bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance-Graded High-Temperature Selection Criterion: Can We Do It Better?
Authors: Kern Jeffrey S. , Carpenter Samuel H.
Published: April 2007

The Superpave binder grading system provides a selection process based on the potential performance characteristics of the binder as related to the climatic considerations of the area, principally the temperature. The selection criterion for the high-temperature grade uses the average of the maximum consecutive 7-d high pavement temperatures at a 20-mm depth with requisite grade bumps. This selection criterion is examined as to how well it actually relates to the performance of the asphalt concrete under high temperatures, principally permanent deformations in the mixtures, which is a fundamental connection that must be established before adjustments are made to the binder grade on the basis of the traffic using the pavement. The current temperature criterion is compared with the actual temperature distributions of a number of cities across the United States to demonstrate the disconnected nature of this value in relation to the actual pavement temperatures. The temperature data are further analyzed to present the performance differences that could be incurred in different climates when the 7-d high pavement temperature average is used as the selection criterion with rather arbitrary grade bumps. Georgia loaded wheel rut data are used to illustrate the possible performance differences that may be incurred by ignoring the temperature frequency distribution and using only the maximum consecutive 7-d high pavement temperatures at 20 mm for the selection criterion. A procedure is outlined that would allow inclusion of traffic loads and temperature distribution to develop a simple selection procedure that is based on binder differences.
Evaluating Improvements in Landside Access for Airports
Authors: Shriner Heather Wishart , Hoel Lester A.
Published: April 2007

Access to airports has become increasingly difficult, but the extent of the problem is not known. No method exists to consistently define the performance of landside access that is provided to air passengers. A national survey of U.S. airport authorities was conducted to determine the characteristics of airport access services provided. The results of the survey indicate that landside access to airports is a major concern at airports of all sizes, but there is no significant difference in reported access problems at large, medium, and small airports. An access evaluation methodology was developed to assess landside access service between approaches to the airport and the terminal entrance and is based on performance measures relating to cost, time, reliability, convenience, and quality. It is intended to aid in the assessment of landside access performance and to promote more effective use of limited resources by determining the most needed and beneficial access improvements. This evaluation methodology was demonstrated by investigating landside access facilities at the Richmond International Airport. The methodology is flexible and may accommodate airports with a wide range of assessment needs and resources. Furthermore, the evaluation process corresponds to existing airport planning, requires no special training to complete, and may be undertaken in cooperation with master plan efforts. It is recommended that the evaluation methodology be incorporated into access fund appropriation processes as a consistent means of evaluating performance, identifying access needs, and evaluating potential access improvements.
Prediction of Pile Setup in Clay
Authors: Whittle Andrew J. , Sutabutr Twarath
Published: April 2007

Reliable calculations of pile setup times represent a critical parameter in the design of large-diameter pipe piles that are used to anchor offshore tension leg platforms. Predictions of setup times can be obtained by analyses that simulate the changes in effective stresses and soil properties occurring around a single pile during installation and subsequent equilibration of excess pore pressures. Pile installation is modeled using the framework of the strain path method, assuming that there is no plugging of soil within the pipe pile. Changes in effective stresses and soil properties at all stages of the analysis are described by the MIT-E3 soil model, with input parameters derived from laboratory tests on highquality samples. After installation, the analyses solve the radial dissipation of excess pore pressures around the pile shaft and setup of effective stresses in the soil by nonlinear finite element methods. Dissipation times are controlled by the pile aspect ratio (ratio of diameter to wall thickness), in situ effective stress, stress history, and hydraulic conductivity of the clay. This paper illustrates the validation of the proposed setup analyses with data from instrumented model piles and pile shaft elements at two well-documented test sites.
Fuel-Cycle Greenhouse Gas Emissions Impacts of Alternative Transportation Fuels and Advanced Vehicle Technologies
Authors: Wang Michael
Published: April 2007

The greenhouse gas (GHG) emissions reduction potentials of various near- and long-term transportation technologies were estimated. The estimated per-travel-distance GHG emissions results indicate that alternative transportation fuels and advanced vehicle technologies can help to significantly reduce transportation-related GHG emissions. Of the near-term technologies evaluated, electric vehicles, hybrid electric vehicles, compression-ignition, direct-injection vehicles, and E85 (85 percent ethanol and 15 percent gasoline) flexible-fuel vehicles can reduce fuelcycle GHG emissions by more than 25 percent on a fuel-cycle basis. Electric vehicles powered by electricity generated primarily from nuclear and renewable sources can reduce GHG emissions by 80 percent. Other alternative fuels (such as compressed natural gas and liquefied petroleum gas) offer limited, but positive, GHG emissions reduction benefits. Among the long-term technologies evaluated, conventional sparkignition and compression-ignition engines powered by alternative fuels and gasoline- and diesel-powered advanced vehicles can reduce GHG emissions by 10 to 30 percent. Dedicated ethanol vehicles, electric vehicles, hybrid electric vehicles, and fuel-cell vehicles can reduce GHG emissions by more than 40 percent. Spark-ignition engines and fuel-cell vehicles powered by cellulosic ethanol and solar hydrogen (for fuel-cell vehicles only) can reduce GHG emissions by over 80 percent. In conclusion, both near- and long-term alternative fuels and advanced transportation technologies can play a role in reducing GHG emissions from the transportation sector.
Comparison of Speed-Acceleration Profiles from Field Data with NETSIM Output for Modal Air Quality Analysis of Signalized Intersections
Authors: Hallmark Shauna L. , Guensler Randall
Published: April 2007

New vehicle modal emissions rate models will assess emissions as a function of specific operating mode or engine load surrogates. These new models require that vehicle activity be input by fraction of time spent in different operating modes. However, the ability to realistically model onroad modal vehicle activity currently limits the implementation of these models. Few data on how vehicles operate in a real-world setting exist. Simulation models offer attractive advantages for modal modeling. They are readily available and generally can be used with both simple and detailed data input. Simulation models were developed to model the impacts of signal timing, incidents, or design features on traffic flow and perform well for these applications. However, simulation models, such as CORSIM, use theoretical profiles of vehicle acceleration and speed relationships that have not been validated in the field. To determine the feasibility of using simulation models to predict on-road speedacceleration profiles and to identify potential problems in their use as such, a study intersection was modeled in NETSIM, and the simulation output was compared with data collected from field studies of signalized intersections. Analyses of the simulation output and field data indicate that NETSIM does not adequately simulate instantaneous modal vehicle activity. NETSIM intersection activity shows higher fractions of hard accelerations [≥ 9.7+ km/h/s (6 mph/s)] than are demonstrated by field data for the study intersection. For midblock, the results indicate that field data demonstrate a much greater distribution of speeds and accelerations than the distribution modeled by NETSIM.
Market Barriers to Natural Gas Vehicles and the Role of Clean Air Credits
Authors: Anderson Jon F. , King Thomas A.
Published: April 2007

The Clean Air Act Amendments of 1990 and the Energy Policy Act of 1992 called for the introduction of cleaner, alternative fuels into transportation fleet markets. Despite federal mandates for alternative-fuel vehicle (AFV) use and federal and state incentives, the growth in sales of AFVs and compressed natural gas vehicles (NGVs) has not matched expectations. Some of the reasons why AFVs in general and NGVs in particular have yet to gain a strong market presence are briefly reviewed. Insight into the potential role of clean air credits is offered. The use of clean air credits is one mechanism by which the environmental benefits of some AFVs can be quantified and used to push the economic equation in favor of NGV ownership. Applicable regulations, guidance, and programs are discussed, with examples of successful and unsuccessful attempts to apply open-market trading concepts to advance NGV use provided. Estimates of the potential value of credits in specific applications demonstrate the magnitude of improvement in the economics of NGVs that clean air credits offer. Key questions and practical constraints that states seeking to implement clean air credit programs encounter and needed regulatory clarifications are identified.
Safety Evaluation of Rolled-In Continuous Shoulder Rumble Strips Installed on Freeways
Authors: Griffith Michael S.
Published: April 2007

Single-vehicle run-off-the-road crashes result in about one-third of all highway fatalities and one-half million people injured annually, with a societal cost of $80 billion each year. Continuous shoulder rumble strips (CSRS) are one countermeasure used to address this significant safety problem. Data were analyzed for two states (California and Illinois) from the Highway Safety Information System to estimate the safety effects of CSRS on freeways. Before-and-after evaluations of CSRS projects with the use of different comparison groups were conducted. The results from the evaluations indicate that on average CSRS reduce single-vehicle run-off-the-road crashes by 18.3 percent on all freeways (without regard to urban/rural classification) and by 21.1 percent on rural freeways. Two types of potential adverse effects related to safety with CSRS were analyzed. The first type pertains to the crash risk that CSRS may present because of driver startle/panic responses. The second potential adverse effect of CSRS is crash migration. The research findings indicate that these potential adverse effects are insignificant.
Effect of Midblock Access Points on Traffic Accidents on State Highways in New Jersey
Authors: Mouskos Kyriacos C. , Sun Wu , Chien Steven I. , Eisdorfer Arthur , Qu Tao
Published: April 2007

The focus of this research was to conduct a statistical analysis of the effect of various traffic, geometric, and environmental factors on accident rates on New Jersey State highways. The main concern was the effect of midblock access points on accident rates. To identify the characteristics of access-related accidents (section accidents), a comparison study was conducted to investigate the effect of various factors on both section accidents and signalized intersection accidents. Access density was found to be a contributing factor to the occurrence of accidents, but it was not the only factor. About 30 percent of accidents on the study routes in New Jersey are expected to occur between signalized intersections, whereas 7 percent of the accidents are due to maneuvering to and from access points. Accident rates for sections between signalized intersections were better represented by a log-normal distribution than by a normal distribution. The effect of single factors such as access density, median, shoulder, number of lanes, and speed limits on accident rates was also investigated with the Kruskal—Wallis test. Of the above factors, only the number of lanes was found to be nonsignificant to accident rates. Two regression models for four lanes with shoulder, two lanes without shoulder, and four lanes with median were found to have sufficiently good R2 values and their use is recommended with caution. Hourly and subhourly traffic flow data, average operating speed and variance data, and law enforcement data will further improve the analysis of accident data.
Injury, Fatal, and Property Damage Accident Models for Highway Corridors
Authors: Khan Sarosh , Shanmugam Ramalingam , Hoeschen Brian
Published: April 2007

The relationship between fatal, injury, and property damage accident frequencies and traffic volume, segment length (SL), and vehicle miles traveled (VMT) is explored here. For this purpose, a generalized linear regression modeling framework was applied. Poisson, negative binomial, Gaussian, and log-normal distributions were evaluated in terms of their ability to model accident frequency for an interstate highway corridor in Colorado. Results indicate that, for injury, property damage, and total accidents, the Poisson regression with log-transformed predictors performed significantly better than the Poisson regression with linear predictors. For fatal accidents, the log-normal regression performed better than other regression models examined. However, the Poisson model performed better in terms of estimating accidents for the corridor. Models based on data disaggregated by median SL and annual average daily traffic (AADT) or VMT performed better than aggregated models. In addition, the SL-AADT–based models estimated a smaller difference between observed and expected total number of accidents for the corridor than the VMT-based model. SL and traffic volume were significant for injury and property damage accidents. For fatal accidents, an exposure-based predictor VMT was significant across all segment groups.
Rates of Occupant Deaths in Vehicle Rollover: Importance of Fatality-Risk Factors
Authors: Donelson Alan C. , Ramachandran Karuna , Zhao Ke , Kalinowski Ann
Published: April 2007

Fatality-based rates—for example, the numbers of occupant deaths per 10,000 registered vehicle years—are often used to compare the “realworld performance” of passenger vehicles. One assumption, often implicit, is that such rates reflect more the design or characteristics of vehicles and less the human and environmental factors that can increase the risk of fatality. The purpose of this study was to examine the importance of selected fatality-risk factors for the magnitude and meaning of fatality-based rates. The objectives were to quantify the influence of fatality-risk factors, to adjust fatality-based rates for that influence, and to assess how well adjusted rates measured differences for various groupings of vehicles. The focus of this study was on rollovers in single-vehicle crashes involving light-duty trucks. Statistical models of fatality risk were developed with multivariate logistic regression applied to data on single-vehicle rollovers of any severity. Raw counts of occupant fatalities based on data from the fatality analysis reporting system were then adjusted. Finally, the statistical reliability of differences in adjusted rates was estimated. Results indicated that adjusted rates were a very small fraction of crude rates. Differences in rates for light trucks decreased greatly and, in general, became statistically insignificant. Studies comparing fatality-based rates among vehicles need careful, statistical control of factors that increase the risk of fatal injury. Fatal crashes are rare and have special attributes. Rollover research specific to vehicles would do well to concentrate on crashes of any severity, which, for vehicles grouped by make and model, demands reference to large-volume files maintained by states.
Automated Bus Dispatching, Operations Control, and Service Reliability: Baseline Analysis
Authors: Strathman James G. , Dueker Kenneth J. , Kimpel Thomas , Gerhart Rick , Turner Ken , Taylor Pete , Callas Steve , Griffin David , Hopper Janet
Published: April 2007

Tri-Met, the transit provider in Portland, Oregon, is implementing a new computer-aided bus dispatching system that uses a satellite-based global positioning system to track vehicle location. It is expected that the new system will produce improvements in service reliability. Presented is a baseline analysis of service reliability on selected routes, focusing on running times, headways, and on-time performance. Reliability is found to vary according to route characteristics, direction, and time of day.
Carsharing and Partnership Management: An International Perspective
Authors: Shaheen Susan , Sperling Daniel , Wagner Conrad
Published: April 2007

Most cars carry one person and are used for less than 1 hour per day. A more economically rational approach would be to use vehicles more intensively. Carsharing, in which a group of people pays a subscription plus a per-use fee, is one means of doing so. Carsharing may be organized through affinity groups, large employers, transit operators, neighborhood groups, or large carsharing businesses. Relative to car ownership, carsharing has the disadvantage of less convenient vehicle access but the advantages of a large range of vehicles, fewer ownership responsibilities, and less cost (if vehicles are not used intensively). The uncoupling of car ownership and use offers the potential for altering vehicle usage and directing individuals toward other mobility options. The perceived convenience (e.g., preferred parking) and cost savings of carsharing have promoted a new modal split for many carsharing participants throughout the world. Societal benefits include the direct benefit of less demand for parking space and the indirect benefits arising from linking costs to actual usage and matching vehicles to trip purpose. The experience of carsharing in Europe, North America, and Asia is reviewed, and its future prospects through expanded services, partnership management, and advanced technologies are explored.
Praxitèle: Preliminary Results from the Saint-Quentin Station-Car Experiment
Authors: Massot Marie-Hélène , Allouche Jean-François , Bénéjam Evelyne , Parent Michel
Published: April 2007

The Praxitèle system is the first large-scale, operational, public individual-transportation system—or station-car system—using self-service electric vehicles. It was developed in France by a consortium of industrial companies and research institutes, formed in 1993. Its operation started in the city of Saint-Quentin-en-Yvelines, a high-tech center near Paris, at the end of 1997 with 50 electric vehicles from Renault. At midterm in the experiment, close to 500 participants were using the system. This is the first report on the experiment, which continued until the end of 1998. Preliminary conclusions show that users have expressed a high level of satisfaction and a desire to expand the system. However, no conclusion can be drawn yet on the economics of such a system, which remains expensive and underutilized.
System Time Minimization in Route Guidance with Elastic Market Penetration
Authors: Lo Hong K. , Chen Anthony , Yang Hai
Published: April 2007

Route planning and guidance (RPG) services are intended to provide benefits to their users, in the form of either convenience or, more importantly, travel time savings. The reduction in system travel time, if achieved, is a “side effect.” How should the transportation management agency then respond to these services? Under what circumstances should the agency encourage or discourage their implementation? A model to answer these questions is developed. Two ingredients are important in the model discussed. First, the market penetration of RPG is modeled in an elastic manner. Analogous to a supply-demand equilibrium, market penetration is determined endogenously in an equilibrium between the benefits and cost of acquiring the services. It is argued that the cost of RPG services could be used as a way to alter the elastic market penetration, and hence modify and, it is hoped, lower the total system congestion. Thus, a bilevel program to capture the situation is formulated. The lower-level program models the multiclass (equipped and unequipped) equilibrium problem with elastic market penetration. The upper-level program then minimizes the system travel time by using the cost of RPG services as a control variable. Numerical results of a small network are provided to illustrate the behavior of this model.
Simplified Formulation of the Toll Design Problem
Authors: Chen Mei , Bernstein David H. , Chien Steven I.J. , Mouskos Kyriacos C.
Published: April 2007

Much of the existing literature on congestion pricing has assumed that it is possible to toll every link in the network. Whereas this is very interesting theoretically, it is not of much use in practice where only a limited number of links can be tolled (e.g., certain bridges, tunnels, and freeways). To accommodate this situation, a bilevel formulation of the toll design problem that is similar in spirit to bilevel formulations of the continuous network design problem can be developed. Unfortunately, such formulations can be difficult to solve. A simplified, single-level formulation of the toll design problem that may prove to be more applicable in practice is presented.
Influence of Total Aggregate Gradation on Freeze-Thaw Durability and Other Performance Measures of Paving Concrete
Authors: Cramer Steven M. , Carpenter Andrea J.
Published: April 2007

Transportation-related agencies are experimenting with increased control of aggregate gradation in their concrete pavement specifications. There is anecdotal evidence that shows that total aggregate gradation can be optimized to yield improved concrete performance during construction and service life. Strong scientific data are less numerous in supporting this idea because of the variability in aggregates that can occur and practical considerations in avoiding waste particle sizes. The influence of total aggregate gradation on the freeze-thaw durability of concrete test specimens that employed a variety of sedimentary and igneous aggregates common in Wisconsin is examined. Optimized gradations consisted of increased amounts of aggregate particles in the No. 4 to No. 16 sieve size range and decreased amounts of fines in the No. 50 to No. 200 sieve size range. A near-gap gradation was fabricated by removing some particles in the No. 4 to No. 16 sieve size range and increasing the amount of fine material in the No. 30 to No. 100 sieve size range. Several methodologies and practical considerations were considered in establishing the aggregate gradations. A control gradation utilized a 60-40 blend of coarse/fine aggregate with gradations determined by the naturally occurring particle sizes. The concrete specimens prepared in this study were subject to strength, shrinkage, permeability, and accelerated freeze-thaw testing. All concretes had well-controlled water-cement ratios and showed excellent freeze-thaw durability. The optimized gradation mixes did not show consistently improved performance compared with the control mixes. The near-gap mixes showed reduced strength, reduced freeze-thaw durability, and increased shrinkage.
Bond Interaction Between Concrete Pavement and Lean Concrete Base
Authors: Tarr Scott M. , Okamoto Paul A. , Sheehan Matthew J. , Packard Robert G.
Published: April 2007

In the past, concrete pavement design procedures have been based on stresses computed with the assumption of either a frictionless or a fully bonded interface between pavement layers. It is recognized that neither of these assumptions is realistic for layers not intentionally bonded. Information on the degree of interaction between pavement layers is provided. Full-scale load-induced strain and falling weight deflectometer testing was conducted to measure the degree of bonding between portland cement concrete pavement and a lean concrete base (LCB) layer prepared using five commonly specified interface treatments. For each interface treatment, the effect of extending the LCB layer beyond the slab edge was also evaluated. Strain gauges installed at different pavement depths measured the load-induced edge and wheelpath stress profiles, which allowed the degree of layer interaction to be evaluated. By analysis of load-induced stress and deflection, it was verified that a double layer of polyethylene promotes an unbonded interface with very little frictional interaction. Other interface treatments create varying degrees of friction or partial bond between the layers, reducing the loadinduced stress. Slab bottom tensile stress reductions were computed in comparison with measured slab top compressive stress, measured polyethylene interface tensile stress, and theoretically calculated unbonded stress. Overall, the most effective stress-reducing interface treatments were asphalt emulsion and plain (no treatment) conditions, where tensile stress reductions of more than 40 percent were measured.
Investigation of Design Parameters Affecting Transverse Cracking in Jointed Concrete Pavements
Authors: Frabizzio Michael A. , Buch Neeraj J.
Published: April 2007

Environmental effects and repetitive traffic applications can lead to the development of transverse cracks in jointed concrete pavements (JCPs). Maintaining adequate aggregate interlock load transfer across these cracks is essential to preserving the functional and structural integrity of these pavements. The objectives of this study were to determine the design parameters that significantly affect transverse cracking and to demonstrate methods available for evaluating cracked pavements. Field data collected from in-service JCPs located throughout southern Michigan were used to accomplish these objectives. Joint spacing, coarse aggregate type, shoulder type, and pavement temperature were found to have significant effects on transverse crack development and/or performance. The surface texture of crack faces was assessed using a promising new test method called Volumetric Surface Texture (VST) testing. VST results provided an indication of the aggregate interlock potential of pavements containing various aggregate types. Three performance parameters capable of mechanistically characterizing crack performance were discussed. A relatively simple procedure was described for determining these parameters and evaluating crack condition. Field data were also used to demonstrate and validate a voids-analysis procedure.
Geochemical Method for Identifying Alkali-Silica-Reaction Gel
Authors: Guthrie George D. , Carey J. William
Published: April 2007

A geochemical method for staining various products of the alkali-silica reaction is presented. The method is based on both the composition of alkali-silica-reaction (ASR) gel and one of its properties (the ability to exchange cations with a fluid). Specifically, one stain (sodium cobalt-initrite) reacts with exchangeable potassium in the gel to form a bright-yellow precipitate on the gel surface. The other class of stains (a variety of rhodamine compounds) reacts with calcium-rich portions of the gel (and, for some compounds, with other calcium-rich components of the concrete) to form a pink-stained gel. The significance of the pink staining is twofold. First, it can provide a high contrast to the yellow-stained gels, making them easier to observe. Second, some rhodamine compounds react predominantly with Ca-rich ASR gels. Some aspects of staining by rhodamine remain the subject of continued study and may be useful for a more detailed understanding of ASR progression and other deterioration mechanisms. However, a positive diagnosis of ASR is indicated by the presence of yellow-stained gel within aggregate, at the aggregate-paste interface, along fractures, or in air voids. The technique can be used as a rapid field screening method or as a useful aid for detailed petrographic examinations.
Measuring Results and Demonstrating Performance at Newark Airport Monorail
Authors: Rosenheimer David M. , Dexter John
Published: April 2007

Most transit operations are big and complex and involve large numbers of people and millions of dollars of equipment. Because of their size and the fact that their business is providing service to the public, transit systems must deal with problems effectively. Very often service providers can find themselves in never-ending crisis management, trying to keep the system running, giving equal attention to every problem regardless of its impact, and becoming lost in the technology. During the startup operations of the Newark Airport (airport code EWR) monorail, Booz-Allen created a number of computer programs to perform automated analysis of the monorail’s daily automatic train supervision log. These programs provided metrics for measuring the progress of problem resolution for the various subsystems involved with train operations. These analysis tools, which helped managers and technicians to make the decisions prioritizing resources and to characterize the behavior of new technology, are discussed.
Marketing and Fare Nexus Applied in San Diego
Authors: Hurwitz Elliot Paul , Williamson Jennifer S.
Published: April 2007

The multimodal operator environment and fare structure of San Diego’s transit system have, for the past several years, been structured to encourage transfers and to provide easy access between the bus and rail systems. During the past year, marketing efforts in the region were expanded to penetrate new markets and aggressively pursue new customers for the region’s bus and trolley services. The real issue was how to effectively integrate the existing fare structure with the new markets and retain existing customers. The San Diego Metropolitan Transit System had a great opportunity to expand its market with the opening of a new trolley extension to Mission Valley. At the same time, bus services were also being expanded. A new effort resulted in a commitment from the policy board to move ahead with a more aggressive marketing and fare strategy to capture new riders. The objective of the new fare policy was to relate it to new markets while retaining existing markets. The fare policy was designed with a pricing strategy to closely respond to different market segments, both new and existing. The new fares were implemented on November 23, 1997. The goal was to increase ridership and fare revenues and minimize impacts on existing riders. Initial results, based on the first 9 months of the new strategy, indicate that ridership increased 13.5 percent and revenue increased 10.6 percent.
Metropolitan Atlanta Rapid Transit Authority Fare Elasticity Model
Authors: Harris Annie E. , Thomas Robert , Boyle Daniel
Published: April 2007

The introduction of a variety of fare media has increased riders’ choices of how to pay for transit and has provided transit agencies with the ability to price fare media differently. An aggregate elasticity value such as the Simpson-Curtin formula provides cannot capture the shifts among fare media, and elasticities for specific fare payment categories do not directly address these shifts. The Metropolitan Atlanta Rapid Transit Authority (MARTA) fare elasticity model was developed to identify shifts among fare payment methods and to forecast ridership and revenue changes resulting from a fare change. The key element in predicting shifts among fare media is the identification of the propensity of riders to choose one fare medium over another even if their prices are identical. After current ridership is adjusted to take account of these shifts, fare elasticities are then applied to predict post-fare-change ridership levels by fare payment method. The new ridership figures are used to forecast new revenue. The model requires minimal input from the user, primarily current ridership by fare payment mode and current and proposed fare levels. Elasticities can also be changed by the user to test the sensitivity of the elasticity assumptions, and factors such as the intensity of weekly and monthly TransCard use are additional input options. The model has proved to be very accurate when applied to the most recent MARTA fare change on July 1, 1995, predicting overall ridership within 0.05 percent and revenue within 0.7 percent. A model enhancement allows the user to recalibrate the model after any future fare changes by testing the accuracy of different elasticity assumptions.
Enhancing Transit’s Competitiveness: A Survey Methodology
Authors: Schaller Bruce
Published: April 2007

Attracting customers to the bus and subway is an often-discussed goal for transit agencies. Current research methodologies such as travel demand, stated preference, and discrete choice models and opinion research are sometimes poorly suited to determining which types of service improvements, facility designs, or fare policy initiatives will be most effective in attracting potential customers. Drawing on elements of established methods, an approach is developed for use by New York City Transit focusing on travelers’ actual experience of the subway, bus, automobile, taxi, and car service and their reasons for mode choice. Survey questions were developed from focus group findings that New Yorkers actively choose between competing modes on the basis of six major factors, from how long the trip will take to availability of parking. Travelers choose the mode that presents the least difficulty for a particular type of trip. Survey results show that the areas of subway service improvement with the greatest potential ridership payoff are reducing how long it takes to make a trip, increasing the availability or ease of use of transit, and making traveling on the subway a more comfortable and relaxing experience. Two external factors—parking availability and taxi fares—are also found to significantly affect subway ridership.
Railway Noise Model
Authors: Macdonald John M. , Wayson Roger L.
Published: April 2007

The Railway Noise Model (RWNM) was developed at the University of Central Florida and predicts sound levels at receivers near railway operations for analyses used in environmental documents. The RWNM is a simulation model, and trains are modeled as moving point sources of sound. The user can create model objects, tracks, barriers, and receivers, using either the mouse or spreadsheet interfaces. During simulation, the user observes trains moving along railways and the relationships to receiver locations. The RWNM simulates a 24-h period of rail traffic and computes day/night sound pressure level (Ldn), maximum sound pressure level (Lmax), sound exposure level (SEL), and equivalent sound pressure level (Leq) at the receivers. The RWNM uses REMEL (reference energy mean emission levels) curves based on Federal Transit Administration (FTA) reported Lmax pass-by levels for locomotives and rail cars. In addition, the model has the ability to model heavy rail locomotives and rail cars, which makes it applicable to Federal Railroad Administration projects. Testing has shown that the RWNM results match those of the FTA-approved spreadsheet, although heavy rail validation is limited.
Cumulative Impact Assessment and Its Application to a Transportation Project
Authors: Page John , Parkins Lorna
Published: April 2007

A proposed bridge would connect mainland Currituck County, North Carolina, with the county’s Outer Banks. The Outer Banks are rapidly developing with rental recreation homes. Cumulative impacts, particularly their secondary (indirect) impacts components, are one of the principal issues in deciding whether to build the bridge. The components of cumulative impact assessment represent an expansion of the traditional components of an impact assessment: scoping, description of the affected environment, and determination of environmental consequences and mitigation of effects. Scoping broadens to include past, planned, and unplanned induced governmental and nongovernmental actions and their effects, as well as a broader range of analysis limits. The affected environment encompasses a description not only of existing conditions but also of past trends, development and environmental goals, the project area’s potential for growth, and forces of change. The assessment of environmental consequences looks at the incremental difference between the build and the no-build future. The absolute impact of both scenarios also is important because one might find that neither scenario is desirable. The components of cumulative impact assessment as derived from the literature and the application of cumulative impact assessment to the specific problem of the Mid-Currituck Sound bridge project are discussed.
Field Demonstration of Highway Embankment Construction Using Waste Foundry Sand
Authors: Partridge Barry K. , Fox Patrick J. , Alleman James E. , Mast David G.
Published: April 2007

Considerable savings are available to the metal casting industry through the development of reuse applications for waste foundry sand (WFS). Departments of Transportation (DOTs) that are facing increased pressure to reuse waste materials may also save from using low-cost WFS as a source material in transportation construction. In 1996, the Indiana Department of Transportation (INDOT) and Purdue University constructed a demonstration embankment using WFS from a ferrous foundry. WFS and control embankments were instrumented to monitor geotechnical and environmental performance during and after construction. Stockpile WFS samples were also tested. The geotechnical performance of the WFS was comparable to that of natural sand, with small internal deformations and a high-standard penetration resistance. However, the WFS had a hydraulic conductivity considerably lower than that of natural sand and cannot be considered as freely draining. Minor problems were encountered during construction due to foreign objects and dust in the WFS. Environmental testing consisted of Microtox™ and Nitrotox bioassays, ion chromatography, and inductively coupled plasma testing for metals. Bioassay results indicate the WFS has not resulted in inhibitions (toxicity) higher than those expected from natural sands. Ion migration from the WFS into the foundry sand lysimeter and down-gradient wells was found but at concentrations below regulatory reuse criteria. Metal concentrations also were below regulatory reuse criteria and typically below drinking water standards. The WFS did not result in a negative environmental impact at the site.
Next Frontier in Accessible Traveler Information Systems: World Wide Web-Based Information Systems
Authors: Hunter-Zaworski Katharine , Stewart Ronald
Published: April 2007

Ergonomic guidelines for traveler information systems were developed as one part of an effort to ensure that new technologies associated with Intelligent Transportation Systems are available to all persons, and especially to persons with sensory, cognitive, and mobility impairments. The importance of ensuring that World Wide Web-based traveler information systems are accessible is highlighted. The ergonomic guidelines are based on research and empirical evidence from Europe and North America and are primarily concerned with static, dynamic, and tactile signs or signage systems that are used in passenger transport facilities. Many sections of the guidelines have broader applications to other information systems that involve the person-machine interface. The ergonomic guidelines are in the process of being converted to an accessible format that will be available on the Technology Access Program website at Oregon State University. The development of ergonomic guidelines for passenger information systems has been under way for a number of years in Europe and North America. The source documents from these areas are integrated, and commentary or discussion is provided where there are significant differences of opinion or discrepancies in operating practices. The guidelines have been developed for use both by transportation and by design professionals involved with the specification, procurement, and implementation of basic or sophisticated information systems. Design standards need to recognize the variability and the associated needs of all persons. The underlying principle of “design for all” is the basis for the ergonomic guidelines.
Mobility Changes: Their Nature, Effects, and Meaning for Elders Who Reduce or Cease Driving
Authors: Burkhardt Jon E.
Published: April 2007

Definite mobility changes occur when older drivers reduce or cease driving. In a majority of cases, mobility declines. Fewer trips will be taken, shorter distances will be traveled, fewer or no trips will be taken under certain conditions, and the older person will be more often traveling according to the schedules and convenience of others. Older drivers make about six trips/week, in contrast to two trips/week for older nondrivers. The older person who reduces or ceases driving bears the brunt of the changes that occur in terms of monetary, social, psychological, and emotional costs. When it is not possible to maintain previous connections established by our elderly citizens, society suffers from the lack of access to the expertise of these older adults as well as from the loss of their productivity as workers and volunteers. Thus there are many reasons to take steps to reduce the potential mobility losses associated with the reduction or cessation of driving. The concept that life depends on driving is less prevalent when other travel options are available. Adults who had access to a well-developed public transportation system and who could live in close proximity to the kinds of shopping and recreational opportunities that appeal to seniors felt that a car was not a necessity to live an active life. They could control their mobility choices and could make reasoned choices about whether to drive.
Bus Accessibility for People with Cognitive Disabilities
Authors: Hunter-Zaworski Katharine , Hron M. L.
Published: April 2007

With the passage of the Americans with Disabilities Act (ADA) it has become a civil rights violation to deny access to public transportation by people with disabilities. ADA requires transit agencies to provide accessible buses or equivalent services to people with mobility, sensory, or cognitive impairments. Issues concerning people with cognitive impairments, and their access to fixed-route transit services, are examined in this study. The literature concerning access to public transit by people with cognitive disabilities is summarized in this paper, along with exemplary training programs and technologies that have improved transit accessibility for people with cognitive disabilities. On review of the available literature, the authors noted that there was very little information concerning people with cognitive impairments. To fill in this knowledge gap, surveys and interviews were conducted with people with cognitive and other impairments, with people who trained people with sensory and cognitive impairments, and with people who provide special transportation services. A major conclusion of this study is that, for people with cognitive impairments, technological solutions are not the best solutions to increase bus accessibility. Personal interaction is needed to solve each individual situation with the transit user. Training for transit personnel, transit users, and travel trainers is needed to help people with cognitive impairment use the transit system with grace, speed, efficiency, and dignity. Another conclusion of the study is that to be effective all visual signage must be consistent—location, lighting, contrast, and content of visual signs.
Determining the Right Size of a Rental Vehicle Fleet: Case Study
Authors: Hanson Robert A.
Published: April 2007

The Virginia Department of Transportation’s Division of Fleet Management (DFM) maintains a fleet of vehicles for short-term rental to state employees traveling on official state business. This fleet, known as the trip pool, is a subset of the state-owned centralized fleet. Until May 1996, vehicles in the trip pool were not assigned in the most efficient manner, thereby limiting their maximum potential use. In May 1996, a vehicle-rental contract with a private-sector company allowed DFM to change its vehicle-assignment practices to use the vehicles in the trip pool more effectively. The private-sector vehicle-rental contract enabled DFM to reduce the size of the trip pool because excess demand could be met with private-sector vehicles. Data collected from an unpublished 1995–1996 study of DFM, together with updated data, were incorporated into a revised inventory model. The results show that the vehicle-rental contract with a private-sector company resulted in an approximate quantifiable savings of $20,000 per year. The full amount of the savings cannot be quantified because of the lack of available data. Other results indicate that the overall cost of state employee travel can be reduced by an estimated additional $20,000 per year if DFM resizes the trip pool.
Snow and Ice Expenditure Stabilization and Cost Savings Using Weather Hedges and Insurance
Authors: Hyman William A. , Levey Jerry
Published: April 2007

Annual winter maintenance operations totaling approximately $2 billion nationwide account for a significant percentage of state, county, and municipality highway maintenance budgets. A key challenge is dealing with weather variability, especially weather extremes. Maintenance organizations have many strategies to mitigate the impacts of this variability and to balance workloads from year to year. However, for the most part, these strategies are not designed to deal with uncommon occurrences in a manner calculated to address risk of abnormal costs. As new financial markets have emerged, new techniques have been developed to manage weather variability and risks that can result in significant cost savings to transportation departments. The electric utility industry and other economic sectors are now using weather hedges to stabilize costs and revenues, and in some cases, to achieve net savings. This paper discusses the potential of weather hedges involving derivatives of weather and agency cost data to stabilize and potentially reduce costs of winter maintenance. Also briefly discussed is the purchase of insurance as an alternative to weather hedges. To make weather hedges feasible and acceptable to maintenance managers, executives, administrators, and financial officers in transportation agencies, as well as elected officials, several barriers must be overcome. It is estimated that weather hedges or insurance can potentially reduce net outlays for snow and ice control by 10 to 20 percent of winter maintenance costs in years in which the number of annual snow events would be expected to exceed the mean by one standard deviation.