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Horizontal curves have been shown to exhibit crash rates significantly higher than comparable tangent segments. Extensive research has investigated the causes of crashes on horizontal curves, particularly the curve navigation process and driver speed selection. Research in this area has generally been limited by the nature of the data, which is often inhibited by practical constraints as to the number of locations and drivers that can be observed. This study overcomes these hurdles through the use of naturalistic driving data, providing insights on how drivers navigate and react to curves on rural two-lane highways. Nearly 10,000 vehicle traces were collected from 202 drivers on 219 horizontal curves as a part of this study. All driving traces were collected on rural two-lane highways with prevailing posted speed limits of 45 mph or 55 mph, as well as a diverse range of curve advisory speeds. Regression models are estimated via generalized estimating equations to discern those factors affecting mean speeds on curves. A log-linear relationship was found between curve radius and mean vehicle speed, with speeds relatively stable on radii of 900–1000 ft. or more, decreasing more rapidly as radii decreased below this range. Drivers were found to reduce speeds when curve advisories were present, but the magnitude of these reductions was much less than suggested by the advisory signs. Speeds were significantly lower when a W1-6 curve arrow sign was present adjusting for the curve radius. There were also some differences in speeds based on driver age and gender. Ultimately, this paper provides insights into driver curve navigation and demonstrates the potential of high-fidelity naturalistic driving data to assess speed management and geometric design on horizontal curves.

Introduction This study investigates how speed limits affect driver speed selection, as well as the related crash risk, while controlling for various confounding factors such as traffic volumes and roadway geometry. Data from a naturalistic driving study are used to examine how driver speed selection varies among freeways with different posted speed limits, as well as how the likelihood of crash/near-crash events change with respect to mean speed and standard deviation. Method Regression models are estimated to assess three measures of interest: the average speed of vehicles during the time preceding crash/near-crash and baseline (i.e., normal) driving events; the variation in travel speeds leading up to each event as quantified by the standard deviation in speeds over this period; and the probability of a specific event resulting in a crash/near-crash based on speed selection and other factors. Results Speeds were relatively stable across levels-of-service A and B, within a range of 1.5 mph on average. Speeds were marginally lower (3.3 mph) on freeways posted at 65 mph versus 70 mph. In comparison, speeds were approximately 10.2 to 13.4 mph lower on facilities posted at 55 mph or 60 mph. Speeds were shown to be 2.5 mph lower in rainy weather and 11 mph lower under snow or sleet. Conclusions Significant correlation was observed with respect to speed selection behavior among the same individuals. Mean speeds are shown to increase with speed limits. However, these increases are less pronounced at higher speed limits. Drivers tend to reduce their travel speeds in presence of junctions and work zones, under adverse weather conditions, and particularly under heavy congestion. Crash risk increased with the standard deviation in speed, as well as on vertical curves and ramp junctions, and among the youngest and oldest age groups of drivers.

The interaction of motorists and bicyclists, particularly during passing maneuvers, is an area of concern to the bicycle safety community as there is a general perception that motor vehicle drivers may not share the road effectively with bicyclists. This is a particular concern on road sections with centerline rumble strips where motorists are prone to crowd bicyclists during passing events. One potential countermeasure to address this concern is the use of a bicycle warning sign with a “Share the Road” plaque. This paper presents the results of a controlled field evaluation of this sign treatment, which involved an examination of driver behavior while overtaking bicyclists. A series of field studies were conducted concurrently on two segments of a high-speed, rural two-lane highway. These segments were similar in terms of roadway geometry, traffic volumes, and other relevant factors, except that one of the segments included centerline rumble strips while the other did not. A before-and-after study design was utilized to examine changes in motor vehicle lateral placement and speed at the time of the passing event as they relate to the presence of centerline rumble strips and the sign treatment. Centerline rumble strips generally shifted vehicles closer to the bicyclists during passing maneuvers, though the magnitude of this effect was marginal. The sign treatment was found to shift motor vehicles away from the rightmost lane positions, though the signs did not significantly affect the mean buffer distance between the bicyclists and passing motorists or the propensity of crowding events during passing. The sign treatment also resulted in a 2.5 miles/h (4.0 km/h) reduction in vehicle speeds. Vehicle type, bicyclist position, and the presence of opposing traffic were also found to affect lateral placement and speed selection during passing maneuvers.

The extant traffic safety research literature includes numerous examples of studies that assess those factors affecting the degree of injury sustained by crash-involved motor vehicle occupants. One important methodological concern in such work is the potential correlation in injury outcomes among occupants involved in the same crash, which may be due to common unobserved factors affecting such occupants. A second concern is unobserved heterogeneity, which is reflective of parameter effects that vary across individuals and crashes. To address these concerns, a random parameters bivariate ordered probit model is estimated to examine factors affecting the degree of injury sustained by drivers involved in angle collisions. The modeling framework distinguishes between the effects of relevant factors on the injury outcomes of the at-fault and not-at-fault parties. The methodological approach allows for consideration of within-crash correlation, as well as unobserved heterogeneity, and results in significantly improved fit as compared to a series of independent models with fixed parameters. While the factors affecting injury severity are found to be similar for both drivers, the magnitudes of these effects vary between the at-fault and not-at-fault drivers. The results demonstrate that injury severity outcomes are correlated for drivers involved in the same crash. Further, the impacts of specific factors may be over- or under-estimated if such correlation is not accounted for explicitly as a part of the analysis. Various factors are found to affect driver injury severity and the random parameters framework shows these effects to vary across crashes and individuals. The analytical approach utilized provides a useful framework for injury severity analysis.

A decision framework was developed for context-sensitive planning in the roadside right-of-way (ROW). The primary component of this framework was a roadside suitability assessment model that supported decisions related to ROW use and development, particularly those that were nontraditional in nature. The model accommodated a broad range of potential types of development while a diverse range of roadside contextual features, including land use (current and future), land cover, environment, natural resources, and plant and animal habitats was considered. The primary function of the model was to identify the areas along a highway corridor that were most (or least) suitable for development in the roadside ROW. After the model parameters were calibrated to satisfy local conditions, a roadside suitability index was computed for each area along the selected corridor with available geospatial data as the primary model inputs. The roadside suitability index provided a relative indication of the overall suitability for a particular development in the roadside ROW. The model was demonstrated with a 20-mile pilot section of I-94 in southwest Michigan. Four types of nontraditional ROW development were considered for implementation along the corridor, including solar panels, wind turbines, agriculture and farming, and green infrastructure (e.g., stream or wetland mitigation). The resultant roadside suitability scores for the pilot corridor generally were consistent with standard considerations for planning land use.

Roadside rest areas provide valuable and convenient services to road users as well as tangible safety benefits. However, these benefits are not always enough to warrant the costs, and therefore these facilities are not always economically justified. As such, understanding the factors that affect rest area demand is important for transportation agencies to design and maintain these facilities efficiently within their jurisdictions. The effects of nearby comparable facilities and rest areas on the demand characteristics of roadside rest areas have not been well analyzed in previous literature. This paper presents the results of binary logistic regression and negative binomial regression models on the demand characteristics of 47 roadside rest areas in Michigan. These models were developed separately for passenger cars and commercial trucks because the decision-making processes for these types of road users were likely different. Key results include the finding that greater distances between rest areas and n...

On April 13, 2012, Michigan instituted reforms to its long-standing universal helmet law (UHL) and thus became the 28th state with a partial helmet law, which requires helmet use by only a subset of the riding population. Given continuing increases in motorcycle fatalities, helmet use remains a divisive policy issue facing state governments. The existing research literature includes several before-and-after studies that evaluate the effects of changes in motorcycle helmet laws on metrics such as helmet use and statewide motorcycle fatalities. However, a comprehensive assessment of the effects of helmet use laws on the full range of crash injury outcomes is lacking. Important evidence was added to inform the continuing debate about the efficacy of UHLs. A detailed, disaggregate-level study was conducted to assess the degree of injury severity sustained by motorcyclists involved in crashes before and after Michigan's transition from a UHL to a partial helmet law. By controlling for various rider, roadway, t...

Pedestrian and bicycle safety for school-aged children is a particular concern as traffic crashes continue to be a leading cause of death for children 5 to 14 years old. For this concern to be addressed, Safe Routes to School (SRTS) programs have been implemented in communities across the country, with one of the primary objectives being to provide safe and convenient routes for children to walk or bike to school. Unfortunately, SRTS programs allocate limited funding for such projects. Consequently, it is imperative that programs are implemented at locations where they are likely to have the greatest impact. The primary focus of this study was to develop a safety Performance function (SPF) for use in prioritizing candidate schools for SRTS programs. Traffic crashes over a 5-year analysis period were examined and linked to data that included the school enrollment, the socioeconomic and demographic data for each school district, and the functional class of the roadway on which each school was located. Schools on local roads were found to experience more crashes than those located on other, higher-class road facilities. Crashes also varied with average family size, number of parents per household, population density, and median family income. Crashes were less frequent in school districts that exhibited greater ethnic diversity. The SPF developed as a part of this research can be used for prioritization of candidate schools as well as to assess the efficacy of SRTS programs on a longitudinal basis and thus provide a valuable tool for school administrators and others involved in child pedestrian and bicycle safety.

Although a considerable amount of prior research has investigated the impacts of speed limits on traffic safety and operations, much of this research, and nearly all of the research related to differential speed limits, has been specific to limited access freeways. The unique safety and operational issues on highways without access control create difficulty relating the conclusions from prior freeway-related speed limit research to 2-lane highways, particularly research on differential limits due to passing limitations and subsequent queuing. Therefore, the objective of this study was to assess differences in driver speed selection with respect to the posted speed limit on rural 2-lane highways, with a particular emphasis on the differences between uniform and differential speed limits.Data were collected from nearly 59,000 vehicles across 320 sites in Montana and 4 neighboring states. Differences in mean speeds, 85th percentile speeds, and the standard deviation in speeds for free-flowing vehicles were examined across these sites using ordinary least squares regression models.Ultimately, the results of the analysis show that the mean speed, 85th percentile speed, and variability in travel speeds for free-flowing vehicles on 2-lane highways are generally lower at locations with uniform 65 mph speed limits, compared to locations with differential limits of 70 mph for cars and 60 mph for trucks.In addition to posted speed limits, several site characteristics were shown to influence speed selection including shoulder widths, frequency of horizontal curves, percentage of the segment that included no passing zones, and hourly volumes. Differences in vehicle speed characteristics were also observed between states, indicating that speed selection may also be influenced by local factors, such as driver population or enforcement.

Many emerging contaminants tend to be biologically active at very low concentrations, occur in water as part of complex mixtures, and impact biota in ways that are not detected using traditional toxicity tests (e.g., median lethal concentration). To evaluate emerging contaminants, the authors developed a method for detecting sublethal behavioral effects by quantifying the swimming behavior of Daphnia pulex, a model organism for studying aquatic toxicity. This optical tracking technique is capable of measuring many swimming parameters, 2 of which-cumulative distance and angular change-are presented. To validate this technique, 2 prototypical compounds that exhibit different modes of action as well as corresponding insecticides that are commonly found in surface waters were investigated. The acetylcholinesterase (AChE) inhibitor physostigmine was used as the prototypical compound for the large number of AChE inhibitor insecticides (e.g., chlorpyrifos). Nicotine was used as the prototypical compound for neonicotinoid insecticides (e.g., imidacloprid). Results demonstrate that this assay is capable of detecting sublethal behavioral effects that are concentration-dependent and that insecticides with the same mode of action yield similar results. The method can easily be scaled up to serve as a high-throughput screening tool to detect sublethal toxic effects of a variety of chemicals. This method is likely to aid in enhancing the current understanding of emerging contaminants and to serve as a novel water-quality screening tool.

How travelers select and value public rest areas was investigated. A comprehensive survey was conducted at 15 public rest areas throughout Michigan; a similar survey was performed at two large commercial travel centers for comparison purposes. The primary objectives of this survey were to (a) identify the reasons motorists stop at public rest areas versus commercial service facilities, (b) estimate the value of services provided by public rest areas, and (c) determine the probable action taken by motorists in the event that a public rest area was unavailable. Results of the survey indicated that patrons at both public rest areas and commercial service facilities generally preferred rest areas for basic services (e.g., restroom use, short break) primarily because of the convenient freeway access. The median patron-reported value of services at standard public rest areas was $1.68 per stop compared with $2.21 per stop at rest areas that included a traveler information center. Even though drivers of commercial vehicles were the most frequent users of public rest areas, they tended to be less satisfied and gave a lower value to services provided. Had a particular public rest area not been available, approximately two-thirds of travelers in private vehicles would have diverted off the freeway to a commercial service facility, whereas one-quarter would have continued to the next rest area along the route. Commercial truck drivers were equally likely to continue to the next rest area as to divert off the freeway.

Public rest areas along limited-access freeways throughout the United States allow quick access and free 24-h availability to basic amenities such as parking and restrooms. The recent economic downturn has made it increasingly difficult for state agencies to maintain rest areas and has forced many states to consider downsizing services or closing facilities. Although rest areas provide many benefits to motorists, the safety and economic impacts associated with rest areas and traveler information centers have proved difficult to quantify. A benefit–cost (B-C) analysis methodology was developed for public rest areas and traveler information centers on limited-access freeways. This methodology considered a broad range of benefits associated with public rest areas, including travel diversion savings, comfort and convenience benefits, and crash reductions. Increased tourism spending was also considered for traveler information centers. The costs were almost exclusively related to those incurred by the agency, which included construction, rehabilitation, operation, and routine maintenance. The methodology was demonstrated with data provided by the Michigan Department of Transportation. Because the estimated benefits were strongly correlated with annual use of the facility, the facilities with the highest B-C ratios included heavily used facilities located on the primary freeway routes. Those with the lowest B-C ratios were underused facilities with high operation or maintenance costs.

Fatigue-related crashes account for 2.2% to 2.6% of all fatal crashes in the United States on an annual basis. These types of crashes are prevalent in rural areas, and public roadside rest areas were developed largely to alleviate motorist fatigue and reduce the opportunity for such crashes by providing safe parking areas for tired drivers. However, research about the safety effects of rest areas has been limited. Results are presented of a spatial analysis that investigates how a road segment's proximity to a rest area affects the frequency of fatigue-related crashes. Poisson and negative binomial models are estimated for freeways and two-lane highways to isolate the effects of proximity while controlling for other relevant factors, such as traffic volume. The results of these models indicate that the proximity of a road segment to the nearest rest area significantly influences crash frequencies on both freeways and two-lane highways, where traffic volumes tended to have similar effects, although the effects of proximity were slightly more pronounced on two-lane highways. The study results suggest that roadside rest areas provide a safety benefit, and the crash prediction models developed as a part of this research provide a starting point for quantifying these impacts.

Median-crossover crashes are among the most hazardous events that can occur on freeways, often resulting in severe or fatal injuries. The primary countermeasure to reduce the occurrence of such crashes is the installation of a median barrier. When installation of a median barrier is warranted, transportation agencies are faced with the decision among various alternatives including concrete barriers, beam guardrail, or high-tension cable barriers. Each barrier type differs in terms of its deflection characteristics upon impact, the required installation and maintenance costs, and the roadway characteristics (e.g., median width) where installation would be feasible. This study involved an investigation of barrier performance through an in-depth analysis of crash frequency and severity data from freeway segments where high-tension cable, thrie-beam, and concrete median barriers were installed. A comprehensive manual review of crash reports was conducted to identify crashes in which a vehicle left the roadway and encroached into the median. This review also involved an examination of crash outcomes when a barrier strike occurred, which included vehicle containment, penetration, or re-direction onto the travel lanes. The manual review of crash reports provided critical supplementary information through narratives and diagrams not normally available through standard fields on police crash report forms. Statistical models were estimated to identify factors that affect the frequency, severity, and outcomes of median-related crashes, with particular emphases on differences between segments with varying median barrier types. Several roadway-, traffic-, and environmental-related characteristics were found to affect these metrics, with results varying across the different barrier types. The results of this study provide transportation agencies with important guidance as to the in-service performance of various types of median barrier.

Objective Driving under the influence of alcohol is a crime that places the lives of all motorists in danger. Though it is a largely preventable act, the impaired driving has accounted for 31% to 38% of fatal crashes across the country over the last decade. When an impaired operator crashes his or her vehicle, there is often a second unit, of which the operator is not impaired, involved in the crash. Methods This research looks at approximately 14,000 two-unit crashes involving an impaired operator in the State of Ohio from 2008 through 2012. The research is focused on determining the effects of crash and operator characteristics in two unit alcohol related crashes through the use of two mixed logit models. Results It is found that several factors have similar effects on the injury severities of both the impaired and non-impaired operators including head-on crashes, the use of seat belts, and the deployment of airbags. There are, however, several factors that affect the two operators differently. It is found that the impaired operator's injury severity is based on the type, and more importantly the size of the vehicle they are driving, the roadway geometry, and the speed of the vehicle driven by the non-impaired operator. The non-impaired operator is equally affected by the speed of impaired vehicle as much as their own speed, and the non-impaired operator's injury severity is virtually independent of the type of vehicle being driven. Conclusions The researchers may disseminate the results to community groups such as Mothers against Drunk Driving and Safe Communities, to increase awareness of the dangers of drunk driving in an effort to reduce the number of alcohol related crashes.

Traffic incidents are a principal cause of congestion on urban freeways, reducing capacity and creating risks for both involved motorists and incident response personnel. As incident durations increase, the risk of secondary incidents or crashes also becomes problematic. In response to these issues, many road agencies in metropolitan areas have initiated incident management programs aimed at detecting, responding to, and clearing incidents to restore freeways to full capacity as quickly and safely as possible. This study examined those factors that impact the time required by the Michigan Department of Transportation Freeway Courtesy Patrol to clear incidents that occurred on the southeastern Michigan freeway network. These models were developed using traffic flow data, roadway geometry information, and an extensive incident inventory database. A series of parametric hazard duration models were developed, each assuming a different underlying probability distribution for the hazard function. Although each modeling framework provided results that were similar in terms of the direction of factor effects, there was significant variability in terms of the estimated magnitude of these impacts. The generalized F distribution was shown to provide the best fit to the incident clearance time data, and the use of poorer fitting distributions was shown to result in severe over-estimation or under-estimation of factor effects. Those factors that were found to impact incident clearance times included the time of day and month when the incident occurred, the geometric and traffic characteristics of the freeway segment, and the characteristics of each incident. Copyright © 2012 John Wiley & Sons, Ltd.

A before-and-after field evaluation assessed the impacts that centerline and shoulder rumble strips on rural two-lane roadways have on various characteristics of driver behavior. The following characteristics were assessed as part of this evaluation: passing maneuvers, lateral lane placement, and centerline and edgeline encroachments. The data were collected with video cameras temporarily installed at 18 passing zones and 12 curves on rural two-lane roadways throughout Michigan. The cameras were installed at the same locations before and after the installation of rumble strips. A manual review of the videos was performed to assess the various behavioral characteristics. Nearly 78,000 vehicles were observed during review of the passing zone videos, and more than 50,000 vehicles were observed during review of the curve videos. Centerline rumble strips were found to improve driver central lane positioning tendencies and decrease the occurrence of centerline encroachments. The inclusion of shoulder rumble strips in addition to centerline rumble strips provided incremental improvements in central lane positioning and reduced edgeline encroachments. Most notable, centerline and shoulder rumble strips greatly reduced the occurrence of drivers laterally shifting to the inside while maneuvering through curves (i.e., corner cutting). In addition, centerline rumble strips did not reduce the rate of passing maneuvers. Collectively, these results suggest that both centerline and shoulder rumble strips have a positive impact on surrogate measures for roadway safety and do not negatively affect driver behavior.

This study assessed the lateral placement of motor vehicles as they passed bicyclists, with a focus on the influence of centerline rumble strips. Driver behavioral data were collected through field studies on two segments of a high-speed (55-mph speed limit) rural two-lane highway. The study segments were similar for key traffic and geometric characteristics, but only one of the segments had centerline rumble strips. The segments were located close to one another; this feature ensured a relatively uniform sample of drivers and bicyclists. Centerline rumble strips were found to decrease the likelihood of a motor vehicle driving onto the center line. However, this decrease in the probability of centerline encroachment was less pronounced in comparison with similar data collected in the absence of bicyclists; this increased probability of encroachment suggests a compensatory effect. Drivers were also more likely to contact or cross over the centerline when bicyclists were nearer to the travel lane. The type of motor vehicle also played a role in that motorcycles and passenger cars were less likely to contact the centerline, and the presence of opposing traffic was found to reduce the likelihood of contact with the centerline.

Reducing the severity of injuries resulting from motor-vehicle crashes has long been a primary emphasis of highway agencies and motor-vehicle manufacturers. While progress can be simply measured by the reduction in injury levels over time, insights into the effectiveness of injury-reduction technologies, policies, and regulations require a more detailed empirical assessment of the complex interactions that vehicle, roadway, and human factors have on resulting crash-injury severities. Over the years, researchers have used a wide range of methodological tools to assess the impact of such factors on disaggregate-level injury-severity data, and recent methodological advances have enabled the development of sophisticated models capable of more precisely determining the influence of these factors. This paper summarizes the evolution of research and current thinking as it relates to the statistical analysis of motor-vehicle injury severities, and provides a discussion of future methodological directions.

The purpose of this study was to examine statewide motorcycle crash data from the state of Ohio to identify those factors most strongly associated with the level of injury sustained by motorcyclists involved in crashes. The year 2009 marked the first time since 1997 that Ohio experienced fewer motorcycle fatalities than in the previous year; this result was consistent with national trends over this same period. Since anecdotal evidence suggested that much of this result was due to decreases in motorcycle travel, an investigation of rider, crash, and environmental factors that influenced injury severity was an important step toward sustaining this reduction. The effects of such factors in various types of motorcycle crashes were compared. Multinomial logit models were developed for single-vehicle and multivehicle motorcycle crashes at both intersection and nonintersection locations. The results showed that the impacts of relevant crash factors varied by crash type and location and that severe injuries were more likely when high speed or alcohol was involved. Collisions with fixed objects and high-impact crashes, such as angle and head-on collisions, also produced dramatic increases in injury severity. Helmet use continued to provide the most promising means of reducing severe and fatal injuries in all types of crashes. Helmet use was found to reduce the likelihood of injury by 34.4% in single-vehicle crashes and between 12.4% and 14.1% in multivehicle crashes.

Research was performed to explore the impact on driver behavior of steady-burn warning lights on drums used in highway work zones in the state of Michigan. Various characteristics related to nighttime driver behavior were evaluated with data collected in actual work zones. Thirty-six randomly selected work zones in 15 counties throughout lower Michigan were investigated in this study. Collectively, the work zones represented a broad range of commonly occurring scenarios. Work zones that used drums with steady-burn warning lights and work zones that did not were examined in a comparative parallel study. Data on nighttime driver behavior were collected by recording the movements of randomly selected subject vehicles as they were followed by a survey vehicle through the study work zones. For each subject vehicle, three measures of driver behavior were collected. The measures were (a) percent of time spent in the center lane position, (b) percent of time spent in the lane position closest to the drums, and (c) rate of steering reversals per minute. The data were compared by using analysis of variance techniques. The results showed that the presence of steady-burn warning lights on drums used to channelize traffic in work zones did not significantly affect either the time vehicles spent in the center lane position or the rate of steering reversals. The presence of steady-burn warning lights did, however, increase the tendency of drivers to travel in relatively close proximity to the drums. Collectively, the research findings suggest that the use of steady-burn warning lights on channelizing drums in work zones does not have a substantive impact on nighttime driver behavior.

The purpose of this study was to develop, test, and evaluate two pilot enforcement programs aimed at the improvement of pedestrian safety in the city of Detroit, Michigan, through reductions in the incidence of pedestrian traffic violations. Separate targeted enforcement programs were conducted in coordination with the Detroit Police Department and the Wayne State University Police Department. Both programs demonstrated that targeted enforcement could be used to reduce the rate of pedestrian traffic violations effectively and that these changes could be sustained for some time after enforcement had been completed. The city-wide program was found to reduce violations by up to 17.1% during the enforcement period, with sustained reductions of 7.8% being detected several weeks after enforcement was completed. Similarly, the program on the Wayne State University campus reduced violations by 27% during enforcement and showed sustained reductions of 9.8%. The results generally varied on a case-by-case basis, and infrastructure deficiencies contributed to increased violations. As a part of this study, a strategy for collection of data in the field was developed. The strategy allowed the covert, unobtrusive monitoring of pedestrian behavior during the periods before, during, and after enforcement.

Research was performed to explore the differences in the nighttime luminance of drums, with and without steady-burn warning lights, that are used in work zones to channelize traffic. Two evaluations were performed: one in the field, which included luminance measurements of 372 drums in 15 freeway work zones throughout Michigan, and another, controlled evaluation, which included luminance measurements of 24 common drum scenarios in a vacant parking lot. Drums with and without steady-burn lights were considered in both evaluations. All luminance measurements were performed from the passenger seat of a vehicle under low-beam headlamp illumination. The results of the controlled evaluation showed that the addition of a steady-burn warning light increased the average luminance of drums with high-intensity sheeting by 0.165 candelas per square meter (cd/m2) (2.6%). The added light increased the average luminance of drums with microprismatic sheeting by 0.50 cd/m2 (3.9%). Similar results were obtained during the field evaluation. It was concluded that drums with high-intensity sheeting and without steady-burn warning lights typically provided adequate levels of nighttime luminance when viewed from a vehicle under low-beam headlamp illumination. If additional nighttime brightness was desired, however, microprismatic sheeting offered far greater luminance than a steady-burn warning light.

A pedestrian safety educational training program was presented to more than 930 students in Grades 2 through 7 at five public schools in Detroit, Michigan. Initial student training was performed at four of the schools during spring 2008 and at the remaining school during fall 2008. Retraining was performed 7 to 12 months after the initial training. The same training procedures were used during both the initial training and the retraining sessions. The training program was evaluated with the use of both written pre- and posttesting and before-and-after observations of the street-crossing behavior of children near the schools included in the study. Two measures of effectiveness (MOEs) were used for the evaluation: (a) the violation rate for child pedestrians and (b) the percentage of correct test responses. The child pedestrian violation rate decreased shortly after the initial training; this decrease was sustained for several months. Retraining produced an additional incremental decrease in the child pedestrian violation rate. Initial training also produced increases in the percentages of correct responses between the pre- and posttests for children in all participating grade levels. The increases in correct response percentages were partially sustained several months after the initial training, although measurable decreases in test scores were observed. Retraining provided a statistically significant incremental increase in test scores that negated the decreases observed several months after the initial training. The cumulative impact of initial training combined with retraining was consistently larger than the impact of initial training alone for both the testing and the violation rate MOEs.

Motorcycle crashes and fatalities have been increasing rapidly during the past 12 years both in Ohio and across the rest of the United States. In response to these issues, various studies have examined aspects of motorcycle safety in recent years. However, there has been limited research on the effects of site-specific roadway geometry on the frequency of motorcycle crashes, particularly at nonintersection locations. Typically, researchers employ Poisson and negative binomial crash prediction modeling techniques in these types of studies. The research presented in this paper uses a negative binomial model, applying full Bayes methods to improve model performance and to assess the impacts of horizontal curvature and other geometric features on the frequency of single-vehicle motorcycle crashes along segments of rural two-lane highways. The data used in this study include crash records for the years 2002 through the spring of 2008, in combination with available geometric design information, for those curves maintained by the State of Ohio. The analysis data set includes 30,379 horizontal curves that experienced a total of 225 motorcycle crashes during the study period. The findings show that the radius and length of each horizontal curve significantly influence the frequency of motorcycle crashes, as do shoulder width, annual average daily traffic, and the location of the road segment in relation to the curve.

Horizontal curves have been identified as a target area for improving safety on rural two-lane highways in Texas. This study involved the development of multinomial logit models to assess driver injury severity resulting from single-vehicle crashes on such roads. Likelihood ratio tests warranted the development of separate injury severity models for curves of small, medium, and large radius. Various driver, vehicle, roadway, and environmental characteristics were found to affect injury severity among the 10,029 crashes analyzed. Run-off-the-road crashes, particularly those resulting in collisions with roadside objects, were found to increase injury severity significantly. Females were more likely to sustain injury and older drivers to be critically injured, particularly on curves of smaller radius. Various driver actions and behaviors were also significant determinants of injury severity. Unbelted drivers were up to 10 times more likely to suffer fatal injuries, and drivers who were uninsured, fatigued, or under the influence of drugs or alcohol were more likely to be seriously injured. Several of these behavioral factors were more pronounced on sharper curves.

A pedestrian safety educational program was presented to a total of 4,305 students ranging from kindergarten through 8th grade at 16 participating schools in Detroit, Michigan, between May 2008 and January 2009. The goal of the educational program was to improve student awareness of proper pedestrian behavior and street-crossing techniques, which the authors hypothesized would result in proper street-crossing behavior. This study improves on methodologies used in previous studies by performing an objective evaluation of the program's effectiveness, considering both message comprehension and natural street-crossing behavior of students at the schools where the program was implemented. Two measures of effectiveness were used for the program evaluation: (a) violation rate for child pedestrians observed before and after presentation of the program and (b) correct response rate obtained from written tests given before and after implementation. A total of 4,835 child pedestrians were observed during field data collection performed at 10 of the 16 schools. The child pedestrian violation rates were found to decrease in the after period at nine of the 10 schools where data were collected, with an overall decrease in violation rate of 4.44%, which was statistically significant at a 95% confidence level. Significant increases in the percentage of correct responses between the pre- and posttests were also observed at each of the schools and for all grade levels with the exception of kindergarten. The overall increase in correct response rate between the pre- and posttests was 23.2%, which was statistically significant.

Michigan is plagued by more than 60,000 deer–vehicle crashes on an annual basis. Although the majority of these crashes result in property damage only, a substantial number lead to significant injuries and fatalities, illustrating the need for a better understanding of the many interrelated factors that affect crash severity. A database of all single-vehicle deer–vehicle crashes (DVC) reported to Michigan law enforcement agencies between January 1, 2004, and December 31, 2005, was used to estimate a multinomial logit model of driver injury severity. Results revealed a number of driver, vehicle, and environmental factors that significantly influenced injury severity. Younger drivers were more likely to be injured as a result of a DVC, a possible indication of a lack of appropriate skills or knowledge on the part of these drivers when they encounter deer on the roadway. Female drivers were found to be at an increased risk of injury, as were drivers who had a passenger in the vehicle at the time of the crash. Seatbelt and airbag usage were found to be the most effective means of reducing the likelihood of severe injuries, although airbags did increase the likelihood of minor injuries. Impacting deer head-on and avoiding run-off-the-road collisions were also found to reduce the propensity of injury. Educational and enforcement initiatives, such as the “Don't Veer for Deer” campaign, may provide a cost-effective means of combating the DVC problem.

Persistent increases in motorcycle fatalities and injuries in recent years have heightened safety awareness and have focused attention on the role that motorcyclist training and education can play in reducing accident rates. In this study a 2005 sample of Indiana motorcyclists was used to estimate statistical models of the effectiveness of existing training programs in reducing accident probabilities. Statistical models relating to motorcyclist speed choice and helmet usage behavior were also estimated. The findings showed that those individuals who took beginning rider training courses were more likely to be involved in an accident than those who did not and that those who took the beginning course more than once were much more likely to be involved in an accident. Although explanations for these findings can range from the use of ineffective course material to changes in risk perception as a result of taking the course, another explanation is that riders who take the course are inherently less skilled than those who do not. The findings underscore the need for a careful and comprehensive study of rider skills and risk perceptions to maximize the effectiveness of motorcycle training courses.

Indiana geometric design policy, consistent with national standards, allows for the design of intersections on superelevated curves if other solutions are prohibitively expensive. Consequently, the Indiana Department of Transportation (DOT) has built a number of such intersections. Following a series of fatal crashes at one of these intersections, Indiana DOT made a decision to avoid designing intersections on segments with steep superelevation. This design restriction calls for expensive alternatives, such as realigning roads or adding grade separations. This research was done to determine whether superelevated intersections were more hazardous than similar intersections located on tangents and, if so, to determine what combination of factors made this true. The research focused on two-way stop-controlled intersections where the mainline was a high-speed four-lane divided highway located on a superelevated curve. An attempt was made to analyze as many factors as possible by using appropriate comparison techniques. Negative binomial models were developed to determine the statistical relationship between crash occurrence and intersection geometric characteristics, including curvature of the main road. Crash severity and the joint impact of curvature with weather and lighting conditions were examined by using binomial comparisons of proportions. Research findings show significant increases in crash frequency and severity at intersections located on superelevated curves.

Contaminant exposure in aqueous systems typically involves complex chemical mixtures. Given the large number of compounds present in the environment, it is critical to identify hazardous chemical interactions rapidly. The present study utilized a prototype for a novel high-throughput assay to quantify behavioral changes over time to identify chemical interactions that affect toxicity. The independent and combined effects of 2 chemicals, diazinon (an insecticide) and 4-nonylphenol (a detergent metabolite), on the swimming behavior of the freshwater crustacean Daphnia pulex were examined. Cumulative distance and change in direction were measured repeatedly via optical tracking over 90 min. Exposure to low concentrations of diazinon (0.125-2 µM) or 4-nonylphenol (0.25-4 µM) elicited significant concentration- and time-dependent effects on swimming behavior. Exposure to 0.5 µM 4-nonylphenol alone did not significantly alter mean cumulative distance but did elicit a small, significant increase in mean angle, the measure of change in direction. When 0.5 µM 4-nonylphenol was used in combination with diazinon (0.125-0.5 µM), it augmented the adverse impact of diazinon on the swimming behavior of Daphnia. Additionally, enhanced sensitivity to diazinon was observed in animals exposed to treated wastewater effluent for 24 h prior to a diazinon challenge. The present experiments demonstrate that exposure to 4-nonylphenol and complex chemical mixtures (e.g., treated wastewater) can enhance the toxicity of exposure to the insecticide diazinon.

Controlled field studies were performed at 12 locations to evaluate the impacts of milled centerline rumble strips on exterior roadside noise adjacent to rural two-lane highways as a function of rumble strip depth and pavement type. Twenty controlled pass-bys were performed at each location using a minivan traveling at 88.5 km/h (55 mph). An equal number of passes were made both while traveling on and off of the centerline rumble strips, with the latter condition providing baseline noise data. The maximum noise was recorded during each pass using a digital sound meter that was placed 15.24 m (50 ft) laterally from the centerline of the roadway at a height of 1.52 m (5 ft) above the pavement surface. Multiple linear regression models were estimated to ascertain the effects of depth and pavement type while controlling for baseline noise. The milled depth of the rumble strips was the strongest predictor of roadside noise, and this effect was stronger for hot mix asphalt pavements compared to chipsealed pavements. For every 1.5875 mm (1/16-in.) increase in centerline rumble strip depth, roadside noise increased by 2.3 decibels on hot mix asphalt pavements, compared to 1.4 decibels on chipsealed pavements.

INTRODUCTION: The effects of cell phone use and safety belt use have been an important focus of research related to driver safety. Cell phone use has been shown to be a significant source of driver distraction contributing to substantial degradations in driver performance, while safety belts have been demonstrated to play a vital role in mitigating injuries to crash-involved occupants. METHOD: This study examines the prevalence of cell phone use and safety belt non-use among the driving population through direct observation surveys. A bivariate probit model is developed to simultaneously examine the factors that affect cell phone and safety belt use among motor vehicle drivers. RESULTS: The results show that several factors may influence drivers' decision to use cell phones and safety belts, and that these decisions are correlated. PRACTICAL APPLICATIONS: Understanding the factors that affect both cell phone use and safety belt non-use is essential to targeting policy and programs that reduce such behavior. Keywords: Driver distraction; Language: en

Many emerging contaminants tend to be biologically active at very low concentrations, occur in water as part of complex mixtures, and impact biota in ways that are not detected using traditional toxicity tests (e.g., median lethal concentration). To evaluate emerging contaminants, the authors developed a method for detecting sublethal behavioral effects by quantifying the swimming behavior of Daphnia pulex, a model organism for studying aquatic toxicity. This optical tracking technique is capable of measuring many swimming parameters, 2 of which-cumulative distance and angular change-are presented. To validate this technique, 2 prototypical compounds that exhibit different modes of action as well as corresponding insecticides that are commonly found in surface waters were investigated. The acetylcholinesterase (AChE) inhibitor physostigmine was used as the prototypical compound for the large number of AChE inhibitor insecticides (e.g., chlorpyrifos). Nicotine was used as the prototypical compound for neonicotinoid insecticides (e.g., imidacloprid). Results demonstrate that this assay is capable of detecting sublethal behavioral effects that are concentration-dependent and that insecticides with the same mode of action yield similar results. The method can easily be scaled up to serve as a high-throughput screening tool to detect sublethal toxic effects of a variety of chemicals. This method is likely to aid in enhancing the current understanding of emerging contaminants and to serve as a novel water-quality screening tool.

Motorcycle crashes frequently involve a combination of high-risk behaviors by the motorcyclist or the other crash-involved driver. Such behaviors may include riding or driving without appropriate licensure or while under the influence of alcohol, as well as deciding not to use a safety device such as a helmet or safety belt. Given that these factors frequently occur in combination with one another, it is difficult to untangle the specific effects of individual factors leading up to the crash outcome. This study assesses how various rider-, driver-, and other crash-specific factors contribute to at-fault status in two-vehicle motorcycle crashes, as well as how these same factors affect the propensity for other high-risk behaviors. Furthermore, the interrelationships among fault status and these other behaviors are also examined using a multivariate probit model. This model is developed using police-reported crash data for the years 2006-2010 from the State of Ohio. The results show that younger motorcyclists are more likely to be at-fault in the event of a collision, as are riders who are under the influence of alcohol, riding without insurance, or not wearing a helmet. Similarly, motorcyclists were less likely to be at-fault when the other driver was of younger age or was driving under the influence of alcohol, without insurance, or not wearing their safety belt. Crash-involved parties who engaged in one high-risk behavior were more likely to engage in other such behaviors, as well, and this finding was consistent for both motorcyclists and drivers. The results of this study suggest that educational and enforcement strategies aimed at addressing any one of these behaviors are likely to have tangential impacts on the other behaviors, as well.

Standard multinomial logit (MNL) and mixed logit (MXL) models are developed to estimate the degree of influence that bicyclist, driver, motor vehicle, geometric, environmental, and crash type characteristics have on bicyclist injury severity, classified as property damage only, possible, nonincapacitating or severe (i.e., incapacitating or fatal) injury. This study is based on 10,029 bicycleinvolved crashes that occurred in the State of Ohio from 2002 to 2008. Results of likelihood ratio tests reveal that some of the factors affecting bicyclist injury severity at intersection and non-intersection locations are substantively different and using a common model to jointly estimate impacts on severity at both types of locations may result in biased or inconsistent estimates. Consequently, separate models are developed to independently assess the impacts of various factors on the degree of bicyclist injury severity resulting from crashes at intersection and non-intersection locations. Several covariates are found to have similar impacts on injury severity at both intersection and non-intersection locations. Conversely, six variables were found to significantly influence injury severity at intersection locations but not non-intersection locations while four variables influenced bicyclist injury severity only at non-intersection locations. In crashes occurring at intersection locations, the likelihood of severe bicyclist injury increases by 14.8 percent if the bicyclist is not wearing a helmet, 82.2 percent if the motorist is under the influence of alcohol, 141.3 percent if the crash-involved motor vehicle is a van, 40.6 percent if the motor vehicle strikes the side of the bicycle, and 182.6 percent if the crash occurs on a horizontal curve with a grade. Results from non-intersection locations show the likelihood of severe injuries increases by 374.5 percent if the bicyclist is under the influence of drugs, 150.1 percent if the motorist is under the influence of alcohol, 53.5 percent if the motor vehicle strikes the side of the bicycle and 99.9 percent if the crash-involved motor vehicle is a heavy-duty truck.

Motorcycle fatalities have more than doubled in the United States since 1997--highlighting the need to better understand the many interrelated factors that determine motorcyclists' crash-injury severities. In this paper, using a detailed crash database from the state of Indiana, we estimate probabilistic models of motorcyclists' injury severities in single- and multi-vehicle crashes. Nested logit (estimated with full information maximum likelihood) and standard multinomial logit model results show a wide-range of factors significantly influence injury-severity probabilities. Key findings show that increasing motorcyclist age is associated with more severe injuries and that collision type, roadway characteristics, alcohol consumption, helmet use, unsafe speed and other variables play significant roles in crash-injury outcomes.

In recent years, the State of Indiana has built a number of intersections where one or both of the roads are located on curves. The AASHTO Policy on Geometric Design of Highways and Streets recommends that in such cases “the alignment should be as straight and the gradient as flat as practical.” This wording, consistent with Part V of the Indiana Design Manual, allows for the design of intersections on curves if other solutions prove to be too expensive. Several of these intersections have raised safety concerns and led to expensive corrective measures. Due to these safety and economic issues, INDOT currently avoids designing intersections on segments with steep superelevation. The focus of this research is to determine what effect curvature and superelevation have on intersection safety. Based on the results, the goal is to provide design standards for curvature and superelevation for cases where the major road is located on a superelevated curve.

INTRODUCTION: Alcohol related crashes have accounted for approximately 35% of fatal crashes per year since 1994 nationwide, with approximately 30% involving impairment over the legal blood alcohol content limit of 0.08%. Educational campaigns and law enforcement efforts are two components of multi-faceted programs aimed toward reducing impaired driving. It is crucial that further research be conducted to guide the implementation of enforcement and educational programs. METHOD: This research attempts to provide such guidance by examining differences in alcohol-involved crashes involving motorcycles and passenger cars. Prior safety research has shown that motorcyclists follow a significantly different culture than the average passenger car operator. These cultural differences may be reflected by differences in the contributing factors affecting crashes and the severity of the resulting injuries sustained by the driver or motorcyclist. This research is focused on single-vehicle crashes only, in order to isolate modal effects from the contribution of additional vehicles. The crash data provided for this study are from the Ohio Department of Public Safety from 2009 through 2012. RESULTS: The injury severity data are analysed through the development of two mixed logit models, one for motorcyclists and one for passenger car drivers. The models quantify the effects of various factors, including horizontal curves, speeds, seatbelt use, and helmet use, which indicate that the required motor skills and balance needed for proper motorcycle operation compounded with a lack of mechanical protection make motorcyclists more prone to severe injuries, particularly on curves and in collisions with roadside objects. PRACTICAL APPLICATIONS: The findings of this study have been incorporated into combined motorcycle and sober driving educational safety campaigns. The results have shown to be favorable in supporting national campaign messages with local justification and backing. Language: en