bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of Strategic Highway Research Program Pressure Aging Vessel Procedure Using Long-Term, Low-Temperature Aging Experiments and Asphalt Kinetics
Authors: Domke Christopher H. , Liu Meng , Davison Richard R. , Bullin Jerry A. , Glover Charles J.
Published: April 2007

An essential element of understanding and predicting long-term asphalt binder performance is understanding asphalt oxidative aging and its effect on physical properties. High-temperature, high-pressure laboratory kinetic studies, pressure aging vessel (PAV) aging, and aging at pavement conditions are compared. The consequences of running the PAV at conditions far from road conditions are examined. An aging model previously reported in the literature was used to describe the data. Important asphalt aging parameters include the pressure reaction order (α), activation energy ( E), initial jump in carbonyl content, and hardening susceptibility. All of these parameters are asphalt dependent. PAV tests were performed on asphalts for which kinetic data were available, and the results were compared with the kinetic model and with results obtained after 135 days of aging at 333 K (140°F) air. The high temperature and pressure used in the PAV test sometimes results in serious errors in the performance ranking of asphalts of different E and α. Nevertheless, the test often ranks asphalts remarkably well because of fortuitous cancellation of several effects of pressure and temperature and the dampening effects of diffusion. Diffusion slows the oxidation rates, and asphalts with higher rates harden at the surface faster, increasing the diffusion resistance and slowing the observed bulk rate. The relative hardening of different asphalts is affected by the choice of PAV time, temperature, and pressure.
Quantitative Analysis of Polymers and Crumb Rubber in Hot-Mix Asphalts
Authors: Ling Mei , Curtis Christine W. , Hanson Douglas I. , Hool James N.
Published: April 2007

A method was developed to analyze quantitatively the amount of polymer in polymer-modified hot-mix asphalts (HMA). The polymers used were styrene-butadiene rubber (SBR) and styrene-butadiene styrene (SBS) at concentrations ranging from 1 to 6 mass percent in asphalt. The aggregates used were granite, gravel, and limestone. The procedure involved removing the polymer-modified asphalt from the aggregate by using tetrahydrofuran extraction and then analyzing the modified asphalt for polymer content with Fourier transform infrared (FTIR) analysis. In addition, an FTIR analysis procedure was developed for crumb rubber in HMA; this procedure used the same FTIR method used for SBR and SBS. Previous research reported individual calibration lines for a given polymer in several different asphalt cements. Quantitation of the polymer content involved developing a calibration line for each polymer-modified asphalt. The effect of combining the data for a given polymer in three different asphalts into one universal calibration line was evaluated.
Another Way To Go?: Some Implications of Light-duty Diesel Strategy
Authors: Stork Kevin , Mintz Marianne , Vyas Anant , Stodolsky Frank , Cuenca Roy
Published: April 2007

Conventional wisdom suggests that a large-scale shift from gasoline to diesel light-duty highway vehicles would have an impact on energy consumption, emissions, and infrastructure. Under a relatively modest scenario, based on French experience since 1970, a dieselization strategy could have displaced slightly more than half a quad of petroleum (3.7 percent of the energy consumed by light-duty vehicles) in 1992, while reducing carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) emissions by 6.3, 0.8, and 0.09 million tonnes, and increasing sulfur oxides (SOx) and particulates (PM-10) by 0.03 and 0.2 million tonnes, respectively. As a percentage of pollutants attributable to light-duty vehicles, these values represent decreases of 11 percent, 10 percent, and 2 percent for CO, HC, and NOx and increases of SOx and PM-10 of 36 percent and 39 percent, respectively. The projected oil displacement and emissions impacts would have been achieved by using a diesel technology that is significantly less efficient than what is currently available and what may become available as a result of current research. Energy consumed in refining would also have been marginally reduced, although additional processing could have been required to increase the fraction of distillate and decrease that of gasoline. Finally, a shift to diesel could have broad implications on U.S. and world oil markets, modifying crude oil supply-demand balances and requiring a different mix of unit operations in domestic refineries that, in turn, could change the capital investment path of the industry, which is currently geared to maximizing gasoline production.
Emissions Impact of Eliminating National Speed Limits: One Year Later
Authors: Mullen Maureen A. , Wilson James H. , Gottsman Laura , Noland Robert B. , Schroeer William L.
Published: April 2007

The National Highway System (NHS) bill passed by Congress in November 1995 eliminated the national maximum speed limit. It has allowed states to set their own speed limits, which many have changed during the past year. This analysis examines the impact of speed limit changes 1 year after passage of the NHS. Oxides of nitrogen (NOx), carbon monoxide, and volatile organic compounds are analyzed and are found to have increased nationwide by up to 6, 7, and 2 percent, respectively. Much of the increase has occurred in western states, which generally have increased vehicle speeds more than in eastern and midwestern states. For example, in Texas NOx emissions are estimated to have increased by 35 percent due to large increases in highway and arterial speed limits.
Reducing Damage to Low-Volume Roads by Using Trucks with Reduced Tire Pressures
Authors: Kestler Maureen A. , Berg Richard L. , Moore Thomas L.
Published: April 2007

Heavy-volume highways in seasonal frost areas are designed to resist the effects of spring thaw. However, timber access roads, county roads, and other low-volume roads with thin bituminous surfaces can be quite susceptible to pavement damage during midwinter- and spring-thaw periods. To reduce damage to low-volume roads, towns, cities, and states typically either post reductions in allowable load or completely prohibit hauling during damage-susceptible periods. Associated economic impact can be significant. To evaluate the effects of tire pressure on cumulative road damage, a mechanistic pavement design procedure developed by the U.S. Army Corps of Engineers for use in seasonal frost areas was used on a matrix of tire pressures, low-volume pavement cross sections, and environmental conditions. A series of computer simulations showed ( a) trucks operating with conventional tire pressures can cause excessive damage, particularly in the form of cracking, to low-volume roads with thin bituminous surfaces during relatively short thaw periods; ( b) pavement damage could be reduced substantially by restricting hauling to trucks operating with reduced tire pressures; and ( c) there are “threshold” tire pressures under which only minimal damage occurs, even during critical spring thaw. These results could influence guidelines for hauling restrictions and, in turn, associated economics.
Mix Design for Flowable Fill
Authors: Bhat S. T. , Lovell C. W.
Published: April 2007

The grout-like material called flowable fill has experienced new popularity, particularly the controlled low-strength material variety, which is easily excavated. The properties ordinarily desired of the mix are: (a) flow under gravity; (b) hardening for early walkability and cover; and (c) ultimate strength low enough to allow ready excavation. Flowability of fresh material is evaluated in a simple spread test. Hardening is measured by a mortar penetrometer, and these values are correlated with unconfined compressive strength. It is desirable to keep the ultimate strength to less than 1 035 kPa (150 lbf/in.2); somewhat less target strength is selected for the 28-day value. Mix design is empirical, but the time and expense required may be reduced by following a rational and logical procedure, which is described. The materials emphasized in this paper are Class F coal combustion fly ash and waste sands from greensand ferrous castings.
Performance-Based Testing of Chemical Stabilizers
Authors: Petry Thomas M.
Published: April 2007

Chemical stabilizing agents have been introduced that have performed in field applications to improve the behavior of earth materials. The same agents and materials subjected to standardized laboratory tests have often resulted in no improvement. For example, the tests often require pulverization of materials to finer states than are needed in the field or may require remolding when field applications are done in situ, as with injection applications. Some of the physical tests do not place treated materials in a situation resembling conditions in the field, yet they are applied to determine the use of these agents. The experiences of the author in developing performance-based testing of chemical stabilizers that better simulate field conditions are described. The situations include a physical erosion test to determine dispersion of clays that have been treated, two swell test preparation sequences simulating injection of chemicals into clays, a wet-dry test sample preparation using field gradation specifications, and a three-dimensional swell test for stability of treated clays when subjected to wetting. Also, the standardized physical test results that did not adequately represent behavior are discussed. The applications and indications of successful testing are reviewed. Possible development processes for performance-based tests, involving parameters of variance, are included for consideration.
Chemical Additives for Dust Control: What We Have Used and What We Have Learned
Authors: Bolander Peter
Published: April 2007

The Pacific Northwest region of the USDA Forest Service has been using chemical additives for dust abatement for many years. The traditional additives include dust oils, lignin sulfonate, and chlorides. Increased product costs, environmental concerns, and the continual quest for improved performance has led to consideration of other additives, including synthetic polymer emulsions, tall oil emulsions, clay additives, and penetrating asphalt emulsions. Some road tests have been performed to evaluate their suitability and cost-effectiveness. From these tests and experience, it has been learned that lignin sulfonate, chlorides, and clay additives, when properly matched to the site, have a consistent and predictable performance; polymer and tall oil emulsions, based on limited use, have provided inconsistent performance. The reason for this inconsistency has not been addressed other than the speculation that in some situations the additive did not completely cure, that the cured additive may be water soluble, or there might be variability in the quality of the manufactured product.
Earth Materials Catalyst Stabilization for Road Bases, Road Shoulders, Unpaved Roads, and Transportation Earthworks
Authors: Randolph Robert B.
Published: April 2007

Frequency of use of concentrated liquid stabilizers to improve stability of aggregate and soil materials in constructing roads and other transportation-related structures is increasing. Concentrated stabilizers are formulated specifically for modification, improvement, and stabilization of aggregate and soil materials and require dilution in a water solution before application to allow for adequate dispersion. Applied costs of treatment are generally much less than conventional chemical stabilization treatment, because application is much simpler and product and transportation costs are less. Treatments are applied to aggregate materials to reduce base course and subbase structural sections and to strengthen resistance to repetitive loading and environmental factors. Gravel loss and maintenance frequency have been greatly reduced for unpaved roads and road shoulders. A report of these findings is timely, because both public and private sectors are seeking cost-effective treatments to improve long-term performance of conventional pavements and to help use limited budgets to address environmental regulations mandating dust control and sediment control for road shoulders and unpaved surfaces. Representative case studies of federal and state agency projects that used an earth materials catalyst (a concentrated liquid stabilizer) document the benefits of appropriate application of concentrated liquid stabilizer technology.
Comparison of Road Mix and Plant Mix Cement-Treated Aggregate Base Course
Authors: Corley-Lay Judith B.
Published: April 2007

A study was undertaken to determine the advantages of plant mix over road mix cement-treated aggregate base course (CTABC). Ten projects known to have cement-treated base course were selected. Each had been tested with a falling-weight deflectometer and had been cored to determine layer thicknesses and properties either in the past or as part of the current effort. Three possible benefits were considered: improved uniformity of material properties, reduced deflections, and increased strength or stiffness. Neither the coefficient of variation nor a developed uniformity coefficient showed a significant difference between plant mix and road mix. Plant mix resulted in lower average deflections and lower deflections when sites were compared with equal thicknesses of asphalt above the base course. However, road mix sites had higher compressive strengths than did plant mix sites. Backcalculated moduli for CTABC were higher for plant mix than for road mix, but the elastic moduli were similar for plant and road mix when determined by pulsevelocity testing. It was concluded that no clear benefit could be determined from using plant mix based on the sample of 10 projects, although the benefit of an adequate thickness of asphalt above the CTABC was clearly demonstrated.
Stabilization of High Soil and Rock Cut Slope by Soil Bioengineering and Conventional Engineering
Authors: Sotir Robbin B. , McCaffrey Michael A.
Published: April 2007

Construction of a 274.5-m-long (900-ft) and 24.4-m-high (80-ft) soil (upper) and rock (lower) cut slope on the eastbound side of the Massachusetts Turnpike at mile mark 94.1 eastbound for the proposed interchange with Route 146 combined conventional engineering and soil bioengineering solutions. Geologic mapping identified three sections (east, middle, and west) that had different patterns of rock discontinuities, which controlled rock cut design. Each required a different slope design for a stable rock cut. The soil cut design was controlled by soil density, groundwater seepage, and erosion potential from seepage and surface runoff. Soil bioengineering was used to control surface drainage and erosion on the cut soil slope above the 12.2-m-high (40-ft) rock cut and rapidly revegetate the disturbed soil slope, which addressed the project's environmental and aesthetic goals. Conventional crushed-stone drains augment the living soil bioengineering drains. Woody vegetation was used to reinforce the cut soil slope surface. Branches from native living woody plants were installed into the slope face, offering surface reinforcement. Root development along branch lengths provided additional reinforcement. The hydrologic regime was modified as growing plants remove moisture through transpiration and embedded bundled branches channel water off the slope. Basic soil bioengineering stabilization principles by using live fascines and brush layers for soil and rock cut slope stabilization are presented. Discussions include preconstruction conditions, environmental benefits, vegetation harvesting and design, installation, and performance as of October 1996. Cut slope stabilization through soil bioengineering produced an environmentally, aesthetically, and mechanically sound solution, illustrating the benefits of combined technologies.
Test Methods for Evaluation of Cold-Applied Bituminous Patching Mixtures
Authors: Estakhri Cindy K. , Button Joe W.
Published: April 2007

A Texas Department of Transportation study performed by the Texas Transportation Institute was undertaken with a goal of providing methods to assure the quality of cold-applied, asphalt-stabilized maintenance mixtures. Test procedures and acceptance criteria were developed for hot-mix, cold-laid asphalt concrete patching mixtures. Two specific objectives were to develop a test procedure to simulate approximately six months of stockpile-aging and a test procedure to quantify workability of maintenance mixtures. The protocol developed is designed to estimate the relative ability of a maintenance mixture to retain adequate workability after outdoor stockpile storage. This protocol could be useful as part of a specification to promote quality. Two test procedures were evaluated regarding their potential to quantify the workability of maintenance mixtures: a triaxial test and an unconfined compression test. Test results indicated that both procedures provide a relatively good measure of workability before and after aging. Two laboratory aging procedures were evaluated for their ability to predict workability of a stockpiled maintenance mixture after six months of field aging. Procedure A appeared to provide a reasonable approximation of six months of field aging.
Cost-Effectiveness-Based Priority Programming of Standardized Pavement Maintenance
Authors: Li Ningyuan , Huot Michel , Haas Ralph
Published: April 2007

A new optimization model and priority programming for pavement network maintenance and rehabilitation management are described. The optimization formulation is directed to determining the most cost-effective treatment action plans for preserving the pavement network’s serviceability above a specified level. The priority programming is conducted on a year-by-year basis, whereas a comprehensive prediction model for pavement deterioration versus time is considered. It is governed by traffic volume, pavement performance, a set of designed standard treatment alternatives, and budget limitations for network preservation. Each standardized pavement treatment alternative, including minor and major maintenance and rehabilitation, is defined by its effect on or level of improvement of the existing pavement surface quality and the corresponding costs. The effectiveness is calculated as a yearly product of the area under the performance curve and a minimum acceptable pavement condition index level multiplied by pavement length, traffic volume, and service days. The costs for applying any one of the standardized alternative treatments are expressed on a present worth basis. The prediction for each individual pavement deterioration is modeled as a time-related (nonhomogeneous) Markov transition process, in which pavement structural and functional improvements upon application of a treatment action are considered. The focus is on an integrated approach to pavement network preservation programming through cost-effectiveness analysis and comprehensive performance prediction in combination with standardized pavement treatment strategies. A case study application to a regional asphalt pavement network in Ontario, Canada, illustrates the use of the optimization model. The priority programming is practical and flexible with regard to the size of a road network, and the results of the example run are discussed.
Goal-Oriented Optimization Procedure for Long-Term Highway Investment Planning
Authors: Ravirala Venkatesh , Grivas Dimitri A. , Arminio Salvatore , Garrabrant Richard
Published: April 2007

A goal-oriented optimization procedure for analyzing investment choices associated with rehabilitation of large pavement networks is presented. The procedure consists of three steps: (a) project-level planning, encompassing the tasks of condition characterization, treatment identification, cost estimation, and performance prediction; (b) network-level goal setting, involving specification of desired condition and investment levels for multiple years; and (c) optimization analysis, consisting of formulating and solving a goal program. The procedure is implemented in a prototype software system and is used to evaluate various management-suggested pavement program scenarios. The system facilitated the analysis of competing needs and the evaluation of implications of various pavement program scenarios for the New York State Thruway Authority’s pavement network. The paper presents significant findings from application of the optimization procedure, including a functional relationship between the network condition and expenditure. Important conclusions regarding the goal-oriented approach to highway management are also presented.
Investigation of Relationship Between Deterministic and Probabilistic Prediction Models in Pavement Management
Authors: Li Ningyuan , Haas Ralph , Xie Wei-Chau
Published: April 2007

A good pavement management system should have the capacity to predict pavement structural and functional deterioration versus age or accumulated traffic loading. Basically, there are two types of performance prediction models in pavement management: deterministic and probabilistic. Although both performance models can be used to predict pavement deterioration, the inherent relationship between the two models has not been explored. An investigation was directed to find the relationship in terms of system conversion. Some of the findings related to system conversion, including the concepts and techniques applied in model conversion, the characteristics of model development, comparisons of prediction results between the two models, sensitivity analysis of the probabilistic models, and sample applications in real situations, are highlighted. The deterministic models that are to be converted to probabilistic models are the flexible pavement deterioration model used in the Ontario Pavement Analysis of Costs system and the flexible pavement design model recommended in the 1993 AASHTO design guide. The converted probabilistic models are time-related (nonhomogeneous) Markov processes, which are represented by a set of yearly transition probability matrices (TPMs). TPMs can be established for any individual pavement section in a road network.
Universal Pavement Distress Evaluator Based on Fuzzy Sets
Authors: Shoukry Samir N. , Martinelli David R. , Reigle Jennifer A.
Published: April 2007

Setting priorities for pavement maintenance and rehabilitation depends on the availability of a universal scale for assessing the condition of every element in the network. The condition of a pavement section has traditionally been assessed by several condition indexes. The present serviceability index (PSI) is one common evaluator used to describe the functional condition with respect to ride quality. Pavement condition index is another index commonly used to describe the extent of distress on a pavement section. During the decision-making process, both classes of indexes are needed to evaluate the overall status of a pavement section in comparison to other sections in the network. Traditionally, regression techniques were used for the development of functions that relate condition indexes to the information recorded in the pavement management database. This approach produces mathematical functions that are limited to a particular database. The functions so developed may also suffer from inaccuracies due to errors in data collection and recording. There is a need for a more generalized approach for the evaluation of pavement conditions to enable efficient management of large transportation networks. The development of a universal measure capable of formally assessing the condition of a pavement section within the universe of pavement conditions is described. This is accomplished by the fusion of a set of fuzzy membership functions that describe different parameters in the database with the perception of each parameter’s significance. The model output is the fuzzy distress index (FDI), which combines the extent of structural distress with traditional performance parameters such as roughness to describe the overall status of the pavement section. The behavior of FDI over time is examined for a random sample of pavement sections and is compared with trends in the corresponding PSI values (PSI was used only because it was readily available in the database). The results indicate that the flexible, universal FDI is a consistent and accurate measure of the overall pavement condition. The set of generated membership functions describing the different extents of every distress type can be easily standardized over the 50 states, allowing the model to be implemented on any pavement at any location. Also, the parameter weights used in the assessment may be easily adjusted (increased or decreased) to reflect changes in maintenance policies or budget availability at the local, state, or national decision-making level. Moreover, the concept allows for the omission of any number of parameters that might not be available in a particular pavement management database.
Transportation Planner’s Handbook on Conversion Factors for the Use of Census Data
Authors: Siaurusaitis Victor J. , Saben Larry J.
Published: April 2007

For the 1990 census data to be useful for transportation planners, it must reflect information collected in transportation surveys, such as home interviews and on board transit surveys. These surveys select a survey day that captures a snapshot of transportation activity for that day. Inherent in the 1990 census are problems related to biases created by the way in which the journey-to-work questions are asked. Issues related to questions that ask for “typical” or “usual” activity in the previous workweek tend to overestimate certain trip making, while underestimating others. For example, on a usual workday, an individual would drive an automobile to work. But on any given day, he or she may be forced to take public transportation because the automobile was in for repairs. The analysis looks at the 1990 census and the 1990 Nationwide Personal Transportation Survey and develops factors by urban area size. Factors developed include absenteeism (related to sick time, vacation, personal business, part-time employment, and business-related travel), mode of travel (shifts between highway and transit modes), multiple jobs (for individuals who hold multiple jobs or make multiple trips to the same place of work from home), and trip chaining (distinguish between direct home-to-work trips, as defined in travel model home-based work, and trips that make intermediate stops).
Seasonal Factors Using Vehicle Classification Data
Authors: Stamatiadis Nikiforos , Allen David L.
Published: April 2007

The increased use of equipment having automatic vehicle classification capabilities and weigh-in-motion devices produces a large amount of new data that can provide some insights into understanding traffic patterns more efficiently. These data can be used in determining seasonal adjustment factors for correcting traffic counts, in estimating truck traffic for highway cost allocation studies, and in predicting traffic volumes for roadways. However, due to practical limitations, it is not possible to obtain continuous data collection for all roads; thus, short-term counts are usually performed. Therefore, it is important to understand the relationship of the data obtained in a short-term period to those for the entire year. A study is currently under way that determines these relationships and develops seasonal adjustment factors for the state of Kentucky. The first step of the study was a survey of current uses of vehicle classification data and methods used for data collection throughout the United States. The results indicated that most states use no seasonal adjustment factors nor are they planning to develop any factors in the near future. At the same time, analysis of 2 years of vehicle classification data was used to develop seasonal and daily factors for Kentucky. Currently, the validation of these factors is under way. The preliminary analysis indicated that seasonal adjustment factors are essential in developing accurate estimates of traffic volumes for each vehicle type, and their use can improve the estimation of daily volumes.
Temporal Geographic Information System and Its Application to Transportation
Authors: Zhao Fang , Wang Liping , Elbadrawi Hesham , Shen L. David
Published: April 2007

While geographic information systems (GIS) have proven to be powerful tools that are capable of storing, displaying, and analyzing spatially distributed information, current GIS lack adequate capabilities for handling temporal information. As a result, analyses are mostly performed assuming a fixed time point. Longitudinal analyses that take time into consideration cannot be easily accomplished. For many applications, information constantly changes in both space and time. A temporal GIS, one that is capable of handling temporal as well as spatial information, will greatly expand the current GIS applications and allow new information to be obtained. Some preliminary results are presented of an ongoing study of a temporal GIS. To explore the problems and potential benefits of a temporal GIS, a simple method has been developed to record the changes in spatial objects for time using personal computer ARC/INFO relational databases as well as a set of commands to query the spatiotemporal data. The use of this temporal GIS method is illustrated using an example of transit service analysis.
Opportunities for Collecting Highway Inventory Data With the Global Positioning System
Authors: Brich Stephen C. , Fitch G. Michael
Published: April 2007

Research is currently being conducted at the Virginia Transportation Research Council to determine some of the problems associated with the implementation of a geographic information system (GIS). The collection and development of the data sets required to drive the GIS are two of the largest expenses associated with GIS implementation. This research looked at the feasibility of using the global positioning system (GPS) to collect point, line, and polygon features that are representative of some of the locational and attribute data required to run the Virginia Department of Transportation’s (VDOT’s) GIS. Data sets identified in VDOT’s 10-year GIS strategic plan were collected and transferred to ARC/INFO, a proprietary system, by way of handheld, mapping-grade GPS receivers. Methods for the collection and transfer of the data sets are outlined. Point accuracies of approximately 2 m were obtained. Time requirements and data collection problems are also described.
Dimension and Frequency Profiles of Concrete Highway Bridges in New Madrid Region of Southeastern Missouri
Authors: Dusseau Ralph Alan
Published: April 2007

The results of a study funded by the U.S. Geological Survey as part of the National Earthquake Hazards Reduction Program are presented. The first objective of this study was the development of a database for all 211 highway bridges along I-55 in the New Madrid region of southeastern Missouri. Profiles for five key dimension parameters (which are stored in the database) were developed, and the results for concrete highway bridges are presented. The second objective was to perform field ambient vibration analyses on 25 typical highway bridge spans along the I-55 corridor to determine the fundamental vertical and lateral frequencies of the bridge spans measured. These 25 spans included six reinforced concrete slab spans and two reinforced concrete box-girder spans. The third objective was to use these bridge frequency results in conjunction with the dimension parameters stored in the database to develop empirical formulas for estimating bridge fundamental natural frequencies. These formulas were applied to all 211 Interstate highway bridges in southeastern Missouri. Profiles for both fundamental vertical and lateral frequencies were then developed, and the results for concrete highway bridges are presented.
Pressure Distribution in Sliding Interface of Spherical Bridge Bearing
Authors: Campbell T. I. , Green M. F. , Koppens N. C. , Agarwal A. C.
Published: April 2007

Relevant literature indicates that the critical parameters relating to load transfer in the curved, sliding, compression-only, polytetra-fluoroethylene (PTFE)-metal interface of a spherical bearing under an external applied horizontal load are the ratio of the horizontal load to the vertical load and the ratio of the radius of curvature to the plan diameter of the interfacing spherical surfaces. An experimental program measuring the stress-displacement relationship of confined PTFE discs under uniaxial and eccentric compressive loadings is described, and a bilinear stress-displacement relationship is proposed. This stress-displacement relationship is incorporated into a displacement model to predict the stress distribution in the PTFE in the curved interface, and results from the model are compared with those from a finite-element model. The displacement model is used to develop design charts for spherical bearings under combined vertical and horizontal loads.
Construction, Instrumentation and Load Testing of the Danish Road Testing Machine for the International Pavement Subgrade Performance Study
Authors: Macdonald Robin A. , Zhang Wei
Published: April 2007

A flexible test pavement, instrumented to measure stresses and strains in three primary axes within the upper 42 cm (16.5 in.) of the subgrade, was constructed and load tested in the Danish road testing machine, as part of the international Pavement Subgrade Performance Study, to improve the mechanistic subgrade failure criterion. The test pavement was constructed in 1995 and load tested between 1995 and 1996. Simulated traffic loads were applied by a dual-tire loading cart within a climate chamber maintained at a temperature of approximately 25°C (77°F). Two dual-tire load levels of 20 kN (4495 lbf) and 40 kN (8990 lbf) were applied for 50,000 load repetitions each. Instruments installed in the test pavement included strain measuring sensors (strain deformation transducers and an ॖ strain-measuring system using induction coils), soil pressure cells, asphalt strain gauges, soil moisture probes, and pore pressure sensors. Routine monitoring of the pavement at regular intervals during the load testing program included measurement of surface profiles with a profilometer and falling weight deflectometer testing. Described here are the test pavement, the pavement materials, the types and positions of instruments installed in the pavement, typical instrument readings, and the surface profile monitoring and structural testing undertaken during the load testing program.
Instrumenting Ohio Test Pavement
Authors: Sargand Shad M. , Green Roger , Khoury Issam
Published: April 2007

The Ohio Department of Transportation (ODOT) constructed a test pavement on US-23 in Delaware County, Ohio. Of the nine Specific Pavement Studies (SPS) formulated by the Strategic Highway Research Program (SHRP), four (SPS-1, SPS-2, SPS-8, and SPS-9) were included at the OH-SHRP DEL-23 site. Sensors were carefully selected and installed to monitor structural response and seasonal parameters on the basis of prior field experiences accumulated in the United States and Canada. Criteria used to select the sensors were cost, accuracy, sensitivity, longevity, and level of success in previous pavement research projects, especially projects in Ohio. Described here is the development of the Ohio test pavement in terms of objectives, overall instrumentation plan, and selection of sensors as well as typical instrumentation plans for asphalt concrete and portland cement concrete sections.
Instrumentation of a Geosynthetic-Reinforced Flexible Pavement System
Authors: Perkins Steven W. , Lapeyre Joseph A.
Published: April 2007

Geosynthetics have been proposed and used to reinforce base course layers in flexible pavement sections to reduce base course thickness, or life-cycle costs, or both. Studies show conflicting results regarding the level to which geosynthetics can improve the performance of flexible pavements. To examine the reinforcement role of geosynthetics, a program of study has been initiated to define the mechanisms of base course reinforcement, to define and quantify the effect of site-specific parameters on the level of improvement observed, and to devise a design tool that can be readily applied in practice. This program will eventually involve the instrumentation of a full-scale pavement subjected to moving traffic loads, the success of which is essential to meeting the three objectives. As a first examination of the performance of proposed instruments, a pilot test section was constructed and monitored for approximately 3 months. The test section was chosen and constructed not necessarily to establish geosynthetic performance but rather to evaluate instrument installation techniques and subsequent instrument performance. Instruments designed to measure strain in the geosynthetics, base course, and asphalt concrete were included.
Implementing New York State Department of Transportation’s Pavement Preventive Maintenance Program
Authors: Denehy Edward J.
Published: April 2007

The New York State Department of Transportation developed and implemented an aggressive pavement preventive maintenance program in the early 1990s. The program was initiated in a bottom-up approach based on an informal pavement preventive maintenance program used for 20 years by field personnel. Upper-level managers were convinced of the efficacy of the preventive maintenance strategy, and executive management adopted such a program. Executive management included a preventive maintenance strategy in the Long-Term Financing Plan that became the Dedicated Highway and Bridge Trust Fund of 1991. The program succeeded in NYSDOT’s decentralized environment because of the inclusion of field-level personnel in its development. The treatment cycles of the pavement preventive maintenance program are described as are the newly developed contracting tools. The first two successful years of the program are highlighted. Various threats to the program, such as reduced funding due to the scarcity of budget resources, no. funding for several months in the construction season due to budget delay, inappropriate use and over-application of treatments, and internal competition for limited resources from other program areas, are discussed. Other highway agencies intending to implement a pavement preventive maintenance program may benefit from the experience described in New York.
Finite-Element Model of Modified Eccentric Loader Terminal (MELT)
Authors: Ray Malcolm H. , Patzner Gregory S.
Published: April 2007

Improving the performance of guardrail terminals and end treatments in impacts with passenger vehicles has been an active area of research over the past decade. One particular W-beam guardrail terminal that has been the focus of recent full-scale crash testing is the Modified Eccentric Loader Terminal (MELT). The development of a nonlinear, finite-element model of a recent modification of the MELT is being used to learn more about the performance of this type of guardrail terminal. A finite-element model of the MELT was developed using the TrueGrid preprocessor and the LS-DYNA3D finite-element software was used to perform the analysis. Results of the analysis are compared with data from a full-scale crash test involving a small passenger car.
Reconciling Transportation Corridor Preservation and National Environmental Policy Act Process: Evaluation of North Carolina Phased Environmental Approach
Authors: Lackey Ann E.
Published: April 2007

In recent years, transportation agencies have become increasingly interested in using corridor preservation to protect future highway locations from development. However, the preparation of National Environmental Policy Act (NEPA) documents in the late stages of the transportation planning process makes uses of these measures difficult. In an attempt to make the corridor preservation and NEPA processes more compatible, the North Carolina Department of Transportation and FHWA have developed the phased environmental approach, an environmental review process that allows early selection of highway location and makes the use of protection techniques feasible and effective. Although the phased approach has been used in several pilot projects and is intended to become a part of the state’s standard planning process, the procedure’s compliance with the requirements of NEPA has not been evaluated. The compliance of the phased environmental approach with NEPA is examined. Several disparities are identified that place the new procedure in violation of the statute. Considering these problems, three options for modifying the phased approach to provide for compliance with NEPA are identified. These options are compared on the basis of their capacity to provide those benefits offered by the phased approach. A tiered environmental impact statement (EIS) is determined to be the best alternative to the phased environmental approach. This option provides the same benefits as the phased approach while remaining consistent with NEPA. Although several potential problems have been cited regarding the practicality of using a tiered EIS in transportation projects, these concerns may not apply in many cases.
Skagit Countywide Air, Rail, Water, and Port Transportation System Study
Authors: Sorensen Paul C. , Irelan Eric , Winningham Brian , Noyes Thomas A.
Published: April 2007

Skagit County, a rural county approximately 96 km (60 mi) north of Seattle, Washington, and 120 km (75 mi) south of Vancouver, British Columbia, is experiencing strong growth in population and employment. Much of the increase is expected to occur in sectors that generate freight. Substantial growth in goods movement is expected at the county’s intermodal facilities. Decision makers realized that a major factor contributing to the economic growth in the county was its relatively unconstrained access to major markets in the north and south. They also understood that the efficient movement of people and goods is dependent on an integrated multimodal transportation network. The main purpose of the Skagit Countywide Air, Rail, Water and Port Transportation System Study was to provide in-depth analysis of the movement of freight, according to mode of transportation (i.e., road, rail, water, air, and pipeline). The methodology used to estimate existing, and forecast future, freight traffic flows by mode and by location is presented.
Analysis of Vehicles for International Motor Transport of Freight Between Mexico and Other NAFTA Countries
Authors: Mendoza Alberto , De Alba Miguel , Mayoral Emilio
Published: April 2007

Traditionally, the operative and normative practices of motor transport in the three countries that are party to the North American Free Trade Agreement (NAFTA), Mexico, the United States, and Canada, have been substantially different. In view of the imminent enforcement of the NAFTA motor transport accords, and with the aim of making transport more efficient, it is necessary to standardize such practices. Truck size and weight regulations in the three NAFTA countries are reviewed. A series of vehicles are ranked according to their transport productivity and their circulation possibilities through the part of the Mexican network that is most relevant to Mexico’s international commerce with the United States and Canada. The analysis includes the most commonly used vehicles authorized by federal regulations and others that are authorized only regionally but whose more extensive utilization could mean important productivity increases for the freight motor industry. The vehicle types that are most convenient to use considering the current condition of Mexican roads are identified. Other recommendations for making motor transport under NAFTA more efficient are addressed.
Environmental Impact Assessment of Transporting Hazardous Waste Generated by Maquiladora Industry in U.S.-Mexico Border Region
Authors: Ashur Suleiman A. , Baaj M. Hadi , Pijawka K. David , Serhan Derar S.
Published: April 2007

Hazardous waste shipments from U.S.-owned industries in the northern part of Mexico near the border with the United States are a growing problem. Today, the Mexican Environmental Agency requires all U.S. industries to return the waste produced by their plants to the United States. Currently, there is no database on the amount of hazardous waste transported from these firms, the pattern of shipments (from what origins to what destinations), and the nature of the risks to the population and environment along the shipment routes. In addition, there is a growing need to develop a risk assessment model and framework to focus on the transport of hazardous waste in the United States–Mexico border region, given the anticipated changes resulting from implementation of the North American Free Trade Agreement. Results of the data collection and analysis task and the risk assessment model formulation task are presented. The methodology is demonstrated in a case-study area of the United States–Mexico border region, namely, the Arizona-Sonora border area, and should be a valuable tool for evaluating various transport risk management scenarios of importance to the border area.
Interactive Spatial Decision-Support System for Multiobjective Hazardous Materials Location-Routing Problems
Authors: Coutinho-Rodrigues João , Current John , Climaco João , Ratick Samuel
Published: April 2007

Hazardous materials (hazmat) logistics management has received increased attention in the past two decades. Important decisions in such management include the selection of sites for hazmat processing and storage, the selection of transportation routes from sources to processing facilities, and the determination of quantities of hazmat shipped over these routes. These decisions are frequently based on multiple criteria (e.g., cost, risk, equity). A personal computer–based, interactive spatial decision-support system was designed to assist decision makers with such problems. Although presented within the framework of a hazmat problem, the system’s components can be modified to analyse any multiobjective location, routing, or location-routing problem.
Analysis of Freeway Accident Detection
Authors: Corby M. J. , Saccomanno F. F.
Published: April 2007

Instrumented traffic management can assist in the detection of freeway incidents and reduce the time required to initiate effective traffic management strategies and emergency response measures. Although instrumented freeway traffic management is concerned primarily with general incidents, reportable vehicle accidents are the focus of this research. Reportable accidents account for 20 percent of all freeway incidents and give rise to much of the nonrecurrent traffic congestion experienced on many freeways. Explored here is how the use of various accident-detection criteria, such as change in speed, vehicle occupancy, and traffic volume, affects the time to detection for a mix of factors (preaccident traffic characteristics, accident lane-blockage pattern, position and distance of detector with respect to each accident). A representative sample of Toronto freeway accidents for 1994 was analyzed using analysis of variance. The results of this analysis suggest ways in which instrumented detection of freeway accidents can be made more efficient by reducing the time to detection.