medial capsular plication with removal of a loose chondral body and microfracture and 3 knees required minor reoperations. CONCLUSION: Combined acute osteochondral fragment fixation and MPFL reconstruction using a quadriceps tendon graft offers good radiological and patient-reported outcomes with high satisfaction and low rates of recurrent patella dislocation. To our knowledge, this is currently the largest series of its kind in the literature and the results of this study provide a rationale for a combined approach using a quadriceps tendon graft for this cohort. LEVEL OF EVIDENCE: Level IV.

Cranial anatomy of the mekosuchine crocodylian Trilophosuchus rackhami Willis, 1993.

One of the best-preserved crocodylian fossil specimens from the Cenozoic of Australia is the holotype of the mekosuchine Trilophosuchus rackhami, from the middle Miocene (13.56 ± 0.67 Ma) Ringtail Site at Riversleigh, northwestern Queensland. Although lacking most of the snout, the holotype skull of T. rackhami (QMF16856) has an exceptionally well-preserved cranium. Micro-CT scanning of the holotype has allowed for all the preserved cranial bones to be digitally disarticulated, facilitating an unprecedented insight into the cranial anatomy of not just T. rackhami, but any mekosuchine. Trilophosuchus rackhami was a small-bodied crocodylian and one of the most morphologically distinct mekosuchines, characterized by a unique combination of cranial characteristics several of which are exclusive to the species. Fossil material that is definitively referrable to the species T. rackhami is currently known solely from the middle Miocene Ringtail Site. However, an isolated parietal from Hiatus Site at Riversleigh demonstrates that Trilophosuchus also occurred during the late Oligocene (~25 Ma), extending the range of the genus by more than 10 million years. The new description of T. rackhami also allowed for a reevaluation of its phylogenetic relationships. Our results reaffirm the placement of T. rackhami as a member of Mekosuchinae within the subclade Mekosuchini. In all analyses, Mekosuchinae was consistently found to be monophyletic and part of the larger crocodylian clade Longirostres. However, the assignment of Mekosuchinae as a subset of Crocodylidae is brought into question, suggesting that the status of Mekosuchinae as a subfamily should be reconsidered.

Waymo simulated driving behavior in reconstructed fatal crashes within an autonomous vehicle operating domain.

Preventing and mitigating high severity collisions is one of the main opportunities for Automated Driving Systems (ADS) to improve road safety. This study evaluated the Waymo Driver's performance within real-world fatal collision scenarios that occurred in a specific operational design domain (ODD). To address the rare nature of high-severity collisions, this paper describes the addition of novel techniques to established safety impact assessment methodologies. A census of fatal, human-involved collisions was examined for years 2008 through 2017 for Chandler, AZ, which overlaps the current geographic ODD of the Waymo One fully automated ride-hailing service. Crash reconstructions were performed on all available fatal collisions that involved a passenger vehicle as one of the first collision partners and an available map in this ODD to determine the pre-impact kinematics of the vehicles involved in the original crashes. The final dataset consisted of a total of 72 crashes and 91 vehicle actors (52 initiators and 39 responders) for simulations. Next, a novel counterfactual "what-if'' simulation method was developed to synthetically replace human-driven crash participants one at a time with the Waymo Driver. This study focused on the Waymo Driver's performance when replacing one of the first two collision partners. The results of these simulations showed that the Waymo Driver was successful in avoiding all collisions when replacing the crash initiator, that is, the road user who made the initial, unexpected maneuver leading to a collision. Replacing the driver reacting (the responder) to the actions of the crash initiator with the Waymo Driver resulted in an estimated 82% of simulations where a collision was prevented and an additional 10% of simulations where the collision severity was mitigated (reduction in crash-level serious injury risk). The remaining 8% of simulations with the Waymo Driver in the responder role had a similar outcome to the original collision. All of these "unchanged" collisions involved both the original vehicle and the Waymo Driver being struck in the rear in a front-to-rear configuration. These results demonstrate the potential of fully automated driving systems to improve traffic safety compared to the performance of the humans originally involved in the collisions. The findings also highlight the major importance of driving behaviors that prevent entering a conflict situation (e.g. maintaining safe time gaps and not surprising other road users). However, methodological challenges in performing single instance counterfactual simulations based solely on police report data and uncertainty in ADS performance may result in variable performance, requiring additional analysis and supplemental methodologies. This study's methods provide insights on rare, severe events that would otherwise only be experienced after operating in extreme real-world driving distances (many billions of driving miles).

An omni-directional model of injury risk in planar crashes with application for autonomous vehicles.

Objective: Automated driving systems (ADS) are actively being deployed within the driving fleet. ADS are designed to safely navigate roadways, which entails an expectation of encountering varying degrees of potential conflict with other road users. The ADS design and evaluation process benefits from estimating injury severity probabilities for collisions that may occur. Current regression models in the literature are typically bespoke analyses involving targeted principal directions of force (PDOFs) and occupant positions. It is preferable to rely on injury severity models derived from a single source to provide a continuous function of risk for all planar collisions, while also accounting for specific vehicle and occupant characteristics. The novel feature of the proposed models is continuous, parametric injury risk surfaces that encompass the full spectrum of available United States field data.Methods: We used years 2001-2015 of the National Automotive Sampling System, Crashworthiness Data System (NASS-CDS) and years 2017-2019 of the Crash Investigation Sampling System (CISS) to estimate injury risk at the maximum abbreviated injury scale (MAIS) 3 and higher (3+) and 5 and higher (5+) levels for all adult occupants traveling in 2002 or newer passenger vehicles which were less than 10 years old at the time of the crash. The models account for occupant, vehicle, and crash characteristics. Interactions with vulnerable road users (e.g., pedestrian, bicyclist) were not considered.Results: We present statistical models suitable to predict injury in all non-rollover crashes at the maximum MAIS3+ and 5+ levels, and show that these models can be comparable to similar single scenario (e.g., frontal) crash models. We discuss challenges with imputing missing field data, and discuss handling of covariates that may not be known at the time of the crash.Conclusions: Collision severity assessment is a vital component of the ADS design process. We developed a novel injury risk function that can assess occupant injury risks across the spectrum of foreseeable planar collisions. These models can provide insight on potential outcomes of counterfactual simulations, injury risk and crashworthiness considerations for human driven vehicles, and provide an evaluation tool that can be applied in ADS safety impact evaluation.

Excellent Clinical Outcomes and Rates of Return to Play After Arthroscopic Rotator Cuff Repair for Traumatic Tears in Athletes Aged 30 Years or Less.

PURPOSE: To evaluate clinical outcomes and rate of return to play (RTP) among athletes aged 30 years or younger who have undergone an arthroscopic rotator cuff repair (ARCR) after trauma. METHODS: We performed a retrospective review of patients who underwent an ARCR with a minimum of 12 months' follow-up between 2012 and 2019. Patients were followed up to assess the American Shoulder and Elbow Surgeons score, Subjective Shoulder Value, visual analog scale score, and satisfaction level. Whether patients were able to RTP was reported, in addition to the timing of return and the level to which they returned. RESULTS: Our study included 20 athletes (20 shoulders), with a mean follow-up period of 31.8 months. All patients were satisfied with their surgical procedure, and all would opt to undergo surgery again. Overall, 85% returned to sport and 50.0% returned to the same level or a higher level. The overall mean American Shoulder and Elbow Surgeons score was 92.4; mean Subjective Shoulder Value, 87.0; and mean visual analog scale score, 0.7. At final follow-up, only 1 patient (5.0%) had undergone a revision procedure. Of the 15 patients who played collision sports, 93.3% returned to sport but only 60.0% returned to the same level or a higher level. CONCLUSIONS: After ARCR, athletes aged 30 years or younger show excellent functional outcomes with high rates of patient satisfaction and RTP after the procedure. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Clinical Outcomes of Patients With Anterior Shoulder Instability and Glenolabral Articular Disruption Lesions: A Retrospective Comparative Study.

BACKGROUND: Anterior shoulder instability is a common clinical condition that often requires surgical stabilization. Glenoid labral tears are often associated with instability, with glenolabral articular disruption (GLAD) lesions occasionally being identified arthroscopically during repair, particularly in collision athletes. PURPOSE: To evaluate the clinical outcomes and recurrence rates in patients who had GLAD lesions and underwent arthroscopic Bankart repair (ABR) and compare them with a control group without GLAD lesions. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A retrospective review of patients who underwent ABR with GLAD lesions, by a single surgeon between July 2012 and March 2017, was performed. Additionally, these were pair matched in a 2:1 ratio for age, sex, sport, and level of play with a control group who underwent ABR without GLAD lesions. Return to sport, the level of return, and the timing of return were assessed. The visual analog scale (VAS) for pain score, Rowe score, Shoulder Instability-Return to Sport after Injury (SIRSI) score, and Subjective Shoulder Value (SSV) were evaluated. RESULTS: The study included a total of 66 patients (22 and 44 patients for the GLAD and control groups, respectively), with a mean age of 25.8 years and a mean follow-up of 66 months. Overall, there was no significant difference in any of the clinical outcome scores (VAS, Rowe, SIRSI, and SSV) utilized for the GLAD and control groups (P > .05 for all). Similarly, there was no significant difference in the total rate of return to play (90.9% vs 88.6%; P > .99) or return at the same/higher level (68.2% vs 72.7%; P = .78). There was no significant difference in timing of return to play (6.3 ± 6.6 months vs 6.4 ± 2.5 months; P = .98). There were 3 cases (13.6%) requiring further surgery (1 revision stabilization, 1 arthroscopic release, and 1 rotator cuff repair) in the GLAD group and 2 cases (4.5%) requiring further surgery (both revision stabilization) in the control group; the difference was not statistically significant (P = .32). CONCLUSION: After arthroscopic repair, patients with GLAD lesions had similar midterm outcomes when compared with a control group without GLAD lesions.

90-Day Complication Rate After the Latarjet Procedure in a High-Volume Center.

BACKGROUND: The Latarjet procedure is indicated for patients with recurrent anterior shoulder instability, previous failed soft tissue stabilization, glenoid bone loss, or high-risk factors for recurrence, although there is still a concern with the surgical complication rates associated with the Latarjet procedure. PURPOSE: To evaluate the 90-day complication rate after the open Latarjet procedure in a high-volume center. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A retrospective review was performed of patients who underwent an open Latarjet procedure at our institution over a 5-year period between January 2015 and December 2019. The complications, readmissions, and reoperations within 90 days were evaluated. RESULTS: A total of 441 patients with a mean age of 23.0 ± 5.7 years was included; 97.5% of the patients were male. There were 2 intraoperative complications (0.5%): 1 coracoid fracture and 1 anaphylactic reaction to vancomycin. Overall, there were 19 postoperative complications (4.3%) in 18 patients, with 4 (0.9%) readmissions for revision surgery. Hematomas were the most common complication, occurring in 12 patients (2.7%), with 9 (2.0%) requiring a return to the operating theater during their stay for an evacuation. In those who required a readmission for a reoperation, 1 was for a hematoma requiring a washout, 2 were for irrigation and debridement of a surgical site infection, and the third was for a biceps tenodesis in a patient with severe bicipital pain. No patients had recurrence or any postoperative graft complications; additionally, there were no neurovascular complications. CONCLUSION: We found that in a high-volume center, the open Latarjet procedure has a low 90-day complication rate with a low revision rate. Hematomas were the most common complication experienced by patients who underwent the Latarjet procedure, while there was no recurrent instability or neurological or hardware complications reported among the 441 patients included in this study.

Factors Associated With an Increased Risk of Recurrence After a First-Time Patellar Dislocation: A Systematic Review and Meta-analysis.

BACKGROUND: Recurrent dislocations after a first-time lateral patellar dislocation may occur in more than 50% of patients and can cause long-term disability. Many factors have been suggested to influence the risk of recurrence. PURPOSE: To systematically review and quantitatively synthesize the literature for factors associated with an increased risk of recurrence after a first-time patellar dislocation. STUDY DESIGN: Systematic review and meta-analysis of observational studies. METHODS: A total of 4 electronic databases were searched to identify relevant studies published before February 7, 2019. A quality assessment was performed with the National Heart, Lung, and Bone Institute quality assessment score. Factors assessed for their effect on the recurrence rate were documented, and the rates of recurrence were compared. Pooled dichotomous data were analyzed using random-effects meta-analysis with odds ratios (ORs). RESULTS: A total of 17 studies met the criteria for inclusion. The overall rate of recurrent dislocations after a first-time lateral patellar dislocation was 33.6%. An increased risk of recurrence was reported in patients with a younger age (OR, 2.61; P < .00001), open physes (OR, 2.72; P < .00001), trochlear dysplasia (OR, 4.15; P = .009), an elevated tibial tuberosity-trochlear groove (TT-TG) distance (OR, 2.87; P < .00001), and patella alta (OR, 2.38; P = .004). Sex, patterns of medial patellofemoral ligament injury, and history of contralateral dislocations were not found to be associated with an increased recurrence rate (P≥ .05). In studies that reported on the presence of multiple risk factors, recurrence rates were 7.7% to 13.8% when no risk factors were present but increased to 29.6% to 60.2% when 2 risk factors were present and to 70.4% to 78.5% when 3 risk factors were present. CONCLUSION: Younger age, open physes, trochlear dysplasia, elevated TT-TG distance, and patella alta were key risk factors for the recurrence of lateral patellar dislocations. Despite being not infrequently cited as risk factors, patient sex and a history of contralateral dislocations were not found to be significant risk factors. The presence of multiple risk factors increased the risk, and the development of predictive instability scores in large patient cohorts using all established risk factors should be a focus of future studies.

Crash and injury prevention estimates for intersection driver assistance systems in left turn across path/opposite direction crashes in the United States.

Objective: The objective of this research study was to estimate the number of left turn across path/opposite direction (LTAP/OD) crashes and injuries that could be prevented in the United States if vehicles were equipped with an intersection advanced driver assistance system (I-ADAS). Methods: This study reconstructed 501 vehicle-to-vehicle LTAP/OD crashes in the United States that were investigated in the NHTSA National Motor Vehicle Crash Causation Survey (NMVCCS). The performance of 30 different I-ADAS system variations was evaluated for each crash. These variations were the combinations of 5 time-to-collision (TTC) activation thresholds, 3 latency times, and 2 different response types (automated braking and driver warning). In addition, 2 sightline assumptions were modeled for each crash: One where the turning vehicle was visible long before the intersection and one where the turning vehicle was only visible within the intersection. For resimulated crashes that were not avoided by I-ADAS, a new crash delta-V was computed for each vehicle. The probability of Abbreviated Injury Scale 2 or higher injury in any body region (Maximum Abbreviated Injury Scale [MAIS] 2+F) to each front-row occupant was computed. Results: Depending on the system design, sightline assumption, I-ADAS variation, and fleet penetration, an I-ADAS system that automatically applies emergency braking could avoid 18-84% of all LTAP/OD crashes. Only 0-32% of all LTAP/OD crashes could have been avoided using an I-ADAS system that only warns the driver. An I-ADAS system that applies emergency braking could prevent 47-93% of front-row occupants from receiving MAIS 2 + F injuries. A system that warns the driver in LTAP/OD crashes was able to prevent 0-37% of front-row occupants from receiving MAIS 2 + F injuries. The effectiveness of I-ADAS in reducing crashes and number of injured persons was higher when both vehicles were equipped with I-ADAS. Conclusions: This study presents the simulated effectiveness of a hypothetical intersection active safety system on real crashes that occurred in the United States. This work shows that there is a strong potential to reduce crashes and injuries in the United States.

Palaeoecological inferences for the fossil Australian snakes Yurlunggur and Wonambi (Serpentes, Madtsoiidae).

Madtsoiids are among the most basal snakes, with a fossil record dating back to the Upper Cretaceous (Cenomanian). Most representatives went extinct by the end of the Eocene, but some survived in Australia until the Late Cenozoic. Yurlunggur and Wonambi are two of these late forms, and also the best-known madtsoiids to date. A better understanding of the anatomy and palaeoecology of these taxa may shed light on the evolution and extinction of this poorly known group of snakes and on early snake evolution in general. A digital endocast of the inner ear of Yurlunggur was compared to those of 81 species of snakes and lizards with known ecological preferences using three-dimensional geometric morphometrics. The inner ear of Yurlunggur most closely resembles both that of certain semiaquatic snakes and that of some semifossorial snakes. Other cranial and postcranial features of this snake support the semifossorial interpretation. While the digital endocast of the inner ear of Wonambi is too incomplete to be included in a geometric morphometrics study, its preserved morphology is very different from that of Yurlunggur and suggests a more generalist ecology. Osteology, palaeoclimatic data and the palaeobiogeographic distribution of these two snakes are all consistent with these inferred ecological differences.

Injury mitigation estimates for an intersection driver assistance system in straight crossing path crashes in the United States.

OBJECTIVE: Accounting for one fifth of all crashes and one sixth of all fatal crashes in the United States, intersection crashes are among the most frequent and fatal crash modes. Intersection advanced driver assistance systems (I-ADAS) are emerging vehicle-based active safety systems that aim to help drivers safely navigate intersections. The objective of this study was to estimate the number of crashes and number of vehicles with a seriously injured driver (Maximum Abbreviated Injury Scale [MAIS] 3+) that could be prevented or reduced if, for every straight crossing path (SCP) intersection crash, one of the vehicles had been equipped with an I-ADAS. METHODS: This study retrospectively simulated 448 U.S. SCP crashes as if one of the vehicles had been equipped with I-ADAS. Crashes were reconstructed to determine the path and speeds traveled by the vehicles. Cases were then simulated with I-ADAS. A total of 30 variations of I-ADAS were considered in this study. These variations consisted of 5 separate activation timing thresholds, 3 separate computational latency times, and 2 different I-ADAS response modalities (i.e., a warning or autonomous braking). The likelihood of a serious driver injury was computed for every vehicle in every crash using impact delta-V. The results were then compiled across all crashes in order to estimate system effectiveness. RESULTS: The model predicted that an I-ADAS that delivers an alert to the driver has the potential to prevent 0-23% of SCP crashes and 0-25% of vehicles with a seriously injured driver. Conversely, an I-ADAS that autonomously brakes was found to have the potential to prevent 25-59% of crashes and 38-79% of vehicles with a seriously injured driver. I-ADAS effectiveness is a strong function of design. Increasing computational latency time from 0 to 0.5 s was found to reduce crash and injury prevention estimates by approximately one third. For an I-ADAS that delivers an alert, crash/injury prevention effectiveness was found to be very sensitive to changes in activation timing (warning delivered 1.0 to 3.0 s prior to impact). If autonomous braking was used, system effectiveness was found to largely plateau for activation timings greater than 1.5 s prior to impact. In general, the results of this study suggest that I-ADAS will be 2-3 times more effective if an autonomous braking system is utilized over a warning-based system. CONCLUSIONS: This study highlights the potential effectiveness of I-ADAS in the U.S. vehicle fleet, while also indicating the sensitivity of system effectiveness to design specifications. The results of this study should be considered by designers of I-ADAS and evaluators of this technology considering a future I-ADAS safety test.

Predicting crash-relevant violations at stop sign-controlled intersections for the development of an intersection driver assistance system.

OBJECTIVE: Intersection crashes resulted in over 5,000 fatalities in the United States in 2014. Intersection Advanced Driver Assistance Systems (I-ADAS) are active safety systems that seek to help drivers safely traverse intersections. I-ADAS uses onboard sensors to detect oncoming vehicles and, in the event of an imminent crash, can either alert the driver or take autonomous evasive action. The objective of this study was to develop and evaluate a predictive model for detecting whether a stop sign violation was imminent. METHODS: Passenger vehicle intersection approaches were extracted from a data set of typical driver behavior (100-Car Naturalistic Driving Study) and violations (event data recorders downloaded from real-world crashes) and were assigned weighting factors based on real-world frequency. A k-fold cross-validation procedure was then used to develop and evaluate 3 hypothetical stop sign warning algorithms (i.e., early, intermediate, and delayed) for detecting an impending violation during the intersection approach. Violation detection models were developed using logistic regression models that evaluate likelihood of a violation at various locations along the intersection approach. Two potential indicators of driver intent to stop-that is, required deceleration parameter (RDP) and brake application-were used to develop the predictive models. The earliest violation detection opportunity was then evaluated for each detection algorithm in order to (1) evaluate the violation detection accuracy and (2) compare braking demand versus maximum braking capabilities. RESULTS: A total of 38 violating and 658 nonviolating approaches were used in the analysis. All 3 algorithms were able to detect a violation at some point during the intersection approach. The early detection algorithm, as designed, was able to detect violations earlier than all other algorithms during the intersection approach but gave false alarms for 22.3% of approaches. In contrast, the delayed detection algorithm sacrificed some time for detecting violations but was able to substantially reduce false alarms to only 3.3% of all nonviolating approaches. Given good surface conditions (maximum braking capabilities = 0.8 g) and maximum effort, most drivers (55.3-71.1%) would be able to stop the vehicle regardless of the detection algorithm. However, given poor surface conditions (maximum braking capabilities = 0.4 g), few drivers (10.5-26.3%) would be able to stop the vehicle. Automatic emergency braking (AEB) would allow for early braking prior to driver reaction. If equipped with an AEB system, the results suggest that, even for the poor surface conditions scenario, over one half (55.3-65.8%) of the vehicles could have been stopped. CONCLUSIONS: This study demonstrates the potential of I-ADAS to incorporate a stop sign violation detection algorithm. Repeating the analysis on a larger, more extensive data set will allow for the development of a more comprehensive algorithm to further validate the findings.

Analysis of Driver Evasive Maneuvering Prior to Intersection Crashes Using Event Data Recorders.

OBJECTIVE: Intersection crashes account for over 4,500 fatalities in the United States each year. Intersection Advanced Driver Assistance Systems (I-ADAS) are emerging vehicle-based active safety systems that have the potential to help drivers safely navigate across intersections and prevent intersection crashes and injuries. The performance of an I-ADAS is expected to be highly dependent upon driver evasive maneuvering prior to an intersection crash. Little has been published, however, on the detailed evasive kinematics followed by drivers prior to real-world intersection crashes. The objective of this study was to characterize the frequency, timing, and kinematics of driver evasive maneuvers prior to intersection crashes. METHODS: Event data recorders (EDRs) downloaded from vehicles involved in intersection crashes were investigated as part of NASS-CDS years 2001 to 2013. A total of 135 EDRs with precrash vehicle speed and braking application were downloaded to investigate evasive braking. A smaller subset of 59 EDRs that collected vehicle yaw rate was additionally analyzed to investigate evasive steering. Each vehicle was assigned to one of 3 precrash movement classifiers (traveling through the intersection, completely stopped, or rolling stop) based on the vehicle's calculated acceleration and observed velocity profile. To ensure that any significant steering input observed was an attempted evasive maneuver, the analysis excluded vehicles at intersections that were turning, driving on a curved road, or performing a lane change. Braking application at the last EDR-recorded time point was assumed to indicate evasive braking. A vehicle yaw rate greater than 4° per second was assumed to indicate an evasive steering maneuver. RESULTS: Drivers executed crash avoidance maneuvers in four-fifths of intersection crashes. A more detailed analysis of evasive braking frequency by precrash maneuver revealed that drivers performing complete or rolling stops (61.3%) braked less often than drivers traveling through the intersection without yielding (79.0%). After accounting for uncertainty in the timing of braking and steering data, the median evasive braking time was found to be between 0.5 to 1.5 s prior to impact, and the median initial evasive steering time was found to occur between 0.5 and 0.9 s prior to impact. The median average evasive braking deceleration for all cases was found to be 0.58 g. The median of the maximum evasive vehicle yaw rates was found to be 8.2° per second. Evasive steering direction was found to be most frequently in the direction of travel of the approaching vehicle. CONCLUSIONS: The majority of drivers involved in intersection crashes were alert enough to perform an evasive action. Most drivers used a combination of steering and braking to avoid a crash. The average driver attempted to steer and brake at approximately the same time prior to the crash.

Skull of the large non-macrostomatan snake Yurlunggur from the Australian Oligo-Miocene.

Understanding the origin and early evolution of snakes from lizards depends on accurate morphological knowledge of the skull in basal lineages, but fossil specimens of archaic snakes have been rare, and either fragmentary or difficult to study as a result of compression by enclosing sediments. A number of Cenozoic fossil snakes from Australia have vertebral morphology diagnostic of an extinct group, Madtsoiidae, that was widespread in Gondwana from mid-Cretaceous (Cenomanian) to Eocene times, and also reached Europe in the late Cretaceous period. Despite this long history, only about half the skull is known from the best-known species Wonambi naracoortensis, and the few known cranial elements of other species have added little further evidence for phylogenetic relationships. Conflicting hypotheses have been proposed for their relationships and evolutionary significance, either as basal ophidians with many ancestral (varanoid- or mosasaur-like) features, or advanced (macrostomatan) alethinophidians of little relevance to snake origins. Here I report two partial skeletons referred to Yurlunggur, from the late Oligocene and early Miocene of northern Australia, which together represent almost the complete skull and mandible. The exceptionally preserved skulls provide new evidence linking Yurlunggur with Wonambi and other madtsoiids, falsifying predictions of the macrostomatan hypothesis, and supporting the exclusion of Madtsoiidae from the clade including all extant snakes.

Snake phylogeny based on osteology, soft anatomy and ecology.

Relationships between the major lineages of snakes are assessed based on a phylogenetic analysis of the most extensive phenotypic data set to date (212 osteological, 48 soft anatomical, and three ecological characters). The marine, limbed Cretaceous snakes Pachyrhachis and Haasiophis emerge as the most primitive snakes: characters proposed to unite them with advanced snakes (macrostomatans) are based on unlikely interpretations of contentious elements or are highly variable within snakes. Other basal snakes include madtsoiids and Dinilysia--both large, presumably non-burrowing forms. The inferred relationships within extant snakes are broadly similar to currently accepted views, with scolecophidians (blindsnakes) being the most basal living forms, followed by anilioids (pipesnakes), booids and booid-like groups, acrochordids (filesnakes), and finally colubroids. Important new conclusions include strong support for the monophyly of large constricting snakes (erycines, boines. pythonines), and moderate support for the non-monophyly of the trophidophiids' (dwarf boas). These phylogenetic results are obtained whether varanoid lizards, or amphisbaenians and dibamids, are assumed to be the nearest relatives (outgroups) of snakes, and whether multistate characters are treated as ordered or unordered. Identification of large marine forms, and large surface-active terrestrial forms, as the most primitive snakes contradicts with the widespread view that snakes arose via minute, burrowing ancestors. Furthermore, these basal fossil snakes all have long flexible jaw elements adapted for ingesting large prey ('macrostomy'), suggesting that large gape was primitive for snakes and secondarily reduced in the most basal living foms (scolecophidians and anilioids) in connection with burrowing. This challenges the widespread view that snake evolution has involved progressive, directional elaboration of the jaw apparatus to feed on larger prey.

Treatment of severe tricyclic antidepressant overdose with extracorporeal sorbent detoxification.

Tricyclic overdose can be a medical emergency, and therapy with intravenous bicarbonate is not always successful in preventing cardiac toxicity or coma. Mortality in patients developing these complications is from 1% to 15%. Extracorporeal detoxification with sorbents has been used in treatment of patients with very high drug levels and declining clinical condition. Ten patients with serious drug overdose caused by tricyclics failed to respond quickly to standard therapy and were in stage 3-4 encephalopathy. Nine of these patients were on respirator support, 5 had hypotension, and 6 had QRS widening. Average level was 1,423 microg/L at presentation. Enteral activated charcoal and intravenous (IV) bicarbonate were initiated in the emergency room. The patients were treated for 3 to 4 hours with the Liver Dialysis Unit, a hemodiabsorption device using a cellulosic plate dialyzer and sorbent suspension as dialysate. Inflow and outflow blood levels indicated that the hemodetoxifier removed modest amounts of the tricyclics, metabolites, and other consumed drugs. The clinical improvement of the patients was dramatic, with patients reaching stage 0 or 1 encephalopathy during the treatment. Ventilator support was removed at the end of treatment for 3 patients who had not already developed pneumonia, and for others was prolonged up to 48 hours because of pneumonia, rather than mental status. Average length of stay in the intensive care unit (ICU) was 4.8 days (range 1 to 7 days). None of the patients died despite their high risk for ventricular arrhythmias, seizures, and death. Clinical improvement may have been attributable to removal of free drug from the blood or to removal of drug metabolites.