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Increases in new National Sexually Transmitted Diseases Curriculum registrants and learning groups during the COVID-19 pandemic demonstrate that e-learning platforms can be leveraged to meet rapidly changing training needs., The National Sexually Transmitted Diseases Curriculum is an e-learning platform. New registrations and learning group creations in March to April 2020 were compared with previous 12-month data. Substantial increases in registrations and learning groups demonstrate that the National Sexually Transmitted Diseases Curriculum was successfully leveraged to meet rapidly shifting training needs due to the COVID-19 pandemic.

BACKGROUND With increasing rates of sexually transmitted infections in the United States, there is a critical need to educate health professionals on the prevention, diagnosis, and treatment of sexually transmitted infections. The National Sexually Transmitted Disease Curriculum (NSTDC, https://www.std.uw.edu) is a free, online curriculum, funded by the Centers for Disease Control and Prevention. The purpose of this article is to evaluate the reach, utilization, and engagement of users with the curriculum. METHODS Data on NSTDC utilization was collected for 24 months after the February 1, 2017 launch. For all users, Google Analytics was used to determine total number of users, geographic location, age and sex, and average session duration. For registered users, additional data analysis included work-role, demographics, and completion of self-study modules, check-on-learning questions, and question banks. User satisfaction was measured on a 5-point Likert scale. RESULTS During the evaluation period, 136,270 individual users accessed the NSTDC, including 24,652 registered users. Among all registered users, 10,660 (43.2%) were registered nurses, 2810 (11.4%) physicians, 4942 (20.1%) Advanced Practice Nurses and Physician Assistants, and 6213 (25.2%) nonclinicians. Among registered users, 18,533 (75.2%) completed at least 1 module, 7898 (32.0%) completed all 7 modules, and 19,804 (80.4%) answered optional check-on-learning questions. Median satisfaction with the content was (5) very satisfied (interquartile range, 4-5). CONCLUSIONS The NSTDC is a free, guideline-based, online curriculum with novel dual functionality that has achieved extensive reach with a broad array of health professionals who engage deeply with the material. The wide usage of NSTDC demonstrates the need for high-quality, unbiased, free content in user-focused formats.

Rapid diagnostic tests (RDTs) have the potential to identify infectious diseases quickly, minimize disease transmission, and could complement and improve surveillance and control of infectious and vector-borne diseases during outbreaks. The U.S. Defense Threat Reduction Agency’s Joint Science and Technology Office (DTRA-JSTO) program set out to develop novel point-of-need RDTs for infectious diseases and deploy them for home use with no training. The aim of this formative study was to address two questions: 1) could community members in Iquitos, Peru and Phnom Penh, Cambodia competently use RDTs of different levels of complexity at home with visually based instructions provided, and 2) if an RDT were provided at no cost, would it be used at home if family members displayed febrile symptoms? Test kits with written and video (Peru only) instructions were provided to community members (Peru [n = 202]; Cambodia [n = 50]) or community health workers (Cambodia [n = 45]), and trained observers evaluated the competency level for each of the several steps required to successfully operate one of two multiplex RDTs on themselves or other consenting participant (i.e., family member). In Iquitos, >80% of residents were able to perform 11/12 steps and 7/15 steps for the two- and five-pathogen test, respectively. Competency in Phnom Penh never reached 80% for any of the 12 or 15 steps for either test; the percentage of participants able to perform a step ranged from 26–76% and 23–72%, for the two- and five-pathogen tests, respectively. Commercially available NS1 dengue rapid tests were distributed, at no cost, to households with confirmed exposure to dengue or Zika virus; of 14 febrile cases reported, six used the provided RDT. Our findings support the need for further implementation research on the appropriate level of instructions or training needed for diverse devices in different settings, as well as how to best integrate RDTs into existing local public health and disease surveillance programs at a large scale., Author summary Rapid diagnostic tests (RDTs) are becoming increasingly available and are useful during outbreaks of infectious and vector-borne diseases. This study set out to answer two questions regarding the use of RDTs in community settings. First, how well could community members at two diverse sites–Iquitos, Peru and Phnom Penh, Cambodia–perform an RDT on themselves and willing family members with only written and/or video instructions, and with two tests of different complexity? Second, and only in Iquitos, if RDTs were made widely available at no cost to households, would residents choose to use one for a family member showing febrile symptoms? In Peru, 202 community members were provided written and/or video instructions and a test kit, and then were observed operating the RDT on themselves or family members in their own homes. In Cambodia, 45 Community Health Workers and 50 community members were provided only written instructions at a local health center and asked to carry out the test. In both locations, trained observers scored each of the 12–15 steps necessary to conduct the test on a 3-point scale (1 being lowest proficiency level, 3 being highest), for one of the two RDTs in this study. In Iquitos, >80% of residents were able to perform 11/12 steps and 7/15 steps for the two- and five-pathogen test, respectively. Competency in Phnom Penh never reached 80% for any of the 12 or 15 steps for either test, with the percentage of participants demonstrating high competency ranging from 26–76% and 23–72%, for the two- and five-pathogen tests, respectively. Finally, in Iquitos, RDTs were distributed to households with earlier confirmed cases of dengue or Zika virus: about half of all household members that developed fevers were self-tested or tested by another family member. This study is consistent with our earlier findings from focus group discussions suggesting that implementation of simple home-based rapid diagnostic devices, could be used in different settings, but further research is needed to determine the best type and level of instructions to do this.

The AASHTO Highway Safety Manual (HSM) now includes crash prediction procedures for ramps. Research was undertaken to assess how well these new crash prediction methods represented the safety performance of two ramp types with distinctly different geometrics: loop ramps and diamond ramps. The HSM crash prediction procedures were applied to 235 loop ramps and 243 diamond ramps in two states—California and Washington—and the results were compared with 5 years of actual crash data for the same ramps. The results indicate that the HSM crash prediction method can be applied to both loop and diamond ramps, but to compare the safety performance of these two ramp types properly, separate calibration of loop and diamond ramps is needed.

In 2012, the U.S. Defense Threat Reduction Agency Joint Science and Technology Office initiated a program to develop novel point-of-need diagnostic devices for surveillance of emerging infectious diseases including dengue, malaria, plague, and melioidosis. Prior to distribution of devices to observe their correct use among community members in Iquitos, Peru, and Phnom Penh, Cambodia, research was conducted to: 1) assess acceptability of use, including the motivation to use a rapid diagnostic test (RDT) before or instead of seeking care at a health facility, 2) explore comprehension of RDT use instructions, and 3) examine possible strategies for large scale RDT distribution and use at each site. In February 2014, 9 focus group discussions (FGD) with community members and 5 FGD with health professionals were conducted in Iquitos, and 9 FGD with community members and 9 in-depth interviews with health professionals in Phnom Penh. In both places, participants agreed to use the device themselves (involving finger prick) or could identify someone who could do so in their home or neighborhood. The main incentive to RDT use in both sites was the ability for device results to be used for care facilitation (post confirmatory tests), specifically reduced wait times to be seen or obtain a diagnosis. Comprehension of RDT use instructions was assessed in Iquitos by asking some participants to apply the device to research team members; after watching a short video, most steps were done correctly. In Phnom Penh, participants were asked to describe each step after reading the instructions; they struggled with comprehension. Health professionals’ main concerns in both sites were their community’s ability to accurately use the test, handle complicated instructions, and safety (i.e., disposal of lancets). Health system structure and ability to use home diagnostic devices varied in the two disease endemic sites, with substantial challenges in each, suggesting the need for different strategies for RDT large scale community use, and illustrating the value of formative research before deployment of novel technologies., Author summary Development and use of devices to diagnose infectious diseases outside of health facilities (i.e., at home or in remote areas) continues to increase, providing new options for the follow up and treatment options of individuals, depending on the diseases. In this qualitative study, researchers in Iquitos, Peru, and Phnom Penh, Cambodia explored what local people thought about the possible availability of such a device to diagnose dengue and malaria in their own houses, and what would motivate them to use such a device instead of going directly to a health facility for the diagnosis. Participants reported being willing to use device on themselves and were motivated by the possibility that, by using this diagnostic device and taking the result to their health facility, they might be able to obtain quicker and more optimized attention at the health facility; for example, by obtaining a positive result to dengue or malaria on the rapid diagnostic device, they are aware they might still need confirmatory tests, but they would be able to reduce the wait time for obtaining a definitive diagnosis and starting treatment by a full day. Questions regarding accuracy of tests, complicated instructions and safety of using these devices in the community were brought up by participants—individuals living in the communities and local health professionals. Also, in this study, it was clear that if these devices were to be made available in Peru and Cambodia, different strategies for disseminating and using these in the communities would be needed to accommodate for different health infrastructure in both sites.

Background The National Sexually Transmitted Diseases Curriculum (NSTDC) is an online, guideline-based, interactive curriculum developed at the University of Washington in Seattle with funding from the Centers for Disease Control and Prevention (CDC) National Network of STD Clinical Prevention Training Centers (NNPTC). The NSTDC has dual-functionality to provide users with the option of engaging in (1) sequential, longitudinal learning and/or (2) quick access to specific content. We describe the first evaluation of the reach, utilization and effectiveness of the NSTDC. Methods We evaluated user data collected from survey completion, Google Analytics, and the Health Professional Application for Training (HPAT) between the launch of NSTDC in February 1, 2017 through August 31, 2018. Chi-square and ANOVA tests were used to determine significant differences between prescribers, nurses, and non-clinicians. Results month period and 54,910 hours of CE awarded. Registered users were mostly women (16,133, 84%), and 8,476 (44%) were registered nurses, with an additional 6,052 (34%) prescribing providers (physicians, nurse practitioners, physician assistants, and dentists). The most common programmatic focus was primary care (4,886, 25%). While 18,175 (95%) of users were in the United States, users were located around the world (Figure 1). Referral patterns differed significantly by occupation (Figure 2). Users engaged deeply with the curriculum. Average site session time was 28 minutes for registered users and 14 minutes for all users. Registered users completed an average of 4.37 out of 7 total modules. Nurses were more likely to complete all modules, (48% vs. 34% of prescribers and 30% of non-clinicians, P < 0.0001). Over 15,000 users answered at least one optional check-on-learning (COL) question. On average, 77% of COL questions were answered in modules where COL questions were initiated. Over 60% of the users found the content and experience highly satisfying. Overall 39% of users intended to change practice following completion of the modules. Conclusion The NSTDC has a broad reach, leads to high user engagement and satisfaction, and fosters intent to change practice. This web-based curriculum is a novel and effective strategy to disseminate recommendations from CDC Guidelines. Disclosures All authors: No reported disclosures.

This paper demonstrates that the crash reduction benefits of improving stopping sight distance (SSD) vary substantially over the highway system, with the greatest benefits likely at locations where a horizontal curve, intersection, or driveway is in a sight-restricted area. The paper analyzes crash data for 452 crest vertical curves on two-lane highways in the state of Washington, approximately equally distributed between sites with SSD below and above existing design criteria. Preliminary analyses found statistically significant differences in crash frequency between the groups of sites in SSD categories, but the statistical significance of these differences disappeared when a factor was introduced to account for the presence of horizontal curves, intersections, or driveways that were hidden from an approaching driver's view by the sight restriction. The presence of such hidden features was found to be highly statistically significant. There is a need for highway design guidance to give higher priority to addressing sight distance limitations when hidden roadway features are present and to recognizing that sight distance improvements may have little effect on crash frequency or severity when such hidden features are not present. Consideration should also be given to development of SSD models for use in highway design to reflect better the differences in SSD needs on various elements of the roadway system.

Several methods have been used to emphasize the presence of a pedestrian crossing, including one that supplements signage with beacons or embedded LEDs. Rapidly flashing beacons constitute one type of treatment used at midblock pedestrian crossings to bring drivers’ attention to a crossing pedestrian. This study evaluated the effect of the activation of the beacon and traffic volumes on driver yielding behavior when a crossing pedestrian was present. Rectangular rapid-flashing beacons (RRFBs) and circular rapid-flashing beacons (CRFBs) were installed at 12 sites in four cities. At approximately half of the study sites, RRFBs were initially installed and later replaced with CRFBs. At the other study sites, CRFBs were initially installed and later replaced with RRFBs. The same flash pattern was used for both beacon shapes. Driver yielding rates were compared between pedestrian crossings when a beacon was activated and when it was not. The results of the analysis showed that when a beacon, whether rectangular or circular, was activated, a driver was 3.68 times more likely to yield to pedestrians than when the beacon was not activated. The results of an analysis of the relationship between traffic volume and driver yielding indicated that driver yielding behavior was not influenced by traffic volume at the study sites.

The objective of this research was to develop recommendations for bicycle lane width for various roadway and traffic characteristics. An observational field study involved installing temporary lane line markings to delineate bicycle lanes of varying width at midblock locations and then observing the lateral positioning of bicyclists and motorists within the roadway cross section. The final database from the field study included data for 4,965 bicyclists, 3,163 passing vehicles, and 994 parked vehicles. The primary findings of the study showed that a buffered bike lane provided distinct advantages over simply widening a bike lane and that as traffic volumes and truck percentages increased, bicyclists moved away from vehicles in the travel lane and positioned themselves closer to parked vehicles or the curb. General design guidance is provided along with recommended parking lane, buffer, bike lane, and travel lane widths most applicable to urban and suburban two-lane undivided roadways with constrained roadway width.

The objective of this study was to develop superelevation criteria for sharp horizontal curves on steep grades. Field studies were undertaken and vehicle dynamics simulations (point mass, bicycle, and multibody) were performed to investigate combinations of horizontal curve and vertical grade design criteria. The vehicle dynamics simulations used AASHTO design criteria and field-measured data to investigate the safety margins against skidding and rollover for several vehicle types on sharp horizontal curves with steep grades. Research results indicated that for a simple horizontal curve, the maximum rate of super elevation should not exceed 12% on a downgrade. A spiral curve transition is recommended if the maximum superelevation rate is greater than 12%. On upgrades of 4% and greater, the maximum superelevation rate should be limited to 9% for minimum-radius curves under certain conditions. The superelevation attained at the point of curve entry should be checked and compared with a lateral friction margin condition so that the lateral friction margin on curve entry is not less than the margin within the curve. On multilane highways, the “Stay in Lane” sign should be installed in advance of sharp horizontal curves on steep downgrades.

The development of relationships between safety and congestion is documented; traffic volume, speed, and crash data by 15-min periods for urban freeways in the areas of Seattle, Washington, and Minneapolis–Saint Paul, Minnesota, were used. The safety–congestion relationships were developed to provide a basis for estimating the safety effects of design treatments intended to reduce nonrecurrent congestion and increase travel time reliability. The relationships were developed with traffic volume and speed data from detectors in individual lanes for 564 urban freeway segments during study periods of up to 3 years. Traffic crash records were obtained for the same time periods as the volume and speed data. The U-shaped relationship between crash rate per million vehicle miles of travel and traffic density (the level-of-service measure for freeways) was found, with the highest crash rates at low and high traffic densities and the lowest crash rates in the middle range of traffic densities. The high crash rates at lower traffic densities represent predominantly single-vehicle crashes, whereas the high crash rates at higher traffic densities represent predominantly multiple-vehicle crashes. Quantitative safety–congestion relationships were developed for the range of traffic densities from 20 to 78 passenger cars per hour per lane, corresponding to the level-of-service range from C to F.

This paper presents the results of a study to develop improved design guidance for high- to low-speed transition zones on rural highways. The primary steps of the research included a literature review and state-of-practice review on speed reduction treatments used in transition zones and observational field studies of several transition zone treatments in the United States. The principal findings from the observation field studies are that roundabouts and transverse pavement markings increase the rate of compliance of vehicles traveling at or below the speed limit at the end of a transition zone by 15% and 20%, respectively, as compared with no treatment. Roundabouts increase the rate of compliance of vehicles traveling within 5 mph (8 km/h) of the speed limit at the end of a transition zone by 11%, compared with no treatment. The findings support previous research that indicates the need to provide additional measures through the community to maintain speed reduction downstream of the transition zone through the community. This paper also addresses several issues to be considered in the design of high- to low-speed transition zones, including definitions and site characteristics of the geographical limits or boundaries of the transition zone study area; a methodology for assessing whether a high- to low-speed transition zone has speed limit compliance or safety issues to support the need for, and the selection of, an appropriate treatment to address the issues; and guiding principles and design concepts to be considered in the design of a transition zone.

The paper presents the results of research undertaken to evaluate how the safety performance of intersection approaches with channelized right-turn lanes compares with that of intersection approaches with conventional right-turn lanes or shared through and right-turn lanes. Crash data for nearly 400 intersection approaches in Toronto, Ontario, Canada, including intersection approaches with channelized right-turn lanes, conventional right-turn lanes, and shared through and right-turn lanes, were analyzed to compare the safety performance of the three right-turn treatment types. The research results indicate that intersection approaches with channelized right-turn lanes appear to have similar motor vehicle safety performance as approaches with conventional right-turn lanes or shared through and right-turn lanes. This result was found both at the downstream end of the channelized right-turn lane (where the right-turning vehicle merges with the cross street traffic) and at the upstream end of the channelized right-turn lane (where the right-turning vehicle begins the right-turn maneuver). Intersection approaches with channelized right-turn lanes also appear to have similar pedestrian safety performance as approaches with shared through and right-turn lanes. Intersection approaches with conventional right-turn lanes have substantially more pedestrian crashes (approximately 70% to 80% more) than approaches with channelized right-turn lanes or shared through and right-turn lanes.

The safety effects of horizontal curves and grades on highways have been quantified separately, but it is not currently known whether or how the safety performance of horizontal curves interacts with that of grades. Although the first edition of the AASHTO Highway Safety Manual provides crash modification factors for the safety effects of horizontal curvature and percent grade on rural two-lane highways, the manual does not have a method for accounting for the interactions between these effects. In other words, in the Highway Safety Manual procedures for rural two-lane highways, the safety effect of a horizontal curve is the same whether the curve is located on a level roadway, a straight grade, or a vertical curve. Similarly, the safety effect of a straight grade is the same whether it is located on a tangent roadway or horizontal curve. Researchers have always supposed that there are interactions between the safety effects of horizontal and vertical alignments, but these interactions have not been demonstrated in a form useful for safety prediction. The results of research undertaken to quantify the safety effects of five types of horizontal and vertical alignment combinations based on Highway Safety Information System data and crash records from 2003 to 2008 in Washington State are summarized. The outcome is a set of safety pre diction models for fatal and injury and property-damage-only crashes. To present the results in a form suitable for incorporation into the Highway Safety Manual, crash modification factors representing safety performance relative to level tangents were developed from these models for each of the five combinations.

Current low participation rates in vector control programmes in Arequipa, Peru complicate the control of Chagas disease. Using focus groups (n = 17 participants) and semi-structured interviews (n = 71) conducted in March and May 2013, respectively, we examined barriers to and motivators of household participation in an indoor residual spray (IRS) campaign that had taken place one year prior in Arequipa. The most common reported barriers to participation were inconvenient spray times due to work obligations, not considering the campaign to be necessary, concerns about secondary health impacts (e.g. allergic reactions to insecticides), and difficulties preparing the home for spraying (e.g. moving heavy furniture). There was also a low perception of risk for contracting Chagas disease that might affect participation. The main motivator to participate was to ensure personal health and well-being. Future IRS campaigns should incorporate more flexible hours, including weekends; provide appropriate educational messages to counter concerns about secondary health effects; incorporate peer educators to increase perceived risk to Chagas in community; obtain support from community members and leaders to build community trust and support for the campaign; and assist individuals in preparing their homes. Enhancing community trust in both the need for the campaign and its operations is key.

Many transportation agencies use shoulder rumble strips to address the problem of single-vehicle run-off-the-road crashes by alerting inattentive or drowsy motorists that their vehicles have drifted out of the travel lane. The application of rumble strips has expanded to include the installation of centerline rumble strips along the centerlines of undivided highways to reduce head-on and opposite-direction sideswipe crashes. Installing rumble strips along either the shoulder or centerline without considering the effect on other highway users (i.e., bicyclists and motorcyclists) may lead to unintended consequences. This research addresses a number of safety issues: (a) the safety effectiveness of shoulder rumble strips on different roadway types, (b) the safety effectiveness of shoulder rumble strip placement relative to the edgeline, (c) the safety effectiveness of centerline rumble strips on different roadway types, and (d) the safety effectiveness of centerline rumble strips along horizontal curves and tangents. The safety evaluations considered all severity levels (total crashes) and fatal and injury crashes. Statistical models for predicting noise levels in the passenger compartment of a vehicle for use in designing rumble strip patterns were also developed. The results of this research were combined with results from previous research to address important policy issues for transportation agencies to consider in the design and application of shoulder and centerline rumble strips.

The U.S. Road Assessment Program, in cooperation with road assessment programs in other countries, has developed a protocol to assign ratings to roads on the basis of the presence or absence of key design features related to safety. This protocol rates roads by assigning them one to five stars according to approximately 20 key roadway safety features. A recently developed web-based software tool uses the roadway inventory data on which the star ratings are based to identify cost-effective safety improvement programs for the road networks covered by the ratings. The research results are presented to validate the relationship between the star ratings and crash rates for selected roadways. The research developed star ratings for approximately 3,000 mi of rural and urban roadways of various types in Iowa and Washington State and compared the star ratings with crash rates for the same roads. Relationships between star ratings and crash rates were found for two-lane undivided highways, four-lane undivided highways, and four-lane divided nonfreeways. No clear relationships could be demonstrated for freeways because the design characteristics of freeways are very uniform.

An understanding of the relationship between lane width and traffic operations is important in making decisions about urban and suburban arterials. Numerous geometric elements, including lane width, affect the saturation flow rate at an intersection on an urban or suburban arterial. Several studies have been conducted to evaluate the relationship between lane width and saturation flow rate at intersections. This relationship is investigated on urban and suburban signalized intersection approaches by using field-study sites with the most ideal conditions possible. Research results indicate that saturation flow rate varies with lane width. Average saturation flow rate was in the range of 1,736 to 1,752 passenger cars (pc)/h/ln for 2.9-m (9.5-ft) lanes, 1,815 to 1,830 pc/h/ln for 3.3- to 3.6-m (11- to 12-ft) lanes, and 1,898 to 1,913 pc/h/ln for lane widths of 4.0 m (13 ft) or greater. These measured saturation flow rates are generally lower than those currently used in the Highway Capacity Manual (HCM). Furthermore, the percentage difference in saturation flow rate between sites with 2.9- and 3.6-m (9.5- and 12-ft) lanes was about half the value used in the HCM. Because data were limited to queue lengths between 8 and 11 vehicles, the research results do not directly address queue lengths longer than 11 vehicles.

Right-turn deceleration lanes reduce the potential for rear-end collisions from vehicles slowing to make right-turn maneuvers. Right-turn lanes also improve arterial capacity by removing slower-moving vehicles from the main traffic stream. Transportation agencies must have an understanding of the traffic operational and safety effects of right-turn lanes to determine effectively where right-turn lanes are needed. Therefore, in this research, a computer simulation study of motor vehicles and pedestrians at right-turn lanes was conducted to determine their operational effects. A benefit-cost analysis of right-turn lanes that considered both their operational and safety effects was performed. The research indicates that right-turn maneuvers from a two-lane arterial at an unsignalized intersection or driveway can delay through traffic by 0 to 6 s per through vehicle where no right-turn lane is present. Delays to through traffic due to right turns in the same situation on a four-lane arterial are substantially lower, in the range from 0 to 1 s per through vehicle. Pedestrians at unsignalized intersections or driveways can have a substantial impact on delay to through vehicles due to slowing of right-turning vehicles yielding to pedestrians. Provision of a right-turn lane can reduce pedestrian-related delays to through traffic by as much as 6 s per through vehicle, depending on pedestrian volume. Also presented is an economic-analysis procedure that can identify unsignalized intersections and major driveways at which provision of right-turn lanes is cost-effective.

Congestion on urban freeways often creates a need to increase freeway capacity by adding an additional lane. Although adding a lane by widening the existing roadbed is often difficult and expensive, restriping the traveled way with narrower lanes, converting all or part of the shoulder to a travel lane, or a combination of both often is a practical solution. An observational before-and-after evaluation with the empirical Bayes method was done to examine the safety effects of projects involving narrower lanes or shoulder conversions on existing urban freeways in California with four or five lanes in one direction of travel. The evaluation found that projects converting four lanes to five lanes resulted in increases of 10% to 11% in accident frequency. Projects converting five lanes to six lanes resulted in smaller increases in accident frequency. These increases in accident frequency may be the result of accident migration caused by relocation of traffic operational bottlenecks.

The results of research involving a well-designed before-and-after evaluation of the safety effects of providing left- and right-turn lanes for at-grade intersections are presented. Geometric design, traffic control, traffic volume, and traffic accident data were gathered for a total of 280 improved intersections as well as 300 similar intersections that were not improved during the study period. The types of improvement projects evaluated included installation of added left-turn lanes, added right-turn lanes, and extension of the length of existing left- or right-turn lanes. An observational before-and-after evaluation of these projects was performed by using several alternative evaluation approaches. Three contrasting approaches to before-and-after evaluation were used: the yoked comparison or matched-pair approach, the comparison group approach, and the empirical Bayes approach. The research not only evaluated the safety effectiveness of left- and right-turn lane improvements but also compared the performances of these three alternative approaches in making such evaluations. The research developed quantitative safety effectiveness measures for installation design improvements involving added left-turn lanes and added right-turn lanes. The research concluded that the empirical Bayes method provides the most accurate and reliable results. Further use of this method is recommended.

The United States (US) Environmental Protection Agency (EPA) estimated that the use of technical grade pentachlorophenol (PCP) between 1970 and 1995 to treat wood was approximately 400 000 metric tons in the US, and that between 4800 and 36 000 g of 2,3,7,8-tetrachlorodibenzo- p -dioxin toxic equivalents (TEQs) were incorporated annually in treated wood. The EPA has been unable, however, to estimate the rate of release of polychlorinated dibenzo -p- dioxins and dibenzofurans (CDD/Fs) from treated utility poles into the environment. There is some evidence that CDD/Fs leach from treated poles into the surrounding soils, but these studies do not allow for the calculation of a rate of release from this mechanism. Another possible release mechanism is the volatilization of dioxins into the atmosphere, but there are no data to demonstrate, much less quantify, this release. While not directly measuring the release of dioxins from treated utility poles into the environment, this study was designed to examine the potential for such release. The general approach taken was to collect PCP-treated poles of varying ages, to remove and analyze multiple samples from each pole cross-section, and to compare the spatial distribution of CDD/F congeners among poles of different ages. Evidence of concentration–depth profile changes over time may provide insight into the potential for dioxins to migrate through and then out of PCP-treated utility poles. It was found that the CDD/F concentrations were consistently higher in the outer portions of the poles than the center. This trend tends to be most marked in older poles and for the lower chlorinated congeners. The trend for dioxins to concentrate in the outer portions of the pole over time suggest migration within the poles, and this migration may result in some environmental release. Other possible explanations were also offered.

Cross-median collisions (CMCs) on high functional class roadways are a concern because of the potential economic and social losses that often accompany these crashes. The Pennsylvania Department of Transportation (PENNDOT) design policy suggests protecting medians on divided highways where the median width is less than 10m (32.8 ft) and the average daily traffic is above 20,000 vehicles per day. However, CMC crashes have occurred where a barrier was not warranted by the policy. The methodology used to assess median safety on Interstates and expressways in Pennsylvania is reviewed, and the findings are reported. A critical review of literature and an assessment of various state department of transportation median safety practices were undertaken. An expert panel qualitatively assessed median safety practices and provided input for quantitative data collection. Two PENNDOT databases, police accident reports, photologs, and field data were analyzed to complement the qualitative findings. Qualitative results suggest that the three-strand cable system, strong-post W-beam guiderail, or the concrete safety shape are recommended median barriers in appropriate site conditions. Quantitative results show that CMC crashes are rare events; however, nearly 15% involve fatalities and 72% involve nonfatal injuries. In addition, CMC crash rates at earth-divided highways decrease as the median width increases, CMC crashes appear more likely to occur downstream of interchange entrance ramps, and CMC crashes are more likely to involve adverse pavement surface conditions (wet or icy) than are other crashes. Negative binomial regression models were used to model CMC crash frequencies on earth-divided highways.

This report documents and presents the results of research to develop design guidance for channelized right-turn lanes. Observational field studies were conducted at 35 intersection approaches in cities to assess pedestrian crossing behavior, motorist yield behavior, and the interaction between pedestrians and motor vehicles at channelized right-turn lanes. Simulation modeling was performed to quantify the traffic operational benefits of channelized right-turn lanes with various types of traffic control and to compare the delay reduction of channelized right-turn lanes and conventional right-turn lanes. Crash data for nearly 400 intersection approaches in Toronto, Ontario, Canada, including intersection approaches with channelized right-turn lanes, conventional right-turn lanes, and shared through/right-turn lanes, were analyzed to compare the safety performance of the three right-turn treatment types. The research results indicate that channelized right-turn lanes have a definite role in improving operations and safety at intersections. However, to achieve these benefits they should have consistent design and traffic control and should be used at appropriate locations. The research provides design guidance for channelized right-turn lanes that addresses geometric elements such as crosswalk location, special crosswalk signing and marking, island type, radius of turning roadway, angle of intersection with cross street, acceleration and deceleration lanes, and traffic control.

Nonrecurring traffic congestion, which comprises the majority of total congestion, results from random incidents that cause unexpected delays, such as crashes, weather, and work zones. Road users are frustrated by unexpected delays that can make for unreliable arrival times at their destinations. The delivery of travel time reliability is becoming an emerging business activity and performance measure for transportation agencies to meet the increasing expectations of the public and freight industry. The purpose of this guide is to give transportation engineers, designers, planners, and decision makers an understanding and technical reference on how different high-way geometric design elements can be deployed, in new designs or site retrofit actions, to contribute specifically to the reduction of nonrecurring congestion and travel time reliability improvement on both urban and rural freeways. The guide introduces the nonrecurring and travel time reliability topics and metrics, a catalogue of design elements, and a process for selecting candidate design elements to evaluate for a specific site. For individual design elements, example content includes a description of that element, advantages and disadvantages, factors to consider when selecting the element, applicability to nonrecurring congestion, design criteria and practices, safety effectiveness, typical applications, and costs. In addition, there is an evaluation procedure that allows practitioners to compare alternative design treatments and select the best treatment solution for a specific site.

This research report presents the findings on the identification and evaluation of the use of highway geometric design features on freeways to reduce nonrecurrent congestion and improve travel time reliability. General guidance is provided on the range of design elements that could be used by transportation agencies to improve travel time reliability and reduce nonrecurrent congestion, analysis procedures and models to measure their operational and safety effectiveness, as well as a life-cycle benefit–cost method to support decision making on the possible use of individual treatments to address actual nonrecurring traffic conditions. For the safety effectiveness analysis, a new relationship between safety and congestion was explored and a mathematical model developed to quantify crash frequency at various levels of service.

This report describes the impact of the controlling roadway design criteria on safety and operations for urban and rural roads. In 1985, the FHWA designated 13 specific design elements as controlling criteria for roadway design. The 13 controlling criteria are (1) design speed, (2) lane width, (3) shoulder width, (4) bridge width, (5) structural capacity, (6) horizontal alignment, (7) vertical alignment, (8) grade, (9) stopping sight distance, (10) cross slope, (11) superelevation, (12) vertical clearance, and (13) horizontal clearance. Federally assisted highway construction and reconstruction projects must meet the established design criteria for these elements, or a formal design exception must be prepared and approved. Different procedures apply to rehabilitation projects, but these design elements are still key considerations in design. Since their designation, the 13 controlling criteria and their application have not been reconsidered as new knowledge has been gained about the relationships between geometric design elements and safety and operations. In this research project, the research team investigated what is known about the safety and operational effects of the 13 controlling and other important geometric design criteria. Several small studies were done to augment the information found in the literature. This information was used to assess the sensitivity of safety and operations to design decisions for these criteria for different types of roads. The research also addressed how to reduce confusion related to the definitions of the controlling criteria. The use of the controlling criteria in design exception processes was also explored, including through interviews with state department of transportation (DOT) personnel. This report will be useful to geometric designers and those responsible for reviewing designs, particularly in agencies that are transitioning away from “standards-based design.”

Sharp, horizontal curves on steep downgrades represent a potential safety concern for vehicles, especially heavy vehicles. Examples where this combination may occur are interchange ramp movements, curves on mountainous roads, or high-speed downgrade curves on controlled-access roadways. At these locations, the complicating factors of grade, pavement cross slope, and pavement friction fully tax the driver’s ability to provide correct vehicle positioning without compromising control of the vehicle. Superelevation criteria, horizontal curvature, and other associated geometric criteria needed to be developed for situations where steep grades are located on sharp horizontal curves. This report provides superelevation criteria for horizontal curves on steep grades. A series of field studies and vehicle dynamics simulations were undertaken to investigate combinations of horizontal curve and vertical grade design. Three classes of passenger vehicles and three classes of trucks were considered for safety analysis. The report provides design guidance based on the analyses for sharp horizontal curves on steep grades.

The purpose of this research project was to demonstrate one application of the Strategic Highway Research Program 2 (SHRP 2) Naturalistic Driving Study (NDS) data, showing how these data can be used to answer a highway safety question and provide guidance for the implementation of safety countermeasures. The specific safety countermeasure evaluated in this project is offset left-turn lanes. The research team evaluated the effect of left-turn lane offset on gap-acceptance behavior, which serves as a surrogate safety measure for this study. Specifically, the objective was to evaluate left-turning gap rejection and acceptance by a large number of drivers at a large number of intersections with a broad distribution of left-turn lane offsets (ranging from negative to positive). The primary source of data for this study consisted of the forward- and rear-facing cameras placed in the vehicles of NDS drivers. Clips of these videos were obtained for instances in which NDS drivers made a left-turning maneuver at one of the study intersections. From the videos, data were collected for a large number of variables, most importantly, the start and end time of each gap rejected or accepted by the turning driver. The primary analysis for the study was a logistic regression to predict the critical gap length for each offset category, both when sight obstructions were present and when they were not. Differences in critical gap between specific offset categories were not found to be statistically significant; however, the data clearly showed that negative-offset left-turn lanes resulted in longer accepted gaps than positive-offset left-turn lanes because opposing left-turn vehicles were much more likely to cause a sight restriction at negative-offset left-turn lanes than at positive-offset left-turn lanes. Therefore, even intersections with opposing left-turn lanes with a minimally negative offset have the potential to benefit from shifting the lanes to a positive offset. In addition, the data did not show that offsetting the left-turn lanes to make them less negative would have a substantial effect on safety or operational concerns.

Whether at the national, state, or local level, guidelines that have been developed for bicycle lane widths provide only general guidance on how bicycle lane widths should vary based on the conditions of the roadway. Thus, there was a need to conduct scientifically based research to develop more specific guidance on recommended bicycle lane widths for various roadway conditions. This report presents an analysis of the research and design guidance for bicycle lane widths on existing travel lane widths and parking lane widths. The research is based on a review of literature, the current state of practice, and a series of observational field studies. Temporary pavement markings were installed at several locations to delineate bicycle lanes of varying widths. The lateral positioning of both bicyclists and motorists was measured and used as surrogates to evaluate the safety effects of the allocation of roadway width between parking lanes, bike lanes, buffered spaces, and motor vehicle travel lanes. The data-collection sites included three midblock locations with on-street parking and two midblock locations where on-street parking was prohibited. The bicycle lane widths evaluated ranged from 3.5 to 6 ft. A supplemental grade study was also performed to evaluate lateral movement of bicyclists pedaling on a moderate upgrade. The report presents recommendations for bicycle lane widths for various roadway and traffic characteristics, including traffic volume, vehicle mix (i.e., percent trucks), lane width and/or total roadway width, and presence/absence of on-street parking. The conclusions are most applicable to urban and suburban roadways with level grade and a posted speed limit of 30 mph and should be used cautiously for the design of roadways with motor vehicle speeds outside of the range of 25 to 35 mph, and in particular for higher-speed roadways. This report will provide valuable guidance for traffic and design engineers in areas where bicycle lanes are being considered and implemented.

Strategic Highway Research Program 2 (SHRP 2) Reliability Project L07, Identification and Evaluation of the Cost-Effectiveness of Highway Design Features to Reduce Nonrecurrent Congestion, provided (1) general guidance on the range of design elements that could be used by transportation agencies to improve travel time reliability and reduce nonrecurrent congestion on urban freeways and (2) the Analysis Tool for measuring operational and safety effectiveness and calculating a life-cycle benefit–cost value. This value can be used to support decision making about the possible use of individual treatments to address actual nonrecurrent traffic conditions. The tool is a Visual Basic for Applications (VBA) interface overlaying a Microsoft-based Excel 2007 spreadsheet. Analysts can input data about a highway such as geometrics, volumes, and crash totals, and the tool computes delay and reliability indicators resulting from various design treatments and translates those results into life-cycle costs and benefits. For the safety-effectiveness analysis, a new relationship between safety and congestion was explored, and a mathematical model was developed to quantify crash frequency at various levels of traffic density. This supplemental report presents the research findings on the effort to further develop and refine the original safety and congestion relationship model using two additional independent freeway data sets. The results of this additional research confirmed the graphical relationship between crash frequency and traffic density developed in the original research. The crash rate on urban freeways varies with traffic density in a U-shaped curve. The lowest crash rates occurred at medium traffic densities, with slightly higher crash rates (single-vehicle- dominant) recorded at lower traffic densities and much higher crash rates recorded at higher traffic densities (multiple-vehicle-dominant). Therefore, if a design treatment is effective in reducing nonrecurrent congestion conditions at higher levels of service, it should also be effective in reducing crashes, resulting in a safety benefit.

The service life of durable pavement markings was evaluated over a period of nearly 4 years. The evaluation included 85 study sites in 19 states at which a total of 362 longitudinal pavement marking lines (edgelines, centerlines, and lane lines) were installed. Marking materials included epoxy, flat and profiled polyester, flat and profiled poly(methyl methacrylate), flat and profiled thermoplastic, and profiled preformed tape; glass beads; and standard and snow-plowable raised retroreflective pavement markers. One site with conventional paint markings and three sites with waterborne paint markings were included for comparison. The service life of marking materials and roadway types was modeled as a function of time and cumulative traffic passages. Regression modeling identified large variations in the shape of the relationship for identical materials and types of lines between different sites within a given state and required that modeling be done separately for each pavement marking line at each study site. Variations in service life can be attributed to roadway type, region of the country where the markings were installed (e.g., weather conditions, manufacturers of marking materials and glass beads, and individual state highway agencies), marking specifications, contractors installing the markings, quality control at the time of installation, and winter maintenance snow removal policies.

A consistent design allows drivers to perform safely the task of driving, allowing attention or capacity to be dedicated to obstacle avoidance and navigation. A measure of the consistency of a design is the amount of visual information needed by a driver to maintain an acceptable path on the roadway. Vision occlusion is a technique that measures driver visual demand on a roadway. It allows a more direct evaluation of the effects of various geometric elements on the driver. Studies of the effects of variations of curve radius, deflection angle, spacing, and sequences revealed several relationships between roadway geometry and visual demand. Curve radius and its reciprocal were found to be significantly related to visual demand in both on-road and test track studies. Small changes in visual demand were also found between types of curve pairs (S and broken back) with differing spacing between the curves. Visual demand was found to be a promising measure of effectiveness for use in studies of design consistency.

This study investigated two methods for analyzing composite dust wipes for lead. The term composite means two or more wipes collected from common components in a dwelling that are combined in the field and analyzed as a single sample. Two methods--a modified Environmental Protection Agency (EPA) Method 3050A and a Wisconsin Occupational Health Laboratory (WOHL) method--were selected based on their anticipated ability to handle the added mass of materials and dust expected in a composite. The study used off-the-shelf wipes to prepare single-, two-, and four-wipe samples. Wipes were spiked with a standard reference material at either a low dust loading level or a high level, and three laboratories analyzed the samples using both methods and both flame atomic absorption spectrometry and inductively coupled plasma-atomic emission spectrometry techniques (ICP). Good agreement with known spiked levels was possible using either method; the modified EPA 3050A showed particular promise. When up to four wipes were combined, all three laboratories found that modified EPA Method 3050A resulted in recoveries between 89 and 101% of the known standard. Although it was possible to achieve good agreement with spiked levels using the WOHL method, some difficulties were encountered, particularly when followed by ICP analysis and when using four wipes. The increased time required to digest the multiwipe composites was not proportional to the number of wipes in a composite: the two- and four-wipe composites did not take two to four times as long as a single-wipe sample. Laboratory analysis of a four-wipe sample cost an average of 65% less than analysis of four single-wipe samples for each method.

The relationship of safety to five candidate measures of geometric design consistency for rural two-lane highway alignments was examined. The measures that were evaluated included: ( a) speed reduction on a horizontal curve relative to the preceding tangent or curve, ( b) average radius, ( c) ratio of maximum radius to minimum radius, ( d) average rate of vertical curvature, and ( e) ratio of individual curve radius to average radius. All of these measures were found to have statistically significant relationships to accident frequency in the direction expected and are recommended as candidate measures for assessment of geometric design consistency. The relationships between design consistency measures and accident frequency were developed using Poisson, negative binomial, and lognormal regression analysis.

A procedure was developed for determining work zone speed limits usable during the design or construction phases of a roadway construction project. The procedure classifies work zones by the potential hazard present, as represented by the location of work activities or traffic controls in relation to the traveled way, instead of the prevailing speed of traffic. Research by others showed that accident rates increase with deviation from average speed. The most desirable work zone speed limit policy minimizes the increase in accident rate during the construction period. Accident and speed studies showed that the minimum increase in accident rate and speed variance occurred in work zones with a 16 km/h (10 mph) reduction in the work zone speed limit. In a follow-up study, the procedure was implemented on a trial basis in work zones with speed limits up to and including 105 km/h (65 mph). Research showed that the procedure was implementable and can be used to establish speed limits that maximize traffic safety in work zones. Guidelines were developed for implementing the procedure.

Field surveys of pavement-marking retroreflectivity were conducted throughout the United States. Thirty-two state and local highway agencies participated in the study by identifying pavement-marking sites for measurement. The retroreflectivity of both white and yellow pavement-marking lines of six different marking materials—conventional paint, waterborne paint, epoxy, polyester, thermoplastic, and tape—was measured in the field. Field measurements of pavement-marking retroreflectivity for sites under the jurisdiction of all 32 participating agencies were made in the fall of 1994. Selected sites were remeasured in the spring of 1995 for six of the participating agencies. All field measurements were made with a Retrolux Model 1500 retroreflectometer. A comparison of the fall 1994 and spring 1995 results are presented. Data analyses were conducted to determine the mean, standard deviation, and distribution of the coefficient of retroreflected luminance (retroreflectivity) and the contrast ratio between the retroreflectivity of the pavement markings and that of the adjacent pavement surface by color of line and pavement marking material. However, it was difficult to state any definitive comparisons between material types without knowing the relative ages and manufacturers of the markings, and such data were unavailable. The economic implications of particular threshold values for replacement of pavement markings were also evaluated.

A better understanding of speed variance on rural two-lane highways may assist in addressing driver error associated with highway geometric elements. Previous research has identified a direct relationship between speed variance and accident potential. Speed variance increases are associated with an increase in accidents. Therefore, identifying relationships between speed distribution measures of free-flowing vehicles and roadway characteristics may identify inconsistent roadway features. Horizontal and vertical curves from four geographic regions were identified based on selected criteria, and speed data were collected at the midpoint of the preceding tangent and the curve. Four hypotheses were explored to determine if relationships between speed statistics and geometry could be used to identify design inconsistencies. Statistical tests were conducted to identify relationships between mean speed, speed variance (standard deviation), and roadway characteristics for tangents, horizontal curves, and vertical curves. The findings suggest that speed distribution measures do not appear to be useful in the evaluation of design consistency.

A stability study of 44 organochlorine pesticides (OCPs) and 47 organophosphorus pesticides (OPPs) was conducted. Compounds were spiked into solvent only (hexane-acetone, 1 + 1; methylene chloride-acetone, 1 + 1; methyl tert-butyl ether [MTBE]; and toluene-methanol, 10 + 1), solvent/dry soil suspensions, and solvent/wet soil suspensions (20% water, w/w). Spiked matrixes were heated in closed vessels with microwave energy at 2 temperatures (50° and 145°C) for 5 or 20 min. For comparison and for determination of nitrogen blowdown losses, spiked matrixes that had not been exposed to microwave energy were concentrated by using the blowdown technique and analyzed for each of the spiked compounds. For OCPs, temperature had the most significant effect on compound recovery, followed by matrix. All 3 pairwise comparisons of the 3 matrix types were statistically significant. The solvent factor was also significant, with average recoveries of 97.8% with methylene chloride-acetone, 96.3% with toluene-methanol, 92.8% with hexane-acetone, and 92.3% with MTBE. Of the 6 pairwise comparisons among the 4 solvents, all but 2 - methylene chloride-acetone versus toluene-methanol and hexane-acetone versus MTBE - were statistically significant. For OPPs, temperature also had the most significant effect on recovery, followed by matrix. All 3 pairwise comparisons of the 3 matrix types were statistically significant in the same order as for OCPs. The solvent factor was also significant, but average recoveries - 89.5% with hexane-acetone, 89.4% with methylene chloride-acetone, and 81.5% with either MTBE or toluene-methanol - are in a slightly different order from that for OCPs. Of the 6 pairwise comparisons among the 4 solvents, all but 2 - hexane-acetone versus methylene chloride-acetone and MTBE versus toluene-methanol - were statistically significant. Compounds that appear to degrade under microwave-assisted extraction conditions include TEPP, phosphamidon, trichlorfon, naled, monocrotophos, demeton-O, and demeton-S.

Dengue is an arthropod-borne virus of great public health importance, and control of its mosquito vectors is currently the only available method for prevention. Previous research has suggested that insecticide treated curtains (ITCs) can lower dengue vector infestations in houses. This observational study investigated individual and household-level socio-demographic factors associated with correct and consistent use of ITCs in Iquitos, Peru. A baseline knowledge, attitudes, and practices (KAP) survey was administered to 1,333 study participants, and ITCs were then distributed to 593 households as part of a cluster-randomized trial. Follow up KAP surveys and ITC-monitoring checklists were conducted at 9, 18, and 27 months post-ITC distribution. At 9 months post-distribution, almost 70% of ITCs were hanging properly (e.g. hanging fully extended or tied up), particularly those hung on walls compared to other locations. Proper ITC hanging dropped at 18 months to 45.7%. The odds of hanging ITCs correctly and consistently were significantly greater among those participants who were housewives, knew three or more correct symptoms of dengue and at least one correct treatment for dengue, knew a relative or close friend who had had dengue, had children sleeping under a mosquito net, or perceived a change in the amount of mosquitoes in the home. Additionally, the odds of recommending ITCs in the future were significantly greater among those who perceived a change in the amount of mosquitoes in the home (e.g. perceived the ITCs to be effective). Despite various challenges associated with the sustained effectiveness of the selected ITCs, almost half of the ITCs were still hanging at 18 months, suggesting a feasible vector control strategy for sustained community use.

This report presents guidance for designing the transition from a high-speed rural highway to a lower-speed section, typically approaching a small town. The report includes a methodology for assessing these highway sections and a catalog of potential treatments for addressing problems. It will be useful to geometric designers and traffic engineers responsible for these situations. The TRB website includes two significant products derived from this project. The first is a spreadsheet that can be used to create a straight-line diagram of a site that brings together all of the relevant information for analysis. The second is a Design Guidance document that a transportation agency can adapt to meet its own purposes and needs.

A study was carried out to evaluate the Soxtec extraction of 29 target compounds (7 nitroaromatic compounds, 3 haloethers, 7 chlorinated hydrocarbons, and 12 organochlorine pesticides) from spiked sandy clay loam and clay loam. The study also compared 2 solvent mixtures (hexane–acetone (1 + 1) and methylene chloride–acetone (1 + 1)) and investigated the effect on method recovery of 5 factors (matrix type, spike level, anhydrous sodium sulfate addition, total extraction time, and immersion/ extraction time ratio), their 2-way interactions, and a 3-way interaction (matrix × spike × time). Of the 5 factors investigated, matrix type, spike level, and total extraction time had a significant effect on method performance at the 5% significance level for 16 of the 29 target compounds (4 compounds were not recovered at all, and analysis of variance was not significant at the 5% significance level for 9 compounds). Anhydrous sodium sulfate addition and immersion/extraction time ratio had insignificant effects for all but one of the target compounds. This effect may have been a random occurrence. The data indicate that the 2 solvents performed equally well and 4 compounds were not recovered at all. These 4 compounds were apparently lost from the spiked matrix. Experiments were performed to determine compound recovery at each step in the extraction procedure. Limited experimental work was performed with 64 basic/neutral/acidic compounds spiked onto clay loam and with 3 standard reference materials certified for polynuclear aromatic hydrocarbons. From the 64 compounds spiked onto clay loam at 6 mg/kg, 20 had recoveries of greater than 75%, 22 had recoveries from 50 to 74%, 12 had recoveries from 25 to 49%, and 10 had recoveries of less than 25%.

An environmental monitoring program was established to determine the impact of emissions from resource recovery facilities on the background of PCDDs and PCDFs. Fish, sediment, and soil samples were collected from areas surrounding five resource recovery facilities and one control site. Over 500 samples were analyzed to characterize the environmental levels before and after the resource recovery facilities initiated operations. All samples were analyzed for total tetra- through octahomologs and 2,3,7,8-substituted isomers. The resulting data base was investigated by multivariate statistical techniques (cluster analysis and principal component analysis—PCA) to determine the relationships of the residue levels between sample types and sample locations. The results of the effort demonstrate distinct differences between the sample matrices. The PCA provided a clear separation of patterns for fish versus soil and sediment. In addition, there were distinct groupings of patterns influenced by fish species.

This report provides guidance for the design and application of shoulder and centerline rumble strips as an effective crash reduction measure, while minimizing adverse effects for motorcyclists, bicyclists, and nearby residents. Using the results of previous studies and the research conducted under this project, safety effectiveness estimates were developed for shoulder rumble strips on rural freeways and rural two-lane roads and for centerline rumble strips on rural and urban two-lane roads. The report will be of particular interest to safety practitioners with responsibility for roadway design.

The objective of this study was to evaluate, by pattern recognition techniques, the relationships of PCDDs and PCDFs in human adipose tissue among the analytes themselves and with respect to demographic variables (military/civilian status, age, collection year, race, and geographic region). The conclusions of this study provide a multivariate context for the data and strengthen the conclusions obtained in a univariate study (on 2,3,7,8-TCDD) previously conducted by the Department of Veterans Affairs (VA) and the U.S. Environmental Protection Agency (EPA). From a principal component analysis, the result of most interest, based on a set of matched specimens (36 Vietnam veterans, 79 non-Vietnam veterans, and 80 civilians), is that Vietnam veterans in this study do not exhibit higher levels of 2,3,7,8-TCDD, PCDDs, and PCDFs than the other two groups. Also, cluster analysis of the PCDDs and PCDFs demonstrates that 2,3,7,8-TCDD is not strongly correlated with any of the other analytes, indicating possible differences in exposure routes to these chemicals.

INTRODUCTION: The Strategic Highway Research Program 2 (SHRP 2) Naturalistic Driving Study (NDS) data were used to evaluate gap acceptance behavior of drivers at left-turn lanes with negative, zero, or positive offsets ranging from -29ft to +6ft. The objectives of the study were to develop guidance for the design of offset left-turn lanes used as a safety countermeasure, and to provide insight regarding the use of the NDS data to future users. METHOD: The study included 3350 gaps in opposing traffic evaluated by 145 NDS volunteer drivers and 275 non-NDS drivers at 14 two-way stop-controlled intersections and 44 signalized opposing left-turn pairs. Logistic regression was used to model the critical gap length for drivers as a function of offset, under conditions when their view was either blocked or not by an opposing left-turning driver. RESULTS: The analysis found that the critical gap was longer at left-turn lanes with negative offsets than at those with zero or positive offsets, and was also longer when sight distance was blocked by an opposing left-turning vehicle. Sight distance was much more likely to be restricted by an opposing left-turning vehicle at negative-offset and drivers at those intersections were less likely to accept a gap when an opposing left-turn driver was present. CONCLUSIONS: Longer gap lengths could potentially result in decreased operational efficiency of an intersection. In addition, drivers making left-turns at negative-offset left-turn lanes are, on average, more likely to leave the shortest amount of time between their turn and the arrival of the next opposing through-vehicle, which may present a potential safety concern. PRACTICAL APPLICATIONS: The findings provide guidance for highway designers considering using offset left-turn lanes as a crash countermeasure. This research also highlights the benefits and limitations of using the SHRP 2 NDS data to answer similar research questions. Language: en

A multi-laboratory study was conducted using the U.S. EPA HRGC/HRMS Method 8290 to establish realistic method detection and practical quantification limits for 2,3,7,8-substituted polychlorodibenzo-p-dioxins (PCDDs) and 2,3,7,8-substituted polychlorodibenzofurans (PCDFs) in hazardous waste incinerator scrubber water. The data were required by the U.S. Environmental Protection Agency to establish guidelines for the disposal of PCDD- and PCDF-contaminated scrubber water.