bluuebunny/crossref_metadata_2025 huggingface dataset:
Commuter-Based Carsharing: Market Niche Potential
Authors: Shaheen Susan A.
Published: April 2007

The automobile accounts for more than 95 percent of all person miles traveled in the United States, whereas transit accounts for less than 3 percent of all trips. Between the private automobile and traditional transit, niche markets exist for other transportation services, such as airport and transit feeder shuttles and carsharing. Commuter-based carsharing, by which individuals share a fleet of vehicles linked to transit, could potentially fill and expand one such niche; complement existing services, mainly transit and feeder shuttles; and develop into a viable transportation alternative. A brief overview is presented of transit feeder services, particularly in Northern California. The CarLink I field test is described—a commuter-based carsharing model developed and tested in the San Francisco Bay Area in 1999. Key behavioral findings are highlighted. Recommendations are made for strengthening the viability of this innovative service, mainly on the basis of experience from the CarLink I field test. Empirical evidence suggests that CarLink could be sustainable if certain conditions exist: strong cooperation with local businesses and transit is established; parking limitations and congestion are prevalent; system feasibility is demonstrated; incentives are used (e.g., preferred parking and transit pass subsidies); higher user fees are generated; and technology and management costs are lowered. Further, CarLink’s long-term potential and viability could be strengthened by a combination of approaches, including cost reduction strategies, policy incentives, linkages to other complementary services (e.g., ridesharing), and local program support (e.g., demonstration grants).
Effect of Superpave Gyratory Compactor Type on Compacted Hot-Mix Asphalt Density
Authors: Shane Buchanan M. , Ray Brown E.
Published: April 2007

The SUperior PERforming Asphalt PAVEments (Superpave) gyratory compactor was developed as a tool in the Superpave mix design system to better simulate the field compaction of hot-mix asphalts. All Superpave gyratory compactors are designed to meet the specification criteria found in AASHTO TP4. At the present time, AASHTO TP4 does not contain a precision statement. Furthermore, many agencies have reported differences in the bulk specific gravity of compacted samples from different Superpave gyratory compactors, which have been properly calibrated. Data are presented and analyzed from three gyratory compactor proficiency sample testing programs, from field project Superpave gyratory compaction comparisons, and from mix design and quality control and assurance results from a state department of transportation. The data were then analyzed to determine the statistical (precision) and potential project implications that result from the observed differences. The results indicate that the precision of the Superpave gyratory compactor is better than the mechanical Marshall hammer. However, there were significant differences between the bulk specific gravity of mixes compacted in different gyratory compactors. These differences could potentially lead to discrepancies during the mix design verification and quality control and assurance testing of a given mix.
Examination of Operator Variability for Selected Methods for Measuring Bulk Specific Gravity of Hot-Mix Asphalt Concrete
Authors: Hall Kevin D. , Griffith Frances T. , Williams Stacy G.
Published: April 2007

The ability of different operators to obtain similar results when performing laboratory tests on the same material is vital for producing accurate testing results. By conducting trials in triplicate for each of three different testing methods, a measurement of the bulk specific gravity (Gmb) of compacted hot-mix asphalt concrete (HMAC) cores was obtained. An analysis of the variability between operators was investigated using a total of almost 1,300 test results, using HMAC sampled from six projects in Arkansas. Three methods were used to determine the bulk specific gravity of compacted HMAC samples, including saturated surface dry (SSD) (as per AASHTO T166), height and diameter (as per AASHTO T269), and vacuum sealing (using the Corelok vacuum sealing device). In almost all cases, Gmb values determined using the height and diameter method were statistically different from those determined using the SSD and Corelok methods; further, statistical differences were noted in paired analyses between the SSD and Corelok methods. The Corelok method exhibited a lower degree of variability than the other two methods used, based on the standard deviation of test results obtained by different operators. In direct comparison with the SSD method, the Corelok exhibited a lower variability (standard deviation) in 81 percent of the cases. Overall, the Corelok method appears to offer a viable alternative for determining the bulk specific gravity of compacted HMAC. However, agencies seeking to use the Corelok must consider the effect of an apparent shift in Gmb values obtained on resulting HMAC volumetric and compaction properties.
Paris–Lexington Road Project: Project Report
Authors: Werkmeister Raymond F. , Hancher Donn E.
Published: April 2007

The Paris-Lexington Road Project is the four-lane roadway reconstruction project of the two-lane Paris Pike, a 19-plus-km (12-plus-mi) section of US-27/58. This section of highway has been dedicated as a historic corridor and has had its share of archeological and environmental sensitive sites along the corridor. In addition, Paris Pike is one of the major thoroughfares through picturesque horse farms that make up the prosperous Kentucky thoroughbred industry. Over the years, safety and traffic operations problems had become noticeable to the Kentucky Transportation Cabinet (KyTC). However, when KyTC attempted to use standard department procedures to study, plan, design, and construct a solution to rectify these problems, they found that the special circumstances of Paris Pike required something innovative. Some background is given on the circumstances that KyTC had to consider: historic, environmental, and political. To ensure compliance with the historic and environmental preservation requirements of this project, KyTC used innovative approaches in contracting the design segments. Preliminary findings are reported on the effectiveness of the construction phase of the first three of five design segments that have been contracted. Although further investigation is ongoing, a comparison can be made of the results observed and the typical results achieved for highway construction projects performed under traditional design-bid-build contracting methods.
Railroads in the City: Overlooked Rail Transit Opportunities
Authors: Allen John G.
Published: April 2007

Transportation officials today are under pressure to deliver attractive rail transit at affordable prices. Although rail rights-of-way are often the least costly on a unit basis, planners frequently prefer other alignments that can better serve major origins and destinations. Yet occasionally rights-of-way built for railroads connect major activity centers with one another. In these cases, using rail alignments offers the dual benefits of economy and effective service to markets. A survey examines four existing and two proposed operations that link the region’s largest downtown with at least two other major destinations within, or adjacent to, the central city along rail rights-of-way. These systems cover a full range of operating technologies and metropolitan sizes. The opportunities for using railroad rights-of-way to provide rail transit between major urban activity centers are not widespread and vary widely from city to city. Nevertheless, some possibilities do exist, and their potential has yet to be fully tapped.
Interurban Electric Railway: A Tale of Two Centuries
Authors: Levinson Herbert S. , Hoey William F.
Published: April 2007

The interurban electric railway played an important role in linking communities in the early 20th century. A long-term decline in the following years reflected the growing number of motor vehicles operating over improved intercity highways. Despite a brief respite during World War II, the decline continued. By about 1965, the interurban electric railway had virtually vanished from the American scene. But then in the last quarter of the century, new rail transit lines emerged that often embodied many aspects of the interurban. The rise, fall, and rebirth of the interurban electric railway are traced from the perspectives of 1925, 1950, 1975, and 2000.
Pedestrian Warning and Control Devices, Guidelines, and Case Studies
Authors: Siques Joaquin T.
Published: April 2007

A high percentage of collisions between light rail vehicles (LRVs) and pedestrians result in injuries or fatalities. As such, properly identifying potentially hazardous crossings and providing pedestrian treatments to those crossings are integral to the design of new light rail transit systems or extensions and for the evaluation of existing systems. An approach is discussed to select pedestrian treatments at grade crossings, and examples of innovative treatments for existing systems are given. The focus is four key factors that enable pedestrians to walk through a grade crossing safely: (a) pedestrian awareness of the crossing, which can be enhanced by passive signs and tactile warnings; (b) the pedestrian path across the trackway, which is subject to pedestrian channelization and positive control devices; (c) pedestrian awareness of and ability to see an approaching LRV, which depends on pedestrian sight distance at the crossing and can be improved through active warning devices; and (d) pedestrian understanding of the potential hazards at grade crossings, which requires public outreach and education. These four factors are discussed, and treatments for each are provided.
Fast Ferry Safety Analysis for San Francisco Bay: Needs Assessment and Preliminary Framework
Authors: Walther Mary , Aspland Jerry
Published: April 2007

Fast ferry traffic and vessel speed are on the rise in San Francisco Bay. A conservative analysis estimates that daily fast ferry trips may increase from today’s 100-plus trips to 665 trips in only 10 years. Although providing great opportunities for industry and travelers alike, increasing speed and congestion raise important safety considerations that could overwhelm the existing safety infrastructure. The U.S. Coast Guard, California Maritime Academy, and Pacific Transit Management Corporation have developed the outline for a formal safety assessment (FSA) that will consider the effect of more fast ferries on San Francisco Bay from a port-waterway systems perspective rather than from the traditional vessel safety approach. The FSA process will detail existing project risks and forecast future risks, identify best practices, and recommend the implementation of the most effective, efficient, and equitable risk management alternatives. Safety issues raised by increasing fast ferry traffic are discussed, FSA aspects are detailed, and the most recent information on progress toward understanding and improving fast and safe ferry operations in San Francisco Bay is presented.
Transition or Transformation?: Emerging Freight Transportation Intermediaries
Authors: Song Jiongjiong , Regan Amelia C.
Published: April 2007

During the past 2 years, traditional freight transportation intermediaries, which include freight forwarders, brokers, and third-party logistics (3PL) providers, have been joined by new intermediaries. The main drivers in the development of these new companies are advances in information and communications technologies, development of web-based or online freight transportation marketplaces, and worldwide emergence of business-to-business electronic marketplaces and business-to-consumer e-tailers. Advances in information technology enable many new operational paradigms and, potentially, the efficient integration of supply chains. These new companies are examined, including their potential benefits and costs of shifting from traditional 3PL to these online service providers. Also addressed is the extent to which changes in the industries appear to be more of a transition than a large-scale transformation.
We’re Really Asking for It: Using Surveys to Engage the Freight Community
Authors: Lawson Catherine T. , Riis Anne-Elizabeth
Published: April 2007

Freight transportation concerns and issues have received increasing attention during the 1990s. Various public-sector agencies have attempted to identify locations where improvements are needed to facilitate freight movements. Needed improvements have been determined via modeling, technical data and estimates, reviews of plans and other documents, personal observations, and public input. Various observers think that information from these sources should be combined with more specific information from shippers and motor carriers moving freight. No definitive research has been conducted on how best to survey shippers and motor carriers. To establish the most effective means of obtaining views from the freight community about infrastructure problems on state highways and the supporting road network, the Oregon Department of Transportation sponsored the development of a method to conduct a shipper and carrier survey. Pilot instruments and methods were systematically administered to a stratified, random sample of Oregon freight shippers and motor carriers.
SOFTICE: Survey on Freight Transport Including a Cost Comparison for Europe
Authors: Musso Antonio
Published: April 2007

To achieve a better understanding of freight transport costs in Europe, a Survey on Freight Transport Including a Cost Comparison for Europe—SOFTICE—was sponsored by the European Commission and intended to answer two fundamental questions: (a) which factors affect freight cost structure and demand for transport and (b) how may a change in transport policy affect transport costs and, consequently, the relative competitiveness of industries in different countries? First, SOFTICE focused on the main parameters affecting cost structure. A cost data collection survey was conducted with a group of 40 European shippers. The main methodological issues were developed for market segmentation, types of integrated supply chains, and quality of service, which were used to analyze the situation and test the effects of various factors and market sensitivities. The consequences of different policies of taxation and cost internalization on spatial production organization were assessed. A second shippers’ survey was conducted to evaluate the shippers’ reactions to policy changes in European countries. An overview of freight cost structure is provided, and survey results are presented for shipment costs and the effects of working hour regulations. Selected findings from the main methodological issues are emphasized. Key features of the shippers’ reactions to policy changes are outlined, and lessons learned on pricing and policy coordination are identified.
North American Free Trade Agreement and Transportation: A Canadian Scorecard
Authors: Brooks Mary R.
Published: April 2007

A Canadian perspective is presented on the successes and failures of the North American Free Trade Agreement (NAFTA) as related to the transportation sector. For the agreement, 2001 is a watershed year when most of the agreement provisions should be in place. Canada’s intentions at the negotiating table and its stake in trilateral trade are discussed. Changes promised by NAFTA in the transportation business environment are examined. The impacts of NAFTA on nontariff barriers are detailed, including operating and safety standards, access to cargo ("cabotage"), ownership regulations, and investment screening. This analysis is a sequel to a presentation made at the 1994 TRB Annual Meeting and subsequently published in Transport Reviews. That paper concluded that NAFTA offered greater opportunity to American transport firms with the financial and managerial strength to exploit the agreement’s potential, and received mixed reviews in Canada. Seven years have passed since NAFTA implementation; this analysis looks at the promise that was NAFTA and produces a scorecard from a Canadian point of view. The grade is not good.
Estimating Texas-Mexico North American Free Trade Agreement Truck Volumes
Authors: Figliozzi Miguel A. , Harrison Robert , McCray John P.
Published: April 2007

North American Free Trade Agreement (NAFTA) truck traffic continues to grow on the international trade highway corridors linking the United States to Mexico. This situation presents planning challenges to accommodate NAFTA truck traffic along these highways and at U.S.-Mexican border ports of entry. Because transportation data are lacking, the numbers of trucks, particularly those carrying NAFTA trade to and from Mexico, are difficult to estimate. Two data sources available for estimating the number of trucks crossing the border are the counts of trucks crossing the bridges and the U.S. international trade data. Two methods of estimation, each using one of these data sets, are developed and described. Two separate truck flows derived from the models are explained and compared using a standardized truck type (equivalent trade truck) to represent truck flows. Interestingly, both methods provide useful outcomes.
Applying the Least-Cost Transportation Model to Estimate the Effects of Major Transportation System Changes: Case Study of Dam Breaching on the Snake River
Authors: Fowler Chris
Published: April 2007

In studies conducted between September 1998 and March 2000, estimates were made of economic costs and benefits resulting from the loss of commercial barge navigation on the Snake River. These analyses estimated the effects on producers, agricultural production levels, transportation providers, highway and railroad infrastructure costs, and changes in fuel efficiency and emissions because of transportation mode shifts, based on a single least-cost transportation model (LCTM) that simulated the transportation patterns for wheat and barley in eastern Washington. An LCTM, such as the one used in these studies, can answer many of the critical questions about the effects of major changes to transportation systems and their users. Given its flexibility and sophistication, LCTM is an appropriate tool for predictive modeling when decision makers must consider the costs and benefits of a proposed transportation project or system modification. Although agricultural economists often use LCTM in their research, few transportation planning analysts apply this tool. The application of LCTM to transportation planning is illustrated by analyzing the economic effects likely resulting from changes to the transportation system in the Pacific Northwest related to the proposed breaching of four dams on the Snake River.
Certification of Performance-Based Standards for Truck Size and Weight Limits: Implementation Considerations and Enforcement Issues
Authors: Field Mary A.
Published: April 2007

In the context of regulating truck weight limits, the concept of performance-based standards (PBS) may be applied to three areas—infrastructure, traffic operations, and safety. Using a certification as documentation of vehicle compliance with a PBS has been suggested as an option for PBS enforcement. Enforcement is essential in encouraging voluntary compliance with laws or regulations governing vehicle weight and operation. The traditional method of vehicle weight enforcement is to use static, portable, or semiportable scales to determine the axle or gross weight of a vehicle. Any proposal to use a certification as documentation of PBS compliance for truck size and weight limits must be examined closely for enforceability. Maryland’s use of a certification for enforcement of a lift-axle weight regulation is examined from an enforcement perspective, and the process used to develop the regulations is discussed. Enforcement of the lift-axle weight limit is based on the air pressure setting, not on weighing the axle with a scale. The certification is important because it documents the air pressure setting required of the lift-axle on a loaded, four-axle dump truck at 31 780 kg (70,000 lb). This study represents the first external review of issues identified in using the certification, and the enforcement experience since implementation.
Risk Assessment for National Transportation of Selected Hazardous Materials
Authors: Hwang Steve T. , Brown David F. , O’Steen James K. , Policastro Anthony J. , Dunn William E.
Published: April 2007

A quantitative risk assessment was conducted to estimate the national risk from transporting (a) six toxic-by-inhalation (TIH) chemicals that account for more than 90 percent of total TIH transportation-related risk, (b) liquefied petroleum gas, (c) gasoline, and (d) explosives. For TIH materials, highway and rail transportation and two classes of incidents are examined, those occurring (a) during a traffic accident or train derailment and (b) en route from origin to destination but not during an accident or derailment. For the other toxic materials, only accident-related incidents in highway transportation are considered, because these materials are dominated by highway incidents. An overview is provided of the hazardous materials and their consequences, the risk assessment method, the databases used to determine hazardous materials commodity flow and incident rate, and study results. To illustrate the method used, the risk assessment for ammonia is discussed. Risk distributions and quantitative risk measures for additional materials as calculated in the study are also presented, and conclusions drawn from these results are discussed. This study has demonstrated the capability to evaluate the national risk of transporting certain hazardous materials. The risk distributions provide valuable information on the probability of certain effects in a given time period, whereas risk measures provide a convenient way to compare relative risk for different commodities, transportation modes, and incident types.
Assessing the Economic Effect of Incidents Involving Truck Transport of Hazardous Materials
Authors: Abkowitz Mark D. , DeLorenzo Joseph P. , Duych Ron , Greenberg Art , McSweeney Tom
Published: April 2007

Because of its potential to harm human health and the environment, transportation of hazardous materials has become an important national safety issue. Although the general assumption is that incidents that occur in shipping hazardous materials are costly, a method to characterize their full economic effect has not been developed. As a result, comparing the need to improve safety among hazardous and nonhazardous cargo shipments, and among different classes of hazardous materials shipments, has been difficult. A method has been developed to assess the economic effect of incidents involving truck transport of hazardous materials. Annual commodity flow and incident occurrences were estimated, and a comprehensive assessment was made of the economic consequences of each incident. Impact considerations included injuries and fatalities, cleanup costs, property damage, evacuation, product loss, traffic incident delay, and environmental damage. The method was applied to Class 3 shipments in 1996 to illustrate its use and to evaluate its potential as a policy tool.
Security Considerations for the ParcelCall Real-Time Tracking and Tracing System
Authors: Wallbaum Michael , Pils Carsten
Published: April 2007

Although many transport and logistics companies have tracking and tracing systems, these systems typically are proprietary solutions. At the same time, supply chains are becoming increasingly complex, involving multiple carriers and transport modes. Accurate, up-to-date information exchange across different carriers and modes of transport is in high demand. The objective of the European project ParcelCall is the development of an open and standardized architecture for seamless tracking and tracing across the entire logistics and transportation chain. Security issues that arise in this context are discussed.
Statistical Model of Pavement Rutting in Asphalt Concrete Mixes
Authors: Ricardo Archilla Adrián , Madanat Samer
Published: April 2007

Pavement deterioration models are important inputs for the efficient management of pavement systems, the allocation of cost responsibilities to various vehicle classes for their use of the highway system, and the design of pavement structures. The development of an empirical rutting progression model with an experimental data set from WesTrack is described. The salient features of the model specification are as follows: ( a) three properties of the mix are sufficient to model the performance of the asphalt concrete pavement at WesTrack accurately; ( b) the model captures the effects of the high air temperatures at WesTrack; and ( c) the model predicts rut depths by adding predicted values of the increment of rut depth for each time period, which is particularly advantageous in a pavement management context. The three mix properties are a gradation index, which is obtained from the aggregate gradation; the voids filled with asphalt obtained for the construction mix in the Superpave gyratory compactor; and the initial in-place air voids. The specified model is nonlinear in the variables and the parameters and is estimated by using a random-effects specification to account for unobserved heterogeneity. The estimation results and prediction tests show that the model replicates the observed pavement behavior at WesTrack well.
Evaluation of Road Surface Profiler and Transverse Profilograph for Determination of Rut Depths
Authors: Mehta Yusuf , Roque Reynaldo , Lopp George , Villiers Claude
Published: April 2007

In recent years, the road surface profiler (RSP), also known as the high-speed profiler, has been used as the standard equipment for measurement of rut depths. Typically, for highway pavements an RSP with a three-sensor configuration is used to measure rut depth. Rut-depth measurements were taken with an RSP with three sensors at a spacing of 0.87 m and with a transverse profilograph (TP) on six projects, each of which was approximately 8 km (5 mi) long. At any given location the rut depth taken with the RSP was, on average, three times less than that taken with the TP. Different values of rut depth were determined by simulating the lateral movement of the vehicle, effectively, vehicle wander. Comparison of the rut-depth measurements obtained with the actual RSP and those obtained with the simulated RSP showed that the RSP vehicle had wandered from the center in almost all cases and that the wander in some cases was up to 0.57 m. The distance between the maximum rut depths within each wheel-path varied from 1.55 to 2.19 m, with an average of 1.86 m. The measured rut depth increased by as much as 300 percent when the sensor spacing was varied from 0.75 to 1.20 m. Measurement of the transverse profile was determined to be the most accurate method of rut-depth measurement. It will be possible to accomplish this either with additional sensors required to capture the transverse profile in the RSP or with a TP.
Measurement of Pavement Macrotexture with Circular Texture Meter
Authors: Abe Hironari , Tamai Akinori , Henry J. J. , Wambold James
Published: April 2007

The results of tests conducted with the circular texture meter (CTMeter), which measures the profile of a circle approximately 800 mm in circumference, are discussed. It is shown that by analyzing the profile data obtained with the CTMeter one can obtain reliable predictions of volumetric mean texture depth (sand patch texture depth) and the outflow times of several designs of outflow meters. Data from 3 years of testing are used to evaluate the correlation of the mean profile depth obtained with the CTMeter to the volumetric mean texture depth and the outflow time. In all cases the correlation coefficients ( R2 values) were very high. Recommendations for additional studies that might be conducted to exploit additional information that can be obtained by processing the CTMeter profiles are made. In particular, the analysis of the directional properties of the surface texture as they may relate to wet pavement friction and tire-pavement noise is suggested.
Study of Precision of Transverse Evenness Measurements in FILTER Experiment: Forum of European National Highway Research Laboratories Investigation on Longitudinal and Transverse Evenness of Roads Experiment
Authors: Descornet Guy , Berlemont Bruno , Martin Jean-Marc
Published: April 2007

The results of an analysis of the transverse profile measurement data collected in the FILTER Experiment are presented. The purpose of the analysis was to determine the repeatabilities, reproducibilities, and accuracies of the measurements. Application of the International Organization for Standardization 5725 standard resulted in the detection of a significant proportion of outlying results with most if not all devices. After removal of the outliers, average standard deviations ( SDs) for repeatability were typically 0.1 percent for cross fall, 0.5 to 0.9 mm for rut depth, and 0.25 mm for water depth: cross-fall measurements exhibited an average SD for reproducibility of 0.5 percent; for rut depth measurements the values were 1.7 to 2.7 mm, and for water depth measurements the values were 2.1 to 2.2 mm. The overall SD for the accuracies of the profile measurements was found to be 1.9 mm. The rather wide range of (in)accuracy (0.8 to 3.2 mm) among the different test sections is explained by the influence of longitudinal unevenness (international roughness index). Operating speed in the speed range used in the experiment had no significant influence on most measurements obtained. Moreover, speed had no significant influence on the repeatabilities or the reproducibilities of the indices or on profile measurement accuracy. Averaging distance had a significant influence on the SD for repeatability, which decreased by a factor of 2 to 4 when the averaging distance increased from 50 to 500 m. The reproducibilities of the indices did not significantly depend on the averaging distance in any systematic way.
EVEN Project: Experiment to Compare and Harmonize Methods for Assessment of Longitudinal and Transverse Evenness of Pavement
Authors: Schmidt Bjarne
Published: April 2007

The analysis performed on longitudinal profiles measured on in-service roads during the Permanent International Association of Road Congresses—World Road Association (PIARC) second international experiment, the EVEN project, which was conducted in the United States, Japan, and Europe in 1998, is described. The European experiment was carried out by the Forum of European Highway Research Laboratories, but the results of the European experiment are not included. In the United States and Japan profile measurements were obtained for a number of in-service roads that have various levels of evenness, ranging from approximately 0.6 to 6 m/km. Tests were performed with all devices at different speeds. An analysis of the correlation between the international roughness index (IRI) for the test sections on the basis of the measurements obtained with high-speed devices and the true profile obtained with a combination of three different hand-operated profiling devices is provided. A detailed analysis of measurements was conducted for the test sites for which the poorest correlation between the IRI obtained with the high-speed devices and the true profile was found. Also, a detailed analysis was carried out for the test sections for which the best correlation between the high-speed devices and the true profile was obtained. Finally, the results of an analysis of the repeatabilities and the reproducibilities of the participating devices in United States and Japan are presented.
Basic Analysis of Measurement Data from Japan in EVEN Project
Authors: Kawamura Akira , Takahashi Morito , Inoue Takemi
Published: April 2007

The second Permanent International Association of Road Congresses—World Road Association International Experiment to Harmonize Longitudinal and Transverse Profile Measure and Reporting Procedures (EVEN Project) was conducted in 1998 in three regions of the world. The aim of the research is to harmonize and correlate measures of road profiles for applications in pavement construction and management. The basic analysis and measurement results for roughness conducted in Hokkaido, Japan, are summarized. The longitudinal profile measurements obtained with seven high-speed profilometers in Japan, their influence on roughness indices such as the international roughness index, and the correlations between roughness indices, together with Japan’s current measurement and evaluation system for roughness, are also compared and analyzed.
Analysis of Correlations Between Longitudinal Indices in FILTER Experiment: Forum of European National Highway Research Laboratories Investigation of Longitudinal and Transverse Evenness of Roads Experiment
Authors: Alonso Marta , Yanguas Sixto
Published: April 2007

The Forum of European National Highway Research Laboratories (FEHRL) Investigation on Longitudinal and Transverse Evenness of Roads (the FILTER project) is a research project on evenness developed by FEHRL. The laboratories involved in this project are from Belgium, Denmark, France, Germany, the Netherlands, Slovenia, Spain, Sweden, and the United Kingdom. Guy Descornet (of the Belgium Road Research Center) has coordinated the project. The FILTER project is divided into some tasks that deal with theoretical and experimental analysis of data on evenness. One of these tasks is to analyze the European data obtained from an experiment that was conducted by Technical Committee C1, Surface Characteristics, of the Permanent International Association of Road Congresses—World Road Association in 1998. This experiment was accomplished in the United States, Japan, and Europe (the FILTER experiment). The FILTER experiment was carried out in Germany and the Netherlands in September 1998. The participants (who used the profilometers commonly used in Europe) should report their results on the profiles and indices of both transversal evenness and longitudinal evenness. The Road Research Center of the Center of Research and Experimentation of Public Works (Madrid, Spain) was in charge of analyzing the results regarding longitudinal indices from the FILTER experiment. The method used to analyze these data and some of the conclusions obtained are explained. The work contributes to the achievement of the FILTER project, one aspect of which is to try to harmonize the different methods of measuring evenness in Europe.
Estimation of Effects of Washington State’s Trip-Reduction Program on Traffic Volumes and Delays: Central Puget Sound Region
Authors: Hillsman Edward L. , Reeves Paula , Blain Larry
Published: April 2007

Washington State requires large employers in its nine most populous counties to encourage their employees to reduce commuting vehicle trips and to monitor progress by surveying employees. The monitoring requirement yields roughly 250,000 surveys every 2 years. Analysis of the survey results for 1999 and previous years estimated that the program removed an average of 18,500 vehicles from the road during the morning peak in 1999, with 12,600 of these in the Seattle metropolitan area. Information from the surveys was used to construct an origin-destination table for these trips, and the table was then used in a four-step modeling process to estimate the corridors and links that realized the greatest effect of the trip-reduction program. The modeling compared a baseline, which assumed effects of the trip-reduction program, with a case in which trips removed were added back into the trip tables. Results indicate that the trip-reduction program has measurable effects on traffic volumes and delay, both areawide and in specific corridors. The analysis is unique in having these types of data on which to draw for a metropolitan area whose modeling system can use them.
Voluntary Ridesharing After Deregulation: Findings from Work Sites Exempted from California Rule 2202, On-Road Motor Vehicle Mitigation Options
Authors: Kneisel Robert
Published: April 2007

Beginning January 1, 1997, with the passage of Senate Bill 836, California work sites with between 100 and 249 employees were exempted from the South Coast Air Quality Management District’s Rule 2202, On-Road Motor Vehicle Mitigation Options. Rule 2202 had required these work sites to reduce mobile source emissions by implementing an emission-reduction strategy such as scrapping old vehicles, participating in the Air Quality Investment Program, or implementing an Employee Commute Reduction Program (ECRP). To estimate the resulting shortfall in emission reductions, surveys of voluntary ridesharing at deregulated work sites were conducted in each subsequent year: 1997, 1998, and 1999. Survey results indicate that average vehicle ridership (AVR) at deregulated work sites has declined compared with the AVR while under regulation. However, the AVR over the 1997 to 1999 period has remained relatively constant. For those work sites that had been complying with Rule 2202 by implementing an ECRP, the future baseline AVR was assumed to increase annually at the rate of increase before deregulation. For work sites that had chosen the other two options, the AVR target remained at 1.5, the same as prior to deregulation. Using the difference between the target AVR and the AVR measured in the surveys, for each of the three options, the emission reduction shortfall was calculated. The shortfall increased from 1997 to 1998 but fell from 1998 to 1999.
Low-Temperature Thermal Cracking of Asphalt Binders as Ranked by Strength and Fracture Properties
Authors: Anderson David A. , Lapalu Laurence , Marasteanu Mihai O. , Le Hir Yann M. , Planche Jean-Pascal , Martin Didier
Published: April 2007

The original Superpave low-temperature specification for asphalt binders placed limits on the low-temperature stiffness and m-value. A recently approved alternative to the original Superpave asphalt binder low-temperature specification makes use of the measured stiffness and tensile strength of the binder to determine a critical cracking temperature. Thermal cracking temperatures are presented for 42 plain and modified asphalt binders. Thermal cracking temperatures determined by the original and recently approved alternative Superpave specification are compared. The fracture toughness, KIC, can also be used to evaluate low-temperature cracking properties of asphalt binders. Fracture properties obtained for 14 asphalt binders are compared with the thermal cracking temperatures determined by the original and recently adopted alternative Superpave specifications. The set of 14 binders was produced from a common base material but modified by different means. For the set of 14 binders, there is little difference in their ranking according to both the original and recently proposed alternative Superpave low-temperature criteria; however, their ranking is quite different on the basis of the fracture properties as measured by KIC. KIC appears to provide a much more discriminating ranking of the binders than either of the Superpave specification criteria.
Effect of Silicone Rubber Molds on Low-Temperature Binder Grading Parameters: Bending Beam Rheometer S[60] and m-Value
Authors: Dongré Raj , D’Angelo John , Antle Charles
Published: April 2007

A study was conducted to determine whether test specimen produced using silicone (Si) rubber molds affect the Superpave low-temperature grading parameters, S(60) and m-value, determined using the bending beam rheometer (BBR; AASHTO-TP1). Six laboratories participated in this study. Four unmodified asphalt binders with low-temperature performance grades between -6°C and -30°C were tested. The thickness of each test specimen was measured using the “flip” technique. The results showed that the Si rubber molds produce significantly thinner beams than the required 6.35 ± 0.05-mm thickness. This affects the calculated S(60) values but not the m-value. Aluminum (Al) molds were also used in this study according to AASHTO-TP1. It was found that the stiffness values S(60) calculated in the BBR test are significantly lower when Si rubber molds are used to produce test specimen as compared with those test beams produced using Al molds. The cause is the peculiarity of the calculation process specified in AASHTO-TP1. AASHTO-TP1 requires that the thickness of the test beam must always be assumed to be 6.35 mm for computing S(60). This study suggests that the test beams produced using the Si rubber molds are significantly thinner; therefore, assuming a thickness of 6.35 mm to calculate S(60) for these beams produces a negative bias. It is shown that when thickness is measured using the flip technique and the measured thickness is then used to calculate S(60), there is no statistically significant difference between the S(60) values of the test beams produced using either the Al or Si rubber molds.
Design, Construction, and Early Performance of Virginia’s Hot-Mix Asphalt Stabilizer and Modifier Test Sections
Authors: Prowell Brian D.
Published: April 2007

Three modifiers and two types of fibers (stabilizers) for hot-mix asphalt commonly available in Virginia were evaluated. Ten test sections were built on I-66, west of Manassas, Virginia. The modified asphalts complied with the specifications for performance grade 76-22 and were placed in dense-graded Marshall and coarse-graded Superpave mixes. The fibers were placed only in the dense-graded Marshall mixes. During design the dense-graded Marshall mix complied with all of the Superpave requirements except for the gradation, which passed through the restricted zone. Samples from the sections were tested for asphalt content, gradation, and Superpave and Marshall volumetrics and were rut studied using both the Georgia loaded-wheel tester and the asphalt pavement analyzer. Field samples generally passed Marshall volumetrics and generally failed Superpave volumetrics. Neither laboratory compaction method correlated with the ultimate field densities. Both tests indicated that the sections were rut resistant. All of the sections have been rut resistant and have performed well in the field after 45 months of service.
Advanced Characterization of Crumb Rubber-Modified Asphalts, Using Protocols Developed for Complex Binders
Authors: Kim Sohee , Loh Ssu-Wei , Zhai Huachun , Bahia Hussain U.
Published: April 2007

The use of crumb rubber modifiers (CRMs) to change asphalt binders was evaluated. Blending two base asphalt binders of performance grade 70-22 and 64-22 with three sizes of a CRM at two rubber contents resulted in varying grades of asphalt binders. In addition to these binders, two binders modified with reacted crumb rubber using a patented process were included in the study. Testing was conducted at different temperatures, testing frequencies, and strain conditions, using methods recently developed as part of the NCHRP 9-10 project (Superpave Protocols for Modified Asphalt Binders) for complex binders. The new testing includes the particulate additives test (PAT), which determines the volume of particulate material greater than 75 μm in asphalt, and the laboratory asphalt stability test (LAST), which measures the potential for separation and degradation of additives in asphalt. Strain sweeps, fatigue testing, and low-temperature failure and creep properties were also measured. The results indicate that the concentration and size of crumb rubber affect the viscosity of the resulting modified binders significantly and influence the volume of residue collected in PAT. It was observed that concentration and size of rubber are, however, not important compared with other factors in LAST and that keeping the binders agitated during storage can reduce separation significantly. On the basis of the rheological testing, it was found that both fatigue and strain dependencies are highly sensitive to asphalt binder type, rubber size, and rubber content. The failure properties of CRMs measured using the direct tension test indicate that failure stress and strain are reduced by increasing rubber size and concentration.
Asphalt Permeability Testing: Specimen Preparation and Testing Variability
Authors: Maupin G. W.
Published: April 2007

Concern over asphalt mixtures allowing surface water to enter has led to an interest in developing a reliable permeability test. Several studies have been conducted on permeability testing, and ASTM is currently developing a falling-head test method to determine asphalt permeability. The Virginia Department of Transportation became interested in testing its pavements and using permeability as a design consideration. An ASTM task group investigated the effect of sawing specimens, a technique for separating the layers of asphalt. Sawing did not lead to reduced permeability when the sawing process was properly controlled. Since a falling-head test might be used in acceptance and design specifications, it was important to determine its associated variability. Permeability variability was computed from test data derived from field cores and specimens prepared in the laboratory. Repeat tests by different operators indicated differences that warrant additional investigation.
Evaluation of Microdamage, Healing, and Heat Dissipation of Asphalt Mixtures, Using a Dynamic Mechanical Analyzer
Authors: Kim Yong-Rak , Little Dallas N. , Lytton Robert L.
Published: April 2007

Microdamage accumulation due to fatigue loading, healing due to rest periods, and hysteresis heating during fatigue testing of asphalt mixtures using a dynamic mechanical analyzer were investigated. Specially fabricated sand-asphalt specimens were tested under a repetitive, controlledstrain torsional mode at 25°C and 10 Hz. Fatigue performance was evaluated using hysteresis loops of stress-pseudostrain and a simple parameter, pseudostiffness, based on the elastic-viscoelastic correspondence principle. Heat generation and dissipation during fatigue testing were also investigated by measuring temperature changes of a tiny thermocouple inside the asphalt mixtures. The results demonstrate that microdamage healing due to rest periods results in an increase of fatigue life. It was observed that the effects of hysteresis heating on the changes of stiffness during the fatigue test were not significant. Successful development of this testing method is suggested as a potential specification-type test method because of its rapidity, repeatability, and accuracy.
Microstructure Study of WesTrack Mixes from X-Ray Tomography Images
Authors: Wang L. B. , Frost J. D. , Shashidhar Naga
Published: April 2007

Asphalt concrete is a composite comprised of aggregates, air voids (AVs), and microcracks of various sizes and shapes. The property of asphalt mixes is not only affected by volume fractions of these components such as voids in mineral aggregates (VMA, the complementary volume fraction of aggregates) and AV content but also the size and spatial distributions of these components. However, conventional and Superpave volumetric mix designs specify only bulk values of VMA and AV, which may not be able to capture all the critical factors of a mix. The unexpected WesTrack mixes’ premature failure may reflect this limitation in design specifications. Results are presented of a study to evaluate statistically the spatial and size distribution of the void systems of the mixes and to find other possible parameters that might be better or complementary to the current parameters to characterize the mixture internal structure and performance. Void systems of three original WesTrack mixes were evaluated using X-ray tomography images and stereology methods. The spatial void content variation and void size distribution for six specimens of three mixes were quantified. Specific damaged surfaces (void surfaces were considered damaged surfaces because they do not transmit forces), damage tensor, mean solid path among damaged surfaces, and mean solid path tensor, which indicate damage level and interaction of the damage, were also quantified. It was concluded that coarsegraded mix is more severely inherently damaged and that this set of parameters gave a performance ranking of the three mixes consistent with field observations. Moreover, quantified tensors are applicable in continuum damage mechanics for fatigue and rutting modeling.