Vision in Night Driving: The Roles of Rod and Cone Photoreceptors

Because of the low light levels that are important in night driving, it is possible that both rods and cones contribute to visual performance for drivers at night. However, little evidence has been available about the relative contributions of these classes of photoreceptors. Partly, this may be because until recently the range of light sources has been limited, and consequently the question was not of great practical importance, at least for photometry. However, there is now a much larger variety of sources in use for vehicle lighting, including high-intensity discharge (HID) and light emitting diode (LED) sources. The greater variety of sources and spectral power distributions has increased interest in how the visual response of a driver’s eyes at night varies with wavelength. New evidence indicates that the relative contributions of rods and cones may be different for different driving tasks or different aspects of a driver’s visual experience at night: detection of pedestrians—the task that is most critically affected by darkness— may depend primarily on cones, while subjective impressions of brightness, and perhaps the conspicuity of emergency signals in the visual periphery, may be strongly influenced by rods

Heavy trucks, conspicuity treatment, and the decline of collision risk in darkness

In December 1992, Federal Motor Vehicle Safety Standard (FMVSS) 108, was amended to require conspicuity treatments on all heavy trailers manufactured after December 1, 1993. The standard was later modified and extended to tractors and older trailers such that by June 1, 2009 the entire fleet of tractors and semitrailers on United States roadways would reach full compliance with the regulation. To investigate the effect of the regulation, an analysis was conducted of the change in the odds that a fatal crash occurred in darkness, comparing scenarios in which the conspicuity treatment was likely to be influential to those in which the conspicuity treatment was likely to be irrelevant. From 1987 to 2009, the odds that a fatal collision involving a heavy truck occurred in darkness declined by 58% among the relevant crash scenarios, while little evidence of decline was found among the irrelevant scenarios. Disaggregations of crash scenario types suggest that the largest declines occurred in fatal rear end and angle collisions. A comparative analysis of light vehicles also found declines, although they were smaller and less sensitive to crash type. Similar but weaker trends were observed for nonfatal rear end collisions. The results are consistent with causal mechanisms that suggest that detection failure may be a significant contributor to the risk of striking a tractor-semitrailer in darkness, and that conspicuity treatments have significantly reduced this risk.The University of Michigan Industry Affiliation Program for Human Factors in Transportation Safetyhttp://deepblue.lib.umich.edu/bitstream/2027.42/89938/1/102820.pd

Distance Perception with a Camera-Based Rear Vision System in Actual Driving

Participants drove an instrumented car equipped with conventionalrearview mirrors and with a camera rear vision system. They observed theapproach of an overtaking car in the alternative rear vision systems and indicatedthe last moment at which it would be safe to initiate a lane-change maneuver infront of it. Their judgments were strongly affected by the type of display used toobserve the overtaking car. The longest distances were obtained with the camerabaseddisplay at unit magnification. Distances were substantially shorter with theconventional mirror and with the camera-based display at 0.5 minification. Theseresults are consistent with results from an earlier study conducted under staticconditions

Analysis of motorcycle crashes in Michigan 2009-2013

The goal of this analysis is to assess the consequences of the modification to the motorcycle helmet law that took effect on April 13, 2012, based on crash data from 2009-2013. The key areas of interest include: 1) changes in fatality and injury rates due to helmet non-use; 2) helmet use rates among crash-involved riders, especially those under 21; 3) out-of-state ridership, as it is seen in the crash data; 4) risk-taking behavior such as alcohol use and recklessness, as it relates to injury and fatality outcomes; and 5) motorcycle endorsements among crash-involved ridersMichigan State Police Office of Highway Safety Planninghttp://deepblue.lib.umich.edu/bitstream/2027.42/109726/1/103142.pd

Risk of Fatal Rear-End Collisions: Is There More to It Than Attention?

Rear-end collisions predominantly occur in the daytime under clear, unobstructed viewing conditions and usually involve a lead vehicle that is stopped at the time of collision. These facts suggest that driver inattention plays a significant causal role in rear-end collisions, and mitigation efforts have therefore focused largely on development of warning technologies to alert drivers of an impending crash. However, we note that this pattern of crash data should not lead to the conclusion that drivers have special difficulty avoiding rear-end collisions in broad daylight. Nor should it be concluded that other “environmental” factors do not influence driving behavior to increase rear-end crash risk. Crash frequency is determined both by the inherent risk in the driving task and by the frequency of driver exposure to conditions in which a crash is possible. When exposure level is equated across conditions which differ in ambient light level, we find that rear-end collisions appear to be more than twice as likely in darkness than in daylight

Risk of Fatal Rear-End Collisions: Is There More to It Than Attention?

Rear-end collisions predominantly occur in the daytime under clear, unobstructed viewing conditions and usually involve a lead vehicle that is stopped at the time of collision. These facts suggest that driver inattention plays a significant causal role in rear-end collisions, and mitigation efforts have therefore focused largely on development of warning technologies to alert drivers of an impending crash. However, we note that this pattern of crash data should not lead to the conclusion that drivers have special difficulty avoiding rear-end collisions in broad daylight. Nor should it be concluded that other “environmental” factors do not influence driving behavior to increase rear-end crash risk. Crash frequency is determined both by the inherent risk in the driving task and by the frequency of driver exposure to conditions in which a crash is possible. When exposure level is equated across conditions which differ in ambient light level, we find that rear-end collisions appear to be more than twice as likely in darkness than in daylight

Effect of headlamp area on discomfort glare

This laboratory study evaluated the effect of the size of the glare source on discomfort glare. The subjects performed two simultaneous tasks: continuous compensatory tracking, and evaluation of discomfort from glare stimuli presented periodically in the near visual periphery. The glare stimuli were circles of two sizes (approximately 0.3 and 0.6° in diameter), and produced five illuminance levels (from 0.03 to 3.1 lux) at the observer's eye. Subjects used a nine-point response scale to evaluate discomfort glare. The results indicate that there was a small but statistically significant effect of the size of glare source, with the smaller glare stimuli resulting in more discomfort glare. The mean difference over the range of glare illuminances tested was 0.2 points on the nine-point response scale.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68669/2/10.1177_096032719002200105.pd

Driver Assessment and Training in the 1980s and 1990s: An Analysis of the Most Cited-Publications

This study analyzed the most-cited publications in the area of driverassessment and training. The citation counts were obtained from both the ScienceCitation and Social Science Citation databases, which at the time of the analysiscontained a total of over 27 million items. The search was restricted to items thatwere published during the 20-year period from 1980 through 1999. The focus ofthe search was on the assessment and training of driving-related skills. Inaddition to documenting the most influential publications, the results are alsopresented in terms of changes over time by topic and by publication outlets

Effects of voltage drop on the rise time and light output of incandescent brake lamps on trucks

This study evaluated the effects of voltage on rise time and light output from incandescent brake lamps for a range of voltages representing realistic values for large trucks. The findings indicate that, relative to nominal voltage of 12.8 V, realistic voltages for large trucks lead to significant increases in rise time and to decreases in light output. At 9 V, for example, 90% of the asymptotic light output is reached about 113 ms later than at 12.8 V, and the asymptotic light output is about 28% of the output at 12.8 V. Analogous comparisons of 6 V with 12.8 V indicate an increase in the rise time to 90% of asymptotic light output of about 316 ms and a decrease in asymptotic light output to about 5%. The changes obtained in rise time and light output of incandescent lamps as a function of voltage are of practical importance because they can be expected to increase following drivers' reaction times to brake signals and to increase the frequency of missed signals.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68667/2/10.1177_096032719402600202.pd

New developments in UTMOST: Application to electronic stability control

The Unified Tool for Mapping Opportunities for Safety Technology (UTMOST) is a model of crash data that incorporates the complex relationships among different vehicle and driver variables. It is designed to visualize the effect of multiple safety countermeasures on elements of the driver, vehicle, or crash population. We have recently updated UTMOST to model the effects of the time-course of fleet penetration of vehicle-based safety measures, as well as changes in the populations of drivers and vehicle types in the fleet. This report illustrates some of the capabilities of UTMOST with examples of predicted effects for one reasonably well understood countermeasure (electronic stability control, ESC) and three countermeasures just entering the vehicle fleet (forward collision warning, FCW; road departure warning, RDW; and lane change warning, LCW). Results include the relative effects of the countermeasures on the overall number of crashes and on drivers of different ages. The report also illustrates the time-course capability of UTMOST by showing year-to-year savings in serious injuries and fatalities for a driver-based countermeasure (increased belt use), which would have an immediate effect throughout the vehicle fleet, compared to ESC, which as a vehicle-based countermeasure would affect new vehicles as they enter the fleet.The University of Michigan Sustainable Worldwide Transportationhttp://deepblue.lib.umich.edu/bitstream/2027.42/64278/1/102395.pd