bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimating Cycling Demand for the Journey to Work or Study in West Edinburgh, Scotland
Authors: Ryley Tim
Published: May 2018

Recent transport policy favors cycling, yet it remains to be seen, in a car-dependent society, whether individuals will increase the amount they cycle. With Edinburgh, Scotland, as a case study, discrete choice models, based on random utility theory and using stated preference data, were developed to determine the propensity to cycle and provide an estimate of cycling demand. The data are from a survey of 997 households in West Edinburgh. Respondents in employment or education were split into population segments according to their propensity to cycle. The survey includes a cycling-based stated preference experiment for those traveling to work or study by car, by bus, or on foot. The study is novel in considering the population as a whole, instead of focusing on cyclists, with the modeling results split by population segments. Model estimation shows that cyclist facilities, primarily at the destination but also en route, largely determine the propensity to cycle to work or study.
Sidepath Safety Model
Authors: Petritsch Theodore A. , Landis Bruce W. , Huang Herman F. , Challa Srikalyan
Published: May 2018

The Florida Department of Transportation has sponsored a project to create a method for determining what bicycle facility types provide the best mobility for bicyclists. This project includes, as a component, developing a model that predicts the relative bicycle and motor vehicle crash rates between on-street facilities and shared-use paths located adjacent to a roadway (sidepaths). This paper describes how this sidepath safety model was developed and how it provides important guidance for bicycle facility type selection and sidepath design. The model was developed using operational and geometric data, user counts, and crash data for 21 roadway sections throughout Florida. Four determining factors were found to be significant and are included in the model: sidepath width (possibly a surrogate for user speed), separation of the sidepath from the roadway, posted speed of the roadway, and number of lanes on the adjacent roadway. The sidepath safety model R2 value is .81. The sidepath safety model also serves to quantify some of the concerns expressed in the AASHTO Guide for the Development of Bicycle Facilities. Using this model, transportation planners and engineers will be able to test alternative design treatments to find the safest one for bicyclists. They will also be able to review existing sidepaths that have crash problems to identify potential solutions. This model provides an important new tool for transportation professionals to use when deciding on and designing bicycle facilities.
Urban Mobility and Sustainability in Asia and the Power of Context
Authors: Dimitriou Harry T.
Published: May 2018

This paper provides an overview of recent developments in urban mobility and sustainability in Asia and highlights the significance of understanding the power of context when relevant policy and planning responses to urban transportation challenges are being formulated. The author argues that the challenge of how best to go about enhancing mobility and sustainability in today's urban Asia is clearly a strategic megaissue that requires a thorough appreciation of the dynamics and the influence of the context in which current Asian developments are taking place. Citing Naisbitt, the paper suggests that this is significant, for what is happening in Asia today is by far the most important current development in the world not only for Asians but for the entire planet. The author concludes by citing critical areas in need of research and claiming that the translation of the aims of the sustainable development vision into the urban transportation sector is one of the most problematic and challenging aspects of urban transportation strategy formulation—a task made more difficult by recent forces of globalization that actively encourage a departure from past practices of using transportation infrastructure to bind and unite cities and regions.
Transportation Sector and Supply Chain Performance and Sustainability
Authors: Hendrickson Chris , Cicas Gyorgyi , Matthews H. Scott
Published: May 2018

Indicators of sustainability and environmental performance can be useful for comparing modes, discerning trends, and formulating appropriate policies. This paper considers the performance of U.S. transportation service sectors through use of 1992 and 1997 benchmark input–output models. Use of these models permits assessment of not only the direct performance of the sectors but also the supply chain impacts required for operation of the transportation sectors. Consideration of indirect impacts is critical for assessment of the overall costs and impacts of particular products or services. Six transportation service sectors (air, rail, water, truck, transit, and pipeline) are examined. Economic impact, energy, greenhouse gas emissions, and toxic emissions are examined. The transportation sectors use large amounts of energy, both in total and per dollar of output and on a per service basis. Pipeline and water transportation have particularly large energy requirements per dollar of output, likely reflecting higher energy intensity and lower labor intensity in these modes. Truck transportation is the most energy intensive of the freight transportation modes per ton-mile of service, but it has a trend toward greater energy efficiency. For greenhouse gas emissions, truck, water, and air transportation have the highest emissions per dollar of output. Water transportation freight rates are sufficiently low that emissions on a per ton-mile basis would be correspondingly low. Finally, the supply chain (indirect) toxic emissions per dollar of output are highest for rail and pipeline transportation. There is considerable work to be done to improve the overall sustainability of the different transportation modes.
Strategy Development of Mixed Land Use for Restraining Trip Generation in Taipei City, Taiwan
Authors: Lin Jen-Jia , Hsiao Po-Cheng
Published: May 2018

Many urban developers recommend mixed land use to achieve urban sustainability. One primary reason is that mixed land use reduces trip generation by enhancing multipurpose and pass-by trips and contributing to development efficiency and environmental protection. This study empirically investigated the effect of mixed land use on trip generation by examining 187 traffic analysis zones in Taipei City, Taiwan. Excessive and intense mixed land use increases trip generation, whereas mixed land uses job–housing and retail–job to reduce trip generation. The retail–housing mix increases trip generation. On the basis of empirical findings, this study presents feasible strategies for both adjusting land use regulations and restraining trip generation to move Taipei City toward sustainability.
Improvement of Portable Concrete Barrier Design Using Computational Mechanics
Authors: Bonin Guido , Cantisani Giuseppe , Loprencipe Giuseppe , Ranzo Alessandro
Published: May 2018

Concrete safety barriers have been employed broadly in Italy since the 1980s, particularly on highways and freeways. Safety barrier homologation and design standards have not yet precisely determined specific fields of application or modality of installation, in particular for concrete barriers. Such barriers have sometimes been judged too rigid and, therefore, inadequate to pass crash tests conducted with lightweight vehicles. No changes have been made nor have new designs (cross-section shape and size) been developed in the past 20 years. For all those reasons, the possibility of achieving better overall performance with concrete barriers has been investigated (containment of heavy vehicles and lower accelerations on occupants of lightweight vehicles). One design proposal for these modular systems is to use lightweight concrete and make the element shorter than the one that is usually adopted in Italy. In that way, the higher lateral deformability of the barrier could lead to a greater dissipation of energy, with a resulting decrease in the dynamic effects for users, maintaining a good containment capability in the high-energy crash tests. In this paper, this new design is evaluated with virtual crash tests carried out with LS-DYNA, a finite element code. The model has been previously validated by comparing results of an actual crash test (using the existing Italian concrete barrier design) with the virtual crash test performed under the same conditions.
Assessing Public Response to Freeway Roadsides
Authors: Wolf Kathleen L.
Published: May 2018

Social science methods can be used to assess how the public values context-sensitive solutions. The roadside landscape is a public lands resource that has many functions and provides many benefits. Diverse stakeholders may have varied expectations for roadside design. The urban forest is often a contested component of the urban roadside. Two research surveys based on landscape assessment literature were used to assess and quantify public preferences and perceptions with regard to trees in highspeed and freeway roadsides. One photo questionnaire was distributed in urban areas nationally and the other in Washington State. To elicit public attitudes about visual quality and community image, each survey included design visualizations constructed with digitally edited photographs. Research results were consistent across both studies. Respondents judged images with increasing amounts of roadside vegetation, including trees, to have a higher amenity value. The presence of more extensive community greening was associated with positive consumer inferences and greater willingness to pay for goods and services. There was little variation in responses across respondent demographics. Results provide an empirical basis for flexible highway design and promote planning options for roadside urban forests that address multiple stakeholder interests.
Structured Public Involvement in Context-Sensitive Noise Wall Design Using Casewise Visual Evaluation
Authors: Bailey Keiron , Grossardt Ted
Published: May 2018

The research team extended its structured public involvement (SPI) protocol to the field of context-sensitive noise wall design. Subject to a minimum sound attenuation capacity, noise walls must present a pleasing visual aspect to their user communities including residents, commuters, and others. This paper details the casewise visual evaluation (CAVE) methodology and discusses its application to a context-sensitive noise wall design in Arizona. The research team designed a fuzzy logic nonlinear modeling process, CAVE, that predicts group preference for specific designs even when such designs have not been created. CAVE offers significant advantages over current visual assessment methods such as the visual preference survey. Key noise wall design parameters, including height, topological variation, color value, plant coverage, and plant complexity, were identified by landscape architecture experts. Group preferences were gathered rapidly, anonymously, and fairly from a focus group by using electronic polling technology to evaluate digital images of samples and potential designs. Highest preference was achieved with berm-type walls combining medium-value, smooth stone featuring a basic pattern with undulating topographic variation and a higher degree of plant complexity. A range of nonlinear preference variations in response to changes in value and plant complexity were noted. Other preferred designs were documented for this context-specific Arizona case study. The advantages of the SPI process using CAVE and obstacles in its implementation are discussed.
Storm Water Low-Impact Development, Conventional Structural, and Manufactured Treatment Strategies for Parking Lot Runoff
Authors: Roseen Robert M. , Ballestero Thomas P. , Houle James J. , Avelleneda Pedro , Wildey Robert , Briggs Joshua
Published: May 2018

Eleven storm water treatment strategies were evaluated for water quality performance and storm volume reduction during rainfall–runoff events between September 2004 and August 2005. Evaluated treatment strategies included structural best management practices (BMPs) (swales, retention ponds), low-impact development (LID) designs (treatment wetland, filtration and infiltration designs), and manufactured BMPs (filtration, infiltration, and hydrodynamic separators). Contaminant event mean concentration, performance efficiency, and mass-based first flush were evaluated for storms with varying rainfall–runoff characteristics. Previous research demonstrated that treatment performance of storm water control measures varies widely in response to site-specific contaminant loading functions. For that reason, the devices were tested in parallel, with a single influent source providing uniform loading to all devices. Treatment strategies were uniformly sized to target a rainfall–runoff depth equivalent to 90% of the annual volume of rainfall. Under the parallel and uniformly sized configuration, a normalized performance evaluation is possible because treatment strategies of the same scale receive runoff from events of the same duration, intensity, peak flow, volume, antecedent dry period, and watershed loading. Runoff constituent analyses included total suspended solids (TSS), total petroleum hydrocarbons-diesel, dissolved inorganic nitrogen, and total zinc. Several water quality parameters (temperature, dissolved oxygen, pH, conductivity) were monitored as real-time data. Performance evaluations indicate that several LID designs have removal efficiencies of 80% to 100%. In contrast, conventional structural BMPs perform poorly for most measures except for the pond with TSS. The manufactured systems tended to vary widely and were dependent on the design and contaminant of interest.
Modeling Stated and Revealed Route Choice
Authors: Parkany Emily , Du Jianhe , Aultman-Hall Lisa , Gallagher Ryan
Published: May 2018

Data from Global Positioning System (GPS) route data collection and a survey conducted after data collection obtain both stated and revealed route choice preferences from respondents in Lexington, Kentucky. A subset of the GPS data was analyzed to reveal how much their chosen routes differ from minimum-time routes. The post-GPS data collection survey includes attitudinal data, travel habits, route descriptors, and demographic data as stated by respondents, who identified preferred and nonpreferred peak and off-peak routes between the University of Kentucky and Kentucky International Airport. Summaries are given of travel habit and work- and shopping-related attitudinal variables. The three most commonly identified routes described by participants were analyzed. Binary models are presented for diverters and people who chose the same route during peak and off-peak conditions. One-third of the respondents are diverters and revealed that they deviate more than 10% from minimum travel time routes. Approximately 60% of the sample stated that they would use the same route during peak and off-peak conditions. Attitudinal data, travel habits, route descriptors, and demographic variables were significant in the models and help explain the behavior. The revealed data and the attitudinal data both help explain consistency in route choice.
Estimation of Trip Generation in Mexico City, Mexico, with Spatial Effects and Urban Densities
Authors: Gamas Julia A. , Anderson William P. , Pastor Carmen
Published: May 2018

Coefficients for work, shopping, and school trip generation models are presented for Mexico City, Mexico. These results were generated for the first stage of a four-stage model that was built for the city for 1994, the most recent year for which data are available. Because no complete urban transportation model that incorporated behavioral aspects of urban travel could be found at the time of this study, these estimates are the first results of their kind to be published in the literature for recent years. Attempts to account for spatial processes have not been undertaken as a general rule in transportation modeling. Therefore, there is a bias in coefficients estimated without taking spatial autocorrelation into account when spatially defined data are used. To address this peculiarity, spatial regression was used instead of the traditional ordinary least-squares estimation method. Trip generation is normally defined on a per capita or per household basis. Surprisingly, these results show that models specified for trip generation densities (trips per unit of area) were as good as or better than more traditional specifications in explaining trip generation. The implication of these findings could potentially be of importance in other cities.
Agent-Based Demand-Modeling Framework for Large-Scale Microsimulations
Authors: Balmer Michael , Axhausen Kay W. , Nagel Kai
Published: May 2018

Microsimulation is becoming increasingly important in traffic demand modeling. The major advantage over traditional four-step models is the ability to simulate each traveler individually. Decision-making processes can be included for each individual. Traffic demand is the result of the different decisions made by individuals; these decisions lead to plans that the individuals then try to optimize. Therefore, such microsimulation models need appropriate initial demand patterns for all given individuals. The challenge is to create individual demand patterns out of general input data. In practice, there is a large variety of input data, which can differ in quality, spatial resolution, purpose, and other characteristics. The challenge for a flexible demand-modeling framework is to combine the various data types to produce individual demand patterns. In addition, the modeling framework has to define precise interfaces to provide portability to other models, programs, and frameworks, and it should be suitable for large-scale applications that use many millions of individuals. Because the model has to be adaptable to the given input data, the framework needs to be easily extensible with new algorithms and models. The presented demand-modeling framework for large-scale scenarios fulfils all these requirements. By modeling the demand for two different scenarios (Zurich, Switzerland, and the German states of Berlin and Brandenburg), the framework shows its flexibility in aspects of diverse input data, interfaces to third-party products, spatial resolution, and last but not least, the modeling process itself.
From Average Travel Time Budgets to Daily Travel Time Distributions
Authors: Hubert Jean-Paul , Toint Philippe L.
Published: May 2018

An analysis of three travel surveys (in Belgium, France, and Great Britain) is used to investigate two conjectures by Kölbl and Helbing. The first one suggests a relation between mode choice and human energy expenditure for travel, which is assumed to be constant in time and space. The second one is the assumption that the distribution form of daily travel time can be derived from an entropy maximization model. The analysis shows the link with energy expenditure to be questionable but also provides alternative views of travel time analysis. In particular, the distribution of daily travel time is shown to be well approximated by three different models. Weekly travel time expenditure is also shown to present different characteristics than the more commonly used daily ones, reinforcing the argument for inclusion of weekly regularities in travel behavior analysis and modeling.
Valuation of Different Types of Travel Time Reliability in Route Choice
Authors: Bogers Enide A. I. , Viti Francesco , Hoogendoorn Serge P. , Van Zuylen Henk J.
Published: May 2018

Travelers sometimes experience extremely long travel times on a route. The Travel Simulator Laboratory (TSL) of Delft University of Technology is used to study the effect of these extreme experiences on route choice. The TSL allows for a completely controlled experiment and good research methodology. It is hypothesized that together with the average travel time and the variance, the most extreme travel times experienced influence a person's perception of the attractiveness of the route. Travel information is assumed to be able to alter this perception. Data from 2,500 respondents were gathered with the TSL. Route switching behavior after a regular experience and after an extreme experience was analyzed. People switched routes after an extreme experience significantly more often when the information that they received before the route choice was wrong than they did when it was correct. Moreover, travelers clearly preferred a route that is sometimes bad and most of the time good over a route that is symmetrically distributed with a large variance and thus less predictable. Furthermore, mixed multinomial logit models for panel data were estimated. Expected travel time, expected variance, and worst experience were found to be negatively valued. The posed hypothesis seems to be correct on a qualitative level and proves to be a promising field of research. However, much work still has to be done on the mathematical model to draw more specific conclusions on a quantitative level as well.
Network Underpinnings of Behavioral Travel Demand
Authors: Burnett Pat , Pongou Roland
Published: May 2018

The connection between behavioral travel demand models and the geometry of the metropolitan transport network is described, followed by the consideration of fractal geometry as a means of studying a wide range of phenomena, including highway networks. Then a fractal analysis is undertaken of the classes of roads in metropolitan Boston, Massachusetts. This analysis yields one exemplary new insight into travel behavior: a phase shift between highway systems and major and local road systems indicating different trip purposes and scales for analysis.
Carsharing in North America
Authors: Shaheen Susan A. , Cohen Adam P. , Roberts J. Darius
Published: May 2018

Carsharing provides members access to a fleet of autos for short-term use throughout the day, reducing the need for one or more personal vehicles. More than 10 years ago, carsharing operators began to appear in North America. Since 1994, 40 programs have been deployed—28 are operating in 36 urban areas, and 12 are now defunct. Another four are planned to launch in the next year. Carsharing growth potential in North America is examined on the basis of a survey of 26 existing organizations conducted from April to July 2005. Since the mid-1990s, the number of members and vehicles supported by carsharing in the United States and Canada has continued to grow, despite program closures. The three largest providers in the United States and Canada both support 94% of the total carsharing membership. Growth potential in major metropolitan regions is estimated at 10% of individuals over the age of 21 in North America. Although carsharing continues to gain popularity and market share, the authors conclude that increased carsharing education, impact evaluation, and supportive policy approaches, including mainstreaming carsharing as a transportation strategy, would aid the ongoing expansion and development of this alternative to private vehicle ownership.
Methodology for Evaluating Mobile Source Air Toxic Emissions
Authors: Claggett Michael , Miller Terry L.
Published: May 2018

With the final update to its on-road mobile source emission factor model, MOBILE6.2, the U.S. Environmental Protection Agency (EPA) added capabilities for predicting emissions factors for a select group of mobile source air toxics (MSATs), commonly referred to as the six priority MSATs. These are acetaldehyde, acrolein, benzene, 1,3-butadiene, diesel particulate matter, and formaldehyde. This paper describes a methodology for computing and evaluating emissions of MSATs among a group of transportation project alternatives. When the future options for upgrading a transportation corridor are evaluated, the major mitigating factor in reducing MSAT emissions is the implementation of EPA's new motor vehicle emission control standards. Substantial decreases in MSAT emissions will be realized from a current base year through an estimated time of completion for a planned upgrading project and its design year some 25 years in the future. Even when anticipated increases in vehicle miles of travel and varying degrees of efficiency of vehicle operation are accounted for, total MSAT emissions are predicted to decline more than 61% from 2005 to 2030. Although benzene emissions are predicted to decline more than 35%, emissions of diesel particulate matter are predicted to decline considerably more (i.e., >92%). The ability to discern remarkable differences in MSAT emissions among transportation alternatives is difficult, given the uncertainties associated with the forecasting of travel activity and air emissions 25 years or more into the future. In this hypothetical congestion mitigation project, differences in MSAT emissions between the build and no-action alternatives range from more than 6% to less than 16%.
Air Quality Measurements inside Diesel Truck Cabs during Long-Term Idling
Authors: Doraiswamy Prakash , Davis Wayne T. , Miller Terry L. , Lam Nicky , Bubbosh Paul
Published: May 2018

The overall objective of this study was to measure the air pollutant concentrations inside and outside of diesel truck cabs under conditions of extended idling at a truck stop. The measurements were conducted under different modes of engine and air conditioner operation at different times of day and night. One-hour average concentrations of fine particulate matter, nitrogen oxides, and carbon monoxide were measured. All trucks showed some level of self-contamination of in-cab air quality from engine emissions during idling. Some trucks showed significantly higher in-cab concentrations than outside concentrations, indicating engine compartment leaks into the cab. Other trucks showed in-cab concentrations similar to or even lower than outside concentrations but showed higher outside and in-cab concentrations during engine idling than when the engine was turned off. In these cases, truck emissions raised the outside concentrations, which then migrated into the truck cab. Carbon monoxide concentrations measured in the cab were insignificant compared with relevant air quality standards, but fine particulate matter and nitrogen dioxide concentrations were higher than some U.S. Environmental Protection Agency ambient air quality standards. None of the measurements was higher than Occupational Safety and Health Administration or National Institute for Occupational Safety and Health air quality standards.
Comparison of Real-World Fuel use and Emissions for Dump Trucks Fueled with B20 Biodiesel versus Petroleum Diesel
Authors: Frey H. Christopher , Kim Kangwook
Published: May 2018

Diesel vehicles contribute substantially to the emissions of nitrogen oxides (NOx), an ozone precursor, and to particulate matter. Real-world, in-use, on-road emissions of selected diesel vehicles fueled with B20 biodiesel and petroleum diesel were measured during normal duty cycles by using a portable emissions measurement system. Four categories of dump trucks were tested: ( a) trucks with a single rear axle and Tier 1 engines, ( b) trucks with a single rear axle and Tier 2 engines, ( c) tandem-rear-axle trucks with Tier 1 engines, and ( d) tandem-rear-axle trucks with Tier 2 engines. Each vehicle was tested for 1 day while it was operating on B20 biodiesel fuel and for 1 day while it was operating on petroleum diesel fuel. On average, there were 4.5 duty cycles per day. Each duty cycle can be represented as a combination of nine operating modes (idle, three levels of acceleration, three levels of cruise, deceleration, and dumping). The average fuel flow and emissions rates on a mass-per-time basis varied substantially among the operating modes. The key factors responsible for the observed variability in fuel use and emissions included operating mode, vehicle size, engine type, vehicle weight, and fuel. Average fuel use and CO2 emissions rates were approximately the same for the two fuels; but the average emissions rates of NO, CO, hydrocarbons, and particulate matter PM decreased by 10%, 11%, 22%, and 10%, respectively, for B20 biodiesel fuel compared with those for petroleum diesel fuel. The decrease in NO emissions observed was different from the results reported by others, based on engine dynamometer testing. The difference may be because of the effect of real-world duty cycles versus the standardized test procedures used in dynamometer testing, and further work is required to determine whether the ratio of NO to total NOx is affected by the duty cycle.
Driver and Road Type Effects on Light-Duty Gas and Particulate Emissions
Authors: Jackson Eric , Qu Yingge , Holmén Britt A. , Aultman-Hall Lisa
Published: May 2018

An instrumented minivan on a 30-mi (48-km) test route was used to measure second-by-second vehicle operating characteristics as well as tailpipe particulate and gas emissions. The research objectives were ( a) to quantify the variability of gas and particulate emissions between 12 drivers and ( b) to measure the relative emissions levels on freeways, signalized arterials, rural two-lane arterials, and local roads. The results reaffirm that individual drivers significantly affect emissions levels. All emissions concentrations were also systematically related to road type. Furthermore, drivers could be grouped by emissions level, but these groupings differed by pollutant and by road type. More data are needed to elucidate driver–road type interactions and to characterize the regional driver pool for more robust microscale emissions models. The relative importance of driver type compared with the importance of other factors known to affect emissions needs to be quantified. Finally, two key issues were identified as affecting the accuracy of instantaneous emissions measurements: instrument response time effects on data alignment and accurate quantification of the full range of on-road exhaust flow rates.
Speed- and Facility-Specific Emission Estimates for On-Road Light-Duty Vehicles on the Basis of Real-World Speed Profiles
Authors: Frey H. Christopher , Rouphail Nagui M. , Zhai Haibo
Published: May 2018

Estimating the emissions consequences of surface transportation operations is a complex process. Decision makers need to quantify the air quality impacts of transportation improvements aimed at reducing congestion on the surface street network. This often requires the coupling of transportation and emissions models in ways that are sometimes incompatible. For example, most macroscopic transportation demand and land use models, such as TransCAD, TranPlan, and TRANUS, produce average link speed and link vehicle miles traveled (VMT) by vehicle and road class. These values are subsequently used to estimate link-based emissions by using standard emissions models such as the U.S. Environmental Protection Agency's MOBILE6 model. In contrast, recent research with portable emissions monitoring systems indicates that emissions are not directly proportional to VMT but are episodic in nature, with high-emissions events coinciding with periods of high acceleration and speed. This research represents an attempt to bridge the gap in transportation and emissions models through the use of the real-world distributions of vehicle-specific power bins that are associated with average link speeds for various road classes. A successful effort in this direction would extend the use of transportation models to improve emissions estimation by using the limited output produced by such models. In addition, the variability of emissions and emissions rates over average speeds for a given facility type is explored, and recommendations are made to extend the methodology to additional facility types.
Proposed Road Pollution Alert System Based on Lagrangian Wall Model
Authors: Marquez Leorey , Lilley William , Cope Martin , Smith Nariida
Published: May 2018

Despite significant improvements in fuel and engine technology, road traffic remains a major source of air pollutants, such as oxides of nitrogen, CO, particulate matter, and volatile organic compounds. Many recent studies have demonstrated associations between traffic-related air pollution and the adverse effects of exposure to traffic-related air pollution in a wide variety of situations. This paper describes the components of a proposed road pollution modeling-and-alert system that can be deployed by local authorities on sections of roads that are under the continuous risk of exceeding thresholds of acceptable air quality. The system features the use of real-time traffic data from intelligent transportation systems and related sources; a power-based model for the calculation of emissions that takes into account the driving mode of the vehicle as well as characteristics of the road segment; a Lagrangian wall model (LWM) to simulate the dispersion of pollutants from different sources; and an alert-and-response system that will need further input from government authorities, industry, and the community. The ability to combine emissions estimates from a power-based motor vehicle emissions model with the LWM dispersion and chemical transformation capabilities significantly enhances the capacity to minimize population exposure and reduce health impacts of pollution from particular roads of interest. This paper discusses development of the LWM and summarizes outcomes of a verification study performed with the California Department of Transportation Highway 99 tracer dispersion data set. It also presents results of a case study performed to demonstrate capabilities of the LWM.
Variability of Personal Exposure to Fine Particulates for Urban Commuters inside Automobiles
Authors: Greaves Stephen P.
Published: May 2018

Over the past decade, a growing body of evidence has emerged to suggest a causal link between short-duration exposure to elevated levels of fine airborne particulate matter and adverse health consequences. It is believed that much of this peak exposure occurs in transport microenvironments both because of the higher levels of fine particulates associated with road traffic, primarily from diesel exhaust emissions, and because of the significant amount of time people spend traveling (for instance, 80 min/day for residents of Sydney, Australia). Although previous studies have suggested substantial differences in exposure rates because of factors such as choice of mode, route, in-vehicle conditions, and meteorological factors, current measurement techniques have restricted insights to fairly coarse sampling intervals (e.g., every hour and every trip). As a consequence, little tangible evidence is available on how pollution varies over a trip and, most critically, about the location, duration, and magnitude of peak excursions within trips. With these issues in mind, this current paper reports on a study in which capabilities of Global Positioning Systems and real-time particle monitors are combined to address the problem for an urban commute in Sydney. This ability to reference pollution data precisely and spatially, and to identify hot spots in particular, holds considerable promise for both understanding and reporting of such data in the future.
Two-Lane Rural Highways
Authors: Brilon Werner , Weiser Frank
Published: May 2018

A series of investigations was performed in Germany to understand traffic operations on two-lane highways and to make the experiences accessible for traffic performance analysis in practice. As an initial step, traffic flow on several sections of rural two-lane highways was observed. The observations led to a set of empirical speed–flow relationships for highways of different characteristics. On the basis of these results, a microscopic simulation model was calibrated. The model was able to produce a comprehensive set of speed–flow diagrams for all kinds of rural two-lane highways. The diagrams revealed several unexpected properties: a concave shape and nonlinear influences of the external geometric parameters such as curvature or gradients. The simulated results were then approximated by a simple quadratic equation with the parameters depending on geometric conditions and the percentage of heavy vehicles. Thus, the speed–flow diagrams were obtained for the German Highway Capacity Manual. In this case density was used as a measure of effectiveness for the definition of levels of service. This guideline has been used successfully for 3 years.
Peer-to-Peer Priority Signal Control Strategy in a Connected Vehicle Environment
Authors: Beak Byungho , Zamanipour Mehdi , Head K. Larry , Leonard Blaine
Published: May 2018

This paper presents a methodology that enhances the priority signal control model in the multi-modal intelligent traffic signal system (MMITSS). To overcome the range limit of vehicle to infrastructure (V2I) and the intersection geometry message (MAP) distance limits, peer-to-peer intersection communications are utilized to send priority requests from adjacent intersections. Through integrated communication, the peer priority control strategy can create a signal plan for prioritized vehicles that considers longer term (headway) arrival times. Transit vehicles are considered in this study. The longer-term signal plan provides a flexible signal schedule that allows local phase actuation. The peer priority strategy is effective in reducing the number of stops and delay for priority eligible vehicles, while minimizing the negative impact on regular vehicles. To validate the strategy, a simulation experiment was designed to compare fully actuated control, coordination, and MMITSS priority control using two different VISSIM simulation networks (Arizona and Utah). The result shows that the peer-to-peer long term planning strategy can improve transit service reliability while limiting the adverse impact on other traffic.
Traffic Operations on Rural Two-Lane Highways: A Review on Performance Measures and Indicators
Authors: Al-Kaisy Ahmed , Jafari Amirhossein , Washburn Scott , Lutinnen Tapio , Dowling Richard
Published: May 2018

Two- lane highways constitute a large proportion of the highway system in the United States, particularly in rural areas. Performance evaluation on those highways is the basis for planning, upgrade, and improvement programs. Such evaluations are conducted using performance measures that should ideally be correlated to performance determinants on those highways. Unlike other highway facilities, two-lane highway performance is notably affected by the platooning phenomenon, which is believed to be a function of traffic level and passing opportunities. Over the last couple of decades, several studies have addressed performance measures on two-lane highways, and are mainly driven by the reported limitations of the current measures used by the Highway Capacity Manual (HCM). This review aims to summarize the performance measures that have been published in the literature or used in practice both in the United States and abroad. The review starts with an historical overview of the HCM performance measures since its inception in 1950. It then discusses the most important criteria for measures to be more effective in describing performance, before presenting the review results for measures that have been proposed in literature or reported as being used in practice. Finally, a subjective assessment of all performance measures against the set of criteria outlined in the article is presented. The review presented in this paper provides information that is valuable for practitioners and researchers in understating the alternative measures for assessing performance on two-lane highways, and the limitations and merits associated with those measures.
Safety Evaluation of Destination Lighting Treatment at Stop Controlled Cross-Intersections
Authors: Goswamy Amrita , Hallmark Shauna , Litteral Theresa , Pawlovich Michael
Published: May 2018

Intersection crashes during nighttime hours may occur because of poor driver visual cognition of conflicting traffic or intersection presence. In rural areas, the only source of lighting is typically provided by vehicle headlights. Roadway lighting enhances driver recognition of intersection presence and visibility of signs and markings. Destination lighting provides some illumination for the intersection but is not intended to fully illuminate all approaches. Destination lighting has been widely used in Iowa but the effectiveness has not been well documented. This study, therefore, sought to evaluate the effect on safety of destination lighting at rural intersections. As part of an extensive data collection effort, locations with destination/street lighting were gathered with the assistance of several state agencies. After manual selection of a similar number of control intersections, propensity score matching using the caliper width technique was used to match 245 treatments with 245 control sites. Negative binomial regression was used to evaluate crash frequency data. The presence of destination lighting at stop-controlled cross-intersections generally reduced the night-to-day crash ratio by 19%. The presence of treatment or destination lighting was associated with a 33%–39% increase in daytime crashes across all models but was associated with an 18%–33% reduction in nighttime crashes. Injuries in nighttime crashes decreased by 24% and total nighttime crashes reduced by 33%. Property damage crashes were reduced by 18%.
Comparing and contrasting corrected errors at four newspapers
Authors: Hettinga Kirstie , Appelman Alyssa , Otmar Christopher , Posada Alesandria , Thompson Anne
Published: May 2018

A content analysis of corrections (N = 507) from four influential newspapers—the New York Times, the Washington Post, The Wall Street Journal and the Los Angeles Times—shows that they correct errors similar to each other in terms of location, type, impact and objectivity. Results are interpreted through democratic theory and are used to suggest ways for copy editors to most effectively proofread and fact-check.
Off-Hours Admissions and Mortality in PICU Without 24-Hour Onsite Intensivist Coverage
Authors: Thabet Farah Chedly , alHaffaf Faisal Ahmed , Bougmiza Iheb Mohamed , Bafaqih Hend Ali , Chehab May Said , alMohaimeed Sulaiman Abdulkareem
Published: May 2018

Objective:

To evaluate whether the off-hours admission has any effect on risk-adjusted mortality and length of stay for nonelective patients admitted to a pediatric intensive care unit (PICU) without 24-hour in-house intensivist coverage.

Design:

Prospective cohort study.

Setting:

A 34-bed tertiary PICU.

Patients:

All consecutive nonelective patients aged 0 to 14 years admitted from January 2012 to June 2015.

Measurements and Main Results:

A total of 1254 patients were nonelectively admitted to the PICU. They were categorized according to time of PICU admission as either office hours (07:30 to 16:30 from Sunday to Thursday and whenever an intensivist is present in the ICU) or off-hours (16:30 to 07:30, Friday and Saturday and public holidays). Standardized mortality rates (SMRs) of patients admitted during off-hours were compared to SMRs of patients admitted during office hours using Pediatric Risk of Mortality (PRISM2) score. Multivariate logistic regression was used to assess the effect of time of admission on outcome after adjustment for severity of illness using the PRISM2. The mortality observed in the office-hours group was 9.4% and in the off-hours group was 8.1%. The PRISM2-based SMR was 0.83 (95% confidence interval [CI]: 0.43-1.47) for the office-hours group and 0.68 (95% CI: 0.34-1.36) for the off-hours group. No significant differences in length of ICU stay or duration of mechanical ventilation were observed between patients admitted during off-hours and those admitted during office hours. In the logistic regression model, off-hours admission was not significantly associated with a higher mortality (odds ratio: 0.85, 95% CI: 0.57-1.27; P = .44).

Conclusions:

The absence of an in-house intensivist during off-hours is not associated with an increase in mortality, length of ICU stay, or duration of mechanical ventilation for patients admitted to our pediatric ICU.
Social Support for Breastfeeding in the Era of mHealth: A Content Analysis
Authors: Schindler-Ruwisch Jennifer M. , Roess Amira , Robert Rebecca C. , Napolitano Melissa A. , Chiang Shawn
Published: May 2018

Background:

Several barriers to successful breastfeeding exist, including a lack of support from peers or professionals. With the emergence of mobile health (mHealth) tools to provide additional breastfeeding support, a more thorough review of social support resources was needed.

Research Aim:

The aim of this study was to determine mHealth breastfeeding support resources and characterize the type of social support they provide.

Methods:

A content analysis of mHealth programs ( n = 65), including text messaging ( n = 12) and mobile applications ( n = 53), was conducted on the basis of searches of the iTunes and Google Play stores ( n = 50) and PubMed, the Cumulative Index of Nursing and Allied Health, and American Business Information/INFORM Complete Plus ( n = 15). Results were then dual-coded for key characteristics and types of support provided.

Results:

Thirty-eight apps (76%) were free to users, 14 (28%) were offered in a variety of languages, and 47 (94%) provided informational support. The mobile applications were targeted largely to postpartum women, focused on breastfeeding duration, and included troubleshooting information. Mobile applications often included media components ( n = 12 [24%]); few were tailored or personalized ( n = 5 [10%]) and interactive ( n = 15 [30%]). Text-messaging programs were available in a variety of countries ( n = 7 [58%]) and provided mostly informational support ( n = 5 [42%]), were pro-breastfeeding ( n = 12 [100%]), were targeted to both pregnant and postpartum women ( n = 6 [50%]), focused on both breastfeeding initiation and duration ( n = 9 [75%]), and had two-way interactivity ( n = 6 [50%]) and personalization ( n = 5 [42%]).

Conclusions:

Although freely available mobile applications and text-messaging programs exist, with potential for wide reach, the majority provide only informational support. These programs would benefit from additional study of their usefulness.
Revision Lingual Frenotomy Improves Patient-Reported Breastfeeding Outcomes: A Prospective Cohort Study
Authors: Ghaheri Bobak A. , Cole Melissa , Mace Jess C.
Published: May 2018

Background:

Lingual frenotomy improves patient-reported outcome measures, including infant reflux and maternal nipple pain, and prolongs the nursing relationship; however, many mother–infant dyads continue to experience breastfeeding difficulty despite having had a frenotomy.

Research aim:

The aim of this study was to determine how incomplete release of the tethered lingual frenulum may result in persistent breastfeeding difficulties.

Methods:

A one-group, observational, prospective cohort study was conducted. The sample consisted of breastfeeding mother–infant (0-9 months of age) dyads ( N = 54) after the mothers self-elected completion lingual frenotomy and/or maxillary labial frenectomy following prior lingual frenotomy performed elsewhere. Participants completed surveys preoperatively, 1-week postoperatively, and 1-month postoperatively consisting of the Breastfeeding Self-Efficacy Scale–Short-Form (BSES-SF), Visual Analog Scale (VAS) for nipple pain severity, and the Revised Infant Gastroesophageal Reflux Questionnaire (I-GERQ-R).

Results:

Significant postoperative improvements were reported between mean preoperative scores compared with 1-week and 1-month scores of the BSES-SF, F(2) = 41.2, p < .001; the I-GERQ-R, F(2) = 22.7, p < .001; and VAS pain scale, F(2) = 46.1, p < .001.

Conclusion:

We demonstrated that besides nipple pain, measures of infant reflux symptoms and maternal breastfeeding self-confidence can improve following full release of the lingual frenulum. Additionally, a patient population was identified that could benefit from increased scrutiny of infant tongue function when initial frenotomy fails to improve breastfeeding symptoms.