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A novel paper using Canada's real traffic accident data to propose a cost-prediction-based decision-making framework incorporating different ethical foundations for AVs. / Autonomous Vehicles (AVs) hold out the promise of being safer than manually driven cars. However, it is impossible to guarantee the hundred percent avoidance of collisions in a real-life environment with unpredictable objects and events. When accidents become unavoidable, the different reactions of AVs and their outcome will have different consequences. Thus, AVs should incorporate the so-called ‘ethical decision-making algorithm’ when facing unavoidable collisions. This paper is introducing a novel cost-prediction-based decision-making framework incorporating two common ethical foundations human drivers use when facing unavoidable dilemma inducing collisions: Ethical Egoism and Utilitarianism. The cost-prediction algorithm consists of Collision Injury Severity Level Prediction (CISLP) and Cost Evaluation. The CISLP model was trained using both Multinominal Logistic Regression (MLR) and a Decision Tree Classifier (DTC). Both algorithms consider the combination of relationships among traffic collision explanatory features. Four different Cost Evaluation metrics were purposed and compared to suit different application needs. The data set used for training and testing the cost prediction algorithm is the 1999-2017 National Collision Data Base (NCDB) which ensures the realistic and reliability of the algorithm. This paper is a novel paper using Canada's real traffic accident data to propose a cost-prediction-based decision-making framework incorporating different ethical foundations for AVs. / Thesis / Master of Applied Science (MASc)

Ballistic shields are used by defense teams in dangerous situations as protection against threats such as gunfire. When a ballistic shield is struck, the shield material will deform to absorb the kinetic energy of the incoming projectile. The rapid back-face deformation of the shield can contact the arm, which can impart a large force over an extremely short duration. This work modified an Anthropomorphic Test Device (ATD) to be used for the characterization of behind ballistic shield blunt impact loading profiles. The modified ATD was instrumented to measure impacts at the hand, wrist, forearm, and elbow to compare the force transfer at different locations of impact. A custom jig was designed to support the ATD behind a ballistic shield, provide a high degree of adjustability, and be subjected to impact testing. Two ballistic shield models, both with the same protection rating, were tested and showed to have statistically different responses to the same impact conditions, indicating further need for shield safety evaluation. To apply these loading profiles to future injury criteria development tests, a pneumatic impacting apparatus was re-designed that will allow the high energy impact profiles to be re-created in the McMaster Injury Biomechanics lab. Understanding the ballistic impact conditions, as well as the response of different ballistic shield models provided insight into the possible methods available to reduce upper extremity injury risk. This work has provided essential data for informing a future standard for shield safety evaluation. / Thesis / Master of Applied Science (MASc) / When a ballistic shield is impacted by a bullet it deforms to absorb the incoming energy. The high-speed deformation of the shield material can impact the arm leading to fracture and possible life-threatening risks if the shield is dropped due to this injury. At the time of this work, there were no standards that limited the amount of allowable back-face deflection or tools available that could measure the force transferred to the arm in this scenario. The purpose of this work was to develop a measurement device that could measure the force transferred to the arm from the behind shield impact. An existing crash test dummy arm was modified to provide measurement capabilities for this loading scenario. Ballistic shield testing was conducted where two different ballistic shield models were impacted to observe how the impact force changed with shield design, as well as the distance the device was placed behind the shield. A pneumatic impacting apparatus was then re-designed in the McMaster Injury Biomechanics lab that will allow the ballistic impact conditions to be re-created for evaluating the injury tolerance of the arm. The results of this work will be used to inform the future development of a ballistic shield evaluation standard.

Driving field experiment data were used to investigate lane changes in which a slow lead vehicle was present to: 1) characterize lane changes, 2) develop predictive models, 3) provide collision avoidance system (CAS) design guidelines. A total of 3,227 slow lead vehicle lane changes over 23,949 miles were completed by sixteen commuters. Two instrumented vehicles, a sedan and an SUV, were outfitted with video, sensor, and radar data systems that collected data in an unobtrusive manner. Results indicate that 37.2% of lane changes are slow lead vehicle lane changes, with a mean completion time of 6.3 s; most slow lead vehicle lane changes are leftward, rated low in urgency and severity. A stratified sample of 120 lane changes was selected to include a range of maneuvers. On the interstate, lane changes are performed less often, <i>t</i>(30) = 2.83, <i>p</i> = 0.008, with lower urgency ratings, <i>F</i>(1, 31) = 5.24, <i>p</i> = 0.05, as compared to highway lane changes, as interstates are designed for smooth flow. Drivers who usually drive sedans are more likely to make lane changes than drivers of SUVs, <i>X</i> ²⁺(1)= 99.6247, <i>p</i> < 0.0001, suggesting that driving style is maintained regardless of which experimental vehicle is driven. Turn signals are used 64% of the time but some drivers signal after the lane change starts. Of cases in which signals are not used, 70% of them are made with other vehicles nearby. Eyeglance analysis revealed that the forward view, rearview mirror, and left mirror are the most likely glance locations. There are also distinct eyeglance patterns for lane changing and baseline driving. Recommendations are to use forward view or mirror-based visual displays to indicate presence detection, and auditory displays for imminent warnings. The "vehicle + signal" logistic regression model is best overall since it takes advantage of the distance to the front and rear adjacent vehicle, forward time-to-collision (TTC), and turn signal activation. The use of additional regressors would also improve the model. Five design guidelines are included to aid in the development of CAS that are useable, safe, and integrated with other systems, given testing and development. / Ph. D.

While driver distraction has been extensively studied in laboratory and empirical field studies, the prevalence of driver distraction on our nation's highways and the relative crash risk is unknown. It has recently become technologically feasible to conduct unobtrusive large-scale naturalistic driving studies as the costs and size of computer equipment and sensor technology have both dramatically decreased. A large-scale naturalistic driving study was conducted using 100 instrumented vehicles (80 privately-owned and 20 leased vehicles). This data collection effort was conducted in the Washington DC metropolitan area on a variety of urban, suburban, and rural roadways over a span of 12-13 months. Five channels of video and kinematic data were collected on 69 crashes and 761 near-crashes during the course of this data collection effort. The analyses conducted here are the first to establish direct relationships between driving inattention and crash and near-crash involvement. Relative crash risk was calculated using both crash and near-crash data as well as normal, baseline driving data, for various sources of inattention. Additional analyses investigated the environmental conditions drivers choose to engage in secondary tasks or drive fatigued, assessed whether questionnaire data were indicative of an individual's propensity to engage in inattentive driving, and examined the impact of driver's eyes off the forward roadway. The results indicated that driving inattention was a contributing factor in 78% of all crashes and 65% of all near-crashes. Odds ratio calculations indicated that fatigued drivers have a 4 times higher crash risk than alert drivers. Drivers engaging in visually and/or manually complex tasks are at 7 times higher crash risk than alert drivers. There are specific environmental conditions in which engaging in secondary tasks or driving fatigued is deemed to be more dangerous, including intersections, wet roadways, undivided highways, curved roadways, and driving at dusk. Short, brief glances away from the forward roadway for the purpose of scanning the roadway environment (e.g., mirrors and blind spots) are safe and decrease crash risk, whereas such glances that total more than 2 seconds away from the forward roadway are dangerous and increase crash risk by 2 times over that of more typical driving. / Ph. D.

Motor vehicle crash (MVC) and its associated injuries remain a major public health problem world wide. In 2005 alone there were 6 million police-reported crashes in the United States resulting in 2.5 million injuries and 46,000 fatalities. The thorax is second only to the head in terms of frequency of injury following MVC, and pulmonary contusion (PC) is the most common intra-thoracic soft tissue injury sustained as a result of blunt chest trauma. The goal of this dissertation research is to mitigate this commonly-sustained and potentially life threatening injury. We have taken a computational approach to solving this problem by developing a predictive injury metric for PC using finite element analysis (FEA). The dissertation begins with an epidemiological examination of the crash modes, vehicles, and patient demographics most commonly associated with PC. This study was conducted using real world crash data from the Crash Injury Research and Engineering Network (CIREN) database and data from government-sponsored vehicle crash tests. The CIREN data showed that a substantial portion of the crashes resulting in PC were lateral impacts (48%). Analysis of the thoracic loading of dummy occupants in lateral crash tests resulted in mean values of medial-lateral chest compression and deflection velocity of 25.3 ± 2.6 % and 4.6 ± 0.42 m·s-1 respectively. These data provided quantified loading conditions associated with crash-induced PC and a framework for the remaining research studies, which were focused on blunt impact experiments examining the relationship between insult and outcome in a living model of this injury. A combined experimental and computational approach was used to develop injury metrics for PC. The animal model selected for this research was the Sprague-Dawley male rat. In the remaining studies that comprise this dissertation, an outcome measure of the inflammatory response in the lung parenchyma was correlated with a mechanical analog calculated via a finite element model of the lung. For all studies, a precise and instrumented electronic piston was used to apply prescribed insults directly to the lungs of the subjects. In the first set of experiments, contusion volume was calculated from MicroPET (Micro Positron Emission Tomography) scans and normalized on the basis of liver uptake of 18F-FDG. The subjects were scanned at 24 hours, 7 days, and 28 days (15 scans), and the contused volume was measured. A tentative criteria based on first principal strain in the parenchyma between 9 and 36% was established. In subsequent experiments Computed Tomography was used to acquire volumetric contusion data. The second set of experiments introduced two important aspects of this dissertation; a semi-automated algorithm for CT segmentation and a technique to match the spatial distribution of contusion within the lung to finite element analysis results. The results of this study indicated that the product of first principal strain and strain rate is the most appropriate output variable upon which to base an injury metric for PC. Digital analysis of histology from study subjects that underwent CT scanning prior to sacrifice was conducted and showed good agreement between CT and histology. A final set of experiments was conducted to synthesize the techniques developed in previous studies to determine an injury metric for PC. A concurrent optimization technique was applied to the FEA model to match force vs. deflection traces from four distinct impact cohorts. The resulting predictive injury metrics for PC were exceeding 94.5 sec-1, first principal strain exceeding 0.284 (true strain, dimensionless), and first principal strain rate exceeding 470 sec-1. The method used in this dissertation and the resulting injury metrics for PC are based on quantified inflammatory response observed in a living model, specifically in the organ of interest. This injury metric improves upon current thoracic injury criteria that rely on gross measures of chest loading such as acceleration, or deflection, and are not specific to a particular injury. We anticipate that the findings of this work will lead to more data-driven improvements to vehicular safety systems and ultimately diminish the instance of PC and mitigate its severity. / Ph. D.

When a vehicle changes speed or direction, the interaction between the contacting surfaces of the tire and the pavement form frictional forces. The pavement's contribution to tire-pavement friction is referred to as skid resistance and is provided by pavement microtexture and macrotexture. The amount of skid resistance depreciates over time due to the polishing action of traffic, and for this reason, the skid resistance should be monitored with friction testing equipment. The equipment use one of four test methods to measure network-level friction: ASTM E 274 locked-wheel, ASTM E 2340 fixed-slip technique, ASTM E 1859 variable-slip technique, and sideways-force coefficient (SFC) technique. The fixed-slip, variable-slip, and SFC techniques are used in continuous friction measurement equipment (CFME). In the United States, skid resistance is traditionally measured with a locked-wheel skid trailer (LWST) equipped with either a ASTM E 501 ribbed or a ASTM E 524 smooth 'no tread' tire. Since the LWST fully-locks the test wheel to measure friction, it is only capable of spot testing tangent sections of roadway. By contrast, the remaining three test methods never lock their test wheels and, therefore, they can collect friction measurements continuously on all types of roadway, including curves and t-intersections. For this reason, highway agencies in the U.S. are interested in transitioning from using a LWST to using one of three continuous methods. This dissertation explores the use of continuous friction measurements, collected with a Sideways-force Coefficient Routine Investigation Machine (SCRIM), in a systemic highway safety management approach to reduce crashes that result in fatalities, injuries, and property damage only. The dissertation presents four manuscripts. In the first manuscript, orthogonal regression is used to develop models for converting between friction measurements with a SCRIM and LWST with both a ribbed and smooth tire. The results indicated that the LWST smooth tire measured friction with greater sensitivity to changes in macrotexture than the SCRIM and LWST ribbed tire. The SCRIM also had greater correlation to the LWST ribbed tire than the LWST smooth tire. The second investigation establishes the relationship between friction measured with a SCRIM and the risk of crashes on dry and wet pavement surfaces. The results of this showed that increasing friction decreases both dry and wet pavement crashes; however, friction was found to have greater impact in wet conditions. Due to the negative relationship between friction and crashes, eventually there will be a point where further losses in friction can result in a rapid increase in crash risk. This point can be identified with a friction threshold known as an investigatory level. When measured friction is at or below the investigatory level, an in- and out-of-field investigation is required to determine whether a countermeasure is necessary to improve safety. The third manuscript proposes a statistical regression approach for determining investigatory levels. Since this approach relies on statistical regression, the results are objective and should be the same for any analyst reviewing the same data. The investigatory levels can be used in a systemic approach that identifies locations where crashes can be reduced based on a benefit-cost analysis of surface treatments. Last, the forth manuscript demonstrates a benefit-cost analysis that selects surface treatments based on crash reductions predicted with continuous friction measurements. / Doctor of Philosophy / When a vehicle changes speed or direction, the tires slide over the pavement surface, creating friction that produces the traction that is necessary for the vehicle to change speed or direction. Friction can diminish when water, dust, and other contaminants are present, or over time due to traffic. Over time, the loss in friction causes the risk of a crash to increase. However, this relationship is non-linear, and therefore, eventually there will be a point where further losses in friction can cause a rapid increase in crash risk. For this reason, the pavement friction is monitored with equipment that slides a rubber tire with known properties over a pavement surface. Since friction is lowest when the pavement is wet, the equipment applies a film of water to the surface directly in front of the sliding tire. There are different types of equipment used to measure friction. The physical designs of the equipment and their method of testing may be different. For example, some devices measure friction by sliding a wheel that is angled away from the path of the vehicle, while others slide a wheel that is aligned with the vehicle but reduced in speed compared to the vehicle. The factors that make the equipment different can affect the quantity of friction that is measured, as well as the timing between each consecutive measurement. The advantages that some equipment offers can entice highway agencies to transition from a pre-existing system to a more advantageous system. Before transitioning, the measurements from the two types of equipment should be compared directly to determine their correlation. Statistical regression can also be used to develop models for converting the measurements from the new equipment to the units of the current, which can help engineers interpret the measurements, and to integrate them into an existing database. The presence of water on a pavement surface can result in a temporary loss of friction that can increase the risk of a crash beyond the normal, dry pavement state. This does not guarantee that dry pavements have sufficient friction as is suggested in most literature. In this dissertation, the relationship between friction and the risk of a crash on dry and wet pavements are evaluated together. The results show that increasing friction can decrease the crash risk on both dry and wet pavement surfaces. The amount of friction that is needed to maintain low crash risk is not the same for every section of road. Locations such as approaches to curves or intersections can increase the risk of a crash, and for that reason, some sections of roadway require more friction than others. Minimum levels of friction called investigatory levels can be established to trigger an in- and out-of-field investigation to determine whether improving friction can improve safety when the measured friction is at or below a specific value. This dissertation proposes a methodology for determining the investigatory levels of friction for different sections of roadway using a statistical regression approach. The investigatory levels are then used to identify locations where pavement surface treatments can reduce crashes based on a benefit-cost analysis. Last, the ability of a surface treatment to reduce crashes is evaluated using another statistical regression approach that predicts changes in crash risk using friction measurements. Since there are several treatment options, a treatment is selected based on estimated cost and benefit.

Crash data suggests that intersections are areas producing conflicts among the various road users because of entering and crossing movements. Traffic signal control systems may not always be sufficient in preventing collisions at intersections between emergency and other vehicles. The Firefighter Fatality Retrospective Study of 2002 illustrates that the second leading cause of fatal injury for firefighters is vehicle collisions. Furthermore, the involvement of an emergency vehicle in a crash can negatively affect the overall efficiency of emergency response services. Thus, there is a need to facilitate the implementation of higher-payoff strategies to improve the safety of emergency vehicle passage through signalized intersections. This research aims to provide a basis for the transportation professionals to identify problem areas and take measures that will potentially enhance intersection safety for emergency vehicles. It includes the presentation and comparison of the EV crash situation in Northern Virginia. The results indicate that 49% of all EV accidents along U.S. Highways in Northern Virginia occurred at signalized intersections. This percentage is 75% along U.S. Highways in Fairfax County, the largest county in Northern Virginia, and it is 79% along U.S. 1 in Fairfax County. The analysis, also, illustrates that the major collision type at signalized intersections was of the angle type, which suggests that an appropriate warning sign may be absent. These findings enhance our understanding of emergency vehicle crash characteristics and thus, may facilitate the identification of possible warrants to be used in determining the appropriateness of installing signal preemption equipment at signalized intersections. / Master of Science