bluuebunny/crossref_metadata_2025 huggingface dataset:
Status of Development and Running Tests on Japan's Superconducting Maglev
Authors: Nakagawa Akira , Matsuda Satoshi
Published: January 2019

In 2005 the Central Japan Railway Company introduced new technological breakthroughs that will enhance revenue service on its superconducting magnetic levitation (maglev) system. This paper covers developments in both basic and applied research, discusses new equipment, and reviews the status of the system's running tests. Superconducting maglev has been developed to be applied to the Chuo Shinkansen, a proposed artery between Tokyo and Osaka. Its basic performance and various functions were already confirmed by 2000 through running tests done on the Yamanashi Maglev Test Line; running tests continue to be conducted to verify the train's durability and reliability and to upgrade its performance with new technologies. One immediate goal of these tests is to finalize the technology necessary for revenue service by March 2005.
Alternatives for Railroad Traffic Simulation Analysis
Authors: White Thomas
Published: January 2019

In North America, the process for determining appropriate railroad infrastructure for new service or an increased volume of existing service usually includes the use of simulation software. Decisions are generally based on statistical analysis of the simulation output. The simulation and analysis that are commonly conducted, however, may not provide an accurate assessment of the adequacy of the infrastructure. Furthermore, the output data comparisons commonly used to describe the effect of infrastructure on traffic may not be easily associated with traffic conditions. These shortcomings can be mitigated with appropriate care in developing the simulation input data and changing the output analysis methodology.
Release Risk and Optimization of Railroad Tank Car Safety Design
Authors: Saat Mohd Rapik , Barkan Christopher P. L.
Published: January 2019

The performance metric for tank cars and other hazardous materials vehicles involved in accidents has generally been conditional probability of release given involvement in an accident. This metric considers the probability of a release event occurring but does not take into account the quantity of product lost in a release incident. In this paper, a new metric termed “release risk” is introduced; it is defined as the expected value of the quantity lost from a tank car given that it is in an accident. The quantity of product lost varies depending on the part of the car that is damaged in an accident; consequently, use of release risk can affect how different modifications in tank car design are considered. The metric was developed in terms of tank-damage-caused and non-tank-damage-caused releases. It was found that tank-damage-caused releases had a higher release risk than non-tank-damage-caused releases. Important elements considered are the probabilities of release and the expected quantities of release from the tank components and non-tank components of a tank car, and the effect of increasing tank thickness in increasing accident exposure and decreasing expected quantity of release. The release risk metric is also used as the objective function in a tank thickness optimization model. The results suggest that release risk may be a useful means of assessing the relative benefits of different tank car safety design modifications.
Comparison of Methods for Allocating Costs of Empty Railcar Movements in a Railcar Pooling System
Authors: Cheng Yao , Lin Wei-Hua
Published: January 2019

Allocating the cost of empty railcar miles to partners in a railcar pooling system is an important pricing problem in railway management. Recently, the authors of this paper proposed a cost allocation scheme for empty railcar movements based on game theory that explicitly considers the level of participation and contribution from each partner, the costs generated before and after cooperation, and the overall benefit obtained by each partner because of cooperation. This paper compares the performance of the model with three other cost allocation models with respect to fairness, stability, and computational efficiency. The comparison is made with two scenarios adapted from examples documented in the literature. The results indicate that the cost allocation scheme based on game theory outperforms other methods in ensuring fairness and enhancing stability in a coalition. Most remarkably, it yields reasonable results even in situations in which other models behave poorly. Computationally, it is manageable for practical problems.
Methodology for Evaluating the Operational Performance of Interchange Ramp Terminals
Authors: Elefteriadou Lily , Fang Clara , Roess Roger , Prassas Elena
Published: January 2019

Interchange ramp terminals are critical components of the highway network. They provide the connection between various highway facilities (e.g., freeway–arterial and arterial–arterial), and their safe and efficient operation is essential. The objective of this research was to develop improved methods for capacity and quality-of-service analysis of interchange ramp terminals. The research focuses on at-grade intersections but not on the freeway proper. All geometric configurations and interchange types except trumpet interchanges are considered, and the scope of the research includes only signalized interchanges and not “Stop” sign–controlled interchanges and roundabouts. The development of the analytical methodology is primarily based on simulation. The reason for using simulation is that adequate samples of field data are not available, and it is prohibitively expensive to collect them for all types of interchange configurations. The research team assessed several simulation models that were identified as capable of simulating all types of interchange ramp terminals and selected the most appropriate one for model development. Once a simulation model was selected, a variety of interchange configurations were simulated, and selected measures of effectiveness were obtained. Analytical models were developed on the basis of the results of simulation to predict different measures, such as average control delay, volume-to-capacity ratio, and queue-to-storage ratio, for a variety of design and traffic control characteristics.
Effect of Lane Width on Speeds of Cars and Heavy Vehicles in Work Zones
Authors: Chitturi Madhav V. , Benekohal Rahim F.
Published: January 2019

Traffic data were collected from 11 work zones on Interstate highways in Illinois in which one of the two lanes was open. The reductions in free-flow speed (FFS) due to narrow lanes and lateral clearances in work zones were studied. It was found that the reductions in FFSs of vehicles in work zones because of narrow lanes were higher than the reductions given in the Highway Capacity Manual for basic freeway sections. The data also showed that the narrower the lane was, the greater the speed reduction was. The data showed that the FFSs of heavy vehicles were statistically lower than the FFSs of passenger cars, even though the speed limit was the same for both types of vehicles. In addition, the reduction in the FFSs of heavy vehicles was greater than the reduction in the FFSs of passenger cars. This greater reduction in the speed of heavy vehicles affected the performance of the traffic stream in work zones. Thus, it should be considered in the computation of the passenger car equivalence for heavy vehicles. It is recommended that 10, 7, 4.4, and 2.1 mph be used for speed reduction in work zones for lane widths of 10, 10.5, 11, and 11.5 ft, respectively.
Video Simulation of Pedestrian Crossings at Signalized Intersections
Authors: Landis Bruce W. , Petritsch Theodore A. , McLeod Peyton S. , Huang Herman F. , Guttenplan Martin
Published: January 2019

This paper compares users’ accommodation-based pedestrian level-of-service (LOS) ratings of signalized intersections in a video simulation environment and the physical roadway environment. Video simulation and walking course responses were compared with the use of data obtained from Walk for Science 2004, in which the participants reported their perceived level of safety and comfort as pedestrians. These data were used to test the hypothesis that subjects rate intersections’ LOSs differently in a controlled (video simulation) environment than they do by walking along a real-world course and experiencing real-time traffic conditions. The results for intersections common to both experiences (549 observations) indicated a statistically significant difference in the respective ratings (t = 2.34). Accordingly, a calibration factor was developed to adjust the participants’ scores from the video event to what they would have scored in the real-time field event. The adjusted video simulation data were then used to refine a field-calibrated model for pedestrian LOS at intersections (which is discussed in detail in another paper). Although further hypothesis testing may be conducted, the resulting general model for the pedestrian LOS at intersections is highly reliable, has a high correlation coefficient ( R2 = .73) with the average observations, and is transferable to the vast majority of metropolitan areas in the United States. This video simulation research design can serve as a model for similar datagathering initiatives in the future as the effort to calibrate the modeling of video simulation data to field-based perception data continues.
Arrival-Based Uniform Delay Model for Oversaturated Signalized Intersections with Poor Progression
Authors: Benekohal Rahim F. , Kim Sang-Ock
Published: January 2019

For oversaturated traffic conditions, the Highway Capacity Manual (HCM) does not apply a progression adjustment factor to the delay model for signalized intersections when there is an initial queue. This causes counterintuitive results in the calculation of delay; for some cases, delay for a nonzero initial queue condition ends up being less than the delay with zero initial queue conditions. Also, for oversaturated traffic conditions, the delay model in the 2000 edition of HCM yields the same uniform delay values for all arrival types when there is an initial queue. This does not seem reasonable because it ignores the effect of platooning on delay. This paper introduces a new approach for computing uniform delay for oversaturated traffic conditions when progression is poor. This approach directly considers the platooning effects in delay and thus eliminates the need to apply a progression adjustment factor. The proposed model is applicable whether there is an initial queue or not. The approach was validated by a comparison of the control delays obtained from a CORSIM simulation to the delays from the proposed model. Validation procedures were conducted on the basis of zero and nonzero initial queue conditions. The proposed approach resulted in more accurate delay values than the HCM model.
Variability of Peak Hour Factor at Intersections
Authors: Tarko Andrew P. , Perez-Cartagena Rafael I.
Published: January 2019

A peak hour factor (PHF) is used to convert hourly traffic volume into the flow rate that represents the busiest 15 min of the rush hour. Past research indicated that PHF had a strong impact on traffic analysis results. The common practice is to use a default value recommended by national or local guidelines or to use limited field observations. This paper investigates the variability of PHF over time and across locations. The day-to-day variability of PHF was found to be as strong as the site-to-site variability. This finding prompts estimation of the PHF on the basis of multiple field measurements or, when it is not possible to obtain measurements, for the use of a model that returns the average value of PHF. This paper presents such a model, which links PHF with the hourly volume, population, and time of day. The paper demonstrates that a large portion of the variability in the sample of observations either can be explained with the model or can be attributed to the day-to-day fluctuation.
Role of Geographic Information Systems in Regional Transportation Planning
Authors: Sutton John C.
Published: January 2019

Geographic information systems (GISs) are becoming more widely used in transportation planning agencies, especially among metropolitan transportation organizations. The extension of GIS into transportation (GIS-T) is driven largely by the requirements of the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA), the Clean Air Act Amendments of 1990, and legislation by states that mandate the development of transportation programs to reduce traffic impacts. Traditionally, transportation modeling of traffic impacts, calculation of vehicle emissions, and consideration of wider transportation planning effects, including transit, have employed different modeling techniques, often in different agencies or in separate sections within an agency. The results from these modeling and planning exercises have more often than not been displayed on different map bases, using different graphic programs to represent the data. The requirements of federal and state programs are encouraging modelers and planners to consider more consistent methods of data integration and display, hence the growing interest in GIS-T. The role of GIS-T in regional transportation planning is evaluated, including data integration issues, the configuration of transportation networks for use with GIS, and the linkage of transportation models to GIS.
Financially Constraining Washington's Transportation Plan
Authors: Ziegler Brian , Meale Eric
Published: January 2019

The Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA) requires states and metropolitan planning organizations (MPOs) to develop long-range transportation plans. These plans must be financially realistic and be based on available revenues. In the past, states and MPOs have not forecast transportation revenues beyond 6 years. The ISTEA requirements prompt the need for new approaches to forecasting revenue. An approach adopted by Washington State in developing its financially constrained 20-year plan for state highways is presented. The methodology predicts a revenue stream based on no changes in revenue sources or levels (called current law). The methodology also forecasts a revenue stream assuming a historical pattern of transportation revenue increases. In Washington State, the current law forecast will fund about one-third of the 20-year needs on state highways. The historical trend forecast will fund about two-thirds of these needs.
Using a Pavement Management System for Allocating Resources: Case Study of Hungary
Authors: Csicsely-Tarpay Marianna , Tapio Raimo , Talvitie Antti
Published: January 2019

An integrated network- and project-level pavement management system is described, and its use for allocating resources to various road maintenance actions and distributing these resources to a country's different regions and subnetworks is reported. Particularly interesting is the nature of the budget constraint, which is discussed from three vantage points: disutility of additional road user charges, performance of the road administration, and uncertainty in user benefits. The case study is set in Hungary, where significant efforts have been made to apply state-of-the-art techniques in road management. Contributions are made in three areas: a systematic, top-down managerial analysis of several budget levels and their effect on users and road condition; illustration of practical considerations in resource allocation by road managers; and the use of budget constraints to help achieve multiple highway management objectives, including productivity improvements in the road administration.
Evaluating Travel and Air Quality Cost-Effectiveness of Transportation Demand Management Projects
Authors: Schreffler Eric N. , Costa Theresa , Moyer Carl B.
Published: January 2019

Many transportation planners and those implementing transportation demand management (TDM) programs have been frustrated by the lack of quantitative information on what types of TDM strategies work best and where. This underscores the need for sound evaluation of TDM programs and demonstration projects. However, many evaluations to date have used a variety of methods and assumptions when quantifying the travel and air quality impacts of TDM projects. A study funded under the AB 2766 vehicle registration fee program in southern California resulted in the development of a standardized methodology and then applied the method to 15 TDM demonstration projects. The method differed from most of the self-evaluations in that it discounted vehicle trip reduction to account for those who switched from one high-occupancy vehicle mode to another and for those who accessed the new commute alternative by driving alone to a pickup point; factored out the emission of shuttle and transit vehicles used in providing new service; and used standardized emission factors to determine reductions in reactive organic gases, carbon monoxide, nitrogen oxide, and fine particulate matter. Results of the application of the method to various TDM projects reveal a range of impacts and point to the inaccuracies of self-reported results, particularly in the area of total emission reductions. More standardization of TDM evaluation methods is called for so that a large data base of consistent and reliable information can be assembled across agencies with the goal of generalizing the effectiveness and transferability of various TDM strategies and programs.
Using GPS Technology to Relate Macroscopic and Microscopic Traffic Parameters
Authors: Barth Matthew J. , Johnston Eric , Tadi Ramakrishna R.
Published: January 2019

Traffic congestion on today's freeways is a serious problem, causing significant delays for both passengers and goods. Freeway traffic congestion also results in increased vehicle emissions; however, this increase has not been quantified using current vehicle emission models. Current models use emission factors based on driving cycles that do not properly represent freeway driving characteristics. This paper presents a new methodology for relating the macroscopic speed, flow, and density parameters measured by traffic sensors with statistics of microscopic driving traces under different levels of congestion. This approach can be used to better estimate freeway emissions when combined with an appropriate modal emissions model. Preliminary experimentation has been carried out with a vehicle equipped with global positioning system (GPS) instrumentation, allowing for precise localization in both space and time. With the GPS, second-by-second velocity traces are acquired and matched with simultaneously measured freeway traffic data obtained by embedded traffic sensors. Statistical measures of velocity variation are derived from the velocity traces and are functionally related to the macroscopic traffic parameters of speed, flow, and density. Given a known distribution of vehicle types, models, and model years, vehicle emissions can be related to these statistical measures of velocity variation using a modal emission model, and, thus given speed-flow-density measures of freeway traffic, localized emissions estimates can be made.
Travel Demand Analysis Impacts on Estimation of Mobile Emissions
Authors: Stopher Peter R. , Fu Haoqiang
Published: January 2019

A series of disaggregation experiments on the use of travel-forecasting procedures aimed at examining the impacts of disaggregation on estimates of mobile source emissions is described. The research used a case study of Baton Rouge, Louisiana, which is an ozone nonattainment area. The procedures in recent use in Baton Rouge were largely adopted as the basis for the research. The steps of disaggregation included estimating emissions at the link level in the loaded network, applying diurnal factors in two alternative methods, applying seasonal and day-of-week factors to standard fall/spring travel-forecasting results, and performing speed postprocessing after assignment. The results show that there are a number of areas in which significant impacts on emissions estimates arise, particularly from the seasonal and day-of-week adjustments and from speed postprocessing. Impacts of diurnal factoring appear less than expected, but are likely to be a function of levels of congestion. The paper concludes by noting some important issues relating to standard modeling practice and also suggests a number of areas for further research.
Issues and Costs Associated with Transition to Alternative Transportation Fuels and Vehicles
Authors: Mintz Marianne , Singh Margaret K.
Published: January 2019

Key issues and barriers that must be overcome for the successful introduction of alternative-fuel vehicles are summarized. A host of market and institutional barriers faced by vehicle purchasers, vehicle manufacturers, fuel suppliers, and the vehicle service industry are broadly described. Although specific estimates of the costs of overcoming these barriers are highly uncertain, an initial estimate of the general magnitude of these transition costs is presented. This is done by analyzing the transition to a specific alternative-fuel vehicle market penetration for the year 2010. Transition costs are shown to be substantial.
Applications of FTA National Transit Data Base for the Intermodal Surface Transportation Efficiency Act Management System Requirements
Authors: Lyons William M. , Collura John , Libberton Sean , Branch Paul
Published: January 2019

The Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA) requires states in conjunction with metropolitan planning organizations (MPOs) to develop, establish, and implement several systems to better manage and improve the efficiency of transportation infrastructure. Among other things, the National Highway System Designation Act of 1995 allows states not to implement one or more of the ISTEA management systems. Although the management systems are now optional, FHWA and FTA continue to believe that the management and monitoring of the performance and condition of the multimodal transportation system should remain an important element of statewide and metropolitan planning. How FTA's National Transit Data Base (NTD) can provide an important source of information as agencies develop the ISTEA management systems or similar mechanisms for managing and monitoring transit facilities and equipment is analyzed. NTD, which contains information on the financial and nonfinancial operations, system performance, and equipment of national public transit systems, is used primarily by transit operators and others in the transit industry. How NTD can contribute to development and operations of the Public Transportation Management System as well as the Congestion and other management systems is discussed. Development of applications for ISTEA management systems, or for similar planning tools, broadens applications of NTD beyond its transit customer base to aid states and MPOs. By contributing comprehensive transit data to systems for managing and monitoring condition and performance of multimodal transportation, NTD can improve representation of transit needs and performance in the ISTEA planning process.
Transit Path Calculation Supported by Special Geographic Information System-Transit Information System
Authors: Chapleau Robert , Allard Bruno , Trepanier Martin
Published: January 2019

The Société de Transport de la Communauté Urbaine de Montréal (STCUM; Montreal Urban Community Transit Corporation) has recently undertaken the task of computerizing its phone information center, called AUT-OBUS. AUT-OBUS provides callers with optimal route choices within the STCUM transit network. An original system based on geographic and operations data bases combined with interactive path calculation and data processing software has already been implemented. A special geographic information system was developed to process the origins and destinations on the basis of the client's specifications. Multiple forms of spatial referencing are provided: street addresses, trip generators and attractors, monuments, special activities, street intersections, transit references (subway and rail stations, bus routes, terminals, etc.). The best path calculation is carried out by using interactively calibrated impedance functions (walking, in-vehicle, waiting, transfers, fares, and mode restriction). An added challenge was the necessary consideration of the network geometry, commercial speed, day type, trip time, and headway and the validation of the computed paths with existing schedules. For a transit network the size of Montreal's, consisting of 16,000 bus stops, 230 bus routes, and a pedestrian network of 80,000 links and 28,000 nodes, the calculation of the optimal path for a given origin–destination pair is less than 2 sec with a typical personal computer with a Pentium processor.
Light Rail Accident Involvement and Severity
Authors: Chira-Chavala T. , Coifman B. , Porter C. , Hansen M.
Published: January 2019

Accident causation and accident severity analyses for a light rail transit system are presented, with a view to providing input for the identification and development of accident and severity countermeasures. Accident reports of the Santa Clara County Transit Authority were used in both analyses. In the accident causation analysis, patterns of critical events for various types of light rail accident involvement were determined. The accident severity model is a binary logit model expressing the probability of injury accident as a function of speeds before collision of both the light rail vehicle and the motor vehicle, movement of the motor vehicle before collision, and peak and off-peak period.
Operational Characteristics of Longer Combination Vehicles and Related Geometric Design Issues
Authors: Harkey David L. , Council Forrest M. , Zegeer Charles V.
Published: January 2019

As the size and configuration of trucks operating on public highways continues to change, how these vehicles operate needs to be better understood to accommodate them through better geometric designs or regulate them through more stringent laws and better enforcement. Longer-combination vehicles (LCVs), a group that includes Rocky Mountain doubles, turnpike doubles, and triples, fall into this category. LCVs handle and perform differently from tractor semitrailers or twin trailers because of their increased lengths and weights. These differences in handling and performance may jeopardize the safety of the LCV as well as other vehicles on the roadway. Several of the LCV's operational characteristics are believed to have an impact on transportation safety and the relationship of these characteristics to geometric design. There is a clear need to conduct additional research to further evaluate LCV operations. Several such research efforts are recommended.
Planning and Geometric Aspects of Shared Streets
Authors: Polus Abishai , Craus Joseph
Published: January 2019

The concept of “shared streets” involves an area in which the street is shared by pedestrians and vehicles. The entire shared street area is paved, and no vertical elevation difference exists between the walking areas and the parking area and the “travel lane.” The concept of travel lane is developed in this paper, and it refers to that part of the shared street that is specifically intended for motorists to travel. The travel lane is often distinguished by blocks with different colors. Because of the narrow lane width, it is possible for only one vehicle to pass through a straight section; two vehicles can meet only in the diagonal section. The angle of the diagonal section and the length and width of the straight section are primary parameters that strongly affect the travel speed along a shared street. Some general planning considerations are discussed, such as creating a discontinuous alignment by inserting a diagonal section between two consecutive tangent sections. Unidirectional or alternating diagonals are discussed, and three general forms of diagonal sections are presented. Safety considerations are also discussed, along with the need to provide sufficient parking space for visitors and residents. It is shown that the geometry determines the path of vehicles that results in a possible safe speed for a given design. Specific design criteria are presented for the recommended length of a tangent section and the recommended minimum width ranges, depending on the length of street. The parameters determining the geometric characteristics of the diagonal section, the angle of turn, the offset between the centerlines of the two adjacent tangent sections, and the width of the road along the tangent and within the diagonal section are also presented and evaluated. It is concluded that shared streets provide an excellent, attractive accessibility solution for residential neighborhoods with low volume of residential traffic resulting from a low density of residential dwellings. If planned properly, a balanced design is achieved, and the reduced speed results in improved safety and enhanced environmental qualities.
Driving Dynamic Aspects and Related Safety Issues for Modern Geometric Design of Non-Built-Up Roads
Authors: Lamm Ruediger , Psarianos Basil , Soilemezoglou George , Kanellaidis George
Published: January 2019

Safety issues affecting modern highway geometric design of roads in non-built-up areas are discussed. The status of knowledge of Safety Criteria I and II (achieving operating speed consistency and design consistency) for two-lane rural roads is briefly reviewed. Considerations for design consistency are also extended to multiple-lane rural and suburban road design to evaluate good, fair, and poor design levels for these road categories. Utilization ratios (n) for maximum permissible side friction factors are developed for different road categories, topography levels, and maximum and minimum superelevation rates. Relevant minimum radii for curve design are established and compared with present AASHTO values insofar as possible. Safety Criterion III (achieving driving dynamic consistency) is further developed, through which reliable and quantitative ranges between the side friction assumed and the actual friction demand at curved sites could be established. AASHTO's design policy is evaluated on the basis of Criteria II and III. The evaluation showed, for lower design speeds (30, 40, and 50 mph), an unbalanced degree of curve and superelevation rate ranges, which lead to poor design practices from a safety viewpoint. By heeding the three safety criteria and the recommended side-friction utilization ratios, sound alignments can be established for the various design cases in future highway geometric design and redesign and for resurfacing, restoration, and rehabilitation strategies.
Design Speed, Operating Speed, and Posted Speed Survey
Authors: Fitzpatrick Kay , Shamburger Brian , Fambro Dan
Published: January 2019

At some locations, the posted speed limit, based on 85th percentile operating speed, exceeds the roadway's design speed. This situation is a result of the fact that criteria used in highway design incorporate a significant factor of safety, that is, roadways are designed for near worst-case conditions. When this situation occurs, however, liability concerns can arise although drivers can safely exceed the design speed. A mail-out survey for state, city, and county transportation departments was conducted to document concerns and difficulties the engineering profession is experiencing with the relationships among design speed, operating speed, and posted speed. The factors most frequently considered when selecting design speed are anticipated operating speed and/or posted speed; however, these were not the most common factors selected by respondents. Urban versus rural and functional class were selected more often by the state respondents, whereas cross section was selected more often by the city/county respondents. Most respondents indicated that a ball bank indicator is used to set advisory speeds on horizontal curves. Many respondents expressed the desire to have a new procedure for selecting advisory speeds. Several agencies acknowledged that they have or have had sites with an operating speed greater than the design speed. The most frequent action taken was to install advance warning signs. Few respondents stated that they reduce the posted speed limit to match the design speed. Although few lawsuits involving the posted speed/design speed issue have occurred, liability concerns still exist. Several respondents provided comments that indicated their concern with current definitions and procedures.
Effect of Offset between Opposing Left-Turn Lanes on Driver Performance
Authors: Tarawneh Mohammed S. , Mccoy Patrick T.
Published: January 2019

The objective of the research described here was to study the effects of the offset between opposing left-turn lanes on the turning performance of drivers with respect to driver age and gender. Left-turn performance of 100 subjects within three age groups (25–45, 65–74, and 75+ years old) was evaluated under normal driving conditions at four intersections of different left-turn offset configurations. The results indicate that driver performance can be adversely affected by offsets that are much less (i.e., more negative) than the negative 0.9-m offset. Such large negative offsets significantly increase the size of the critical gaps of drivers turning left and also seem to increase the likelihood of conflicts between left turns and opposing through traffic. Large negative offsets may be particularly troublesome for older drivers and women drivers, who are less likely to position their vehicles within the intersection to see beyond vehicles in the opposing left-turn lane. Surprisingly, driver perceptions of the level of comfort and degree of difficulty were not found to improve with the increased sight distance provided by larger (i.e., more positive) offsets. The 1.8-m positive offset was associated with a lower level of comfort and a higher degree of difficulty perceived by drivers making left turns than the 0.9-m negative offset, which provided less sight distance. This may have been because the 0.9-m negative offset is much more common than the 1.8-m positive offset.
Volume Warrant for Free Right-Turn Lanes at Unsignalized Intersections on Rural Two-Lane Highways
Authors: Mccoy Patrick T. , Bonneson James A.
Published: January 2019

The objective of the research presented in this paper was to develop a volume warrant for free right-turn (FRT) lanes at unsignalized intersections on rural two-lane highways. The warrant was based on a cost-benefit analysis that determined the right-turn volumes required to justify the construction and maintenance of FRT lanes at such locations. The research involved the evaluation of the safety and operational effects of FRT lanes. The safety effects of FRT lanes were determined from a comparison of the accident experience at intersections with and without FRT lanes. The operational effects of FRT lanes were analyzed using kinematic and traffic flow models. FRT lanes were not found to affect the frequency, severity, or types of accidents that occur at unsignalized intersections on rural two-lane highways. Thus, the benefits of FRT lanes are limited to improving the efficiency of right-turn movements. The results of the research indicate that design-year right-turn annual average daily traffic ranging from 440 to 825 vehicles per day, depending on the percentage of trucks, is required to warrant an FRT lane. A design speed of 64 km/h (40 mph) was found to be the most cost-effective design speed for FRT lanes. However, design speeds up to 89 km/h (55 mph) do not significantly reduce the cost effectiveness of an FRT lane.
Safety at Curves and Road Geometry Standards in Some European Countries
Authors: Brenac Thierry
Published: January 2019

This paper deals with safety at horizontal curves on two-lane roads outside urban areas and the way the road design standards of different European countries account for this safety aspect. After a review of some research results, the main aspects of curve geometry and the curve's place in the horizontal alignment are analyzed. The main conclusions are that the traditional design speed approach is insufficient and that formal complementary rules in road design standards, especially to improve compatibility between successive elements of the alignment, must be introduced. If such complementary rules already exist in some national standards, they are neither frequent nor homogeneous throughout the different countries, and it seems that they are not based on sufficiently developed knowledge.
Highway Noise Barriers: 1994 Survey of Practice
Authors: Storey Beverly B. , Godfrey Sally H.
Published: January 2019

Highway traffic noise is an ever-increasing problem for transportation agencies. The challenge presented to transportation agencies is to incorporate noise abatement into the highway environment without compromising the aesthetic integrity of the surrounding communities. In an effort to guide highway designers, a survey of practice was sent to all state transportation agencies and their equivalents in Puerto Rico and Ontario, Canada. The portions of the survey regarding noise-barrier materials, aesthetic visual quality in design, and public involvement in the design process are discussed in this paper. The literature review revealed a long-standing effort throughout Europe to incorporate many aesthetic features into noise-barrier systems and to use public preferences to guide design. Many new products that provide aesthetically pleasing noise barriers, in addition to the noise-level reductions required of transportation agencies, are now available. Innovative and versatile methods of using standard materials, such as concrete, have provided a continual supply of barrier designs. A multidisciplinary collaboration (including citizen representatives) in the design process has proved to be an effective method of ensuring that the best design is implemented for both sides of the highway environment. Collectively, transportation agencies, private industry, and institutional research programs should work together to advance the knowledge available in noise research and to further develop the aesthetic visual quality of the highway environment.
Testing of Roadside Vegetation for Highway Runoff Pollutant Removal
Authors: Kaighn Robert J. , Yu Shaw L.
Published: January 2019

A field monitoring program was begun in 1991 to test the ability of grassed swales to remove pollutants from highway runoff. The two swales monitored had different slopes, traffic volumes, and vegetation heights, all of which can affect pollutant removal. One had a check dam, which proved to significantly influence pollutant removal. Also, the pollutant-removal ability of a short buffer strip was examined. Pollutants monitored included total suspended solids, chemical oxygen demand, total phosphorus, and total zinc. Manual and automatic sampling techniques were used to monitor runoff. The results suggest that properly designed short buffer strips and swales with check dams can remove pollutants from highway runoff.
Semiarid Precipitation Frequency Project Contrasted with Previously Published Rainfall Atlases
Authors: Vogel John L. , Julian Lesley T.
Published: January 2019

Design of hydraulic structures and management of water resources requires rainfall frequency analyses and depth-area-duration curves to determine design storms and stormwater runoff. For the western United States, two atlases provide rainfall information for return frequencies from 2 to 100 years: NOAA Atlas 2 and Technical Paper 49. The Semiarid Precipitation Frequency Study (Semiarid Study) was begun several years ago to revise these atlases for Arizona, Nevada, New Mexico, Utah, and Southeast California. The Semiarid Study will supersede the previous atlases for these regions. Precipitation frequencies will be provided for events as frequent as six times a year up to 1,000-year return periods and for durations from 5 min to 60 days. New depth-area-duration curves will be provided. The Semiarid Study differs from the earlier studies in (a) 30 percent more daily stations and 230 supplemental stations; (b) new statistical methods permitting more objective quality control, regionalization of data, and objective curve-fitting techniques; and (c) direct use of partial-duration data series. With Utah as an example, comparisons with NOAA Atlas 2 of 100-year, 24-hr return frequency values are also shown. Semiarid Study values are lower in central and southern Utah but higher in the Uinta Mountains and the northern Wasatch Range. Results for the rest of the Semiarid area are similar; that is, values are generally higher than NOAA Atlas 2 in the mountains and lower in the desert regions. Seasonality is illustrated with 45-day events in central and western Utah. The maximum 45-day rainfalls occur in this area in March and April and in August and September, a bimodal distribution.
Transport of Heavy Metals during Infiltration of Simulated Highway Runoff through Large-Scale Soil Columns
Authors: Igloria Ronan V. , Hathhorn Wade E. , Yonge David R.
Published: January 2019

An evaluation was conducted of the performance of three Washington State soils in attenuating trace heavy metals (Cd, Cu, Pb, and Zn) in contaminated water. Although previous investigations of this kind have used relatively small-scale soil columns as indicators of actual performance, large-scale soil columns (0.3 m in diameter and 1 m deep) were tested under loading conditions similar to actual field infiltration basins. The soil columns were loaded periodically to produce quasi-field conditions, with the corresponding metal transport being observed as a function of depth. The data indicate that metals speciation and background metals present in the soil are important factors to consider, because they can affect expected metals removal rates of soils. The hydraulics of the system played a secondary role to the geochemistry. Results suggest that infiltration can be a viable alternative in disposing of runoff at low metals concentrations, if the soil-water system's assimilative capacity is not taken for granted.
Effects of Natural Organic Matter on Heavy Metal Transport during Infiltration
Authors: Igloria Ronan V. , Hathhorn Wade E. , Yonge David R.
Published: January 2019

Washington State, like many others, has begun a program to dispose of highway runoff in which a priority has been given to the use of infiltration technologies (e.g., infiltration basins, dry wells, etc.). Heavy metals are of particular interest, because they are the most prevalent priority pollutant in highway runoff. Though traditionally these heavy metals are thought to possess relatively large retardation factors within the subsurface, previous studies have indicated a possibility of their transport being facilitated through complexation with natural organic matter (NOM). If ignored, this form of transport may pose serious errors in the prediction of metal breakthrough times and mass loadings to underlying groundwaters. In addressing this issue, large-scale soil columns are tested under loading conditions similar to actual infiltration best management practices to assess the performance of these facilities in removing heavy metals (Cd, Cu, Pb, Zn) from infiltrating water. Experiments were performed investigating the effects of high and low concentrations of NOM on metals attenuation by field soils. Results show that high concentrations of NOM actually improved soil column attenuation of the metals.
Network-Level Implementation of URMS: A Graphical Urban Roadway Management System
Authors: Sohail Farrukh , Hudson W. R.
Published: January 2019

The preservation of existing roads and streets has become a major activity for all levels of government. Deteriorating urban roads and reduced funding are major problems for local governments. Funds designated for pavements therefore must be used as effectively as possible. For the most efficient management of urban roadway networks, regulations calling for the involvement of metropolitan planning organizations in the development and implementation of pavement management systems (PMSs) were established by the Intermodal Surface Transportation Efficiency Act of 1991. Considerable effort is now under way at state and local government levels for developing and implementing PMSs. The Urban Roadway Management System (URMS) was developed at the University of Texas at Austin. URMS provides small to medium-sized cities with a simple, flexible, and user-friendly PMS. Implementation of such a system can save money for both the agency and the user and improve not only the efficiency, but also the effectiveness of decision making involved in managing pavements. A research study was conducted at the University of Texas to demonstrate the use of URMS through its implementation in small to medium-sized cities. The implementation was carried out at two levels. At the first level, the city of Lampasas, Texas, was directly assisted in the implementation. At the second level, the city of Terrell, Texas, was assisted over the telephone. The strategy and process of URMS implementation are documented.
Efforts toward Developing a Regional Pavement Management System in Utah
Authors: Cottrell Wayne D. , Lee Hosin , Nepstad Jon , Crandall Mick
Published: January 2019

The Intermodal Surface Transportation Efficiency Act of 1991 has challenged metropolitan planning organizations (MPOs), such as the Wasatch Front Regional Council (WFRC) in Utah, with no traditional involvement in pavement management to cooperate with states and local agencies in developing regional pavement management systems (PMSs). The development is particularly difficult when some of the local agencies already have well-established PMSs that are sufficient for their needs. Eight PMSs were being used in the Salt Lake City-Ogden area by those communities having a formal PMS; local pavement management specialists expressed concern about having their PMSs altered to serve a new, regional PMS. Fourteen localities had no PMS. The disparity between local pavement management activities indicated that the responsibility for pavement data collection and condition and performance analyses should be allocated to the state. Doing this would eliminate the potential inconsistencies associated with having the localities report pavement condition. The plan also relieved the WFRC from the burden of operating a PMS. This approach may be applicable in similar urban regions in which there is extreme variation in the degree of local pavement management. The state department of transportation must be willing to expand its PMS to include not only state highways and the National Highway System, but all Federal-aid highways. The MPO can then focus its efforts on prioritizing pavement improvement projects and selecting candidates for federal funding. Other roles of the MPO would include promotion of, education and training for, and dissemination of information to local agencies and the public on pavement management.
Pavement Performance-Oriented Network Optimization System
Authors: Liu Fengxian , Wang Kelvin C. P.
Published: January 2019

The objective of the current network optimization system (NOS) model used by the Arizona Department of Transportation is to minimize the annual cost over the planning period. An NOS model with the objective of maximizing a network's pavement performance is presented. In this performance-oriented NOS, the annual budget is given as a constraint that is distributed evenly over the planning period. This NOS model aims to provide an approach simulating a possible scenario in a state department of transportation by effectively using a given budget in the planning period. At the same time the performance of the pavement network is also maximized. In relation to annual budget and pavement condition, two types of analysis are conducted: in the first analysis, only annual budget is applied as the constraint for this model; in the second, both annual budget and pavement performance requirements are introduced as the constraints. The necessary minimum annual budgets for various pavement performance requirements are compared; using the results, a rational annual budget for the needed pavement performance standards can be obtained, which may be used as decision support data for future budget allocation.