bluuebunny/crossref_metadata_2025 huggingface dataset:
Prioritizing Major Transportation Improvement Projects: Comparison of Evaluation Criteria
Authors: Speicher Dan , Schwartz Marcy , Mar Tim
Published: April 2007

The lack of funding to meet identified transportation needs, the controversial nature of transportation investment decisions, and the increasing demand by stakeholders to be involved in transportation programming have driven the need to develop effective evaluation criteria within decision processes. The Northeast Area Transportation Study (NEATS), performed by the city of Sacramento, California, incorporated a process in which stakeholders, representing a broad cross section of interests, developed quantitative evaluation criteria to prioritize projects for design and construction. In addition, a set of existing citywide quantitative evaluation criteria was used to prioritize the NEATS projects. Despite the significant differences in the two sets of criteria, the results of the two rankings were very similar. After comparing the criteria, it was concluded both are appropriate for their intended uses. Observations are offered for developing and applying evaluation criteria.
Microsimulation Model of Activity-Travel Patterns and Traffic Flows: Specification, Validation Tests, and Monte Carlo Error
Authors: Veldhuisen Jan , Timmermans Harry , Kapoen Loek
Published: April 2007

Discussed are results pertaining to the application of the Ramblas microsimulation model to predict activity-travel patterns and traffic flows. The validity of the model, which is deliberately based on nationally available time use data, is tested using different national, provincial, and regional data sets. In addition, an analysis of Monte Carlo error is performed. The results of the analyses indicate that the microsimulation model is capable of successfully predicting regional aggregate activity patterns on the basis of a simple set of principles and that the influence of Monte Carlo error on the aggregate results is negligible.
ALBATROSS: Multiagent, Rule-Based Model of Activity Pattern Decisions
Authors: Arentze Theo , Hofman Frank , van Mourik Henk , Timmermans Harry
Published: April 2007

The development of ALBATROSS: A Learning-Based, Transportation-Oriented Simulation System is summarized. This activity-based model of activity-travel behavior is derived from theories of choice heuristics that consumers apply when making decisions in complex environments. The model, one of the most comprehensive of its kind, predicts which activities are conducted when, where, for how long, and with whom, and the transport mode involved. In addition, various logical, temporal, spatial, spatial-temporal, and institutional constraints are incorporated in the model. The conceptual underpinnings of the model, its architecture, the functionality of its key agents, data collection, and model performance are discussed.
Car Scheduling: What’s the Point?
Authors: Lang A. Scheffer , Roberts Paul O. , Sammon John P.
Published: April 2007

During the past 35 years, the major railroad companies and the Association of American Railroads all have invested heavily in the development of computerized car-for-car scheduling systems designed to help keep carload rail traffic moving on schedule. Unfortunately, these systems have not worked as intended, because railroad operations do not really lend themselves to handling cars on an individual basis out in the field. The experience at Consolidated Rail Corporation (Conrail) has borne that out. Beyond that, rail markets have shifted steadily to the large, annual use-rate customers that move heavy carload shipments, and those heavy carload markets are less sensitive to transit-time unreliability than the small carload markets that were more typical in the early postwar era. Shipper cost models developed at Transmode and Science Applications International Corporation have been used to analyze the traffic moving in a number of typical carload markets on Conrail during 1998. That analysis shows why unreliable service, if planned for by shippers and receivers, will not unduly increase “nontransport logistics costs.” Thus, it can be concluded from both experience and theory that the railroads should give up trying to use car scheduling to control carload service quality in real time. They should concentrate, instead, on improving car cycle times and reconfiguring shipper supply chains to take advantage of the lower costs associated with large carload shipments.
Estimating Maintenance-of-Way Costs for U.S. Railroads After Deregulation
Authors: Bereskin C. Gregory
Published: April 2007

The movement of freight on railroads, like most transportation services, is subject to a number of restrictions that make costing of specific traffic a complex process. Among these restrictions are conditions of joint production; economies of scale, scope, and density; and a lack of data on specific expenditures as related to individual freight movements. Yet costing of specific movements is a desirable activity for shippers, railroads, and regulatory bodies. Traditionally, movement costing has involved the use of accounting-based allocative costing models such as the Uniform Rail Costing System developed by the Interstate Commerce Commission for use in regulatory hearings. Most econometric studies have aimed at characterizing the underlying economic nature of costs with little or no application to the cost of providing a specific service, and as such they may be of little use in costing specific traffic. Moving beyond the historic econometric costing models’ application of economic analysis, cost behavior is evaluated for a single sector of railroad activity. The process involves four steps. First, a consistent econometric model of total railroad expenditures is developed by applying a translog function within a multidimensional definition of railroad output. Second, the model is decomposed into individual partial-elasticity estimates relative to each of the several related intermediate output measures within the framework of a total differential of the cost function. Next, specific traffic movements are defined relative to the measures of rail output. Finally, the total differential is applied using several simplifying assumptions to yield estimates of incremental (marginal) costs for the specific traffic definition.
Teenage Drivers’ Understanding of Traffic Control Devices
Authors: Ford Garry L. , Picha Dale L.
Published: April 2007

Teenage drivers are involved in traffic crashes more often than any other driver group, and their fundamental knowledge of traffic control devices and rules of the road is extremely important in safe driving. Only limited data exist, however, on teenage drivers’ understanding of traffic control devices, and little research has been done on determining their comprehension thereof. Research was performed to document teenage drivers’ ability to understand 53 traffic control devices. These traffic control devices included 6 combinations of sign shape and color; 8 regulatory signs; 14 warning signs; 7 school, highway–railroad grade crossing, and construction warning signs; 7 pavement markings; and 11 traffic signals. Research results were then compared with previous comprehension studies to identify specific traffic control devices that the driving public continually misunderstands. In general, the results indicated that surveyed teenage drivers understood the traffic control devices to some degree. Only nine devices were understood by more than 80 percent of the respondents. The devices found problematic to teenage drivers include combinations of sign shape and color, warning-symbol signs, white pavement markings, flashing intersection beacons, and circular red/green arrow left-turn-signal displays. Recommendations include revising states’ drivers handbooks and increasing emphasis in the driver education curriculum to clarify the meaning and intent of problematic traffic control devices.
Drainage of Pavement Base Material: Design and Construction Issues
Authors: Birgisson Bjorn , Roberson Ruth
Published: April 2007

Moisture in pavement base material is a major contributor to pavement failure. Presented is an approach for measuring real-time moisture content in pavement bases during and after rain events. Conceptual models are formed for water flow through pavement sections, and an evaluation of the drainage performance of typical edgedrain configurations is provided. With an extensive sensor network and sophisticated data collection system, the Minnesota Road Research Project (MnROAD) provided an opportunity to study pavement drainage and associated base materials. Understanding the short-term, time-dependent variation in moisture contents allows the systematic evaluation of new and existing edgedrain systems. Two typical drainage configurations constructed at the MnROAD site were chosen for the study. The first section consisted of edgedrains that were introduced into a dense-graded base material to simulate retrofitting of pavements; the second section involved a traditional edgedrain design. Data were collected from an automated weather station and from Time Domain Reflectometry probes. Data collected at the MnROAD site indicated that current edgedrain design and construction techniques may result in pavement drainage systems that are only partially effective in directing flow away from the pavement base.
Finite-Element Analysis of Fatigue Lifetime in Pavements
Authors: Simons Jeffrey W. , Seaman Lynn
Published: April 2007

A computational model was developed to predict fatigue life of pavements under repeated loading and implemented into the three-dimensional finite-element code DYNA3D and the two-dimensional finite-element code NIKE2D. The model simulates the cracking response of flexible or rigid pavements under fatigue. An equation for fatigue crack growth was developed, which grows cracks under single cycles of loading at stresses well below yield. The cracks are incorporated into the material response and result in anisotropic behavior and decreased stiffness for cracked pavements. A procedure for estimating fatigue lifetimes by performing a limited series of calculations was developed. For each calculation, crack growth rate for a single loading cycle is calculated, crack extension is extrapolated to many cycles, and the cracking in the pavement is updated. The next cycle is calculated for the damaged pavement. The procedure is repeated until full damage is reached. Well-controlled laboratory bending fatigue test results generated at the University of California at Berkeley (UCB) for asphalt pavement were used to verify that the model assumptions are appropriate for modeling fatigue damage growth in asphalt pavement. The UCB bending fatigue tests were simulated using the repeat loading algorithm in DYNA3D. Calculations of crack growth for a given load cycle were compared in the NIKE2D and DYNA3D implementations.
Degree and Extent of Wetting Due to Capillary Rise in Soils
Authors: Al-Samahiji Despina , Houston Sandra L. , Houston William N.
Published: April 2007

Increased water content of subgrade soils can lead to degradation of their quality and result in pavement distress. Pavement performance depends on the modulus of the compacted unsaturated subgrade soil as well as that of the underlying natural soil deposits. The soil modulus is a strong function of water content; therefore, changes in water content over the life of the pavement must be understood. In this study, it has been found that for a relatively near-surface groundwater table, significant potential exists for capillary rise into subgrade soils. For fine-grained soils in particular, the height of this capillary rise can be quite substantial. Results from capillary rise column experiments have shown that soils wetted above the groundwater table through capillary rise remain at a degree of saturation averaging about 60 percent. It has also been found that soil suction within this capillary zone must be determined through the use of soil water characteristic curves or direct measurement. The conventional assumption that negative pore water pressures can be estimated by backward extrapolation above the groundwater table of a line of slope γ w is only appropriate in a very thin region above the groundwater table, where soils are wetted to a degree of saturation of 85 percent or more.
Estimation and Application of Dynamic Speed-Density Relations by Using Transfer Function Models
Authors: Tavana Hossein , Mahmassani Hani S.
Published: April 2007

Deployment of intelligent transportation systems (ITS) and availability of a vast amount of online data are opening new opportunities for researchers and practitioners. Many of the previously established methods and applications must be revisited in light of the availability of real-time data. Traffic flow models, particularly speed-density relations, lie at the core of a wide range of applications in almost all areas of traffic engineering and control. In simulation applications and continuum traffic flow models, first-order models use a steady-state or static speed-density relation, whereas higher-order models, with additional terms and parameters, are usually driven by the deviation of speed from this steady-state value. In calibrating speed-density relations using time series data, the existence of serial correlation and other dynamic effects in the data has largely been ignored in previous studies. In this study, transfer function methods (bivariate time series models) are used to specify and estimate dynamic speed-density relations from typical detector data from an advanced traffic management system control center. First the deviation of speed from an equilibrium static relation is estimated, and later the method is extended to directly estimate speed without explicit specification of an equilibrium speed-density relation. The robustness of the model temporally and spatially is investigated. In all cases considered, the method exhibits good performance and robustness in application. Furthermore, since the method is based on the use of online information, it has the capability of being adaptive and adjusting its parameters online.
User Assessment of Intersection Chapter Procedures in Highway Capacity Manual 1997 Update
Authors: May Adolf D. , Skabardonis Alexander , Leiman Lannon
Published: April 2007

Participants from California cities and counties participated in a 1-year local technical assistance program for learning, applying, and evaluating the procedures in the 1997 update to the Highway Capacity Manual (HCM) for the analysis of signalized and unsignalized intersections. Training and technical assistance were provided to the participants on the practical application of the 1997 HCM procedures. Field studies and HCM applications were undertaken at 28 signalized and unsignalized intersections by 25 first-time HCM users in 22 cities and counties. The findings from the project evaluation indicate that the project was highly successful and that similar educational and application experiences should be undertaken for new users of the HCM 2000 in other states. The assessment of the analysis techniques and software will aid the Committee on Highway Capacity and Quality of Service in better understanding the needs and desires of users for future editions of the HCM as well as software developers in better meeting the needs of users.
Development of Driver Population Factors for Capacity Analysis of Signalized Intersections
Authors: Zhou Yanhu , Lu Jian John , Mierzejewski Edward A. , Le Xuewen
Published: April 2007

In the Highway Capacity Manual (HCM), driver population factors are included to adjust for the impact of nonlocal drivers on freeway capacity. There are no such factors in the HCM to account for the possible change of capacity at signalized intersections caused by unfamiliar drivers in the traffic stream. The results obtained from a research study to develop driver population adjustment factors for capacity analysis of signalized intersections are summarized. Detailed procedures for quantifying driver population adjustment factors are presented. The factors were derived on the basis of data collected in Hillsborough, Pinellas, Orange, and Osceola counties in Florida. Study results indicated that nonlocal drivers had a significant impact on the saturation flow rate. When a signalized intersection was identified with a high level of nonlocal drivers, the saturation flow rate as well as the capacity could be reduced by 19 percent, which corresponded to a driver population factor as low as 0.81.
Analysis of Quality Control and Quality Assurance Data for Superpave Mixes
Authors: Parker Frazier , Hossain M. Shabbir , Song Jiansheng
Published: April 2007

Asphalt content, voids, and mat density quality control–quality assurance data were collected for selected Marshall and Superpave mixes during 1997 and for selected Superpave mixes during 1998 and 1999. Analyses indicate that the accuracies and variabilities of asphalt content measurements for Marshall and Superpave mixes are comparable. However, analyses also indicate that the accuracies and variabilities of voids and mat density measurements are not comparable. Moreover, variabilities for Superpave mixes are much higher, and measurements for Superpave mixes are more off target than those for Marshall mixes. The effects of gyratory compactor use, mix design range for an equivalent single-axle load, and maximum aggregate size were investigated to explain the observed differences. Although few consistent trends were observed, all these factors seem to affect the variabilities and accuracies of air voids and mat densities of Superpave mixes.
ILLISIM Program for End-Result Specification Development
Authors: Buttlar William G. , Hausman John J.
Published: April 2007

A new computer simulation program, called ILLISIM, is presented. ILLISIM allows the user to conduct a comprehensive assessment of agency and contractor risks over a wide variety of end-result specification (ERS) parameters. ILLISIM was created to assist the Illinois Department of Transportation (IDOT) in developing an ERS for asphalt pavement construction. The focus is on the use of ILLISIM to explore the possibility of using the nuclear density gauge as a basis for acceptance testing of as-constructed pavement density. Preliminary simulation results from ILLISIM suggest that it may be feasible to use the nuclear gauge for acceptance if stratified random sampling techniques and adequate test replications are used. However, this is true only if test bias is kept under control, for example, if a representative nuclear gauge-to-core correlation is maintained throughout the project. ILLISIM can be used to study the effects of changing device bias, which should be investigated in future work. The results also indicate that a larger sample size will be necessary to increase accuracy and minimize disputes when marginal quality levels are detected.
Rapid Bridge Deck Replacement with Full-Depth Precast Concrete Slabs
Authors: Culmo Michael P.
Published: April 2007

In an attempt to expedite the construction process for deck replacement projects, the Connecticut Department of Transportation investigated a design that would use full-depth precast concrete deck slabs. The idea was to limit the amount of form work and casting of concrete done in the field. There were no standard details or methods for a precast slab bridge deck, so the department researched the subject to develop a knowledge base. The process that the Connecticut Department of Transportation underwent to research past studies with precast bridge elements is outlined. The research included laboratory studies as well as actual construction projects in several states. Using the results of the research, the Connecticut Department of Transportation developed a system that met the objective. This was a case in which information from several research efforts in the past was compiled into a working system that was structurally sound and practical. The system was tried on two distinctly different bridges with different approaches to rapid deck replacements. The first involved a fast-tracked full closure of a ramp with a one-lane bridge, while the second included a long viaduct that could be closed only on weekends. Both projects were a success and have been in service for several years without any problems.
Methods for Controlling Stresses and Distortions in Stage-Constructed Steel Bridges
Authors: Swett Geoffrey D. , Stanton John F. , Dunston Phillip S.
Published: April 2007

Widening and staged construction of steel bridges are becoming more frequent with today’s heavy traffic demands, right-of-way restrictions, and environmental constraints. Both construction practices require the addition of new girders to an existing structure. When new girders are added to an existing structure, inherent constructibility problems arise. The completed structure requires that the new girders, after placement of the new concrete deck, be aligned in both elevation and cross slope with the existing structure. Problems occur when the loading over the new girders is unbalanced, causing a torsional moment and twisting of the bridge. The twisting of the new girders may add undesirable vertical and horizontal displacements. Six design and construction methodologies for staged construction or widening of straight, steel girders are discussed. Research was initiated in response to construction problems experienced by the Washington State Department of Transportation (WSDOT). Several state highway agencies were surveyed, and the survey revealed that the problems experienced by WSDOT were not unique. The six methods are presented and the advantages, disadvantages, and applicable situations are discussed. A finite-element model was developed and used to compare calculated deflections with actual WSDOT case study field measurements. The model was then used to investigate the stresses and deformations for the six methods. A design paradigm is also presented for use in determining the appropriate method to be used for each particular situation.
Rail Track Maintenance Planning: An Assessment Model
Authors: Simson Scott A. , Ferreira Luis , Murray Martin H.
Published: April 2007

In Australian rail freight operations, railway track maintenance makes up between 25 and 35 percent of total train operating costs. Models have shown that track maintenance costs can be reduced by 5 to 10 percent through improved planning. The Track Maintenance Planning Model (TMPM) has been developed to deal with the track maintenance planning function in the medium to long term. In contrast to traditional models, which mainly use expert systems, TMPM simulates the impacts of railway track conditions and related maintenance work by using an existing track degradation model. Track condition data from that model are used to determine whether safety-related speed restrictions are needed and what immediate maintenance work may be required for safe train operation. TMPM outputs the net present value of the financial benefits of undertaking a given maintenance strategy compared with a base-case maintenance scenario. This approach has an advantage over current models in investigating what-if scenarios. The track engineer can assess the possible benefits of reduced operating costs from upgrading track infrastructure or from improving maintenance equipment. Track maintenance and train operating costs also can be simulated over time. The results of applying the model to a test track section using several different maintenance strategies are presented.
Field and Laboratory Evaluation of Cement Kiln Dust as a Soil Stabilizer
Authors: Miller Gerald A. , Zaman Musharraf
Published: April 2007

A field and laboratory study was conducted to evaluate cement kiln dust (CKD) as a soil stabilizer. The performance of CKD from three different cement manufacturers was compared with that of quicklime. Field-work involved construction of test sections along a rural highway in Oklahoma. Observations were made to compare construction requirements for CKD and lime. Treated soil samples were collected from the field to prepare specimens for unconfined compression testing in the laboratory. In situ testing included dynamic cone penetration testing in the stabilized subbase and falling weight deflectometer testing after completion of the pavement. Chemical testing was conducted to determine the chemical makeup of each dust, and soil-CKD mixtures were tested for pH response. Chemical tests on the CKD and CKD-soil mixtures revealed aspects of the CKD composition that can be correlated with the degree of stabilization. Regarding strength improvements, results showed that CKD from one cement plant performed significantly better than lime and CKD from other plants. The laboratory and field test data showed that, overall, CKD was more effective than quicklime for stabilizing soil. Additional laboratory tests showed that the influence of CKD and lime on the plasticity index of soils was similar and that both additives imparted some resistance to freeze-thaw and wet-dry cycles. Observations indicate that treatment with CKD can be cost-effective and that it requires less construction time than treatment with quicklime.
Analysis of Fatal Crashes in Georgia Work Zones
Authors: Daniel Janice , Dixon Karen , Jared David
Published: April 2007

Studies on work zone crashes typically examine a combination of injury, fatal, and property damage crashes to identify factors that contribute to unsafe conditions within work zones. Few studies focus on fatal crashes within work zones, although a clear understanding of the driver, roadway, and work zone conditions associated with fatal crashes will facilitate the development of strategies aimed at improving safety and reducing fatal as well as nonfatal crashes. The Georgia Department of Transportation recently performed a study to identify the manner of collision, location, and construction activity associated with fatal crashes in work zones. This study is expanded further to examine the difference between fatal crash activity within work zones compared with fatal crashes in non-work-zone locations. Using data from three work zone locations in Georgia, fatal crash activity within work zones also was compared with nonfatal crashes within work zones. Finally, fatal crash activity was examined to determine the influence of the work zone activity on the frequency of fatal crashes. The overall findings of the study indicate that the work zone influences the manner of collision, light conditions, truck involvement, and roadway functional classification under which fatal crashes occur. The study also indicates that fatal crashes in work zones are more likely to involve another vehicle than non-work-zone fatal crashes, and fatal crashes in work zones are less influenced by horizontal and vertical alignment than are non-work-zone crashes.
Using Transverse Profile Data to Compute Plastic Deformation Parameters for Asphalt Concrete Pavements
Authors: Ali Hesham A. , Tayabji Shiraz D.
Published: April 2007

Previous studies have shown that the performance of in-service pavements may deviate significantly from that predicted by use of laboratory-calibrated performance models. Therefore calibration of performance prediction models with data from in-service pavements is important. Calibration of mechanistic rutting models by use of transverse profile data is explored. A well-known family of mechanistic rutting prediction models uses plastic deformation parameters [slope of elastic or plastic strain (or both) and load hardening factor] for quantification of the amount of permanent deformation resulting from each load application. For the purpose of obtaining these parameters, two traditional methods have been used: repeated load testing in the laboratory and calibration by use of time-series data from in-service pavements. Although the first suffers from the lack of compatibility between laboratory-predicted and actual performance, the second requires collection of field data for an extended period of time (years of monitoring) and may be interrupted by rehabilitation activities. The transverse profile contains valuable information that can be used for determining the contribution of each pavement layer to the observed rutting and the plastic deformation parameters. Transverse profile data were used for calibration of rutting prediction models. The stability and sensitivity of the computed parameters were also investigated.
Global Positioning System as Data Collection Method for Travel Research
Authors: Draijer Geert , Kalfs Nelly , Perdok Jan
Published: April 2007

The technology of Global Positioning Systems (GPS) provides new ways for collecting information about travel behavior. When it is used in combination with an electronic travel diary, valuable information of high quality about travel behavior becomes available. To learn about the possibilities of this new technology, a pilot study involving 151 people was performed in the Netherlands. What makes this pilot unique is the monitoring of all modes of travel, not just travel by motorized vehicles. The findings suggest that although it is possible to monitor all travel modes, data quality differs among them. The GPS device registered nearly all car driver trips, compared to half of the tram and train trips. When trips are registered, public transport trips are registered with a higher accuracy level than car trips. For specific trips, respondents did not use the equipment because of the burden placed on them or because of a lack of time. This was especially the case for walking, cycling, public transport, shopping trips, and visits. Concerning route, distance, and trip segments, it can be concluded that although valuable information is collected, there remain many difficulties to be overcome.
Determinants of Attrition Rates in Two-Wave, Two-Day Household Activity Diary: Probit Analysis
Authors: Arentze Theo , Borgers Aloys , Ponjé Maarten , Timmermans Harry
Published: April 2007

Transportation researchers often have used panel data to examine the dynamics of travel behavior. Although panel data are probably the best means by which to better understand choice dynamics, they present various challenges to the analyst, with attrition or dropout one of the most critical. Presented are the results of an analysis of the determinants of attrition in a two-wave panel, conducted in the Netherlands. Panelists reported their activities for a consecutive 2 days with 1 year between. Attrition rates between the two waves were predicted as a function of sociodemographics; number of activities, trips and tours; and the amount of reporting error in the first wave, by using a probit model. The results of the study indicate that none of these variables was significant, suggesting that no systematic attrition occurred between the two waves.
Are More Profiles Better Than Fewer?: Searching for Parsimony and Relevance in Stated Choice Experiments
Authors: Stopher Peter R. , Hensher David A.
Published: April 2007

Transportation planners increasingly include a stated choice (SC) experiment as part of the armory of empirical sources of information on how individuals respond to current and potential travel contexts. The accumulated experience with SC data has been heavily conditioned on analyst prejudices about the acceptable complexity of the data collection instrument, especially the number of profiles (or treatments) given to each sampled individual (and the number of attributes and alternatives to be processed). It is not uncommon for transport demand modelers to impose stringent limitations on the complexity of an SC experiment. A review of the marketing and transport literature suggests that little is known about the basis for rejecting complex designs or accepting simple designs. Although more complex designs provide the analyst with increasing degrees of freedom in the estimation of models, facilitating nonlinearity in main effects and independent two-way interactions, it is not clear what the overall behavioral gains are in increasing the number of treatments. A complex design is developed as the basis for a stated choice study, producing a fractional factorial of 32 rows. The fraction is then truncated by administering 4, 8, 16, 24, and 32 profiles to a sample of 166 individuals (producing 1, 016 treatments) in Australia and New Zealand faced with the decision to fly (or not to fly) between Australia and New Zealand by either Qantas or Ansett under alternative fare regimes. Statistical comparisons of elasticities (an appropriate behavioral basis for comparisons) suggest that the empirical gains within the context of a linear specification of the utility expression associated with each alternative in a discrete choice model may be quite marginal.
Web-Based Expert Geographical Information System for Advanced Transportation Management Systems
Authors: Özbay Kaan , Mukherjee Shirsendu
Published: April 2007

The Internet is fast becoming the standard environment for client-server applications that involve multiple users. The proliferation of Internet-based application development tools opens new doors to transportation researchers who work in real-time decision support system development. In the 1990s, one of the most important problems in advanced transportation management systems research was the development of better incident management systems. Although the incident management process has been well studied, the development of real-time decision support systems that can be used by all the involved agencies remains a challenging area of transportation engineering research. Existing incident management systems are developed on various traditional computing platforms, including UNIX and Windows. However, with the advent of the World Wide Web and Internet-based programming tools such as Java, it is possible to develop platform independent decision support tools for the incident management agencies. Web-based support tools offer an invaluable opportunity to develop next-generation online decision support tools for real-time traffic management. The applicability of Web-based tools to the development of online decision support systems for incident management is explored and demonstrated, and a prototype incident management decision support system (DSS) that has most of the capabilities of similar UNIX-based DSS support systems is developed and tested. Briefly described are the implementation and development of a prototype wide-area incident management system using Web-based tools.
Tree Induction of Spatial Choice Behavior
Authors: Thill Jean-Claude , Wheeler Aaron
Published: April 2007

Discussed is the merit of inductive learning as a tool with which to discover geographic knowledge in data-rich environments, and particularly as an analysis tool in spatial decision-making theory. The capability and applicability of Quinlan’s C4.5 decision tree induction algorithm to the class of problems involving the choice among discrete travel destinations within an urban area are analyzed. The C4.5 algorithm and its relation to other decision tree induction algorithms and to spatial behavioral modeling are described, and its implementation on spatial behavior data from the Minneapolis-St. Paul metropolitan area is illustrated.
Driving to Distractions: Recreational Trips in Private Vehicles
Authors: Mallett William J. , McGuckin Nancy
Published: April 2007

An increasing amount of travel, both long- and short-distance trips, is made in private vehicles for recreation. Peak congestion around attractions and leisure spots can be worse than congestion in the city center during peak periods. Moreover, recreational travel within, to, and through metropolitan areas contributes to congestion problems and points to the need for its incorporation into travel forecasting. The importance of leisure travel in state economies raises the question of why this segment of travel is not more often studied. The 1995 American Travel Survey and the 1995 Nationwide Personal Transportation Survey are used to examine the characteristics of recreational trips by private vehicle. Recreational trips by other modes, such as transit and airplane, are not included. Data from the surveys show that private vehicle recreation trips make up about 14 percent of all local trips, 23 percent of all long-distance trips, and 15 percent of total vehicle kilometers traveled on U.S. roads. Recreation trips are not equally distributed among all groups of people, however. African Americans report about half the amount of recreational automobile trips and one-third the average kilometers as whites. Other differences by race or ethnicity indicate that Hispanic families tend to travel in larger groups than African Americans or whites. Age, too, is a determining factor in the amount and type of recreational travel. Both the young and the old make more trips on a daily basis, but they make far fewer long-distance trips than those in middle age.
Long-Span Guardrail System for Culvert Applications
Authors: Faller Ronald K. , Sicking Dean L. , Polivka Karla A. , Rohde John R. , Bielenberg Bob W.
Published: April 2007

A long-span guardrail for use over low-fill culverts was developed and successfully crash tested. The guardrail system was configured with 30.48 m of nested, 12-gauge W-beam rail and centered around a 7.62-m-long unsupported span. The nested W-beam rail was supported by 16 W152×13.4 steel posts and 6 standard CRT posts, each with two 150-mm×200×360 mm wood block-outs. Each post was 1830 mm long. Post spacings were 1905 mm on center, except for the 7.62-m spacing between the two CRT posts surrounding the long span. The research study included computer simulation modeling with Barrier VII and full-scale vehicle crash testing, using 3/4-ton (680-kg) pickup trucks in accordance with the Test Level 3 (TL-3) requirements specified in NCHRP Report 350. Three full-scale vehicle crash tests were performed. The first test was unsuccessful because of severe vehicle penetration into the guardrail system. This penetration resulted from a loss of rail tensile capacity during vehicle redirection when the swagged fitting on the cable anchor assembly failed. A second test was performed on the same design, which contained a new cable anchor assembly. During vehicle redirection, the pickup truck rolled over and the test was considered a failure. The long-span system was subsequently redesigned to incorporate double block-outs on the CRT posts and crash tested again. Following the successful third test, the long-span guardrail system was determined to meet TL-3 criteria.
Land Use, Urban Design, and Nonwork Travel: Reproducing Other Urban Areas’ Empirical Test Results in Portland, Oregon
Authors: Boarnet Marlon G. , Greenwald Michael J.
Published: April 2007

Research on nonwork automobile trip generation and land use previously conducted by researchers is replicated for the Portland, Oregon, region. Additionally, new variables examining new urbanist arguments are incorporated. The results suggest that any links between land use and nonwork trip behavior act primarily by influencing trip costs, in terms of distances traveled and speeds achieved, rather than directly influencing the number of trips made. This analysis is consistent with the other research, suggesting that this model is not sensitive to errors that might arise due to the unique characteristics of the urban area under review.
Land Use and Transportation Planning for Twin Cities Using a Genetic Algorithm
Authors: Balling Richard J. , Taber John , Day Kirsten , Wilson Scott
Published: April 2007

A new approach to future land use and transportation planning for high-growth cities is presented. The approach employs a genetic algorithm to efficiently search through hundreds of thousands of possible future plans. A new fitness function is developed to guide the genetic algorithm toward a Pareto set of plans for the multiple competing objectives that are involved. This set may be placed before decision makers. A Pareto set scanner also is described that assists decision makers in shopping through the Pareto set to select a plan. Some of the differences between simultaneous planning and separate planning of highly coupled twin cities also are examined.
Mechanistic Evaluation of Hydrated Lime in Hot-Mix Asphalt Mixtures
Authors: Mohammad Louay N. , Abadie Chris , Gokmen Rana , Puppala Anand J.
Published: April 2007

Permanent deformation and moisture damage are common distresses found in pavements today. The use of mineral fillers such as hydrated lime is known to provide a decrease in moisture susceptibility. In many cases, mineral fillers will also increase the mixture stiffness. Conventional asphaltic concrete mixtures and mixtures modified with hydrated lime were evaluated for their fundamental engineering properties as defined by indirect tensile strength and strain, permanent deformation characteristics, resilient modulus, and fatigue resistance. A typical Louisiana low-volume dense-graded mixture was used. The test factorial included two aggregate types (limestone and gravel) and two asphalt cement types (a conventional AC-30 and one modified with styrene-butadiene polymer). The results indicated that the addition of hydrated lime as mineral filler improved the permanent deformation characteristics and fatigue endurance of the asphaltic concrete mixtures. This improvement was particularly apparent at higher testing temperatures with mixes containing polymer-modified asphalt and limestone aggregate.
Energy-Derived, Damage-Based Failure Criterion for Fatigue Testing
Authors: Ghuzlan Khalid A. , Carpenter Samuel H.
Published: April 2007

Determination of the failure limit in a repeated-load fatigue test in the laboratory has relied entirely on the arbitrary selection of a fixed criterion. The constant strain and constant stress modes of fatigue loading have been described by a consistent definition of failure in flexural fatigue testing because of the distinctly different application of energy during the loading history. The most widely accepted definition is a decrease in initial stiffness by 50 percent. Procedures examining energy input and dissipated energy have required different schemes for each mode in an attempt to describe similar states of damage in the mixture. A proposed method is presented for examining dissipated energy to select a consistent level of material behavior that is indicative of the damage accumulation in the mixture. This procedure shows the similarity between the constant stress and constant strain modes of testing and is shown to provide the potential for unifying the now phenomenological description of fatigue with a more rational energy-based description.
Behavioral Adaptation, Safety, and Intelligent Transportation Systems
Authors: Smiley Alison
Published: April 2007

It is intrinsic to human nature to modify behavior to suit new conditions. How drivers are likely to change the way they drive if their vehicles are equipped with intelligent transportation system (ITS) devices is considered. It is clear from the antilock braking system experience that improvements in safety cannot be predicted on the basis of proof-of-concept studies alone, in which one simply looks at changes in performance of the task being aided, whether that is braking, navigation, or detection of hazards. One also must look at changes in other aspects of the driving task and at the type of driving being done to determine the likely effect on safety. In particular, one should assume that there may be trade-offs of mobility for safety, that is, more driving in more difficult conditions and at higher speeds leading to more crashes. Further, one should expect drivers to attempt to increase productivity while driving, given reduced driving task demand. The prolific use of cellular phones is evidence of this behavior. Research is needed on driver mental models of ITS devices, to ensure that drivers understand how they function. The best design from a mechanistic point of view may not be the most effective for drivers.
Route and Scheduling Choice Under Travel Time Uncertainty
Authors: Lam Terence
Published: April 2007

This research develops a theoretical model to analyze commuters’ joint decisions of route and departure time in a simple network with two parallel routes: one with free but congested lanes, the other with free-flowing tolled lanes with time-varying tolls. By accounting for trip distance, the theoretical model is able to examine the two different sources of travel time uncertainties: length of commute and type of route. Length of commute causes long-distance commuters to leave home earlier, but type of route may lead to a change of route as well as of departure time to compensate for the higher risk of arriving late for work. Results show that long-distance commuters are less likely to take toll lanes than people with short commutes; that travelers who plan to take toll lanes are unlikely to switch to free lanes en route because their later departure times reflect the savings and reduced uncertainty in travel time; and that provision of pretrip information favors the use of toll lanes and may result in commuters leaving home later, even in heavier-than-normal traffic. The theoretical model provides more flexible demand specification for simulation studies. In addition it has important policy implications because it allows a better understanding of commuters’ travel behaviors on roads with value-pricing schemes, such as the express lanes on CA-91 and high-occupancy toll lanes on I-15 in California.
How Chaos Does Not Destroy Ridership: Operations of an Exclusive Busway Carrying More Than 35,000 Passengers per Hour per Direction
Authors: Ardila Arturo , Rodríguez Daniel A.
Published: April 2007

Busways have been reported to carry up to 28,000 passengers per hour per direction (pphpd). However, recent passenger counts indicate that the exclusive busway in Bogotá, Colombia, has a flow of more than 35,000 pphpd. This passenger flow is achieved despite poor operating conditions and a general lack of maintenance without a city busway management and operation authority. Consequently, there is little police control, no systems management, and scarce information for users. These conditions should affect passenger flow negatively, but the Bogotá busway carries more passengers than all busways for which data are available. The analysis suggests that the Bogotá busway is able to move high passenger flows due to three concurrent and interactive sets of factors. First, the high competition among bus operators provides drivers with an incentive to operate more efficiently. Second, the design provides two lanes, allowing for vehicle overtake, as well as stations that enable six or more buses simultaneously to pick up and discharge passengers. Third, the buses move in platoons along the busway. Each platoon consists of 12 to 16 buses with average 96-s headways. Furthermore, time-distance diagrams indicate that the platoons are not stable, because vehicles keep changing from one platoon to another. The analysis underscores the importance for transit planners of trade-offs among passenger flows, level of service, and optimal system operation.