bluuebunny/crossref_metadata_2025 huggingface dataset:
Freight Components in Louisiana's Statewide Intermodal Transportation Plan
Authors: Apffel Charles , Jayawardana Jay , Ashar Asaf , Horn Kevin , McLaughlin Robert , Hochstein Anatoly
Published: January 2019

Planning procedures used in addressing freight components for Louisiana's statewide intermodal transportation plan are described. The effort was unprecedented in Louisiana, and the experience can be applied in other states. User and provider involvement, demand analysis, network analysis, and recommended policies and programs for the water, rail, and intermodal freight components are described. Although an assessment of system capacity remained at the core of the effort, low cost improvements in system performance were also addressed. Analysis of future demand for facility capacity was performed in three steps. First, baseline historical flow patterns, including volume and modal orientation of inbound, outbound, intrastate, and transhipped movements, were established through extensive processing of data obtained. Second, volume forecasts for 11 major commodity groups were made for each of three possible growth scenarios. Third, a strategic outlook was developed for selected commodity types to examine market structure, productivity trends, and the competitive position of transportation providers in the state. Network capacity analysis identified few weak links or bottlenecks in the state's main line waterway and railroad networks. A stock and flow approach was taken to measure the capacity of various types of cargo transfer terminals. A comparative analysis of maritime terminal productivity and cost was performed to assess the competitiveness of ports in Louisiana. An extensive survey of the physical, operating, and institutional characteristics of terminal roadway and railroad access links was made.
Multimodal Transportation Planning Tool for Rural Areas in Georgia
Authors: Mazur George D. , Sarasua Wayne , Daniel Janice
Published: January 2019

A process under development at the Georgia Institute of Technology to standardize, enhance, and automate planning and project evaluation for transportation projects in rural Georgia is described. The process will incorporate current statewide planning techniques in use at the Georgia Department of Transportation (GDOT) and additional sketch planning techniques that will use existing GDOT data. The purpose of this multimodal transportation planning tool (MMTPT) is to aid GDOT and local agencies in evaluating transportation requirements of rural areas and potential implementation constraints early in the planning process. The tool will include a system-level component to develop a prioritized list of projects by mode for a county and a project-level component to perform more detailed evaluations of roadway project alternatives and multimodal enhancements. The MMTPT will operate in a computerized hybrid system that uses expert system and conventional algorithmic programming techniques. Although organizational, management, and funding constraints that discourage multimodal planning are not overcome, the tool addresses the shortage of analytical planning techniques.
Developing Management Systems for Statewide Transportation Planning: Early Lessons
Authors: Kish Steven J. , Meyer Michael D.
Published: January 2019

The implementation of two management systems, the intermodal and public transportation management systems, in the Georgia Department of Transportation is examined. Early experience with this implementation suggests that key elements of an implementation strategy are characteristic of success in such an organizational environment. These include establishing organizational responsibilities, establishing guidance principles, assessing the organizational planning and decision-making processes, assessing the environmental context for the management system, establishing an implementation strategy that has tangible intermediate results, and identifying an agency “champion” for implementation. The challenge of implementing management systems within any organization is understanding the decision-making process and the information needs of the agency decision makers.
Citizen Concerns and Public Awareness: Metrication Examples
Authors: Turner Daniel S. , Lindly Jay K. , Chester Rodney N.
Published: January 2019

The United States is in the process of implementing the metric system. U.S. highway agencies are among the leaders in this effort. One troublesome aspect of being in the lead is that there appears to be no coordinated national public relations program to set the stage for the conversion. Several metric conversion experiences, those in Canada, Australia, and Great Britain, an Ohio research project, and the recent FHWA rule making for sign conversion, are reviewed to determine public awareness and citizen concerns. The conclusions drawn from those studies reinforce the need for an overall, well-coordinated, strong national public education program. Examples illustrate that success is possible (Canada and Australia) with such a program, but without it metrication can grind to an incomplete halt (Great Britain). Currently, the U.S. experience seems to most closely resemble the British metric conversion experience.
Highway Metrication: Approaching the General Public
Authors: Underwood Gerald T.
Published: January 2019

Commendable progress has been made in recent years in the application of metric dimensions and standards to the design and construction of U.S. road and highway systems and affected industries. The metrication experience of other U.S. industries has clearly shown that the rates of assimilation and adaptation to a change in measurement system correlate closely with the extent of technical background of those directly involved. In less than a decade and with very limited difficulty, the entire U.S. automobile industry changed to the use of the metric system throughout its vast network of design, manufacturing, and service organizations. Remarkably, that elaborate changeover yielded almost no public outcry because of the excellent strategy used by the industry. Use of the metric system was given a very low level of publicity because very few retail customers were affected. Beyond p-metric tire designations and mile-kilometer speed indications, few consumers were aware then, or are concerned today, that their automobiles, like all others worldwide, are manufactured entirely to metric dimensions and standards. A similar strategy is now being effectively pursued in that part of the construction industry responsible for major buildings. For all the same reasons and to the fullest extent possible, that strategy should be continued in the metrication of U.S. highway design, construction, and systems management.
Downtown Traffic and Parking Needs Related to Downtown Economic Trends
Authors: Edwards John D.
Published: January 2019

Since the 1950s the economic trends for America's small downtowns (populations less than 50,000) have been characterized by reduced retail sales, vacant stores and buildings, reduced residential occupancy, reduced employment, and reduced assessed valuation. Most downtowns experiencing these conditions have reduced traffic as well. Downtown economic trends are inextricably reflected in traffic and parking needs. The research method used is a comparison of case study floor space, employment, assessed valuation, and traffic data for 1960 to 1970 with data collected from 1990 to 1995. The basic premise to be verified is that decreases in occupied floor space, employment, and residential units in the downtown area will be reflected in reduced traffic on Main Street and that reduced traffic and a comparable reduction in parking demand will allow the design of a more pedestrian-friendly downtown area, which in turn will encourage downtown revitalization. The research discusses trends in population growth and commuting downtown. Also covered are related comparisons of traffic volume trends on Main Street as well as changes in parking demand characteristics. Conclusions drawn from the research indicate that strategies for parking should be changed; that in most small downtowns (populations less than 50,000) congestion is not a significant problem; and that traffic-calming techniques should be practiced.
Extending DRAM Model: Theory-Practice Nexus
Authors: Putman Stephen H.
Published: January 2019

The DRAM and EMPAL models of household and employment location and land use, respectively, have seen numerous applications by regional planning agencies and metropolitan planning organizations. One reason for this is that compared with other location and land use models, they are relatively easy to use. The theoretical structure of these models is that of aggregate multinomial logit. They are representations of choice probability means for household types and employment types, with their structures being derived from location surplus formulations. In operation the parameters of these models’ equations can most easily be estimated by use of a nonlinear programming formulation rather than by logit regression. Use of this technique allows a great simplification in the data requirements for calibration. In addition, this technique permits testing of alternative or auxiliary (to the standard model structures) variables in the model attractiveness formulations. The development of the models’ equation structures is described first. The problems and techniques of calibration-estimation of the equations’ parameters are then described. Finally, several experiments in model augmentation undertaken by agency staff as a part of ongoing model implementation efforts are described. These experiments demonstrate the flexibility of the structure for both application and experiment.
Transit-Oriented Development in the Sun Belt
Authors: Messenger Todd , Ewing Reid
Published: January 2019

Although existing transit-oriented development manuals are chided for lack of empirical foundation and what is known from the empirical literature about the relationship between land use-urban design and transit ridership is reviewed. More is needed to be known about this relationship. What was done in the first of two studies of transit ridership in Dade County is reported and what was learned of relevance to transit-oriented development is summarized. Bus mode share by place of residence proved primarily dependent on automobile ownership and secondarily on jobs-housing balance and bus service frequency. Automobile ownership, in turn, proved dependent on household income, overall density, and transit access to downtown. Thus, three types of variables—sociodemographic, land use, and transit service—were found to affect bus use through a web of interrelationships. Likewise, bus mode share by place of work proved dependent on the cost of parking, transit access to downtown, and overall density, again through a web of interrelationships. By using equations thus derived, densities required to support different levels of transit service and productivity were computed. It takes 8.4 dwellings per acre to support 25-min headways at the transit operator's minimum productivity level and 19.4 dwellings per acre at the systemwide average productivity. As household incomes, parking costs, or other local conditions vary from the county average, required densities rise or fall accordingly. In any event, densities are likely to be well above the old industry standard of seven units per acre.
Assessment of Potential Effect on Travel of Telecommuting in Singapore
Authors: Olszewski Piotr , Lam Soi-Hoi
Published: January 2019

Recently, there has been an increased interest in telecommuting in Singapore. A survey of 630 companies indicated that although only 1.7 percent have a formal telecommuting arrangement, 3.6 percent plan to introduce it in the near future and an additional 21.6 percent would like to explore the concept. Singapore has many of the prerequisites for telecommuting to become popular: a high and growing proportion of information workers, an excellent telecommunications infrastructure, and a large installed base of personal computers. To assess the potential effects of telecommuting, a stratified travel demand analysis was performed by using travel characteristics specific to different groups of information workers. The results indicate that a considerable reduction in vehicle trips to work can be achieved if telecommuting becomes more popular. The potential reduction is up to 4.9 percent in the year 2005 and up to 11.2 percent in 2010. The corresponding savings in distance traveled are in the range of 512 000 to 1 309 000 vehicle-km. Although these predictions have a high degree of uncertainty, they indicate that telecommuting has a potential to provide significant travel reduction benefits in Singapore and should be used as a travel demand management tool.
Modeling the Process of Adoption of Telecommuting: Comprehensive Framework
Authors: Bernardino Adriana , Ben-Akiva Moshe
Published: January 2019

A comprehensive model of the telecommuting adoption process, incorporating employer and employee perspectives, is developed. A probabilistic modeling approach is taken. The employer decision to offer a telecommuting program is modeled as a function of motivations and constraints and of the perceived impacts of telecommuting on the organization's productivity and costs. The employee decision to adopt telecommuting is modeled as a function of motivations and constraints as well as of the impact of the program on lifestyle quality, work-related costs, and income. The results indicate that telecommuting has a significant potential to increase productivity and improve lifestyle quality, if the right program is designed for the right employee. The potential of telecommuting to reduce organization and employee work-related costs is perceived to be limited. An overall negative perception about the potential impact on productivity and lifestyle quality of telework center–based telecommuting programs is identified, pointing to a need for further research to assess the market for telework centers.
Cross Traffic Signing for Stop Signs
Authors: Gattis J. L.
Published: January 2019

Signs warning motorists that traffic on the cross street does not stop can be found at some intersections that are not all-way stop controlled. These “cross traffic” signs have been installed to furnish a special warning where some motorists on the minor approaches may incorrectly assume that the major crossing street also has stop signs. The variety of cross traffic signs in use lack uniformity of message, color, shape, and placement location. A literature review and two surveys were conducted to examine (a) present usage of cross traffic signs, (b) circumstances under which these signs have been installed, (c) studies of the effectiveness of the signs, and (d) future actions. The accident data reviewed offered mixed results about the signs’ effectiveness: at some locations the signs appeared to reduce accident frequencies; at others, accidents continued despite their presence. If the intersections at which these signs have been installed are experiencing right-angle accidents due to a number of different factors, then countermeasures aimed at the right-of-way misperception problem may affect only some of the accidents. Expanded use of the signs could cause drivers to expect them at all two-way stop-controlled situations. More information on the long-term impact of the signs and a study of alternative approaches would help traffic engineers evaluate the desirability of these signs.
Emerging Concepts in Innovative Sign Management Programs
Authors: Pawlovich Michael D. , Jaselskis Edward J. , Souleyrette Reginald R.
Published: January 2019

Transportation agencies deploy and maintain millions of traffic signs in the United States. These include regulatory, warning, guide, work zone, motorist service, recreational and cultural interest, and tourist signs. Managing these large inventories under increasing requirements for reporting, accountability, and liability has caused many transportation agencies to reexamine sign management techniques. Conventional methods of sign management, which range from paper-based systems to relational data bases, have limited capabilities and inherent inefficiencies. Additionally, liability concerns are an increasing concern for many transportation agencies. The identification and application of emerging technologies for improving sign management inventory programs are addressed. Conventional sign management practices are described, and existing technologies promising the potential for more efficient and effective sign management are discussed. Because technologies range in price and complexity, an analysis that sizes technologies to markets is presented. Rather than emphasizing the development of new technology, it is proposed that existing technologies be combined to greatly improve current sign management practices.
Effect on Vehicle-Pedestrian Conflicts of “Turning Traffic Must Yield to Pedestrians” Sign
Authors: Abdulsattar Husham N. , Tarawneh Mohammed S. , McCoy Patrick T. , Kachman Stephen D.
Published: January 2019

Left- and right-turn movements at signalized intersections have been found to be three to six times more hazardous to pedestrians than through movements mainly because drivers fail to observe or yield the right of way to pedestrians. The objective was to evaluate the Turning Traffic Must Yield to Pedestrians sign, which was aimed at reminding turning motorists of their legal obligation to yield the right of way to pedestrians and, consequently, reducing vehicle-pedestrian conflicts. The sign was installed at 12 marked crosswalks in two cities, and vehicle-pedestrian conflict data were collected before and after its installation. The sign was effective in reducing left-turn conflicts 20 to 65 percent and right-turn conflicts 15 to 30 percent; both reductions were statistically significant at the 0.05 level. The sign was significantly more effective in reducing left-turn conflicts than it was for right-turn conflicts. Percentage conflicts between pedestrians and turning traffic decreased as the pedestrian group size increased. In other words, larger pedestrian group sizes encountered fewer conflicts with turning traffic. This result is true for both left- and right-turn movements, regardless of the presence of the sign. Based on the results of this study, it was recommended that the “Turning Traffic Must Yield to Pedestrians” sign be considered for inclusion in the Manual on Uniform Traffic Control Devices.
Easinet: Procedural Package for Development and Analysis of Intersection Control Strategies
Authors: Malek Shahram , Parsonson Peter S. , Moskaluk M. John , Chen Hobih
Published: January 2019

The purpose of the research was to investigate and develop a comprehensive tool to assist traffic engineers in the development and analysis of intersection control strategies. The interactive, microcomputer-based package developed as a result is called EASINET. EASINET consists of a number of tools, including a simulation program, an optimization-capacity analysis program, a knowledge-based system, and a number of support and utility programs. The simulation program is used to model the existing or projected traffic conditions and traffic control strategies. The knowledge-based system module is used to diagnose the problem and recommend solutions. The optimization model is used to perform the necessary computations, evaluate recommended solutions, and provide recommendations. EASINET guides a traffic engineer in designing traffic control strategies for fixed-time, noninterconnected intersections. The knowledge embedded in EASINET and its components is gathered from nationally accepted and respected human experts, publications, and programs. EASINET thereby gives the user access to accepted knowledge of confirmed practices in traffic signal design and operation. EASINET uses the results of the simulation component and capabilities of its components to identify locations with substandard performance, determine possible origins of the problem, generate and evaluate possible solutions to the problem, and make recommendations to the user for implementation. Using EASINET can enable this analysis procedure to be implemented more efficiently and effectively in a fraction of the time that would be required for an engineer to perform the analysis conventionally.
Influence of Visual Environments on Visibility of Traffic Signs
Authors: Akagi Yukiharu , Seo Takuya , Motoda Yoshitaka
Published: January 2019

Japan uses its limited land area intensely and many businesses are located along roads. Because of insufficient regulations in Japan, advertising signs such as billboards are more prevalent there than in Europe and America. Road signs, therefore, are more difficult to recognize, because they may be hidden among such commercial and other signs. The amount of information along roads that is not required for driving, such as billboards and signs on electric poles, is measured and the detectability of road signs is investigated quantitatively through actual road tests. The ratio of area of clutter signs to the total area of the field of view was called the visual noise ratio. Investigation of the relationship between the distance at which a driver first recognized a highway number sign and the visual noise ratio revealed a negative correlation. Differences between the sexes were also observed; for example, female drivers were less affected by the visual noise ratio, but their absolute visible distances were shorter than those of male drivers.
Photometric Requirements for Arrow Panel Visibility
Authors: Mace Douglas , Finkle Mark , Pennak Sara
Published: January 2019

Laboratory and field studies were conducted using older drivers to identify the minimum lamp intensity needed for legibility of arrows and chevrons on Type C arrow panels (APs). A field study was also conducted to determine the maximum intensity required to control disability and discomfort glare at night. Ninety-fifth-percentile data were used to represent worst-case conditions. These data were combined with the results of an analytic study to identify the angularity required for the APs to perform in all geometric situations that conform to accepted standards. The results of the research provide a specification for AP lamps that will result in the proper identification of the AP message by drivers of all ages under most conditions, at distances of up to 467 m (1,500 ft) or greater at all angles that may be anticipated, and at distances of more than ½ mi on-axis. Further, the specification developed sets of minimum and maximum intensity levels for nighttime operations.
Visibility of New Dashed Yellow and White Center Stripes as Function of Material Retroreflectivity
Authors: Zwahlen Helmut T. , Schnell Thomas
Published: January 2019

Economic and environmental concerns have raised questions about the continued use of yellow center lines on two-lane highways and yellow left-edge lines on divided highways or freeway entrance and exit ramps. The use of yellow pavement markings as a warning to indicate opposing traffic appears to be a concept that is compatible with certain human factors population stereotypes and accepted industry standards (yellow for caution), but it is unclear how well the general driver population understands the message conveyed by yellow pavement markings. Another question is how the visibility of yellow center lines or left-edge lines compares with the visibility of similar white pavement markings. The effects of color (white and yellow) and material retroreflectivity (low, medium, and high) on the end detection distance of finite-length center lines at night under automobile low-beam illumination were determined. Ten subjects were used in a field experiment (rural, automobile low-beam conditions) to obtain the end detection distances of finite-length center stripes of 0.1-m width. The data show that the end detection distances of new yellow dashed center stripes and new white dashed center stripes are about the same. The average end detection distance was 30 to 35 m for the low-retroreflectivity material and about 62 m for the high-retroreflectivity material (four- to fivefold retroreflectivity increase). It is tentatively concluded that the use of white center stripes most likely will not result in a significant increase in the end detection distance when compared with the use of similar yellow center stripes. It is also tentatively concluded that an increase in the retroreflectivity of the pavement marking materials will result in a significant and desirable increase of the visibility distance, but to provide a minimum preview time of 3.6 sec (at a vehicle speed of 90 km/hr), even higher-retroreflectivity materials than the ones used in this study will be required.
Light Guides for Tunnels
Authors: Sheldon Jeffrey P. , Lutkevich Paul J.
Published: January 2019

The use of light guides has been limited to accent or specialty lighting and generally has been considered impractical for large-scale applications. After careful study, 2 mi of light guides were installed in Boston's Callahan Tunnel. The 2-year study and design process is reviewed, and the system's performance after a year of operation is assessed.
Levels of Safety on Interurban Roads
Authors: Hakkert Alfred S. , Hocherman Irit , Mensah Abraham
Published: January 2019

The levels of safety of the main interurban road network in Israel are studied, and 70 percent of the total interurban roads are covered. A macro approach to the relation between road safety and various road categories as reflected in the overall geometric and traffic operational features is presented and is limited to road links. The classification and regression tree (CART) analysis, a nonparametric method that generates a binary tree structure from the data showing the criterion (variables) for each split and giving a pictorial representation of the data, is used as a preliminary tool to illuminate the relation between the variables and road accidents as a measure of safety and to identify meaningful candidate variables for deeper analysis. CART results portray the importance of average daily traffic (ADT) and the need for stratification of ADT in accident modeling. It also indicates probable power function models and highlights some interactive variables and the effect of shoulder type among single carriageways. However, no interactive variables were revealed because of the total dominance and masking effect of ADT. Multivariate multiplicative Poisson regression models with log links were fitted to the data set using the generalized linear interactive modeling package. The results again emphasize the safer nature of freeways as compared with conventional single- and dual-carriageway roads and show that the relation between ADT and safety is curvilinear. For the fitted parametric models, the effects of ADT were found to be most important, as in the case of the nonparametric CART analysis. In the case of models for single carriageway roads, other explanatory variables (free flow speed, type of shoulders, and junction frequency) showed some significance.
Estimating Average Automobile Occupancy from Accident Data in New York State
Authors: Asante Seth A. , Adams Louis H. , Shufon John J. , McClean Joseph P.
Published: January 2019

Average automobile occupancy (AAO) data are valuable input to congestion management systems (CMS). Continuous field collection of these data at the system level has been lacking because of high costs associated with current data collection methodology. It is shown how the New York State Department of Transportation (NYSDOT) has built upon prior research by the Connecticut Department of Transportation, which uses traffic accident data to calculate estimates of vehicle occupancy, and has tailored the process to meet NYSDOT's CMS needs. Accident data covering a 3-year period are used to estimate AAOs by county, year of occurrence, month of year, day of week, and time-of-day intervals. Occupancy rates are calculated to be lowest during the morning peak traffic period and highest during the evening period between 6:00 and 11:00 p.m. Occupancy rates are highest for summer months and lowest for winter months. Occupancy rates are highest for the weekends and lowest for weekdays. Accident-based AAOs are compared to multiple-station roadside-observed AAOs. Adjustment factors are developed to convert the former to be comparable to the latter. It is concluded that using accident data to estimate AAO is a viable and economical approach to continuous monitoring of system-level AAO performance. NYSDOT is currently using accident-based AAO data as an integral part of its CMS.
Design of Gate Delay and Gate Interval Time for Four-Quadrant Gate System at Railroad-Highway Grade Crossings
Authors: Coleman Fred , Moon oung J.
Published: January 2019

A design methodology for gate delay and gate interval time for at-grade crossings using four-quadrant gates is developed. The design approach is based on the concept of dilemma zones related to signal change intervals at signalized intersections. The design approach is validated based on data from six sites in Illinois on a proposed high-speed rail corridor. Gate delay and gate interval times are determined that provide an optimal safe decision point to allow a driver to stop before the crossing or to proceed through the crossing without becoming trapped by the exit gates.
Accounting for Nonrandom Arrivals in Estimate of Delay at Signalized Intersections
Authors: Daniel Janice , Fambro Daniel B. , Rouphail Nagui M.
Published: January 2019

The primary objective of this research was to determine the effect of nonrandom or platoon arrivals on the estimate of delay at signalized intersections. The delay model used in the 1994 Highway Capacity Manual (HCM) accounts for nonrandom arrivals through the variable m, which can be shown to be equal to 8kI, where k describes the arrival and service distributions at the intersection and I describes the variation in arrivals due to the upstream intersection. The 1994 HCM delay model m-values are a function of the arrival type, where the arrival type describes the quality of progression at the intersection. Although an improvement to the fixed k I-value used in the 1985 delay model, the 1994 m values are based on empirical studies from limited field data and do not account for the decrease in random arrivals as the volume approaches capacity at the downstream intersection. This research provides an estimate of the variable kI for arterial conditions. An analytical equation was developed as a function of the degree of saturation, and a separate equation was developed for each signal controller type. The results from this research show that the proposed kI's provide delay estimates closer to the measured delay compared with the delay estimates using the kI-values in the 1994 HCM delay model.
Estimating Intersection Approach Delay Using 1985 and 1994 Highway Capacity Manual Procedures
Authors: Braun Stephen M. , Ivan John N.
Published: January 2019

The current methods for determining average stopped delay at signalized intersections were studied. Field measurements of average stopped delay were obtained and compared with values computed using both the 1985 and 1994 editions of the Highway Capacity Manual (HCM). The 1994 HCM uses an equation to predict the progression adjustment factor (PF), a new technique for determining the left-turn adjustment factor for saturation flow rates, and a new set of equations for determining the uniform delay parameter for left-turn lane groups with primary and secondary phasing. Overall, the 1994 HCM produces better estimates of intersection stopped delay than the 1985 HCM.
One-Sided Weaving Operations on One-Way Frontage Roads
Authors: Fitzpatrick Kay , Nowlin Lewis
Published: January 2019

Weaving vehicles can heavily affect the quality of service on a facility. Techniques to evaluate weaving on arterial streets, however, are limited. Similar to arterial streets, the traffic operations on frontage or access roads along freeways can also be heavily affected by weaving. Presented here is a technique for evaluating one-sided weaving areas along with recommended lengths of weaving areas. Data from six sites were used to develop a relationship between number of lane changes and weaving volume. The weaving sections at the sites ranged from three to four lanes and from approximately 137 to 335 m in length. Throughout the large range of volumes present (250 to 2,500 vph), there was a very strong relationship between weaving volume and lane changes. The field data were used to develop a computer simulation model. The relationships between different measures of effectiveness from the simulation model provided information on critical points in which the weaving speed begins to drop more rapidly. Weaving volumes (entrance-ramp plus exit-ramp volumes) of less than 1,500 vph are associated with unconstrained levels of service, volumes between 1,500 and 3,000 vph with constrained service, and volumes over 3,000 vph with undesirable service. Additional information from the models also demonstrated that it is desirable to have a weaving length greater than 300 m. If this length is not achievable, then the minimum length should be approximately 200 m.
Saturation Flow and Capacity of Shared Lanes: Comparative Evaluation of Estimation Methods
Authors: Glannopoulos G. A. , Mustafa Muhammad A. S.
Published: January 2019

The operation of shared lanes, especially in the case of permitted phasing control, is still considered a complicated task and one for which many procedures and methods have been introduced. Dealt with here is the complexity when left- or right-turn movements or both are made during the unsaturated part of the opposing traffic flow. Three main methods used for estimating the shared lane's saturation flow rate and capacity values—that used in the 1985 Highway Capacity Manual (HCM) and the Australian Road Research Board (ARRB) and the Canadian methods—were analyzed and evaluated. The methodology for the comparative evaluation was based on two main approaches. In the first approach, example 1 of Chapter 9 of the HCM was used as a case study in which left through and left through right shared lanes exist in permitted phase control. In this case several computer runs were performed using the programs SIDRA and SINTRAL to estimate saturation flow and capacity values of the shared lanes opposed by different traffic volumes of the conflicting movements. Results of this approach showed that the 1985 HCM and ARRB methods are fairly close in estimating saturation flow and capacity, whereas the Canadian method gave considerably different results. Analysis showed that the sensitivity of the Canadian method to estimate saturation flow rates of the shared lane in cases of different levels of opposing traffic was an average of 10 times higher than the average of the two other methods, which were very close in their estimation of levels of opposing traffic volumes. In the second approach, field measurements of saturation flow rate values of shared lanes at different locations and operational conditions were compared with the values estimated by the three methods under the same conditions. Results, based on field observations, revealed that the Canadian method estimates of saturation flow were always lower than the measured values. At low saturation flow values, HCM estimates were slightly higher than the observed values; however, at higher saturation flow rate values. HCM estimates closely matched the observed ones. The ARRB method estimates were quite close to the observed saturation flow values under all of the different conditions considered in the field observation task.
Capacity at Unsignalized Two-Stage Priority Intersections
Authors: Brilon Werner , Wu Ning , Lemke Kerstin
Published: January 2019

The subject of this paper is the capacity of minor-street traffic movements across major divided four-lane roadways (also other roads with two separate carriageways) at unsignalized intersections. The center of the intersection, corresponding to the width of the median, often provides room for drivers who have crossed the first half of a major road to stop before proceeding across the second major traffic stream. This situation, which is common with multilane major streets, is called two-stage priority. Here the capacity for minor-street through traffic is larger than at intersections without such a central storage space. The additional capacity being provided by these wider intersections cannot be evaluated by conventional capacity calculation models. An analytical theory is presented for the estimation of capacity under two-stage priority conditions. It is based on an approach by Harders although major improvements were necessary to match the results with realistic conditions. In addition to analytical theory, simulations were performed that enable analysis under more realistic conditions. The result is a set of equations that compute the capacity for minor-street through-traffic movement in two-stage priority situations. These equations are complemented by two sets of graphs that enable easy application of the theory in practice.
Variability of Speed-Flow Relationships on German Autobahns
Authors: Brilon Werner , Ponzlet Martin
Published: January 2019

On German autobahns the average speed is strongly dependent on traffic volume. In addition to traffic volume, there is a comprehensive set of parameters that also cause a time dependency of speeds on autobahns. Speed-flow relationships play a key role in the determination of the type of highway for a given design flow and a given desired traffic flow quality. The question, however, is whether the speed-flow relationships from the guidelines are reliable over longer periods and to what extent the short-term speed variations are larger than the flow dependencies. Therefore, the objective of this research project was to determine typical fluctuations of average speeds on autobahns that are not the result of different volumes. Moreover, the consequences of differing speed-flow relationships on the maximum flow (i.e., capacity) should be pointed out. Studies of influences on the speed-flow relationships for German autobahns are presented. In addition to the fundamental influencing factors such as traffic volume and traffic mix, time dependency is also considered. As a data base, the results from 15 sites equipped with automatic traffic counting machines were used, each over a period of 3 years. This study was based both on conventional analysis, that is, separating different sets of data from the whole sample and on analysis of variance methods. The investigations show that two types of time-dependent influences exist. At first, there are changing environmental factors such as daylight or darkness or weather conditions. Darkness causes an average reduction of velocities by about 5 km/hr and wet roadway conditions reduce velocities by about 10 km/hr. Consequently, a reduction in capacity must be expected. The second type of time dependency is induced by varying driver behavior and traffic mix. Here seasonal variations can be found over the year and also over the days of the week. During predominantly leisure traffic, such as on Sundays or during the summer vacation season, lower average speeds can be detected.
Progression Factor for Queue Length and Other Queue-Related Statistics
Authors: Akçelik Rahmi
Published: January 2019

A method is presented that extends the U.S. Highway Capacity Manual (HCM) delay progression factor method to the prediction of queue length, queue clearance time, proportion queued (stopped), and queue move-up rate. These predictions are achieved by the introduction of an additional progression factor and adoption of the HCM overflow term adjustment factor, providing a simple method to allow for the effects of platooned arrivals on the performance of coordinated signalized intersections. The method is useful at the level of basic capacity and performance analysis of a single intersection where detailed platooned arrival patterns generated at upstream signal stop lines are not available. The arrival types defined by the HCM as the basic input to define the characteristics of platooned arrivals are adopted for use in calculating the additional progression factor in the same way as the original HCM progression factor for delay. It is assumed that the reader has a good knowledge of the subject area.
Truck Performance on Argentinean Highways
Authors: Archilla Adrián Ricardo , de Cieza Arístides Osvaldo Fernández
Published: January 2019

Truck performance observed on grades on National Highway 7 in Argentina is described. The observed weight-to-power ratio distribution in Argentina is shown to be considerably higher than that in North America. Also, a speed prediction model based on the simple force balance equation is fitted to the field data. The model explains about 80 percent of the observed variation, and for steep upgrades the predictions are similar to values observed in the United States. Acceleration and deceleration performance curves are also given. Finally, a validation of the model is presented by comparing the predicted and the observed speed profiles along two upgrades for trucks of known weight-to-power ratios. The shapes of the speed profiles predicted by the model closely replicate the observed speed profiles.
Les comportements éthiques et ceux contrevenant aux principes déontologiques de la recherche dans le processus de publication
Authors: Gatignon Hubert
Published: January 2019

Résumé

Cet article répond à certaines des questions que peuvent se poser des chercheurs, et en particulier de jeunes chercheurs, confrontés à des normes déontologiques en matière scientifique qui peuvent avoir des conséquences professionnelles graves lorsqu’elles sont enfreintes. Plus généralement, les problèmes d’intégrité scientifique peuvent relever, au-delà de la déontologie, de comportements éthiques moins codifiés, mais pour lesquels, néanmoins, la communauté scientifique s’accorde sur certains principes. Dans cet article, nous rappelons les principes et les règles qui sont habituellement suivis par les revues scientifiques, même si des différences peuvent être observées d’une revue à l’autre, et nous suggérons un ensemble de pratiques destinées à éviter que ne se développent des comportements qui contreviendraient à l’intégrité.
Campus Law Enforcement Resources for Rape Prevention and Responses to Stalking
Authors: Pinchevsky Gillian M.
Published: January 2019

Although the past few decades have taught us much about college and university responses to various forms of interpersonal violence affecting campus communities, this has largely not extended to campus law enforcement agencies. The lack of attention to this area is unfortunate given the role that these officers play on the campuses that they serve. The current study builds upon previous research using the Survey of Campus Law Enforcement Agencies data to examine the change in individual campus law enforcement resources (i.e., personnel) dedicated to rape prevention and stalking over time (2004-2011) across 4-year institutions of higher education. Of the 352 campus law enforcement agencies under study, over 31%, 24%, and roughly 22% increased their resources/dedicated personnel for stalking, general rape prevention, and date rape prevention, respectively. In fact, the largest percentage of agencies increased their resources/dedicated personnel for stalking compared with 12 other agency-involved campus issues or tasks. Taken together, regardless of their reported resources in 2004, in 2011 a large percentage of agencies reported full-time personnel/units and personnel dedicated to rape prevention and stalking on an as-needed basis, and far fewer relied only on policies and procedures or did not officially address the campus issue or task. These findings are important in light of continued changes in campus responses to crimes affecting their campus communities.
High loading rice husk green composites: Dimensional stability, tensile behavior and prediction, and combustion properties
Authors: Chen Ruey Shan , Ahmad Sahrim , Gan Sinyee , Tarawneh Mou’ad A
Published: January 2019

High-fiber loading green composites were prepared from recycled high-density polyethylene (rHDPE)/recycled polyethylene terephthalate (rPET) blend matrix and rice husk (RH) as filler (from 40 wt% up to 80 wt%) via corotating twin-screw extruder and compression molding. The water absorption (WA) upon immersion in sea water, mechanical behavior, and combustion enthalpy of green composites were examined. The WA mechanisms obeyed the Fickian diffusion. The computed diffusion coefficient (D), thermodynamic solubility (S), permeability (P), and orthotropic swelling were generally increased as a function of RH filler. The increment of tensile strength and modulus of composites were maximized up to 16% and 121%, respectively, which was achieved at 70 wt% RH filler. The theoretical prediction of tensile strength and Young’s modulus from micromechanical models for random oriented RH fiber/blend composites were compared with the experimental results. As the RH weight fraction increased, the combustion enthalpy decreased (by approximately 30–48%) and thereby the enhancing the fire retardancy of green composite.
Fire-resistant flax-reinforced polypropylene/polylactic acid composites with optimized fire and mechanical performances
Authors: Pornwannachai Wiwat , Ebdon John Russell , Kandola Baljinder K
Published: January 2019

Fabrics from commingled natural (flax), thermoplastic (polypropylene (PP)/polylactic acid (PLA)) polymeric fibres were fire retarded with an oragnophosphonate flame retardant (FR). The fire-retarded flax/PP and flax/PLA fabrics were melt pressed to prepare respective thermoplastic composites. The effect of FR concentration on the fire and mechanical properties of composites was studied and the results analysed in terms of concentration of FR elements in the composites. While the UL-94 test was used as a benchmark to achieve a V-0 rating, cone calorimetric parameters were used for in-depth analysis of fire performance. The results show that flax/PP and flax/PLA composites require a minimum 0.9 and 0.6% phosphorus, respectively, to achieve a V-0 rating in the UL-94 test. Mechanical properties, evaluated in tensile and flexural modes, are however slightly impaired, most probably due to the acidity of the FR solution (pH = 3.2). In order to improve the mechanical properties, a buffer solution was used to change the pH to 6.0, which while having a minimal effect on mechanical properties of flax/PP, significantly reduced those of flax/PLA and increased flammability of both composites and hence overall showed no benefit.