bluuebunny/crossref_metadata_2025 huggingface dataset:
Corrections to Mileage Accumulation Rates for Older Vehicles and the Effect on Air Pollution Emissions
Authors: Miller Terry L. , Davis Wayne T. , Reed Gregory D. , Doraiswamy Prakash , Tang Anna , Sanhueza Pedro
Published: April 2007

The MOBILE6 emissions model, currently under development, uses mileage accumulation rates that assume that the average 25-year-old car has been driven more than 337 962 km (210,000 mi), and that the average 25-year-old pickup truck has been driven more than 402 336 km (250,000 mi). Cumulative mileage is used in the model to calculate emission factors that increase with mileage due to air pollution control device “deterioration.” Odometer readings taken in previous studies by the Environmental Protection Agency and additional data indicate that average mileage accumulations may be much less [i.e., 201 168 km (125,000 mi)] than those used in the MOBILE6 model. This has the effect of overestimating emissions from older vehicles. A simple model is presented that accounts for scrappage of older vehicles as a function of cumulative mileage. This model predicts average cumulative mileage that is much closer to actual odometer readings (taken in Nashville, Tennessee) than the default values used in MOBILE6. The use of more accurate cumulative mileage values for older vehicles should provide improvements to the estimation of emissions from the vehicle fleet.
Speed Prediction Models for Trucks on Two-Lane Rural Highways
Authors: Donnell Eric T. , Ni Yingwei , Adolini Michelle , Elefteriadou Lily
Published: April 2007

In the design consistency literature, the development of speed prediction models has concentrated on passenger cars, with little attention given to truck speed models. On some two-lane rural highways, however, trucks represent a large enough percentage of vehicles that they may be considered the design vehicle. The objective of the study was to develop operating speed prediction models for trucks on two-lane rural highways. A series of regression models was developed using a combination of field data and simulated data. First, the “Traffic on Rural Roads” and “Two-Lane with Passing” (TWOPAS) simulation models were critically assessed, and TWOPAS was selected to be used in further analysis. Next, field data from 17 sites were used to evaluate TWOPAS’s capability in the prediction of passenger car speeds and truck speeds. On the basis of the results of this evaluation, 13 sites were selected for use in simulating truck operating speeds. These sites were used to generate additional speed data for inclusion in the database for model development. Finally, a series of regression models was developed to predict 85th percentile truck operating speeds upstream, along, and downstream of a horizontal curve. These models consider the effect of length and grade of approach tangent, horizontal curve radius, and length and grade of departure tangent.
Geometric Design and Safety Aspects of Roundabouts
Authors: Flannery Aimee
Published: April 2007

The findings of a 3-year study conducted at Pennsylvania State University for FHWA on the safety and operational performance and geometric characteristics of roundabouts are presented. The study focused on geometric characteristics that influence the safety and operational performance of roundabouts. Accident data (including driver testimonials) were reviewed along with videotapes developed at several roundabouts in Maryland, Florida, and Nevada. Several conclusions were drawn, including the need to improve geometric design on approaches to rural roundabouts to reduce loss-of-control accidents; the need for adequate right-of-way to properly deflect vehicles around the center island; and the need for guidance regarding operating-volume-to-capacity ratios. The findings from the study will assist planners, designers, and engineers in avoiding unnecessary safety hazards and operational failures.
Controls for Horizontal Curve Design
Authors: Bonneson James
Published: April 2007

Several concerns have been documented in the literature regarding AASHTO’s Green Book guidelines for horizontal curve design. Specifically, some researchers are concerned that the side friction factors are dated and do not reflect today’s drivers, vehicles, and pavements. Some also are concerned that the superelevation distribution method recommended in the Green Book, in combination with the use of multiple maximum superelevation rates, does not promote design consistency. Side friction factors and a distribution method that resolve these concerns have been developed.
Operational Evaluation of Freeway Ramp Design
Authors: Hunter Michael , Machemehl Randy , Tsyganov Alexei
Published: April 2007

Ramp facilities provide all freeway entrance and exit opportunities. Thus, excellent freeway ramp design criteria are critical to freeway operations and safety. Current freeway entry ramp design speed criteria were evaluated by observing six (nonloop) ramps in three Texas cities. Ramp and freeway traffic speed-distance relationships were observed in the field using videotaping methods. Traffic operations were described in terms of ramp and freeway speeds and accelerations, as well as merging locations, accepted time gap sizes, and freeway time headways. Performance characteristics for numerous ramp features and volume combinations were compared. Combined design feature and traffic volume effects on freeway operations and both positive and negative impacts that may be attributed to ramp design features were evaluated. Several notable conclusions were reached. First, for virtually all observations, ramp driver speeds were found to be greater than 50 percent of the freeway design speed; therefore, a 50th percentile design speed might have negative safety implications. Second, the ability of entry ramp drivers to see freeway right-lane traffic, into which merging is intended, before reaching the ramp gore was found to be very important. Therefore, the AASHTO acceleration lane length measurement model for taper-type ramps should be clarified. The acceleration lane should be considered to begin only when ramp drivers have an unobstructed view of freeway right-lane traffic.
Modeling Effects of Anticipated Time Pressure on Execution of Activity Programs
Authors: Timmermans Harry , Arentze Theo , Joh Chang-Hyeon
Published: April 2007

Existing activity-based models are typically concerned with predicting observed activity travel patterns. The study of the dynamics of the activity-scheduling process has received far less attention. To some extent, this situation can be explained by a lack of relevant data, but there is also a lack of conceptualization and simulation work. To fill this gap, the process of how individuals adjust their activity program as a function of anticipated time pressure during the execution of the program is conceptualized and specified.
Modeling Route Choice Behavior with Stochastic Learning Automata
Authors: Ozbay Kaan , Datta Aleek , Kachroo Pushkin
Published: April 2007

Day-to-day route choice behavior of drivers is analyzed by the introduction of a new route choice model developed using stochastic learning automata (SLA) theory. This day-to-day route choice model addresses the learning behavior of travelers on the basis of experienced travel time and day-to-day learning. To calibrate the penalties of the model, an Internet-based route choice simulator (IRCS) was developed. The IRCS is a traffic simulation model that represents within-day and day-to-day fluctuations in traffic and was developed using Java programming. The calibrated SLA model is then applied to a simple transportation network to test if global user equilibrium, instantaneous equilibrium, and driver learning have occurred over a period of time. It is observed that the developed stochastic learning model accurately depicts the day-to-day learning behavior of travelers. Finally, the sample network converges to equilibrium in terms of both global user and instantaneous equilibrium.
Assessing Urban Context-Induced Change in Individual Activity Travel Patterns: Case Study of New Railway Station
Authors: Arentze Theo , Borgers Aloys , Ponjé Maarten , Stams Adrianneke , Timmermans Harry
Published: April 2007

Findings are reported of selective descriptive analyses that were conducted to examine whether the opening of a new railway station had induced any changes in the activity travel patterns of a panel of households. In particular, changes in choices related to trip generation, trip chaining, transport mode, activity start time, and activity duration were analyzed. Moreover, differences in complete activity travel patterns before and after the opening of the new railway station were investigated. The results indicate that the introduction of the railway station led to a change in work pattern, an increase in out-of-home leisure activities, and a decrease in trip chaining. As a result, total travel distance has not increased significantly, but the travel distance by car has decreased. However, before-and-after studies like this cannot exclude the possibility that the factor of time is responsible for or has contributed to the change.
Experiments with Computerized Self-Administrative Activity Survey
Authors: Lee Ming S. , McNally Michael G.
Published: April 2007

The process of activity scheduling is crucial to the understanding of travel behavior changes. In-depth research is urgently needed to unearth this process. A new computer program, REACT!, was developed to collect household activity scheduling data for this purpose. The program is implemented as a stand-alone program with Internet connectivity for remote data transmission. It also contains a geographic information system for location identification and a special feature that traces the decisions in the scheduling process. A pilot study was conducted in Irvine, California, to evaluate the program’s performance. Preliminary analysis validated the program’s capability of guiding participants to complete data entry tasks on their own; thus, the objective of reducing the cost of human resources for such a computerized survey is achieved. Other positive results were obtained regarding the objectives of reducing instrumental biases and expanding program capabilities. Areas for improvement were identified in the pilot study. On the basis of the findings, REACT! represents an ideal platform for a computerized household survey that can produce data for activity-based travel models.
Modeling Automobile Demand and Driver Population in Palestinian Territories: Simultaneous-Equation Estimation Method
Authors: Abu-Eisheh Sameer A.
Published: April 2007

Automobile demand has been extensively investigated because of its direct effects on many related fields, including travel behavior, public policy and management, and transportation impact analysis. A modeling framework is developed to estimate aggregate automobile demand using simultaneous-equation regression analysis. This modeling approach is used to estimate automobile demand and driver population in the Palestinian Territories, where major changes in the political, socioeconomic, and infrastructure systems are currently under way. The developed model captures a number of relevant socioeconomic and political variables believed to affect automobile ownership in the Palestinian Territories. The findings suggest that there is a strong interrelationship and simultaneity between automobile ownership and the population of drivers. Relevant tests are applied to examine the econometric specifications of the presented models, which indicate that income, price, demographic, and employment variables are considered significant in the simultaneous-equation model. The model can be used as a basis for forecasting automobile demand.
Real-Time Variable Message Sign–Based Route Guidance Consistent with Driver Behavior
Authors: Peeta Srinivas , Gedela Shyam
Published: April 2007

The variable message sign (VMS) represents a cost-effective mechanism for disseminating information to drivers unequipped to receive personalized information. The VMS can be used during incidents to divert traffic to less congested areas of the network and circumvent lengthy queues, better utilize network capacity, and improve system performance. A VMS control heuristic framework is proposed and evaluated that seeks diversion during incidents to enable a traffic system controller to favorably manage traffic conditions in real time. The framework ensures consistency with driver diversion response behavior, is responsive to changing traffic conditions, enables computational tractability through stage-based online implementation, and ensures the spatial and temporal consistency of the displayed messages. A hybrid framework is used that consists of offline and online components to determine the information for the VMS. The ability to display messages consistent with driver diversion behavior represents a valuable tool for the controller to enhance system effectiveness by simultaneously satisfying systemwide and individual user objectives. Data on driver VMS response attitudes from the Borman Expressway corridor in northwestern Indiana and simulated experiments are used to derive insights into the practical effectiveness of the proposed VMS control heuristic.
Direct Forecasting of Freeway Corridor Travel Times Using Spectral Basis Neural Networks
Authors: Rilett Laurence R. , Park Dongjoo
Published: April 2007

With the advent of advanced traveler information systems, the prediction of short-term link and corridor travel times has become increasingly important. The standard method for forecasting corridor travel times is a two-step process in which the link travel times are first forecast and then combined into a corridor travel time. If link travel times are not independent, however, there is the potential for erroneous corridor or route travel time estimates. As an alternative to the two-step approach, a direct or one-step approach for freeway corridor travel time forecasting is proposed that automatically takes into account interrelationships between link travel times. The use of spectral basis neural networks to directly forecast multiple-period freeway corridor travel times is examined first. The model is tested on observed travel times collected as part of the automatic vehicle identification component of the Houston Transtar system. The direct forecasting model is also compared with the two-step model, which uses forecast link travel times as input. It was found that the direct forecasting approach gave better results than any of the other models examined and that link travel time forecasting errors are not additive.
Does Public Transit Counteract the Segregation of Carless Households? Measuring Spatial Patterns of Accessibility
Authors: Grengs Joe
Published: April 2007

Although local transit agencies struggle to keep pace with low-density urban development, most people who depend on transit continue to live in concentrated clusters at the core of metropolitan regions, becoming more distant to the variety of places they need to access. Standard transit performance measures fail to help local transportation agencies adapt their services to changes in demographics and urban form. Geographic information systems (GIS) provide a method for measuring transit service at the neighborhood scale while accounting for land-use changes. The first aim was development of a GIS-based accessibility indicator that is straightforward to calculate, easy to interpret, and flexible enough to use for employment and nonwork travel alike. The second objective was to introduce recent advances in spatial statistics to transportation planners to help them quantitatively assess changes in accessibility patterns over time. A case study is examined of accessibility to supermarkets in Syracuse, New York. The analysis finds that over 7,500 households, representing 12 percent of the city’s households, do not have reasonable access to supermarkets. Furthermore, using visual assessment of maps, aspatial database operations, and spatial statistical tests, the study provides statistically significant evidence that poor accessibility is associated both with low-income neighborhoods and with neighborhoods with disproportionately high populations of African Americans.
Effect of Free Parking on Commuter Mode Choice: Evidence from Travel Diary Data
Authors: Hess Daniel Baldwin
Published: April 2007

This study assesses the effect of free parking on mode choice and parking demand. A multinomial logit model is developed to evaluate the probabilities that commuters who do and do not receive free parking at work will choose to drive alone, ride in a carpool, or use transit for the trip to work in the central business district (CBD) of Portland, Oregon. The mode choice model predicts that with free parking, 62 percent of commuters will drive alone, 16 percent will commute in carpools, and 22 percent will ride transit; with a daily parking charge of $6, 46 percent will drive alone, 4 percent will ride in carpools, and 50 percent will ride transit. The mode choice model predicts that a daily parking charge of $6 in the Portland CBD would result in 21 fewer cars driven for every 100 commuters. This translates to a daily reduction of 147 vehicle miles traveled (VMT) per 100 commuters and an annual reduction of 39,000 VMT per 100 commuters. These findings are consistent with previous studies on how parking cost affects mode choice. The policy variables that help influence mode choice decisions for commuters are the parking cost and the travel time by transit. The results suggest that raising the cost of parking at work sites and decreasing the transit travel time (by improving service and decreasing headways) will reduce the drive alone mode share. The results provide little support for the contention that land use is a significant factor in mode choice decisions.
Public Transit Access to Private Property
Authors: Hinebaugh Dennis , Staes Lisa
Published: April 2007

Under contract with the Florida Department of Transportation, the Center for Urban Transportation Research was asked to (a) assess the issues surrounding the legal rights of public transit agencies to enter and serve private property, (b) and identify the major concerns of private property owners as they relate to allowing access to their property by public transit providers. The scope of the project included a literature review to identify any current practices related to developing public transit access to private properties and any news articles that reported instances in which public transit access was denied or withdrawn by private entities; a case review of legal publications to identify cases that involve public or private access, or both, to privately owned major commercial properties; a summary of federal, state, and local case law to determine the legal rights of public transit agencies as pertaining to access to private properties; a written survey to 67 public transit providers in the United States (including the nation’s 30 largest systems as determined by annual ridership); a written survey to selected private property developers, owners, and managers in the United States to identify successful and unsuccessful transit access practices; development of specific state and local government model regulations and development codes that shall support the access of public transit vehicles to private properties; and development of recommendations for successfully achieving public transit access to major private properties, with a corresponding document on transit access to private property negotiation guidelines. Addressed here are only the results of the literature review and surveys of transit properties and property developers and managers.
New Insights into the Value of Transit: Modeling Inferences from Dade County
Authors: Thompson Gregory L.
Published: April 2007

Whether transit accessibility influences labor force participation and income of different racial and ethnic groups is examined. The methodology involves the use of two-stage least-squares analysis to control for possible reverse causality in two of the explanatory variables: transit accessibility and auto ownership. Earlier literature on spatial mismatch theory suggests that transit accessibility should make a difference in unemployment rates for African Americans confined to inner city ghettos. In contrast, more recent literature suggests that other variables, such as workplace discrimination, are far more significant explanatory variables. Because all of these studies used measures of transit accessibility that failed to show the ease with which residents of a geographic area could access jobs in the entire region, this study attempts to do so. The transit accessibility measure is first calculated for traffic analysis zones (TAZs) in Dade County, Florida, and it is then used as one of several explanatory variables in models of African American, Hispanic white, and non-Hispanic white labor force participation; median zonal household income; and automobile ownership in TAZs. This research finds that transit accessibility does not explain labor force participation of any of the groups, but it helps explain household income as well as auto ownership. Higher transit accessibility is concluded to either directly or indirectly increase wage rates significantly for autodisadvantaged groups.
Exploring Customer Loyalty as a Transit Performance Measure
Authors: Foote Peter J. , Stuart Darwin G. , Elmore-Yalch Rebecca
Published: April 2007

The Chicago Transit Authority (CTA) conducted its third biennial random-digit-dial telephone survey of customer satisfaction in December 1999. Between 1997 and 1999, there was a significant increase in the number of riders with positive attitudes toward CTA, measured in a number of different ways. Moreover, this continued the upward trend noted between 1995 and 1997. Specific areas of improved customer satisfaction are reviewed, with an emphasis on a three-part index of customer loyalty. This loyalty index could be a useful summary measure of public transit’s ability to attract additional-choice riders. CTA was, in fact, able to do the latter, as a part of 1997 to 1999 ridership growth that paralleled customer satisfaction and loyalty increases. Investigation of the three basic dimensions of improved customer loyalty to CTA (overall satisfaction, likelihood of continued riding, likelihood of recommending to others) are described. Customer assessments of bus service performance, according to 44 specific aspects of service quality, and rail service performance, according to 52 specific aspects of service quality, are also summarized.
Traffic Signal Luminance and Visual Discomfort at Night
Authors: Bullough John D. , Boyce Peter R. , Bierman Andrew , Hunter Claudia M. , Conway Kathryn M. , Nakata Akiko , Figueiro Mariana G.
Published: April 2007

The visual discomfort from simulated traffic signals under nighttime viewing conditions was assessed. Discomfort increased with increasing signal luminance and decreasing viewing distance. Color identification of signals was very high for all signal colors and luminances studied. Red signals meeting luminous intensity specifications of ITE and specifications being drafted in Europe were unlikely to cause visual discomfort under the conditions tested. Green and yellow signals meeting ITE and European specifications were more likely to cause visual discomfort. Dimming signals using light-emitting diodes might be a feasible strategy for minimizing discomfort under some nighttime viewing conditions.
Influence of Pavement Marking Angular Systems on Visibility Predictions Using Computer Models
Authors: Zwahlen Helmut T. , Schnell Tom , Johnson Norbert , Hodson Neil , Donahue Tim
Published: April 2007

Computer models like CARVE (Computer Aided Roadmarking Visibility Evaluator), which predict the nighttime visibility of pavement markings, require quantitative information about the coefficient of retroreflected luminance RL for selected pavement marking material and selected dimension parameters. To specify the coefficient of retroreflected luminance RL, four angles are necessary (observation, entrance, presentation, and orientation). However, RL values for pavement marking materials are measured as a function of two angles only, whereas the other two are held constant. This two-angle–only approach makes the RL data-collection procedure and subsequent computer models significantly less cumbersome. The objective was to determine the angleranges in real-world driving situations for the International Commission on Illumination’s goniometer, intrinsic, application, and roadmarking four-angle system to measure RL values of different pavement marking materials for sets of the observation, entrance, presentation, and orientation angles and to compare these RL values with RL approximations calculated by using two-angle intrinsic and roadmarking angular systems. RL approximations using the two-angle intrinsic system (based on observation and entrance angles only) overestimate the actual RL values by between 4 and 10 percent. On the other hand, the RL approximations based on the two-angle roadmarking system (taking into account only illumination-elevation and the observation-elevation angles) overestimate the actual RL value by between 25 and 82 percent. Under retroreflective conditions, it is suggested to use the two-angle intrinsic system rather than the two-angle roadmarking system for modeling pavement marking visibility problems because the abridged intrinsic system yields more accurate and more conservative RL approximations.
Methodology for Evaluating Highway-Railway Grade Separations
Authors: Schrader Michael H. , Hoffpauer John R.
Published: April 2007

To better allocate scarce regional transportation resources when considering the construction of grade-separated highway–railway crossings in Central Arkansas, Metroplan, the Metropolitan Planning Organization, created a methodology to provide a consistent quantitative evaluation of potential locations. This methodology considered use of seven quantitative factors: noise, community cohesion, delay, accessibility, connectivity, geographic distribution, and safety. Each factor yielded a value between 0 and 1, which allows an equally weighted comparison between the different factors as well as a net sum of all factors. The net result, then, is an aggregate value that can aid in the evaluation and prioritization of potential highway-railway grade separation locations.
User Query Interface for the Deep-Foundations Load-Test Database
Authors: Satyanarayana Raghavendra , Ealy Carl D. , Dimillio Albert F. , Kalavar Shesh R.
Published: April 2007

The deep-foundation load-test database is a result of research quality data collection over the past 15 years. The database consists of soils data along with the deep-foundations load-test data gathered from prototype tests conducted all over the world. The soils data include general site information, stratigraphy, laboratory, and in situ test details. The foundations data consist of general foundations information including foundation construction, and load-settlement information to failure. Over 1,000 foundations are currently in the database, and more are being added. The database is checked for its validity and correctness both before and after the data are added to the database to make sure that the data integrity is preserved. Also, the data are periodically backed up and the data input is strictly administered by providing controlled access to the designated individuals. The database is structured to follow the rules of relational database management systems (RDBMS). The database resides in a Unix-based Sun Solaris server, and the database engine is Sybase RDBMS. The database front-end query application is under development for the Internet using Java as the programming language and will run under any Internet-capable browser (e.g., Netscape, Microsoft Internet Explorer) environment. The application will use Java applets to communicate with the database server. The user community includes state highway engineers, geotechnical researchers, students, and practicing engineers. Interested users can access the database using the interface to view, download, and chart the data at run-time.
Integrating Seismic and Deflection Methods to Estimate Pavement Moduli
Authors: Abdallah Imad , Yuan Deren , Nazarian Soheil
Published: April 2007

Nondestructive testing (NDT) of pavements has made substantial progress during the past two decades. Most algorithms currently used to determine the remaining life of pavements rely on stiffness parameters determined from NDT devices. One major area of continual improvement is the reliable and rapid extraction of stiffness parameters from nondestructive field data. Two of the most common NDT methods used are the deflection and seismic-based methods. The spectral analysis of surface waves tests are the most common seismic method. In this method, time records obtained with vibration sensors are used to obtain an experimental dispersion curve, which, through an inversion procedure, provides an estimate of the elastic modulus profile of the pavement. Deflection bowls are also used to backcalculate modulus profiles of pavements through the inverse theory. The inversion processes used in both methods are complex and require either a significant computational effort or frequent operator intervention. Each method, of course, has its own limitations and strengths. To improve the accuracy of the predicted moduli, an algorithm for joint reduction of the deflection and seismic-based data has been developed. Thickness and modulus of each pavement layer are estimated in real time using artificial neural network models. An overview of a proposed joint inversion and its practical use in pavement analysis and design is presented. The joint reduction algorithm shows promise since it appears to be more robust and to yield more consistent results when compared with the process and results from each method independently.
Long-Term Strength and Durability of Hydrated Fly-Ash Road Bases
Authors: White David J. , Bergeson Kenneth L.
Published: April 2007

Long-term performance monitoring was conducted on a demonstration project in which road base materials were constructed from reclaimed hydrated fly ash (HFA) and atmospheric fluidized-bed combustion (AFBC) and cement-kiln dust (CKD) by-products were used as calcium activators. Reclaimed HFA is a form of artificial aggregate produced from compacted, hydrated Class C fly ash at pulverized-coal combustion facilities. Strength testing and chemical analysis indicate that AFBC and CKD activators increase cementitious and pozzolanic reactions in the HFA material. Laboratory analysis determined the preferable range of activator to HFA artificial aggregate ratios for AFBC- and CKD-activated mixtures based on strength development, freeze-thaw durability analysis, compaction characteristics, and optimum moisture content ranges. Results of long-term strength gain from core samples show significant strength increase in the CKD-stabilized HFA base mixture, while the AFBC-stabilized HFA mixture shows signs of freeze-thaw durability problems compared with satisfactory performance experienced in the laboratory with the standard for fly ash for use with lime (ASTM C593). It appears that the AFBC section is still performing well but is probably functioning as a flexible aggregate base rather than a stabilized and cemented semirigid base. Long-term testing indicates that the high-volume application of these by-products is an economical and suitable alternative when used with an appropriate calcium activator.
Prototype Tire-Shred Embankment Construction
Authors: Dickson Todd H. , Dwyer Donald F. , Humphrey Dana N.
Published: April 2007

The New York State Department of Transportation constructed a pilot project using tire shreds as embankment fill. The prototype section, measuring 200 m in length, used approximately 2500 metric tons of tire shreds as the core of the embankment section. The tire-shred zone had a maximum thickness of 3 m, and the tire shreds were covered with 1.5 and 1.0 m of embankment fill on the top and sides, respectively. The entire section was then surcharged with an additional 1.25 to 2.50 m of fill. After 4 months, the surcharge was removed to subgrade elevation, the granular base was placed, and the section was paved. The project was designed in accordance with the guidelines to limit internal heating of tire-shred fills distributed by the Federal Highway Administration. The tire shreds were produced by a hook and shear shredder, placed in the fill with a front-end loader, and compacted with a smooth-drum roller. Instrumentation of the prototype section was monitored both during and after construction. In all, 10 settlement platforms, 15 temperature sensors, 2 groundwater collection systems, and a groundwater observation well were installed and monitored. Settlements were as expected based on previous projects, and temperature measurements showed that there was no internal heating of the tire shreds. A unique incentive program developed jointly by the state’s Department of Transportation, Department of Economic Development’s Empire State Development Corporation, and Department of Environmental Conservation resulted in 267,000 tires being removed from abandoned stockpiles.
Cars, Buses, and Jobs: Welfare Participants and Employment Access in Los Angeles
Authors: Blumenberg Evelyn , Ong Paul
Published: April 2007

Some studies suggest that, among other obstacles to employment, welfare participants face a spatial separation from jobs and employment-related services. Using data on welfare participants, low-wage jobs, and public transit in Los Angeles County, an examination was made of the relative access that welfare participants have to employment opportunities. The analysis shows that welfare participants’ access to employment varies dramatically depending on their residential location and commute mode. Many welfare participants live in job-rich neighborhoods and are able to reach numerous jobs without difficulty by either car or public transit. Others, however, live in job-poor neighborhoods where a reliance on public transit significantly reduces their access to employment. In these neighborhoods long and unreliable commutes on public transit often severely limit their ability to find and reliably travel to and from work. Therefore, given the distinctly uneven patterns of employment opportunities in metropolitan areas, policies to address the transportation needs of welfare participants should be targeted to reflect the characteristics of the neighborhoods in which welfare participants live.
Comparison of Light Rail and Bus Transit Noise Impact Estimates per Federal and Industry Criteria
Authors: Staiano Michael A.
Published: April 2007

Design work for a transitway proposed in suburban Maryland near Washington, D.C., using an abandoned railroad right-of-way was begun, then halted, then resumed over a period of time. An initial environmental noise evaluation was performed using the American Public Transit Association (APTA) guidelines. When work resumed, the FTA guidance manual was available. Consequently, noise impacts were assessed via methods from both documents. Three alternative vehicle types to serve the transitway were considered: light rail vehicles, conventional articulated diesel buses, or dual-propulsion (electric motor/diesel engine) articulated buses. Passby noise measurements were performed to quantify or verify the noise emissions of each of the vehicle types, and measurements were compared to other available data. At 15 m (50 ft) and 56 km/h (35 mph), the diesel bus is noisiest; the light rail vehicle is slightly quieter. The electric bus is significantly quieter although its emissions are known with the least confidence. Line operation sound levels were predicted for each of the vehicle types for the entire length of the proposed project. The predictions were in terms of both maximum passby sound levels for comparison to the APTA criteria and day-night average sound levels for comparison to the FTA criteria. For the local land uses and ambient noise conditions, the distances for the unmitigated passby noise exposures to attenuate to the APTA and FTA criteria limits were estimated and the number of included dwellings counted. For the transitway project with 16 percent nighttime operations and proposed vehicle alternatives, the FTA impact-onset (i.e., “some impact”) criterion curve yielded significantly greater noise-exposed areas; the APTA criteria yielded results intermediate to those from the FTA “some” and “severe” impact curves.
Tollbooth Operators’ Response to Traffic Noise and the Performance of an Active Noise Control Headset: Survey Results
Authors: Feist Jeffrey P. , Mongeau Luc , Bernhard Robert J.
Published: April 2007

Two surveys were administered to tollbooth employees working at a toll collection plaza located in Indiana. The first was used to evaluate employees’ subjective response to the ambient noise levels in their occupational environment. The results confirmed that ambient noise is perceived as undesirable and hampers communication between operators and patrons. In the second survey tollbooth attendants were asked to evaluate a specific type of open ear active noise control headphone and rate its performance with respect to noise reduction, speech intelligibility, and comfort. The results showed that the active headset effectively reduced ambient noise, but its ability to improve speech intelligibility could not be demonstrated. Additionally, the active headset was found to cause slight discomfort.
Secondary and Cumulative Effects of Replacing the Woodrow Wilson Bridge: Process and Conclusions
Authors: Plano Stephen , Zeimer Lisa L. , Williamson Sarah , Smith David , DiMisa Joseph
Published: April 2007

Analyzing the secondary and cumulative effects of transportation projects requires objectivity, flexibility, creativity, and close coordination and cooperation between the project team, review agencies, and private organizations that provide information. Although guidelines and processes are available that supply possible approaches, the unique circumstances of each project necessitate a secondary and cumulative effects analysis (SCEA) methodology that assesses the specific resources potentially affected and represents a consensus of the team and reviewers. “Secondary effects” can be defined as effects that are caused by the action and are later in time or farther removed in distance, but are still reasonably foreseeable. “Cumulative effects” are environmental effects that result from the incremental effect of the action when added to other past, present, and reasonably foreseeable future actions, no matter what agency (federal or nonfederal) or person undertakes those other actions. The SCEA for the Woodrow Wilson Bridge Project was uniquely challenging for the multiagency client (FHWA, Maryland State Highway Administration, Virginia Department of Transportation, and the District of Columbia Department of Public Works) and the resource and review agencies who had to agree on a process and methodology. The success of the process was a result of the close and constant collaboration among the project team, the client, and the resource agencies. A description of the process and illustration of the methodology are provided along with a sampling of different environmental resource components. Also covered are lessons learned that could be applied to other transportation projects.
Use of Digital Multispectral Videography to Capture Environmental Data Sets for Virginia Department of Transportation
Authors: Michael Fitch G. , Anderson John E.
Published: April 2007

The Virginia Department of Transportation’s (VDOT) environmental division frequently uses spatial information to analyze and assess a variety of environmental resources. Environmental personnel are constantly looking for faster and more accurate means of collecting and managing these data. Digital multispectral videography (DMSV) is a data collection technology that has shown great potential in other areas in which remote sensing data are used. DMSV provides digital frame coverage in four spectral bands for color infrared imaging, allowing for the detection of soils, vegetation, water bodies, chemically contaminated areas, and various other resources. This type of remote sensing differs from traditional methods in that sensor bandpass or wavelengths are typically ⩽25 nm wide as opposed to the more typical 100+ nm wavelengths. Testing the feasibility of using DMSV for some of VDOT’s environmental data acquisition needs was the purpose of this research. It was accomplished by using the technology to capture imagery-based data sets and then developing a procedure for transforming the image data into georeferenced vector data sets. The vector data were analyzed spatially, and the advantages and shortcomings of the technology were documented during this process. DMSV was very effective in identifying and classifying major plant communities in VDOT’s wetland mitigation sites. Data were quickly collected, corrected, classified, and imported into an ArcView-based geographic information system. From there, the data sets could be analyzed and stored for further query and manipulation.
Estimating Environmental Costs in Port Development: Case Study of Economic Costs to Fisheries of Marine Disposal of Clean Dredge Sediments
Authors: Grigalunas Thomas A. , Opaluch James J. , Luo Meifeng , Chang Young-Tae
Published: April 2007

The economic assessment of potential external costs due to port development is considered. The importance of environmental cost estimates in making decisions about port development is outlined. A case study in Rhode Island is used to illustrate quantification of one important environmental issue—the economic cost to commercial and recreational fisheries resulting from marine disposal of dredged material. The bioeconomic framework, data, and assumptions used are described. Key results are summarized for seven potential disposal sites for 5.1 million cubic yards of clean dredge sediment, three in Narragansett Bay and four in Rhode Island Sound. To reflect the many sources of uncertainty in the analysis, an overstated cost approach is used and several sensitivity analyses are presented. Results suggest that costs of sediment disposal for bay sites are higher than for Rhode Island Sound sites and support including long-term and ecological effects, and recreational as well as commercial losses, in assessments of potential sites for disposal of dredge material.
In Situ Monitoring of Lime-Stabilized Road Subgrade
Authors: Boardman D. I. , Glendinning S. , Rogers C. D. F. , Holt C. C.
Published: April 2007

Two refined clay minerals, English China Clay (predominantly kaolinite) and Wyoming Bentonite (predominantly sodium montmorillonite), were used to develop a method for assessing the time-dependent physicochemical behavior of lime-treated clay subgrade. The two clays, representing the extremes of structural negative charge development, were treated with two lime contents. Changes in the physicochemistry of the samples were monitored after three curing periods by performing batch leaching tests and by monitoring changes in undrained shear strength and Atterberg limits. The effects of changing the batch test operating parameters and increasing the curing period were assessed by measuring changes in solution pH and conductivity and by analyzing eight elements in solution. The solidification mechanisms caused by lime addition were found to be different for the two minerals. Pozzolanic reactions involving English China Clay and Wyoming Bentonite occurred because of the dissolution of aluminum and silicon from the respective mineral. Development of the batch leaching test showed that changing the operational parameters had no effect on the observed trends associated with the time-dependent modification and solidification reactions. In addition, it was shown that successful solidification could be monitored using simple conductivity measurements without the need for extensive and complex elemental analysis.
Evaluation of Structural Contribution of Lime Stabilization of Subgrade Soils in Mississippi
Authors: Yusuf F. A. M. , Little Dallas N. , Sarkar Shondeep L.
Published: April 2007

The Mississippi Department of Transportation has used hydrated lime for more than 30 years to stabilize subgrades. In 1998, a project was initiated to assess material properties and performance derived from lime-treated subgrades. Some pertinent findings of the study are described. In situ properties of lime-stabilized subgrades were identified based on falling weight deflectometer deflection measurements, ground penetration radar profiles, and dynamic cone penetrometer logs. The in situ properties were compared with laboratory strength and resilient modulus test results for the same materials to establish reliable design-resilient and strength properties for these stabilized layers. A laboratory mixture design and testing protocol was developed for lime-stabilized subgrades. A comparison of field test data and laboratory test data showed that laboratory design test properties were achieved in the field. These properties were used in a mechanistic analysis to assess the effectiveness of the lime-stabilized subgrades in Mississippi. The lime-treated subgrade layers in the four pavements evaluated proved to be effective structural layers.
Cross-Anisotropic Characterization of Unbound Granular Materials
Authors: Adu-Osei Alex , Little Dallas N. , Lytton Robert L.
Published: April 2007

The mechanical properties of granular materials are nonlinear and stress dependent. Several researchers have identified cross-anisotropy as a better model for characterizing granular materials. However, determining cross-anisotropic material properties from the conventional triaxial setup has been extremely difficult. A laboratory testing protocol has been developed using theories of elasticity and the system identification method. The testing protocol is efficient and precise. Material properties determined with the testing protocol satisfy elasticity requirements. The cross-anisotropic material properties of four granular materials were determined. The material properties were entered into a finite element program, which was modified to accept these properties, to determine pavement response. Nonlinear crossanisotropic modeling was observed to eliminate tension zones predicted by isotropic models in granular layers. This is an important step because the presence of such tensile zones has required adjustments in layered pavement models to predict pavement performance on the basis of response parameters.
Stress Path Testing for Proper Characterization of Unbound Aggregate Base Behavior
Authors: Chou Fang-Ju , Tutumluer Erol
Published: April 2007

Realistic pavement stresses induced by moving wheel loads were examined in granular base layers, and the significant effects of rotation of principal stress axes were addressed for a proper characterization of unbound aggregate behavior. Granular material resilient moduli are commonly determined at the centerline of wheel loading without taking into account the effects of moving wheel loads and the constantly rotating field principal stress states. Differences that exist between field- and laboratory-applied stress states were identified by comparing the field stresses simulated using a nonlinear axisymmetric finite element program, GT-PAVE, with the stress states commonly used in the standard resilient modulus test procedure, AASHTO T294-94. Three sets of complete triaxial test data obtained from testing aggregates under various realistic in situ stress paths caused by moving wheel loading were analyzed. Eight different granular material modulus models were developed from the experimental test data to include the applied mean stress, the applied shear stress, and the slope of stress path loading. Because of the complex loading regimes followed in the laboratory tests, characterization models that simultaneously analyzed the static and dynamic components of the applied mean and deviator stresses produced a high degree of accuracy. Models that consider the stress path slope variations predict the best stress path dependency of aggregate behavior caused by moving wheel loads. Such advanced models that allow for the effects of principal stress rotation better describe the granular material behavior under the actual field loading conditions.