bluuebunny/crossref_metadata_2025 huggingface dataset:
Field Verification of Laboratory Resilient Modulus Measurements on Subgrade Soils
Authors: Ping W. Virgil , Ge Ling
Published: April 2007

The resilient modulus of roadbed soils is a required input parameter in pavement analysis and design. Most recent research has concentrated on the laboratory resilient modulus test and its correlations with other engineering properties determined from laboratory tests. However, little effort has been focused on calibrating the laboratory resilient modulus measurements using field performance data. The results are presented of an experimental program to evaluate the field bearing characteristics of in-service pavement subgrade layers and to conduct the laboratory resilient modulus measurements on the reconstituted soil samples simulating the field moisture and density conditions. A simplified procedure was adopted for comparing the laboratory equivalent resilient modulus values with the modulus of elasticity of the subgrade layer obtained from the field plate load test. The laboratory resilient modulus test results compared reasonably well with the field plate layer moduli.
Alternative Method of Determining Resilient Modulus of Compacted Subgrade Soils Using Free-Free Resonant Column Test
Authors: Kim Dong-Soo , Kweon Gi-Chul , Lee Kwang-Ho
Published: April 2007

An alternative procedure of determining the resilient modulus ( MR) of compacted subgrade soils using a free-free resonant column (FF-RC) test is proposed. The FF-RC test was used to determine a small-strain Young’s modulus ( Emax) and Poisson’s ratio on the basis of the elastic wave propagation theory. Resonant column (RC) and torsional shear (TS) tests were performed to investigate the effects of loading frequency and strain amplitude on the resilient modulus of subgrade soils. By performing FF-RC, RC/TS, and MR tests on the synthetic specimens of known stiffnesses, the feasibility of using the FF-RC test to measure the MR was evaluated and the MR testing equipment was calibrated. Moduli of subgrade soils determined by FF-RC tests match well with values obtained from RC and TS tests at small strains, indicating that the FF-RC test can provide a reliable estimation of Emax, if the effects of loading frequency are considered. In the proposed method, Emax obtained from the FF-RC test can be combined with the effect of loading frequency and the modulus reduction curve determined by the data base of the RC and TS tests for the compacted subgrade soils of various plasticity indexes. Moduli obtained from the proposed method overlapped nicely with MR values determined by standard MR testing, showing the capability of the proposed method being used in determining MR values, provided that the effects of loading frequency and modulus reduction curve are considered.
Application of Geotechnical Centrifuge Testing To Evaluate Unconventional Highway Materials
Authors: De Anirban , Zimmie Thomas F.
Published: April 2007

The principles involved in using a geotechnical centrifuge to study long-term consolidation and seepage characteristics of an unconventional geotechnical material are described. Results are presented from long-term leaching tests that were performed in a 100 g-ton centrifuge to simulate 30 years of water flow through sludge material from a paper mill. The consolidation and permeability characteristics of these samples were tested, and the leachate flowing through the materials was collected and tested for chemical composition. Two sludges were tested and their behaviors were compared with those of a conventional clay material, also tested in a similar manner. The sludge material was found to be highly compressible and showed large reductions in permeability with time. Chemical analyses performed on the leachate collected after seepage through the sludge material indicated that the sludge material was suitable for the intended use. This same method of testing can also be used in testing new highway materials. The approach can provide information about the geotechnical and hydrological properties of the material and help identify the environmental characteristics by providing leachate for chemical analyses.
Shear and Deformation Characteristics of Municipal Waste Combustor Bottom Ash for Highway Applications
Authors: Pandeline Deborah A. , Cosentino Paul J. , Kalajian Edward H. , Chavez Mario F.
Published: April 2007

Municipal waste combustor (MWC) bottom ash from mass-burn (MB) and refuse-derived-fuel (RDF) facilities was evaluated for potential use as highway fill material. MWC bottom ash exhibits acceptable shear and deformation characteristics for many highway applications. RDF ash contains a lower metals percentage than MB ash. The specific gravity of both ashes was found to be a function of metals content. Moisturedensity relationships and unconfined compressive strengths were found to be a function of compaction energy and moisture content. Allowing compacted ash to age increased its unconfined compressive strength. Stress-strain characteristics of both ashes are similar to those of sands. Cohesion exists possibly because of pozzolonic reactions in the bottom ash. The angle of internal friction increased with compacted density. Elastic moduli are a function of density and confining pressure. RDF ash was found to be twice as stiff as MB ash. California bearing ratio results greater than 100 indicated that MB ash could be utilized as road base, and values between 25 and 95 indicated that RDF would be acceptable for use in subgrade and subbase. Bearing ratio results were highly dependent on moisture conditions. Both ashes exhibit little to no swell and should not cause field problems during saturation.
Pedestrian Fatalities on Interstate Highways: Characteristics and Countermeasures
Authors: Johnson Christopher D.
Published: April 2007

Pedestrian fatalities on Interstate highways account for more than 10 percent of all pedestrian fatalities in the United States. This study identifies crash types and factors contributing to fatal pedestrian crashes on Interstate highways and surveys countermeasures that address the problem. A 3-year sample of 394 police accident reports detailing fatal Interstate pedestrian crashes in Texas, Missouri, and North Carolina was collected. Data from the reports, including light conditions, pedestrian and driver characteristics, and pedestrian activity at the time of the crash were compiled for analysis. Factors contributing to the crashes included pedestrian and driver alcohol use and poor light conditions. Eighty percent of the crashes occurred after dark. Forty percent of the crashes involved pedestrians entering or crossing the highway. Thirty-two percent involved an unintended pedestrian—someone who had a broken-down vehicle, had been involved in a previous crash, or was walking or standing on the shoulder, but who did not set out to enter the Interstate on foot. Twenty percent of the crashes involved a hit-and-run driver. Common counter-measures currently in place include emergency call stations, roving roadside assistance vehicles, and emergency cellular telephone numbers to report disabled vehicles. About half of the respondents to a national survey of state highway representatives cited the need for additional countermeasures, such as educational programs and access barriers. Further research is necessary to find out which countermeasures are most effective. State rankings based on the number of Interstate pedestrian fatalities per Interstate vehicle kilometer traveled reveal Texas, New Mexico, Delaware, Nevada, and Missouri as the states with the worst relative rates. Motorists should avoid stopping on Interstate highways if at all possible, take measures to make themselves visible, and shield themselves from traffic when stopping is unavoidable.
Survey of North American Bicycle Commuters: Design and Aggregate Results
Authors: Moritz William E.
Published: April 2007

Although interest exists in promoting bicycle commuting to help meet air quality and commuter-trip reduction goals, there are virtually no data on bicycle commuters. A comprehensive survey, distributed over the Internet and by mail, of such commuters has been conducted, with 2,374 responses received from all regions of the United States and Canada. Information was gathered in seven categories: about your commuting; about the facilities you use; about your bike; about your motivation; about safety/accidents; about your health; and about you and your household. Comments were also collected. Although the average bicycle commuter is a 39-year-old male professional with a household income in excess of $45,000 per year who rides 10.6 months per year, nearly one in five respondents was female. Average annual bicycle-commuting distance was 3100 km, although these same cyclists rode an average of 5500 km for all trip purposes. Just under 10 percent reported having an accident in the previous 12 months. A relative danger index ( RDI) for various bicycle facilities that relates accident frequency to distance traveled on each facility type is presented. A higher number indicates greater danger. Based on the data in this sample, major streets without bicycle facilities have an RDI of 1.26; minor streets, an RDI of 1.04; streets with bike lanes or bike routes, an RDI of 0.50; bike paths, an RDI of 0.67 and sidewalks, an RDI of 5.30. With the 7.3 million km of bicycle commuting reported, an annual accident rate of 37.1 per million km was calculated. The results of this survey should be of interest to policy makers, businesses, and advocates interested in promoting the use of the bicycle for transportation purposes.
Analysis of Bicycle Commuter Routes Using Geographic Information Systems: Implications for Bicycle Planning
Authors: Aultman-Hall Lisa , Hall Fred L. , Baetz Brian B.
Published: April 2007

A geographic information system (GIS) network data base is used to determine the characteristics of 397 routes used by commuter cyclists in Guelph, Ontario, Canada, and to compare them with the shortest-path routes between each origin and destination. The analysis of route data provides useful insight for understanding factors affecting travel behavior and in this case provides quantitative support for many existing assumptions regarding commuter cyclist behavior. Most commuters divert very little from their minimum path (0.4 km on average) and are found to use major road routes. The cyclists tend to avoid grades, grade-separated railway crossings, and high-activity areas, but not road (as opposed to pedestrian) bridges. Cyclists use traffic signals especially for crossing major roadways and turning. The high-quality direct off-road paths are used only infrequently by the commuter cyclists and the lower quality ones even less. The results of this analysis suggest that efforts to accommodate current commuter cyclists should be focused on improving cycling conditions on the road network, such as providing wider curb lanes, or actuated traffic signal detectors that recognize the presence of bicycles. If potential new commuters are similar to the minority of current commuter cyclists in this study who use mainly local roads, paths or trails, then projects that make the network of local roads and pathways more connective and direct may encourage a higher level of commuter cycling.
Field Analysis of Operation and Design of Single-Point Urban Interchanges
Authors: Dorothy Paul W. , Maleck Thomas L. , Aylsworth-Bonzelet Laura
Published: April 2007

Michigan is considering the much needed rehabilitation and upgrading of many of the freeway interchanges located in urban environments. The single-point urban interchange (SPUI) has been suggested as an alternative to designs presently used, in particular the Michigan urban diamond interchange. To evaluate the appropriateness of the SPUI, a literature review was conducted, along with an e-mail and telephone survey of other state departments of transportation experience with the SPUI. Then, a field review of selected SPUIs was conducted to collect observations about the geometric design, signal operation, pedestrian control, pavement markings, and land use and landscaping of SPUIs. A SPUI with the crossroad going over the freeway was found to be a preferred design. In addition, the smaller designs were observed to function the best. However, the use of continuous frontage roads is believed to counteract the advantages of the design. Currently, progression of the crossroad is not a problem, although the impact of the SPUI on intersections downstream must be considered. Additionally, the need for pavement markings in large SPUIs is paramount. However, these pavement markings overlap and cause driver confusion. Several other observations were also made: most SPUIs reviewed were not able to adequately provide for pedestrians, controlled access near the SPUI is suggested, and landscaping dramatically increases the aesthetics of the interchange. The SPUI is a good design and has a place. However, some of the newer and enhanced designs with the resulting increase in size may be counterproductive.
Guidelines for Offsetting Opposing Left-Turn Lanes on Divided Roadways
Authors: Tarawneh Mohammed S. , McCoy Patrick T.
Published: April 2007

Offsetting opposing left-turn lanes at intersections has been found to improve the driving performance of older drivers. Previously recommended guidelines for offsetting opposing left-turn lanes were based on observations of left-turning vehicles for only one offset condition. The guidelines developed in the present research are based on left-turning vehicle positioning and maneuver-time data collected at intersections with left-turn lane offsets of from –4.3 to 1.8 m (–14 to 6 ft). A 1.2-m (4-ft) offset was found to provide unrestricted sight distances in most situations.
Transportation Technology Transfer Between the People’s Republic of China and the United States
Authors: Yang Zhao-Sheng
Published: April 2007

The private ownership of motor vehicles in China has increased from less than half a million in 1970 to 9 million in 1994. It is expected to reach 19.6 million in 2000, 80 million in 2010, and 354 million in 2020. China needs a good highway system to meet its economic growth. In 1991, the Ministry of Communications addressed this need by calling on all the provinces to draft a 30-year highway transportation network plan. To build the necessary new highways and expressways, China needs access to modern transportation science and technology. The United States has a good highway system and advanced science and technology, which China would like to transfer and use. A technology transfer center (often called a T2 center) would be the best mechanism to accomplish this. The ways in which technology transfer can occur between the United States and China are discussed. A proposal to establish six T2 centers throughout the People’s Republic of China is described. It is argued that this would be beneficial for both China and the United States, facilitating more technical cooperation between the two countries and increasing the export of U.S. technology and road-building equipment to the growing Chinese markets.
Use of Driver and Criminal Records for Judges and Prosecutors
Authors: DeLucia Barbara Hilger , Scopatz Robert A. , Edwards Mark L.
Published: April 2007

A model court records system designed to meet the needs of judges and prosecutors in adjudicating traffic offenses was compared with existing records systems in state and local jurisdictions throughout the United States. The model system incorporates data requirements at each of four phases (enforcement, prosecution, adjudication, and records management) as well as functional descriptions of how the system should operate to provide information in a usable manner to judges and prosecutors. Comparisons of the model system and existing systems were solicited from enforcement agencies, prosecutors’ offices, judges and court clerks, and managers of court and driver history records systems in every state. Results indicate that the majority of the data requirements of judges and prosecutors currently are met through manual systems that fail to provide easy, timely access to information. Further, the results indicate that agencies that generate or store the data have an incomplete understanding of judges’ and prosecutors’ needs. A plan is provided that outlines a sequence of actions that can be taken at the national level to improve court records systems’ ability to meet the information needs of judges and prosecutors adjudicating traffic cases.
Hierarchical Tree-Based Versus Ordinary Least Squares Linear Regression Models: Theory and Example Applied to Trip Generation
Authors: Washington Simon , Wolf Jean
Published: April 2007

Given the continual need for transportation professionals to forecast trends and the increasing availability of sophisticated and improved modeling methods in new and improved software packages, new methods should be explored to determine whether they can replace or supplement more classical statistical methods. One commonly used classical statistical technique for relating a continuous dependent variable with one or more independent variables (continuous or discrete) is ordinary least squares (OLS) regression. This method is routinely applied in transportation to forecast such things as energy use, trip attractions, trip productions, automobile emissions, and growth in vehicle miles traveled (VMT). Despite its widespread use and tremendous utility, however, OLS regression has limitations. It does not deal well with multicollinear independent variables, interactions between independent variables must be specified, the functional relationship between dependent and independent variables must be known (or approximated well), it cannot handle missing data well, and it does not treat satisfactorily discrete variables with more than two levels. Hierarchical tree-based regression (HTBR) may provide a better model for forecasting continuous response variables in transportation applications when the shortcomings of OLS regression are present. The theory of HTBR methods is presented. Then, an example using trip generation data is used to illustrate the types of models that result from OLS regression and HTBR methods. Finally, the limitations of HTBR are presented.
Innovative and Rapidly Installed Mechanically Stabilized Earth System for Highway Embankments: Model Studies
Authors: Mahmud Mahadzer B. , Zimmie Thomas F.
Published: April 2007

Geotechnical centrifuge models were used to study the feasibility of a new installation technique for stabilization of marginally stable slopes. Reinforcing elements were driven horizontally and directly into the existing slope, similar to the installation of vertical wick drains, thus requiring little or no excavation. This results in a rapid and economical solution for slope stabilization. The reinforcing elements used in the model simulated the high-strength nonwoven geotextile strips, which will be used in actual slope remediation work. The geotextile strips perform the dual functions of drainage and reinforcement. Miniature drivers and various instrumentation were used in the models. The results from the model tests provide useful information for the design of the spacing and placement of the reinforcing strips and the design and construction of the actual prototype driving equipment. The proposed construction technique could be beneficial and economical in slope stabilization of highway embankments and related slope work in highway construction.
Physical Modeling of Foundations for Northumberland Strait Crossing
Authors: Kosar Keith , Phillips Ryan , Becker Dennis , Turnham Jim
Published: April 2007

The 13-km-long Northumberland Strait Crossing will become the longest continuous marine span bridge in Canada. The marine and navigational spans of the bridge will be supported by 44 precast concrete piers founded on bedrock using ring-shaped footings in a maximum water depth of 35 to 40 m. Bedrock stratigraphy ranges from massive strong sandstone to a variable sequence of thinly bedded weak mudstones and siltstones. Foundation conditions vary significantly from pier to pier and in several cases can vary through the vertical and lateral extent of a particular foundation. In addition to the complex foundation conditions, the large horizontal environmental loadings on each pier must be considered in the geotechnical analyses. Reduced-scale physical model tests of selected marine piers on a centrifuge investigated potential mechanisms of failure and examined how these mechanisms varied with loading and foundation conditions. The results of the experimental program were used in conjunction with analytical results to enhance the fundamental understanding of the geotechnical aspects of foundation design and have led to an improved design methodology.
Modeling Time-Dependent Behavior of Pavement Drainage Using Linear System Identification and Neural Network Techniques
Authors: Rahman Motiar , Sudharsanan Subramania , Muraleetharan Kanthasamy K. , Zaman Musharraf M.
Published: April 2007

Inadequate drainage continues to be a major cause of problems associated with long-term structural integrity and performance of roadway pavements. To reduce the impact of these drainage-related problems, it is customary to provide measures to prevent water from entering the pavement system and to enhance the drainage capability of the pavement base to rapidly move the water that inevitably finds its way into the pavement system. The performance of different drainage systems in the field is not clearly known. Oklahoma Department of Transportation (ODOT) has been collecting rainfall and outflow information at sites with edge drains since 1992. The sites have different types of surfaces, base courses, and edge drains. The data collected by ODOT at these sites were used to develop two types of numerical models to predict the outflow–time history using rainfall–time history as the input. One model is based on linear system identification theory, and the other model is based on an artificial neural network. The development of these models is presented, and the model predictions are compared with the measured field data. The efficiency of the drainage systems, including the AASHTO criteria for the drainage time, at these sites is compared by using the numerical models and synthetic, but the same, rainfall events.
Estimation of Vertical Capacity of Single Piles Considering Uncertainty
Authors: Juang C. H. , Elton David J. , Lin Pin-Sien
Published: April 2007

The uncertainty in soil parameters and the models that are used for predicting the vertical load-carrying capacity of single piles are addressed. The uncertainty is expressed in terms of fuzzy numbers and incorporated explicitly in the solution process. A new approach is developed by which the model uncertainty, the uncertainty associated with different empirical methods for predicting pile capacity, is reduced through the use of an aggregation technique. The weights used in the aggregation are determined on the basis of sensitivity analysis of each pile-capacity prediction model. Case studies are presented to illustrate the new approach and the developed computer program. The comparison between the predicted and the measured ultimate pile capacity indicates that the predicting capability of the developed computer program is very good.
Effects of Aggregate Degradation on Air Voids of Structural Asphalt Mixture in Florida
Authors: Page Gale C. , Musselman James A. , Romano David C.
Published: April 2007

In an effort to further improve the rut resistance of asphalt pavements in Florida, the Florida Department of Transportation implemented specifications requiring that the production of asphalt mixes be stopped when the air-void content falls below a critical level. To address the problem of low air voids and rutting in north Florida, a proposal was made to reduce the maximum amount of material allowed to pass the 75-μm sieve (P-75μm) at design for asphalt mixtures containing north Florida limestone aggregates. A field study was then undertaken to determine whether this proposal would adequately resolve the problem of low air voids during production due to high P-75μm. The purpose of the study was to determine the amount of degradation to a typical north Florida limestone material and the subsequent effects that degradation has on air voids. The results indicate that although the north Florida limestone aggregates used in this study did degrade significantly, the asphalt contractor was, in general, able to control the amount of P-75μm material in the mix by wasting the baghouse fines. During production, the air voids were low on a number of samples. The source of these low air voids appears to be related to a combination of a high asphalt content in the mix as well as a high P-75μm content. The findings do not support the proposal to reduce the P-75μm content at design at this time. An unexpected finding of this study was that the bulk specific gravities of the commercial aggregate products were less than expected. The impact of this finding is that the voids in the mineral aggregate (VMA) of the mix at design would not meet minimum specification requirements. Although this could make it difficult for an asphalt mixture to have adequate air voids during production, the primary impact of a low VMA is that the pavement would have poor durability and would potentially become brittle and crack prematurely.
Evaluation of Type C Fly Ash in Cold In-Place Recycling
Authors: Cross Stephen A. , Young David A.
Published: April 2007

The Kansas Department of Transportation has developed an innovative method of rehabilitating low-volume pavements using cold in-place recycling (CIR) and Type C fly ash. Previous field test sections have indicated that fly ash improves constructability and moisture sensitivity. However, the same field test sections have exhibited increased cracking with increased fly ash content and a drop in pavement modulus with time. A laboratory study was undertaken to evaluate the effect of fly ash content on CIR. Reclaimed asphalt pavement (RAP) was mixed with 3, 7, 11, and 15 percent Type C fly ash and the fatigue life, durability, freeze-thaw resistance, and thermal cracking potential of laboratory-compacted samples were evaluated. RAP mixed with asphalt emulsion and asphalt emulsion with hydrated lime were evaluated as well. The results indicated that 7 to 11 percent Type C fly ash provided optimal laboratory freeze-thaw and moisture sensitivity performance. Increasing the fly ash content resulted in a brittle fatigue behavior as well as an increased thermal fracture temperature. AASHTO T283 is recommended for selecting the optimum fly ash content.
Managing Construction Safety and Health: Experience of New York State Department of Transportation
Authors: Andrew Laurel B. , Bryden James E.
Published: April 2007

To construct and maintain transportation facilities in a cost-effective manner, management of a large state highway construction program must address health and safety risks to highway users and workers. Successful management of construction-site risks requires defined objectives, strong agency commitment, adherence to fundamental safety and health principles, and clearly defined procedures. Health and safety risks and associated costs inherent in highway construction are examined, and the New York State Department of Transportation’s construction safety and health program is described. These efforts are offered as a model to other large transportation agencies that may be considering adopting such an approach. Key elements in this program include clear-cut contractual requirements, adequate program staffing, an accident reporting system to identify critical concerns and track progress, formalized procedural manuals to provide operational guidance, quality assurance/ quality control procedures, and compliance measures and outreach efforts to the construction industry and other agencies. Problem areas have been identified where greater program focus can obtain results in terms of reduced losses. Initiatives have been directed toward falls, utility contacts, demolition safety, and work-zone traffic control.
Simple Model of Forward Visibility for Snowplow Operators Through Snow and Fog at Night
Authors: Bullough John , Rea Mark S.
Published: April 2007

Backscattered light reflected from falling snow, rain, and fog impairs visibility and can hinder performance of snowplow operators. New York State Department of Transportation snowplow operators cite backscattered glare as an important problem, and many drivers use their own “solutions” to counteract it. A literature review yielded two important conclusions: backscattered light from a lamp in fog and falling snow is reduced, and visibility is improved ( a) as the lamp is moved away from the operator’s line of sight and ( b) with a narrow-beam lamp. Field tests of lighting configurations during inclement weather were conducted to determine the effects of beam type and displacement from the operator’s line of sight on visibility, glare, and satisfaction. On the basis of these data and the literature, a simple mathematical model was developed that predicts the forward-visibility ratings of snowplow operators. This model can be used to guide specifiers in selecting light sources and mounting locations for snowplow operations.
Survey of Snowplow Operators About Forward Lighting and Visibility During Nighttime Operations
Authors: Eklund Neil H. , Rea Mark S. , Bullough John
Published: April 2007

Snowplow operators are a valuable source of information about improving forward visibility at night in snow, fog, or rain. These men and women have a heightened awareness of forward lighting and associated visibility issues and will try various techniques to improve their ability to see. Consequently, these operators have first-hand empirical knowledge about the factors that affect forward visibility. The purpose of this study was to survey a large number of active snowplow operators to determine what issues they believed were most important for forward visibility in perturbed atmospheric conditions at night. A survey was distributed to 300 New York State Department of Transportation snowplow operators throughout New York. Respondents reported that the most effective solution was to place lamps with narrow-beam distributions, what they generally term “spot lamps,” away from the driver’s line of sight. They also reveal some apparently sound, practical observations that also should be considered for improving visibility, especially windscreen and wiper-blade designs. Of special interest too, some believe that the spectral composition of the forward lighting system should be considered. These observations led the authors to speculate on the reasons why operators were so supportive of yellow or amber lights. The results presented here are largely consistent with a similar survey performed by the Minnesota Department of Transportation.
Telerobotics for Infrastructure Maintenance: Safe Raised Pavement-Marker Application
Authors: Rihani Rami A. , Bernold Leonhard E.
Published: April 2007

Application of raised pavement markers is a simple but dangerous operation. In a common scenario, an operator sits in a specially designed bay of a slowly traveling truck and manually applies bitumen with a hand-controlled dispenser and places a marker on the bitumen while traffic is passing only a few feet away. A telerobotic raised pavement-marker applicator that uses the capabilities of advanced technologies to automate the tasks of selection of markers, placement of markers, and dispensing of bitumen is described. Most importantly, the operator is moved from the truck bay into the passenger side seat and observes and controls the entire process with a video interface system. A PC-based microcomputer provided the platform that allowed efficient integration of the pneumatic and hydraulic actuators necessary to place markers remotely.
New, Simple, Rapid, and Precise Method for Trace Analysis of Nickel and Vanadium in Petroleum Asphalt
Authors: Bishara S. W.
Published: April 2007

A wet-digestion method for trace analysis of nickel and vanadium in asphalt is presented. A weighed sample is mixed with nitric acid and hydrogen peroxide and then digested for slightly over 3 hr. Oxides of Ni and V, formed during digestion, dissolve in the acidic medium. Upon cooling, metal oxides insoluble in the acidic medium (e.g., those of Al, Fe, Mo, Cu, and Cr) form a yellowish brown precipitate that coexists with the carbon left after asphalt decomposition. The soluble Ni and V ions are separated by filtration. Ni and V concentrations are measured by inductively coupled plasma emission spectrometry, a selective, sensitive, and rapid analytical tool. Complete analysis (digestion, filtration, and measurement) consumes 4 hr and thus provides a fast measure of asphalt aging propensity; alternative methods require 3 days. Ni + V content correlates very strongly with the molecular weight of SEC-I-1, the first subfraction of the first fraction obtained from size exclusion chromatography. The aging index ( G*sinδ, PAV/ G*sinδ, Tank) correlates very strongly with Ni content. The method also serves for asphalt characterization. The proposed method has good repeatability as measured by the standard deviation and the coefficient of variation of triplicate analyses of each of the eight core asphalts. Results of analysis agree with those reported from earlier studies, reflecting satisfactory accuracy. The procedure, without modification, can be used to determine the concentration of other metals (e.g., B, Ca, K, Mg, Na, Si, Y, and Zn) known to exist in asphalt and, on digestion, to form oxides soluble in the acidic medium.
Conformity: Long-Term Prognoses for Selected Ozone Nonattainment Areas in California
Authors: Thompson Douglas , Baker Michael , Wade Dennis
Published: April 2007

The Clean Air Act requires that long-range transportation plans conform to emissions budgets established for nearer-term attainment years in state implementation plans (SIPs). This poses the question of whether travel growth in the intervening period may overwhelm the benefits of fleet turnover and adopted control strategies, with adverse implications for air quality and for conformity. Emissions trends are examined for three planning areas in California that are nonattainment for ozone. Forecasted emissions of ozone precursors for attainment years are compared with projected emissions for 2020. The latest model for estimation of on-road motor vehicle emissions in California is employed to estimate emissions, augmented by estimated effects of additional control strategies from the 1994 California ozone SIP. Alternative higher-growth travel forecasts for two areas, developed in consultation with regional transportation agency modeling staffs, are then applied to test the sensitivity of emissions to various travel growth scenarios. Ozone precursor emissions are found to remain within attainment year baseline levels for each growth scenario. Oxides of nitrogen emissions approach attainment year levels in one area, due to high projected growth in heavy-duty vehicle travel. Demonstrations of conformity to the ozone SIP for transportation planning horizon years are significantly aided by California’s adopted and planned fuels and motor vehicle emissions control programs.
Development of Comprehensive Modal Emissions Model: Operating Under Hot-Stabilized Conditions
Authors: An Feng , Barth Matthew , Norbeck Joseph , Ross Marc
Published: April 2007

A comprehensive modal emission model for light-duty cars and trucks is being developed. More than 300 real-world vehicles are being recruited for in-house dynamometer testing under as-is conditions to provide the foundation for the model. The model is designed to predict second-by-second tailpipe emissions under a variety of driving conditions. The vehicles can be modeled as individual vehicles with properly functioning, deteriorated, or malfunctioning emission control conditions, or as composite vehicles representing different vehicle technology categories. The model is based on a simple parameterized physical approach and consists of six modules that predict engine power, engine speed, air/fuel ratio, fuel use, engine-out emissions, and catalyst pass fraction. When developing the model, four important vehicle operating conditions are considered: cold and warm starts; normal, stoichiometric operation; high-power enrichment; and lean-burn operation. The model concept and the expected input/output requirements of the model are discussed. The general structure of the model also is presented, focusing on emissions for vehicles operating under hot-stabilized conditions. Preliminary results of the model are given, and comparisons are made between the modeled and measurement results for 17 sample vehicles. Preliminary results show good agreement.
Real-Time Multiple-Objective Path Search for In-Vehicle Route Guidance Systems
Authors: Blue Victor J. , Adler Jeffrey L. , List George F.
Published: April 2007

The application of multiple-objective route choice for in-vehicle route guidance systems is discussed. A bi-objective path search algorithm is presented and its use demonstrated. A concept of trip quality is introduced that is composed of two objectives: minimizing travel time and minimizing trip complexity. Trade-offs between the objectives are examined. The concept is illustrated through simulation modeling on a test network. The experiments serve to demonstrate the effects on the trip performance of pretrip routing and dynamic routing strategies under full market penetration (an idealized condition) and under varying levels of demand and trade-offs between time and complexity.
Automatic Vehicle Identification Technology Applications to Toll Collection Services
Authors: Lu Jian John , Rechtorik Michael J. , Yang Shiyu
Published: April 2007

Intelligent transportation systems technologies are being developed and applied through transportation systems in the United States. An example of this type of innovation can be seen on toll roads where a driver is required to deposit a toll in order to drive on a toll road. To automatically process toll services, automatic vehicle identification (AVI) technologies should be developed and implemented. A summary is presented of a study that focused on the performance analysis of three types of AVI technologies that could be used for toll collection applications on the Crosstown Expressway and the Veterans Expressway in Hillsborough County, Florida. The three AVI technology types were optical/laser scanner, radio frequency, and inductive loop. The study aimed at analyzing the total average delay and AVI market share due to the usage of AVI technologies. Delay performance and market share resulting from the application of each AVI technology type were used to compare the effects of different AVI technology types. The analysis was based on computer simulation using an AVI lane choice model (demand model) and a delay model (performance model) with the data collected from the two toll roads in Hillsborough County. From the simulation results, a cost-benefit analysis was performed to evaluate the impacts of AVI technologies on the ratio of benefit over cost. Results of the cost-benefit analysis can be used to determine the optimal configuration of AVI lanes and manual lanes. A procedure is provided that can be used for planning and designing AVI technologies used in toll service.
Promoting Advanced Traveler Information Systems Among Cellular and Land-Line Phone Users: SmarTraveler Experience in Boston
Authors: Englisher Larry S. , Bregman Susan , Pepin Stephen , Wilson Alicia Powell
Published: April 2007

In 1993 the SmarTraveler advanced traveler information system (ATIS) was introduced to travelers in the greater Boston area as part of an operational test jointly funded by FHWA and the Massachusetts Executive Office of Transportation and Construction. The service offers real-time, route-specific travel information by phone for major highways and public transit. During the 3-year test period from January 1993 to January 1996, service usage grew to nearly 60,000 calls per week, made by an average of more than 20,000 users. To achieve this growth, SmarTraveler was marketed to both cellular and land-line phone users using a variety of strategies over the course of the test. Evaluation and monitoring studies were commissioned to examine the degree to which users responded to SmarTraveler and the marketing program. The evaluation included extensive surveys of users and nonusers as well as tracking of calls and call frequency. The findings of the independent evaluation team on the success of various promotional efforts associated with the SmarTraveler operational test are presented. Overall, the marketing program aimed at the broad target market during the first 2 years appears to have been only partly successful in increasing the public’s level of awareness of SmarTraveler, in convincing its target market of SmarTraveler’s superiority to radio and TV travel reports, and in inducing trials. As a result of the second-year evaluation, changes were made to marketing and pricing during the third year of operation to target cellular telephone users. Further surveys were conducted to examine cellular telephone user response to these changes. SmarTraveler experienced a large increase in calls and users in the third year, especially in the cellular telephone market. Among the survey findings was that this market is quite price sensitive.
Framework for Developing a Regional System Architecture for Intelligent Transportation Systems
Authors: Rodríguez Daniel A. , Sussman Joseph M.
Published: April 2007

Defining an architecture for intelligent transportation systems (ITS) at the regional level, where most ITS deployment occurs, is constrained by jurisdictional, institutional, financial, political, and regulatory factors. These constraints provide opportunities for the architecture that go beyond its traditional role as a guiding tool for technology implementation to a newer role of reorienting institutional relationships. An architecture development approach is proposed that considers regional transportation needs and characteristics so as to increase the benefits from implementing ITS locally. It also provides a new way of thinking about the importance of the National ITS System Architecture in the context of regional ITS deployments. The development approach was tested by considering how regional architectures in New York, Boston, and Houston address regional needs. Findings and implications of the regional ITS architectures of the case study areas are presented.
Machine Learning in Updating Predictive Models of Planning and Scheduling Transportation Projects
Authors: Zhang Liye , Kim Roddis W. M.
Published: April 2007

A method combining machine learning and regression analysis to automatically and intelligently update predictive models used in the Kansas Department of Transportation’s (KDOT’s) internal management system is presented. The predictive models used by KDOT consist of planning factors (mathematical functions) and base quantities (constants). The duration of a functional unit (defined as a subactivity) is determined by the product of a planning factor and its base quantity. The availability of a large data base on projects executed over the past decade provided the opportunity to develop an automated process updating predictive models based on extracting information from historical data through machine learning. To perform the entire task of updating the predictive models, the learning process consists of three stages. The first stage derives the numerical relationship between the duration of a functional unit and the project attributes recorded in the data base. The second stage finds the functional units with similar behavior—that is, identifies functional units that can be described by the same shared planning factor scaled in terms of their own base quantities. The third stage generates new planning factors and base quantities. A system called PFactor built on the basis of the three-stage learning process shows good performance in updating KDOT’s predictive models.
Critical Review of Expert System Validation in Transportation
Authors: Spring Gary S.
Published: April 2007

Expert system validation—that is, testing systems to ascertain whether they achieve acceptable performance levels—has with few exceptions been ad hoc, informal, and of dubious value. Very few efforts have been made in this regard in the transportation area. A discussion of the major issues involved in validating expert systems is provided, as is a review of the work that has been done in this area. The review includes a definition of validation within the context of the overall evaluation process, descriptions and critiques of several approaches to validation, and descriptions of guidelines that have been developed for this purpose.
Technical and Economic Viability of Automated Highway Systems: Preliminary Analysis
Authors: del Castillo José M. , Lovell David J. , Daganzo Carlos F.
Published: April 2007

Technical and economic investigations of automated highway systems (AHS) are addressed. It has generally been accepted that such systems show potential to alleviate urban traffic congestion, so most of the AHS research has been focused instead on technical design and implementation issues. It is demonstrated that, despite making a number of assumptions that are favorable to AHS, the actual viable implementation opportunities for AHS are scarce, and that most existing congested urban areas can be disqualified on the basis of at least one criterion developed herein. Technical investigations are described, including realistic estimates of AHS capacity, interfacing with the local street system, and storage issues. Discussion then turns to identifying criteria to help establish the types of urban areas that might be likely candidates for AHS technology. These criteria relate to the nature of the surrounding infrastructure and the traffic demands placed on it, as well as the economic realities of AHS implementation. Certain “boutique” locations where AHS might be beneficial are identified, but it is uncertain whether enough benefit could be realized to make AHS palatable to the general public. AHS technology is not dismissed, but the simple analyses contained herein should warn that much more research into these areas is required before fully informed decision making about the future of AHS technologies can be accomplished.
Let Me Shingle Your Roadway
Authors: Marks Vernon J. , Petermeier Gerald
Published: April 2007

Approximately 10 million tons (9 071 850 Mg) of waste bituminous roofing are torn off annually in the United States. This volume is a major factor in the rapid filling of landfills. In 1995, Benton County, Iowa, initiated a program to cost-effectively recycle torn-off waste shingles. Nine hundred tons of waste shingles were ground with a Maxigrind. A magnetic roller on the discharge conveyor removed most of the nails. Five hundred tons of the ground waste shingles were blade mixed into 0.6 km (0.4 mi) of a crushed-stone granular surfaced Benton County rural secondary roadway. A magnet attached to the motor grader removed another 0.33 kg (0.75 lb) of nails during the spreading and mixing operation on the 0.6 km (0.4 mi) section of roadway. The bitumen of the waste shingles was very effective in providing a dust-free granular surfaced roadway. It remains relatively dust free 1 year after treatment.