Longitudinal Degradation of Pavement Marking Detectability for Mobile LiDAR Sensing Technology in Real-World Use.

Recent advancements in vehicle automation and driver-assistance systems that detect pavement markings has increased the importance of the detectability of pavement markings through various sensor modalities across weather and road conditions. Among the sensing techniques, light detection and ranging (LiDAR) sensors have become popular for vehicle-automation applications. This study used low-cost mobile multi-beam LiDAR to assess the performance of several types of pavement marking materials installed on a limited-access highway in various conditions, and quantified the degradation in detection performance over three years. Four marking materials, HPS-8, polyurea, cold plastic, and sprayable thermoplastic, were analyzed in the current study. LiDAR reflectivity data extracted from a total of 210 passes through the test sections were analyzed. A new detectability score based on LiDAR intensity data was proposed to quantify the marking detectability. The results showed that the pavement marking detectability varied across the material types over the years. The results provide guidance for selecting materials and developing maintenance schedules when marking detectability by LiDAR is a concern.

Design, synthesis, and evaluation of peptide-imidazo[1,2-a]pyrazine bioconjugates as potential bivalent inhibitors of the VirB11 ATPase HP0525.

Helicobacter pylori (H. pylori) infections have been implicated in the development of gastric ulcers and various cancers: however, the success of current therapies is compromised by rising antibiotic resistance. The virulence and pathogenicity of H. pylori is mediated by the type IV secretion system (T4SS), a multiprotein macromolecular nanomachine that transfers toxic bacterial factors and plasmid DNA between bacterial cells, thus contributing to the spread of antibiotic resistance. A key component of the T4SS is the VirB11 ATPase HP0525, which is a hexameric protein assembly. We have previously reported the design and synthesis of a series of novel 8-amino imidazo[1,2-a]pyrazine derivatives as inhibitors of HP0525. In order to improve their selectivity, and potentially develop these compounds as tools for probing the assembly of the HP0525 hexamer, we have explored the design and synthesis of potential bivalent inhibitors. We used the structural details of the subunit-subunit interactions within the HP0525 hexamer to design peptide recognition moieties of the subunit interface. Different methods (cross metathesis, click chemistry, and cysteine-malemide) for bioconjugation to selected 8-amino imidazo[1,2-a]pyrazines were explored, as well as peptides spanning larger or smaller regions of the interface. The IC50 values of the resulting linker-8-amino imidazo[1,2-a]pyrazine derivatives, and the bivalent inhibitors, were related to docking studies with the HP0525 crystal structure and to molecular dynamics simulations of the peptide recognition moieties.

An examination of teen drivers' car-following behavior under naturalistic driving conditions: With and without an advanced driving assistance system.

Teen drivers are overrepresented in motor vehicle crashes, and most studies concluded it was mainly due to their lack of experiences and tendencies of risk-taking. The design of advanced driving assistance systems (ADAS) aims to provide assistance in multiple stages in human information processing during driving, including environmental sensing, information processing, decision making, and vehicle controlling, in order to improve driving safety. It is expected that novice drivers may benefit more from using ADAS than adult drivers as such technologies can compensate for their frequent errors. This study examined whether and how an integrated crash warning system impacted on drivers' following behavior, and what were the corresponding age-related differences through an analysis of two unique naturalistic driving study datasets. Significant age-related differences in car-following behavior were found. Results showed potential negative effects of ADAS on teen drivers' following behavior that teen drivers tended to have less controlled pedal use during treatment weeks with ADAS than during baseline weeks without ADAS, while such behavior was not observed in adult drivers. All adult drivers tended to keep longer headways when driving at night than during daytime to compensate for poor vision conditions, but no such compensation behavior was observed in the teens. In addition, teen and young-adult drivers had more aggressive following behavior (with shorter mean time headway) than middle-aged and older drivers. One limitation of this study is that the findings of this study are only addressing the short-term effect of ADAS exposure, and future studies are needed to examine the longitudinal effect. The findings of this study suggest that the design of future ADAS should consider minimizing potential negative impacts on teen driver behavior.

Motion sickness in passenger vehicles during test track operations.

As automation transforms drivers into passengers, the deployment of automated vehicles (AVs) has the potential to greatly increase the incidence of motion sickness. A study was conducted to quantify motion sickness response of front-seat passengers performing ecologically relevant passenger activities during conditions consistent with driving on public roadways. Fifty-two adults with a large range of self-reported levels of motion sickness susceptibility and age participated in data collection on a closed test track in a passenger sedan. Motion sickness ratings increased with task vs. no-task and moderate vs. low acceleration test conditions. Increased motion sickness susceptibility was associated with higher motion sickness ratings. In comparison to older participants (age > 60), younger participants (age < 60) experienced increased motion sickness. This is the first in-vehicle study that systematically compared normative passenger activities and acceleration magnitudes typical of normative driving conditions on motion sickness response for a large, diverse sample of passengers, enabling the exploration of the effects of covariates. Practitioner summary: The data demonstrate that a relatively large range of motion sickness response can be expected to result from passengers performing visual tasks in passenger vehicles. Measurement and modelling efforts should seek to elucidate relationships among the factors contributing to motion sickness for the purpose of informing and prioritising future countermeasures for automated vehicles (AVs). Abbreviations: AV(S): automated vehicles; BMI: body mass index; BVP: blood volume pulse; EDA: electrodermal activity; FMS: fast motion sickness scale; GPS: global positioning system; IMU: inertial measurement unit; ISO: International Organization for Standardization; MISC: misery scale; MSDV: motion sickness dose value; NDS: naturalistic driving study; SAE: Society of Automotive Engineers International; UMTRI: The University of Michigan Transportation Research Institute Key Aspect of Research: Motion sickness may be an important barrier to widespread adoption of automated vehicles @UMTRI.

Examining drivers' eye glance patterns during distracted driving: Insights from scanning randomness and glance transition matrix.

INTRODUCTION: Visual attention to the driving environment is of great importance for road safety. Eye glance behavior has been used as an indicator of distracted driving. This study examined and quantified drivers' glance patterns and features during distracted driving. METHOD: Data from an existing naturalistic driving study were used. Entropy rate was calculated and used to assess the randomness associated with drivers' scanning patterns. A glance-transition proportion matrix was defined to quantity visual search patterns transitioning among four main eye glance locations while driving (i.e., forward on-road, phone, mirrors and others). All measurements were calculated within a 5s time window under both cell phone and non-cell phone use conditions. RESULTS: Results of the glance data analyses showed different patterns between distracted and non-distracted driving, featured by a higher entropy rate value and highly biased attention transferring between forward and phone locations during distracted driving. Drivers in general had higher number of glance transitions, and their on-road glance duration was significantly shorter during distracted driving when compared to non-distracted driving. CONCLUSIONS: Results suggest that drivers have a higher scanning randomness/disorder level and shift their main attention from surrounding areas towards phone area when engaging in visual-manual tasks. PRACTICAL APPLICATIONS: Drivers' visual search patterns during visual-manual distraction with a high scanning randomness and a high proportion of eye glance transitions towards the location of the phone provide insight into driver distraction detection. This will help to inform the design of in-vehicle human-machine interface/systems.

A spectral power analysis of driving behavior changes during the transition from nondistraction to distraction.

OBJECTIVE: This article investigated and compared frequency domain and time domain characteristics of drivers' behaviors before and after the start of distracted driving. METHOD: Data from an existing naturalistic driving study were used. Fast Fourier transform (FFT) was applied for the frequency domain analysis to explore drivers' behavior pattern changes between nondistracted (prestarting of visual-manual task) and distracted (poststarting of visual-manual task) driving periods. Average relative spectral power in a low frequency range (0-0.5 Hz) and the standard deviation in a 10-s time window of vehicle control variables (i.e., lane offset, yaw rate, and acceleration) were calculated and further compared. Sensitivity analyses were also applied to examine the reliability of the time and frequency domain analyses. RESULTS: Results of the mixed model analyses from the time and frequency domain analyses all showed significant degradation in lateral control performance after engaging in visual-manual tasks while driving. Results of the sensitivity analyses suggested that the frequency domain analysis was less sensitive to the frequency bandwidth, whereas the time domain analysis was more sensitive to the time intervals selected for variation calculations. Different time interval selections can result in significantly different standard deviation values, whereas average spectral power analysis on yaw rate in both low and high frequency bandwidths showed consistent results, that higher variation values were observed during distracted driving when compared to nondistracted driving. CONCLUSIONS: This study suggests that driver state detection needs to consider the behavior changes during the prestarting periods, instead of only focusing on periods with physical presence of distraction, such as cell phone use. Lateral control measures can be a better indicator of distraction detection than longitudinal controls. In addition, frequency domain analyses proved to be a more robust and consistent method in assessing driving performance compared to time domain analyses.

Can vehicle longitudinal jerk be used to identify aggressive drivers? An examination using naturalistic driving data.

This paper investigated the characteristics of vehicle longitudinal jerk (change rate of acceleration with respect to time) by using vehicle sensor data from an existing naturalistic driving study. The main objective was to examine whether vehicle jerk contains useful information that could be potentially used to identify aggressive drivers. Initial investigation showed that there are unique characteristics of vehicle jerk in drivers' gas and brake pedal operations. Thus two jerk-based metrics were examined: (1) driver's frequency of using large positive jerk when pressing the gas pedal, and (2) driver's frequency of using large negative jerk when pressing the brake pedal. To validate the performance of the two metrics, drivers were firstly divided into an aggressive group and a normal group using three classification methods (1) traveling at excessive speed (speeding), (2) following too closely to a front vehicle (tailgating), and (3) their association with crashes or near-crashes in the dataset. The results show that those aggressive drivers defined using any of the three methods above were associated with significantly higher values of the two jerk-based metrics. Between the two metrics the frequency of using large negative jerk seems to have better performance in identifying aggressive drivers. A sensitivity analysis shows the findings were largely consistent with varying parameters in the analysis. The potential applications of this work include developing quantitative surrogate safety measures to identify aggressive drivers and aggressive driving, which could be potentially used to, for example, provide real-time or post-ride performance feedback to the drivers, or warn the surrounding drivers or vehicles using the connected vehicle technologies.

Effects of an integrated collision warning system on teenage driver behavior.

INTRODUCTION: Crash warning systems have been shown to provide safety benefits, but no studies have examined how teenagers respond. This study sought to find out whether young, inexperienced drivers change behavior in response to warnings. METHODS: Forty 16-17 year-olds drove an instrumented vehicle equipped with a system that warned for lane departures and potential rear-end and lane change/merge crashes. Participants were randomly assigned to experimental or control groups, and their driving was monitored for 14weeks during 2011-12. For the experimental group, this included a treatment period, when crash alerts were received by drivers, and baseline and post-treatment periods, when warnings were recorded but not received. The control group never received warnings. Data were analyzed to determine whether warnings were associated with changes in driving behavior. RESULTS: A total of 15,039 trips were analyzed. Lane drifts accounted for 73% of warnings. Forward collision warning rates doubled for all drivers during the treatment period and continued at an increased rate post-treatment. This was likely a result of the fact that, as time went on, all drivers spent more time following vehicles at close distances. Receiving alerts was associated with effects on following and lane-changing behavior, including more time spent following at close distances (17%), fewer lateral drifts (37%) and fewer unsignaled lane changes (80%). Receiving warnings wasn't associated with an increased likelihood of engaging in secondary tasks. CONCLUSIONS: Warning systems may result in improved lane-keeping and turn-signal behaviors by novice drivers, but there is some indication they may result in more close-following behaviors. PRACTICAL APPLICATIONS: There is some evidence that lane departure warning may improve turn-signal use for young drivers. While there is no evidence of safety benefits from the other types of warnings, there is some evidence of an increase in close-following behavior but no increase in secondary tasks due to the presence of those capabilities.

Real-world effects of using a phone while driving on lateral and longitudinal control of vehicles.

INTRODUCTION: Technologies able to augment human communication, such as smartphones, are increasingly present during all daily activities. Their use while driving, in particular, is of great potential concern, because of the high risk that distraction poses during this activity. Current countermeasures to distraction from phone use are considerably different across countries and not always widely accepted/adopted by the drivers. METHODS: This study utilized naturalistic driving data collected from 108 drivers in the Integrated Vehicle-Based Safety Systems (IVBSS) program in 2009 and 2010 to assess the extent to which using a phone changes lateral or longitudinal control of a vehicle. The IVBSS study included drivers from three age groups: 20­30 (younger), 40­50 (middle-aged), and 60­70 (older). RESULTS: Results from this study show that younger drivers are more likely to use a phone while driving than older and middle-aged drivers. Furthermore, younger drivers exhibited smaller safety margins while using a phone. Nevertheless, younger drivers did not experience more severe lateral/longitudinal threats than older and middle-aged drivers, probably because of faster reaction times. While manipulating the phone (i.e., dialing, texting), drivers exhibited larger lateral safety margins and experienced less severe lateral threats than while conversing on the phone. Finally, longitudinal threats were more critical soon after phone interaction, suggesting that drivers terminate phone interactions when driving becomes more demanding. CONCLUSIONS: These findings suggest that drivers are aware of the potential negative effect of phone use on their safety. This awareness guides their decision to engage/disengage in phone use and to increase safety margins (self-regulation). This compensatory behavior may be a natural countermeasure to distraction that is hard to measure in controlled studies. Practical Applications: Intelligent systems able to amplify this natural compensatory behavior may become a widely accepted/adopted countermeasure to the potential distraction from phone operation while driving.

Using naturalistic driving data to examine drivers' seatbelt use behavior: Comparison between teens and adults.

PROBLEM: Teens and young drivers are often reported as one driver group that has significantly lower seatbelt use rates than other age groups. OBJECTIVE: This study was designed to address the questions of whether and how seatbelt-use behavior of novice teen drivers is different from young adult drivers and other adult drivers when driving on real roads. METHOD: Driving data from 148 drivers who participated in two previous naturalistic driving studies were further analyzed. The combined dataset represents 313,500 miles, 37,695 valid trips, and about 9500 h of driving. Drivers did not wear their seatbelts at all during 1284 trips. Two dependent variables were calculated, whether and when drivers used seatbelts during a trip, and analyzed using logistic regression models. RESULTS: Results of this study found significant differences in the likelihood of seatbelt use between novice teen drivers and each of the three adult groups. Novice teen drivers who recently received their driver's licenses were the most likely to use a seatbelt, followed by older drivers, middle-aged drivers, and young drivers. Young drivers were the least likely to use a seatbelt. Older drivers were also more likely to use seatbelts than the other two adult groups. The results also showed that novice teen drivers were more likely to fasten their seatbelts at the beginning of a trip when compared to the other three adult groups. SUMMARY: Novice teen drivers who were still in the first year after obtaining their driver's license were the most conservative seatbelt users, when compared to adult drivers. PRACTICAL APPLICATION: Findings from this study have practical application insights in both developing training programs for novice teen drivers and designing seatbelt reminder and interlock systems to promote seatbelt use in certain driver groups.

2- and 3-substituted imidazo[1,2-a]pyrazines as inhibitors of bacterial type IV secretion.

A novel series of 8-amino imidazo[1,2-a]pyrazine derivatives has been developed as inhibitors of the VirB11 ATPase HP0525, a key component of the bacterial type IV secretion system. A flexible synthetic route to both 2- and 3-aryl substituted regioisomers has been developed. The resulting series of imidazo[1,2-a]pyrazines has been used to probe the structure-activity relationships of these inhibitors, which show potential as antibacterial agents.

Heavy-truck drivers' following behavior with intervention of an integrated, in-vehicle crash warning system: a field evaluation.

OBJECTIVE: This study is designed to evaluate heavy-truck drivers' following behavior and how a crash warning system influences their headway maintenance. BACKGROUND: Rear-end crashes are one of the major crash types involving heavy trucks and are more likely than other crash types to result in fatalities. Previous studies have observed positive effects of in-vehicle crash warning systems in passenger car drivers. Although heavy-truck drivers are generally more experienced, driver-related errors are still the leading factors contributing to heavy-truck-related rear-end crashes. METHOD: Data from a 10-month naturalistic driving study were used. Participants were 18 professional heavy-truck drivers who received warnings during the last 8 months of the study (treatment period) but not during the first 2 months (baseline period). Time headway and driver's brake reaction time were extracted and compared with condition variables, including one between-subjects variable (driver shift) and five within-subjects variables (treatment condition, roadway types, traffic density, wiper state, and trailer configuration). RESULTS: The presence of warnings resulted in a 0.28-s increase of mean time headway with dense on-road traffic and a 0.20-s increase with wipers on. Drivers also responded to the forward conflicts significantly faster (by 0.26 s, a 15% enhancement) in the treatment condition compared with responses in the baseline condition. CONCLUSION: Positive effects on heavy-truck drivers' following performance were observed with the warning system. APPLICATION: The installation of such in-vehicle crash warning systems can help heavy-truck drivers keep longer headway distances in challenging situations and respond quicker to potential traffic conflicts, therefore possibly increasing heavy-truck longitudinal driving safety.

The conspicuity of first-responder safety garments.

INTRODUCTION: This study compared the conspicuity of three types of first-responder safety garments (NFPA 1971-2007 turnout gear coats, and ANSI/ISEA 107 and 207 safety vests). METHOD: Participants drove instrumented vehicles on a closed track during both daytime and nighttime, indicating when they could first detect pedestrians in a simulated emergency response scene. Pedestrians wore one of the safety garments and stood on either side of the emergency scene, facing or perpendicular to oncoming traffic, and either stationary or walking in place. RESULTS: All three garment standards provided equal levels of conspicuity, in that the distances at which the pedestrians were detected were equivalent. Time of day was a significant factor, with longer mean detection distances being observed in daytime. Pedestrian orientation was significant, with mean detection distances being longest when facing traffic. Pedestrian motion did not result in significant differences in detection distance. DISCUSSION: The results suggest that all three garment types studied are equivalent in making first responders conspicuous as pedestrians when working an emergency response scene in close proximity to traffic. IMPACT ON INDUSTRY: Whether an NFPA or ANSI/ISEA compliant is worn, first responders are equally likely to be detected by passing motorists, and as such these garments should be considered to be equivalent.

The roles of garment design and scene complexity in the daytime conspicuity of high-visibility safety apparel.

INTRODUCTION: This study examines the effects of high-visibility garment design on daytime pedestrian conspicuity in work zones. Factors assessed were garment color, amount of background material, pedestrian arm motion, scene complexity, and driver age. METHOD: The study was conducted in naturalistic conditions on public roads in real traffic. Drivers drove two passes on a 31-km route and indicated when they detected pedestrians outfitted in the fluorescent garments. The locations of the vehicle and the pedestrian were recorded. RESULTS: Detection distances between fluorescent yellow-green and fluorescent red-orange garments were not significantly different, nor were there any significant two-way interactions involving garment color. Pedestrians were detected at longer distances in lower complexity scenes. Arm motion significantly increased detection distances for pedestrians wearing a Class 2 vest, but had little added benefit on detection distances for pedestrians wearing a Class 2 jacket. DISCUSSION: Daytime detection distances for pedestrians wearing Class 2 or Class 3 garments are longest when the complexity of the surround is low. The more background information a driver has to search through, the longer it is likely to take the driver to locate a pedestrian--even when wearing a high-visibility garment. IMPACT ON INDUSTRY: These findings will provide information to safety garment manufacturers about characteristics of high-visibility safety garments which make them effective for daytime use.

Radiant heat and thermal comfort in vehicles.

Infrared-reflective (IRR) treatment of automotive glass has been shown to reduce air temperature in vehicle cabins, thereby increasing fuel economy and occupant comfort. Its effect on radiant heat, however, may augment these benefits. In this study, the hypothesis that radiant heat affects subjective comfort ratings in a vehicle was tested. IRR films were systematically applied to the driver-side window of an outdoor stationary vehicle. In Phase 1, cabin air temperature was controlled while participants rated their thermal comfort. In Phase 2, air temperature was adjusted according to participants' responses. Results in Phase 1 showed that the IRR treatment improved thermal comfort on the left forearm, which was exposed to direct solar irradiance, but not whole-body thermal comfort. In Phase 2, participants indicated that they were comfortable at a higher air temperature (mean of 2.5 degrees F [1.4 degrees C]) with the IRR treatment than in the untreated condition. The results indicate that reducing radiant heat via IRR treatment affects subjective assessments of thermal comfort and allows occupants to maintain the same level of comfort in a warmer vehicle cabin. Applications of this research include future implementations of IRR treatment on automotive glass that may lead to greater fuel economy savings and occupant comfort than have previously been estimated.

High visibility safety apparel and nighttime conspicuity of pedestrians in work zones.

PROBLEM: Every year numerous occupational fatalities result from pedestrians being struck by motor vehicles intruding into work zones. METHOD: Attributes of retroreflective personal safety garments on pedestrian conspicuity at night were assessed in a field study. Using instrumented vehicles on a closed track, participants drove through simulated work zones attempting to detect pedestrians located in the work zones. RESULTS: Configuration of the retroreflective trim, trim color, placement in the work zone, and driver age significantly affected pedestrian conspicuity. Intensity and the amount of retroreflective trim did not. DISCUSSION: Personal safety garments incorporating retroreflective trim significantly improve pedestrian conspicuity in work zones. SUMMARY: The results emphasize the importance of retroreflective trim on personal safety garments, particularly if the trim is located on garment sleeves. IMPACT ON INDUSTRY: We examine the design attributes that contribute to making a personal safety garment conspicuous. The results have implications regarding preferred garment designs, industry standards, and service life of personal safety garments.