bluuebunny/crossref_metadata_2025 huggingface dataset:
Forecasting Overall Pavement Condition with Neural Networks: Application on Florida Highway Network
Authors: Yang Jidong , Lu Jian John , Gunaratne Manjriker , Xiang Qiaojun
Published: April 2007

Timely identification of undesirable crack, ride, and rut conditions is a critical issue in pavement management systems at the network level. The overall pavement surface condition is determined by these individual pavement surface conditions. A research project was carried out to implement an overall methodology for pavement condition prediction that uses artificial neural networks (ANNs). In the research, three ANN models were developed to predict the three key indices—crack rating, ride rating, and rut rating—used by the Florida Department of Transportation (FDOT) for pavement evaluation. The ANN models for each index were trained and tested by using the FDOT pavement condition database. In addition to the three key indices, FDOT uses a composite index called pavement condition rating (PCR), which is the minimum of the three key indices, to summarize overall pavement surface condition for pavement management. PCR is forecast with a combination of the three ANN models. Results of the research suggest that the ANN models are more accurate than the traditional regression models. These ANN models can be expected to have a significant effect on FDOT's pavement management system.
Decision-Making Problem for Managing Pavement Maintenance and Rehabilitation Projects
Authors: Wang Feng , Zhang Zhanmin , Machemehl Randy B.
Published: April 2007

A typical pavement management system (PMS) should help a decision maker select the best maintenance program—that is, which maintenance treatment to use and where and when to apply it—so that maximal use is made of available resources. To provide decision support, a PMS needs a process for setting maintenance and rehabilitation (M&R) priorities. The quality of the prioritization directly influences the effectiveness of available resources, which in most cases is the primary goal of the decision maker. A network-level project selection procedure that uses an operations research optimization method was developed. An integer linear programming model was established to select a set of candidate projects from the highway network over a planning horizon of 5 years. In the model, constraints of available annual budgets and minimum requirements on pavement conditions were satisfied where state transition of each road section was formulated. Two optimization objectives—maximization of the total M&R effectiveness and minimization of the total M&R disturbance cost— were pursued over the planning horizon. A small network of 10 road sections was used as a pilot study for the established model. Pavement management functionalities at the network level are summarized, formulation of the integer linear programming model for the project selection problem is presented, differences in decision makers' value systems and the resulting different undominated solutions are discussed, and a sensitivity analysis of the annual budget constraint is conducted.
Development of Adaptive Performance Models for Oklahoma Airfield Pavement Management System
Authors: Yuan Jie , Mooney Michael A.
Published: April 2007

The Oklahoma airfield pavement management system (APMS) is a set of pavement management tools that can assist with pavement condition evaluation, as well as prioritization and scheduling of pavement maintenance and rehabilitation activities. Pavement performance models were developed to support the APMS for more than 70 Oklahoma general aviation airports. The family modeling method based on the pavement condition index was tailored to fit the deterioration characteristics of these airfield pavements. The statistical and engineering significance of seven levels of pavement factors was investigated, and pavement factors that affect pavement deterioration significantly were identified as family variables. Asphalt concrete pavement families were formed by sorting pavement function, distress cause, and pavement thickness, while portland cement concrete pavements were divided into families according to pavement function and climate zone. The family polynomial curves were able to reveal the expected deterioration patterns and are logical in engineering principle. Rooted by an adaptive database, the system accepts expert opinion and automatically integrates effects of major maintenance and rehabilitation activities into modeling. From the up-to-date database, the performance models update forecasts automatically.
Pavement Management Systems: Past, Present, and Future
Authors: Kulkarni Ram B. , Miller Richard W.
Published: April 2007

The progress made over the past three decades in the key elements of pavement management systems was evaluated, and the significant improvements expected over the next 10 years were projected. Eight specific elements of a pavement management system were addressed: functions, data collection and management, pavement performance prediction, economic analysis, priority evaluation, optimization, institutional issues, and information technology. Among the significant improvements expected in pavement management systems in the next decade are improved linkage among, and better access to, databases; systematic updating of pavement performance prediction models by using data from ongoing pavement condition surveys; seamless integration of the multiple management systems of interest to a transportation organization; greater use of geographic information and Global Positioning Systems; increasing use of imaging and scanning and automatic interpretation technologies; and extensive use of formal optimization methods to make the best use of limited resources.
Network-Level Pavement Performance Prediction Model Incorporating Censored Data
Authors: DeLisle Rodney R. , Sullo Pasquale , Grivas Dimitri A.
Published: April 2007

A methodology is presented for network-level pavement performance prediction that incorporates censored condition data. Censoring occurs when the duration at a specific condition level is not completely observed. This happens when pavement condition is improved and for the duration of the latest condition rating on file for each highway section. Pavement condition history files may contain significant quantities of censored data, yet such data typically are excluded when performance curves are developed. As a result, estimated condition durations and corresponding deterioration curves include deterioration rates that are greater, sometimes substantially greater, than those actually observed. The primary purpose for developing the presented methodology is to correct this shortcoming. Methodology development was facilitated with the use of a comprehensive information basis containing up to 20 years of historical pavement condition data for approximately 19,000 highway sections maintained by the New York State Department of Transportation. Durations at each condition rating were determined for each highway section over the 20-year period, with distinctions made between censored and uncensored observations. A modeling approach, with probability plotting and parameter estimation, was developed that resulted in performance curves. Differences in pavement performance based on geographic region were also investigated. From results obtained with the developed methodology, the main conclusion of this study is that accommodating censored data in pavement performance prediction models not only is feasible but better describes actual performance than if the data were simply excluded from the analysis.
Ten-Year Performance of Dowel-Bar Retrofit: Application, Performance, and Lessons Learned
Authors: Pierce Linda M. , Uhlmeyer Jeff , Weston Jim , Lovejoy Jim , Mahoney Joe P.
Published: April 2007

The Washington State Department of Transportation (WSDOT) has been rehabilitating its aged portland cement concrete pavements over the last 10 years by using dowel-bar retrofit, panel replacements, and diamond grinding. These pavements have been rehabilitated, with dowel-bar retrofit, to extend the performance life beyond the original design life of 20 years. The first dowel-bar retrofit application in Washington was constructed as a test section in 1992. Since then, WSDOT has dowel-bar retrofitted more than 350 lane-kilometers. Dowel-bar retrofit performance and application are described, and lessons learned in the last 10 years are discussed.
Tire Contact Stresses and Their Effects on Instability Rutting of Asphalt Mixture Pavements: Three-Dimensional Finite Element Analysis
Authors: Novak Marc , Birgisson Bjorn , Roque Reynaldo
Published: April 2007

Instability rutting generally occurs within the top 2 in. of the asphalt layer when the structural properties of the asphalt concrete are inadequate to resist the stresses imposed on it. Several researchers have presented observations in attempts to explain instability rutting, but a clear identification of the mechanism does not exist. Stresses in the asphalt layer caused by measured tire interface stresses were analyzed in three dimensions by using finite elements to identify possible mechanisms for instability rutting. The analysis showed that radial tires produce high near-surface shear stresses at low confinements, which are not predicted with traditional uniform vertical loading conditions, in the region where instability rutting is known to occur. The resulting shear stresses tend to be shallower than for the uniformly loaded case, and they are focused in areas where instability rutting has been observed. The observed stress states imply that the characterization of instability rutting requires testing at these low confinement (and sometimes tensile) stress states, rather than at the higher stress states typically used in the strength characterization of mixtures.
Analysis of Travel Time Saving Benefit by Understanding Individual Needs and Value of Activity Time: Case Study of Tokyo and Jakarta
Authors: Prasetyo Irwan , Fukuda Daisuke , Yoshino Hirosato , Yai Tetsuo
Published: April 2007

Quantification of the value of time (VOT) is important for measurement of the benefit of transportation projects in terms of travel time savings. In Japan, VOT is considered higher on weekends than on weekdays because on the weekend people have limited time to allocate to discretionary activities that are not normally done on weekdays, such as family care-related activities. In Indonesia, a culturally diverse country, providers and users seem to have different perceptions of VOT. A method of analyzing the value of activity time is presented. It argues that the benefit of travel time saving should be evaluated in more detail on weekends by considering the value of discretionary activities to explain these phenomena theoretically. Activity diary surveys were conducted in Tokyo, Japan, and Jakarta, Indonesia, to verify the influence of psychological needs on people's holiday activities. Finally, a time allocation model that uses the revealed preference data and a marginal activity choice model that uses stated preference data are proposed to calculate the value of activity time. The theories underpinning these models are Maslow's psychological needs, consumer theory in economics, and a discrete choice model. The empirical results show that an individual's priority of needs influences time allocation. In particular, the results show that in Tokyo, spending time with family on weekends is more valuable than other types of activities, while in Indonesia the value of spending time with family exceeds that of work time even on weekdays.
Application of Artificial Neural Network Models to Activity Scheduling Time Horizon
Authors: Doherty Sean T. , Mohammadian Abolfazl
Published: April 2007

Machine-learning techniques are increasingly being applied in the areas of exploratory data analysis, prediction, and classification. At the same time that analytical techniques are expanding, new conceptual approaches to the modeling of travel are emerging in an effort to improve travel demand forecasting and better assess the impacts of emerging transportation policy. In particular, the shift toward activity-based travel analysis has led to the development of activity scheduling models. One of the key features of emerging models of this type is the attempt to simulate the order in which activities are added during a continuous process of schedule construction. In practice, a fixed order by activity type is often assumed; for example, work activities are planned first, followed by the planning of more discretionary activity types. By using observed data on the scheduling process from a small sample of households from Quebec City, Quebec, Canada, a neural network model that classifies activities according to the order in which they were planned, the planning time horizon (preplanned, planned, or impulsive), was developed. A variety of explanatory variables were used in the model related to individual-, household-, and activity-based characteristics such as spatial and temporal fixities. The model developed exhibited a relatively high degree of prediction with the test data, especially for the preplanned and impulsive categories of the planning time horizon. These results suggest that machine-learning algorithms could be used to predict the order in which activities are selected in emerging activity scheduling process models, thereby avoiding static assumptions related purely to activity type.
Work Travel Mode Choice Modeling with Data Mining: Decision Trees and Neural Networks
Authors: Xie Chi , Lu Jinyang , Parkany Emily
Published: April 2007

Among discrete choice problems, travel mode choice modeling has received the most attention in the travel behavior literature. Most traditional mode choice models are based on the principle of random utility maximization derived from econometric theory. Alternatively, mode choice modeling can be regarded as a pattern recognition problem in which multiple human behavioral patterns reflected by explanatory variables determine the choices between alternatives or classes. The capability and performance of two emerging pattern recognition data mining methods, decision trees (DT) and neural networks (NN), for work travel mode choice modeling were investigated. Models based on these two techniques are specified, estimated, and comparatively evaluated with a traditional multinomial logit (MNL) model. For comparison, a unique three-layer formulation of the MNL model is presented. The similarities and differences of the models' mechanisms and structures are identified, and the mechanisms and structures in the models' specifications and estimations are compared. Two performance measures, individual prediction rate and aggregate prediction rate, which represent the prediction accuracies for individual and mode aggregate levels, respectively, were applied to evaluate and compare the performances of the models. Diary data sets from the San Francisco, California, Bay Area Travel Survey 2000 were used for model estimation and evaluation. The prediction results show that the two data mining models offer comparable but slightly better performances than the MNL model in terms of the modeling results, while the DT model demonstrates the highest estimation efficiency and most explicit interpretability, and the NN model gives a superior prediction performance in most cases.
Space-Time User Benefit and Utility Accessibility Measures for Individual Activity Schedules
Authors: Ashiru Olu , Polak John W. , Noland Robert B.
Published: April 2007

Accessibility is a fundamental concept in human existence, which goes to the heart of the notion of society, equity, and justice. However, despite the importance of the concept, the mathematical measures that have historically been used to quantify accessibility levels have been relatively poorly defined and have encompassed a limited range of observed forms of travel behavior. Existing space–time locational benefit measures are extended to encapsulate more realistic temporal constraints on activity participation and the associated perceived user benefit. The development of a family of space–time route benefit measures is outlined. Despite their apparent theoretical attractiveness, hitherto researchers have not used such measures. It is demonstrated how these route benefit measures can be used to develop an associated family of disaggregate activity-based space–time utility accessibility measures applicable to individual activity schedules and how income constraints can be incorporated within the space–time utility accessibility measures. Finally, the means by which stochastic frontier models can be used in conjunction with existing travel–activity diary data sets to operationalize the proposed measure of accessibility are briefly described.
Some Evidence of Travelers with Zero Value of Time
Authors: Richardson A. J.
Published: April 2007

A small but growing body of evidence that questions the traditional view that travel is a derived demand is beginning to be assembled. Rather than assuming that all the positive components of a trip are contained in the activity at the destination, while the trip itself contains only dis-utility, a view is emerging that perhaps some people actually enjoy the travel component of the trip or at least are not willing to pay for reductions in the duration of the trip. One small addition to the patchwork of studies that are starting to form a basis for challenging the conventional assumption about positive value of time (VOT) is provided. By using the results obtained from a study of VOT in Singapore that used an adaptive stated preference survey technique, it was found that 23% of public mode users in that study had zero VOT, whereas 0% of private mode users in Singapore had zero VOT. Analysis of the characteristics of those with zero VOT shows either that they had lower incomes or that they had a greater degree of flexibility in their use of time. Some recent studies that have considered changes in VOT over time, in which there are indications that the marginal utility of time has been decreasing over time (because of increased free time, the increased utility of time spent traveling because of improved telecommunications, and a range of other factors), are also described. The implications of the findings are described in terms of the modeling of travel behavior and the evaluation of transport proposals.
Roles of Spatial and Temporal Factors in Variable Message Sign Effectiveness Under Nonrecurrent Congestion
Authors: Srinivasan Karthik K. , Krishnamurthy Arun
Published: April 2007

The spatial and temporal network dynamics induced by variable message sign (VMS) information under nonrecurrent congestion are investigated. Computational experiments were performed to analyze the role of incident attributes (number, location, and timing), information characteristics (delay, update frequency, compliance rates), and alternative operational strategies. The network performance of VMSs was compared with those of in-vehicle devices (IVDs). The findings indicate that VMS performance varies dynamically and depends on the interactions between information lag, diversion rate (overconcentration) onto alternative paths, efficiency of reported paths, time-varying interactions between vehicles with VMS information and vehicles without VMS information, residual capacity on alternate paths, compliance rates, and spatial incident characteristics. The VMS strategies that account for information quality, compliance, and overconcentration are likely to outperform purely travel time-based strategies. The findings have important implications for the design, operation, and evaluation of VMS and IVD systems.
Impact of Underreporting on Mileage and Travel Time Estimates: Results from Global Positioning System-Enhanced Household Travel Survey
Authors: Wolf Jean , Oliveira Marcelo , Thompson Miriam
Published: April 2007

Trip underreporting has long been a problem in household travel surveys because of the self-reporting nature of traditional survey methods. Memory decay, failure to understand or to follow survey instructions, unwillingness to report full details of travel, and simple carelessness have all contributed to the incomplete collection of travel data in self-reporting surveys. Because household trip survey data are the primary input into trip generation models, it has a potentially serious impact on transportation model outputs, such as vehicle miles of travel (VMT) and travel time. Global Positioning System (GPS) technology has been used as a supplement in the collection of personal travel data. Previous studies confirmed the feasibility of applying GPS technology to improve both the accuracy and the completeness of travel data. An analysis of the impact of trip underreporting on modeled VMT and travel times is presented. This analysis compared VMT and travel time estimates with GPS-measured data. These VMT and travel time estimates were derived by the trip assignment module of each region's travel demand model by using the trips reported in computer-assisted telephone inter views. This analysis used a subset of data from the California Statewide Household Travel Survey GPS Study and was made possible through the cooperation of the metropolitan planning organizations of the three study areas (Alameda, Sacramento, and San Diego, California).
Technologies for Truck Classification and Methodologies for Estimating Truck Vehicle Miles Traveled
Authors: Benekohal Rahim F. , Girianna Montty
Published: April 2007

Results are presented of a national survey of all state departments of transportation (DOTs), including Puerto Rico, about technologies used for truck classification and methodologies used for estimating truck vehicle miles traveled (VMT). More than two-thirds of state DOTs returned the survey. Procedures were found to classify trucks, to adjust truck data from short-term counts, and to calculate truck VMT. To classify trucks, most state DOTs followed FHWA’s 13 categories. The products from two manufacturers, Peek Traffic and Diamond Traffic Products, with a variety of sensors, dominated the classification devices used by state DOTs. The sensor used most for short-term classification counts was the pneumatic tube. Duration and number of truck-classification counts (machine or manual) varied by state DOT. With machine classifiers, state DOTs collected short-term and continuous truck data for a variety of state highway coverage. Truck data were collected by using machine classifiers unless certain conditions, such as congested highways, demanded manual collection. To adjust truck data from short-term classification counts, most state DOTs developed their adjustment factors from continuous volume counts (not truck counts) and used them to adjust truck volumes. Some state DOTs used different adjustment factors for trucks and cars. For all state DOTs, the general practice of truck VMT estimation was based on traffic counts. When truck data were available, state DOTs directly calculated truck VMT by multiplying truck average daily traffic and the length of a roadway section; when the data were not available, truck VMT was indirectly calculated as a fraction (percentage) of total VMT. For the state highway systems, state DOTs generally relied on the first (direct) method, since the resources were normally available and the standards for conducting traffic counts were also available. However, some states lacked the necessary resources to adequately sample average daily traffic on the local road systems. As a result, many state DOTs used the indirect method to calculate truck VMT.
Correlation Technique for Estimating Traffic Speed from Cameras
Authors: Schoepflin Todd N. , Dailey Daniel J.
Published: April 2007

A new algorithm is presented for estimating speed from roadside cameras in uncongested traffic, congested traffic, favorable weather conditions, and adverse weather conditions. Individual vehicle lanes are identified and horizontal vehicle features are emphasized by using a gradient operator. The features are projected into a one-dimensional subspace and transformed into a linear coordinate system by using a simple camera model. A correlation technique is used to summarize the movement of features through a group of images and estimate mean speed for each lane of vehicles.
Microscopic Traffic Data Collection by Remote Sensing
Authors: Hoogendoorn S. P. , Van Zuylen H. J. , Schreuder M. , Gorte B. , Vosselman G.
Published: April 2007

To gain insight into the behavior of drivers during congestion, and to develop and test theories and models that describe congested driving behavior, very detailed data are needed. A new data-collection system prototype is described for determining individual vehicle trajectories from sequences of digital aerial images. Software was developed to detect and track vehicles from image sequences. In addition to longitudinal and lateral position as a function of time, the system can determine vehicle length and width. Before vehicle detection and tracking can be achieved, the software handles correction for lens distortion, radiometric correction, and orthorectification of the image. The software was tested on data collected from a helicopter by a digital camera that gathered high-resolution monochrome images, covering 280 m of a Dutch motorway. From the test, it was concluded that the techniques for analyzing the digital images can be applied automatically without much problem. However, given the limited stability of the helicopter, only 210 m of the motorway could be used for vehicle detection and tracking. The resolution of the data collection was 22 cm. Weather conditions appear to have a significant influence on the reliability of the data: 98% of the vehicles could be detected and tracked automatically when conditions were good; this number dropped to 90% when the weather conditions worsened. Equipment for stabilizing the camera—gyroscopic mounting—and the use of color images can be applied to further improve the system.
Development of a System for Collecting Loop-Detector Event Data for Individual Vehicles
Authors: Zhang Xiaoping , Wang Yinhai , Nihan Nancy L. , Hallenbeck Mark E.
Published: April 2007

Typical freeway inductive loop detection systems, under normal operation, aggregate individual loop-detector actuations sampled at 60 Hz into 20-s or 30-s averages of velocity, flow, and lane-occupancy measurements. While such aggregations are appropriate for serving as inputs to control system algorithms, and they save disk space for archiving loop data, a large amount of useful data regarding individual vehicles is lost. For single-loop detectors, the lost information includes individual vehicle arrival, departure, and presence times. For speed traps, the lost information also includes the calculated individual vehicle speed and length. Yet this information about individual vehicles is desirable to transportation researchers and planners. The unavailability of this information makes in-depth investigation of detector errors difficult or even impossible. A system for collecting detector event data is proposed. This system can sample loop actuations with sampling rates of 60 Hz or higher and then save, process, and present the collected event data in real time without interfering with the detector controller’s normal operation. A stand-alone Windows program was developed for performing real-time high-frequency loop event data collection. A system reliability test and field application indicate that the system can collect realtime detector event data at a high sampling rate (60 Hz or higher). Additionally, this system makes real-time loop data quality evaluation, loop malfunction identification, and loop error correction feasible.
Predictive Feedback Routing Control Strategy for Freeway Network Traffic
Authors: Wang Yibing , Papageorgiou Markos , Messmer Albert
Published: April 2007

Available routing strategies for freeway networks may be classified as feedback and iterative strategies. Feedback strategies base their routing decisions on real-time measurable or estimable information only, via employment of simple regulators, while iterative strategies run a freeway network model repeatedly to achieve exact user equilibrium conditions over a future time horizon. A predictive feedback routing control strategy was developed with the aim of incorporating the advantages of both classes of strategies on the one hand and attenuating their disadvantages on the other hand. The new strategy runs a mathematical model only once at each time step and bases its routing decisions on the predicted instead of the currently prevailing traffic conditions. The investigations indicate that satisfactory routing results are achieved by use of this strategy. The corresponding performance evaluation was conducted in detail by comparison with the feedback and iterative strategies.
GAID: Genetic Adaptive Incident Detection for Freeways
Authors: Roy Prasenjit , Abdulhai Baher
Published: April 2007

Extensive research on point-detector-based automatic traffic-impeding incident detection indicates the potential superiority of neural networks over conventional approaches. All approaches, however, including neural networks, produce detection algorithms that are location specific—that is, neither transferable nor adaptive. A recently designed and ready-to-implement freeway incident detection algorithm based on genetically optimized probabilistic neural networks (PNN) is presented. The combined use of genetic algorithms and neural networks produces GAID, a genetic adaptive incident detection logic that uses flow and occupancy values from the upstream and downstream loop detector stations to automatically detect an incident between the said stations. As input, GAID uses modified input feature space based on the difference of the present volume and occupancy condition from the average condition for time and location. On the output side, it uses a Bayesian update process and converts isolated binary outputs into a continuous probabilistic measure—that is, updated every time step. GAID implements genetically optimized separate smoothing parameters for its input variables, which in turn increase the overall generalization accuracy of the detector algorithm. The detector was subjected to off-line tests with real incident data from a number of freeways in California. Results and further comparison with the McMaster algorithm indicate that GAID with a PNN core has a better detection rate and a lower false alarm rate than the PNN alone and the well-established McMaster algorithm. Results also indicate that the algorithm is the least location specific, and the automated genetic optimization process makes it adapt to new site conditions.
State Legislative Issues for Managed Lanes in Texas
Authors: Kuhn Beverly , Jasek Debbie
Published: April 2007

The managed lane concept is currently being considered on major free way projects in Texas cities. The term managed lanes encompasses a variety of facility types, including high-occupancy vehicle lanes, high-occupancy toll lanes, single-occupancy vehicle express lanes, special-use lanes, and truck lanes. The premise of the managed lanes concept is to increase freeway efficiency and provide free-flow operations for certain freeway users by packaging various operational and design strategies. The strategies deployed offer the flexibility to be adjusted to match changing corridor and regional goals. Research undertaken in Texas Department of Transportation (TxDOT) research project Operating Freeways with Managed Lanes, which assessed state legislative needs necessary for Texas to legally and successfully implement the various types of managed lane facilities across the state, is discussed. Texas statutes may require changes in various areas to allow the implementation of managed lanes, including defining managed lanes as an operational concept in Texas, authorizing entities to develop managed lane facilities for congestion mitigation purposes, allowing entities operational flexibility with managed lane facilities, authorizing entities to develop exclusive lane facilities for congestion mitigation purposes, authorizing TxDOT to establish lane restrictions for congestion mitigation purposes, removing the time-of-day limitation on current municipal authorization for lane restrictions, and making the unlawful violation of any managed lane facility in Texas punishable by fine.
Microscopic Simulation Model Calibration and Validation: Case Study of VISSIM Simulation Model for a Coordinated Actuated Signal System
Authors: Park Byungkyu (Brian) , Schneeberger J. D.
Published: April 2007

Microscopic simulation models have been widely used in both transportation operations and management analyses because simulation is safer, less expensive, and faster than field implementation and testing. While these simulation models can be advantageous to engineers, the models must be calibrated and validated before they can be used to provide meaningful results. However, the transportation profession has not established any formal or consistent guidelines for the development and application of these models. In practice, simulation model–based analyses have often been conducted under default parameter values or bestguessed values. This is mainly due to either difficulties in field data collection or lack of a readily available procedure for simulation model calibration and validation. A procedure was proposed for microscopic simulation model calibration and validation and an example case study is presented with real-world traffic data from Route 50 on Lee Jackson Highway in Fairfax, Virginia. The proposed procedure consisted of nine steps: ( a) measure of effectiveness selection, ( b) data collection, ( c) calibration parameter identification, ( d) experimental design, ( e) run simulation, ( f) surface function development, ( g) candidate parameter set generations, ( h) evaluation, and ( i) validation through new data collection. The case study indicates that the proposed procedure appears to be properly calibrating and validating the VISSIM simulation model for the test-bed network.
Improved Detection and Control System for Isolated High-Speed Signalized Intersections
Authors: Zimmerman Karl , Bonneson James A. , Middleton Dan , Abbas Montasir M.
Published: April 2007

High-speed signalized intersections have both safety and efficiency problems. The safety problems traditionally have been overcome by using advance detectors. However, at relatively moderate flow rates, multiple advance detector systems tend to extend the green phase to its maximum allowable duration (i.e., max-out). At max-out, drivers on the intersection approach may be faced with the decision to proceed or stop. This creates the safety problem the system was intended to prevent. Also, extending phases to their maximums increases delays to other movements. A new approach to high-speed intersection control is outlined—a dynamic dilemma zone allocation system that uses measured vehicle speeds with a control algorithm to decide when to end the signal phases. The new system was evaluated by simulation and field installation. In both instances, the new system indicated it could improve safety and maintain efficient operations at high-speed intersections.
Advanced Traffic Signal Control for Diamond Interchanges
Authors: Engelbrecht Roelof J. , Barnes Kirk E.
Published: April 2007

Most modern traffic signal controllers contain "advanced" features that are not often used but may improve traffic operations under certain conditions. The Texas Transportation Institute recently completed a research project for the Texas Department of Transportation, investigating how diamond interchange operations can be improved by using advanced controller features. The research evaluated advanced features available in the traffic signal controllers currently used for diamond interchange control in Texas. Eight potentially useful controller features were identified. The effectiveness of these features was evaluated with hardware-in-the-loop traffic simulation. The researchers considered the applicability of these features under different geometric and demand conditions and investigated the effect of detector technology and human factors issues on implementation. One of the main findings of the research was the potential usefulness of the separate intersection diamond control mode. The separate intersection diamond control mode is not commonly used, but, if applied judiciously under specific geometric and demand conditions, it can provide more efficient control than the three-phase or four-phase sequences typically used in Texas. The free separate intersection mode can significantly reduce stops at interchanges under low-volume conditions, especially if permissive interior left turns are allowed and steps are taken to reduce activation of the interior left-turn phases. The coordinated separate intersection mode has the potential to provide more efficient operation than the three-phase or four-phase sequence under certain conditions that can be determined with signal optimization software such as PASSER III, Synchro, and TRANSYT-7F.
Routing Profile Updating Strategies for Online Hybrid Dynamic Traffic Assignment Operation
Authors: Chiu Yi-Chang , Mahmassani Hani S.
Published: April 2007

An online routing profile updating automaton (ORPUA) approach is introduced as a principal mechanism for operating an online hybrid dynamic traffic assignment (DTA) system for real-time route guidance in a traffic network. The hybrid DTA approach integrates the centralized and the decentralized DTA frameworks by partitioning the set of guided users into two classes according to an initial routing profile (IRP). One class receives the centralized DTA guidance, while the other follows the decentralized DTA routing. ORPUA takes the a priori IRP and updates the guidance supplied to vehicles in a real-time fashion according to the unfolding network conditions and relative performance of the two classes of users. It does not anticipate the future network conditions; instead, it reacts to them and optimizes the overall system performance by improving the performance of the underperforming class of vehicles. Simulation experiments illustrate ORPUA’s potential in maintaining desirable system performance and robustness in most of the demand-supply scenarios considered.
Alternative Quasi-Newton Methods for Capacitated User Equilibrium Assignment
Authors: Cheng Lin , Iida Yasunori , Uno Nobuhiro , Wang Wei
Published: April 2007

Two quasi-Newton methods are proposed to deal with traffic assignment in a capacitated network. The methods combine Newton formula, column generation, and penalty techniques. The first method uses the gradient of the objective function to obtain an improving feasible direction scaled by the second-order derivatives. The second one uses a Rosen gradient to obtain an improving direction scaled by the corresponding origin–destination demand. Both methods make a line search to obtain an optimal step size to guarantee the feasibility of either path or link flow. The proposed methods are of fast convergence and high accuracy at the expense of saving path information. Numerical examples verify their efficiency and stability. The quasi-Newton method with a straight gradient demonstrates more stability than the Rosen gradient for capacitated traffic assignment.
Viscoelastic, Viscoplastic, and Damage Modeling of Asphalt Concrete in Unconfined Compression
Authors: Gibson Nelson H. , Schwartz Charles W. , Schapery Richard A. , Witczak Matthew W.
Published: April 2007

A comprehensive constitutive model for asphalt concrete was calibrated that included viscoelasticity, viscoplasticity, and irreversible micro-structural damage in unconfined compression. Three different types of laboratory tests were designed and performed to calibrate each of these response components. Small-strain dynamic modulus tests were used to calibrate the undamaged linear viscoelastic properties. Cyclic creep and recovery tests to failure were performed to calibrate the viscoplastic properties. Constant-rate-of-strain tests to failure were used to calibrate the damage behavior. These tests were performed at a wide range of temperatures, loading rates, and stress levels. Upon calibration of each individual response, the model was validated by predicting the results of other constant-rate-of-strain tests at temperatures and strain rates different from those used in the calibrations. The predictions for these different conditions indicate that the comprehensive model can realistically simulate a wide range of asphalt concrete behavior.
Feasibility of Backcalculation of Nonlinear Flexible Pavement Layer Parameters from Nondestructive Testing
Authors: Meshkani Amitis , Abdallah Imad N. , Nazarian Soheil
Published: April 2007

Nondestructive testing (NDT) methods are typically used to measure the variations in the modulus of different pavement layers. The falling-weight deflectometer (FWD) and the seismic pavement analyzer (SPA) are two of the NDT devices used for this purpose by the Texas Department of Transportation. Since the loads applied by the FWD to the pavement are similar to those exerted by traffic, the FWD moduli are used in pavement design and analysis without adjusting them for the nonlinear behavior of the materials. Seismic moduli are similar to linear elastic moduli since they correspond to small external loads. A constitutive model that considers nonlinear behavior of pavement materials is essential in order to convert seismic moduli to those appropriate for the state of stress applied by a truck. Nonlinear parameters needed for these models can normally be obtained from laboratory testing. A study was carried out to determine whether these nonlinear parameters can be estimated from the FWD deflection basin alone or from integration of the seismic and FWD data. FWD deflection alone in most cases does not seem to contain enough information to reliably provide the nonlinear parameters of the layers. Combining the seismic and deflection data would allow the estimation of some of the nonlinear parameters for weaker pavement structures. In the authors’ experience, the most reliable way to estimate the nonlinear parameters of base and subgrade is still laboratory testing.
Prediction of Remaining Life of Asphalt Pavement with Falling-Weight Deflectometer Multiload-Level Deflections
Authors: Park Hee Mun , Kim Y. Richard
Published: April 2007

The development of prediction methods for the remaining life of flexible pavements using falling-weight deflectometer (FWD) multiload-level deflections is presented. Pavement response models and pavement performance models were used in developing this procedure. The pavement response models were designed to predict critical pavement responses from surface deflections and deflection basin parameters. The pavement performance models were used to develop the relationships between critical pavement responses obtained from pavement response models and actual pavement performance. Pavement distress data and FWD multiload-level deflection data obtained from the Long-Term Pavement Performance database were used to verify the performance prediction procedure. It was found that the performance of fatigue cracking can be predicted using the proposed procedure except for pavements with high and rapidly increasing cracking in wet-freeze regions. Such trends may be due to environment-induced distresses such as low-temperature cracking, permanent deformation of unbound layers, or both, during the spring thaw period. Predicted rut depths using both single-load and multiload-level deflections show good agreement with measured rut depths over a wide range of rutting potentials. However, the procedure using single–load-level deflections consistently underpredicts the rut depths. This observation demonstrates that the rutting prediction procedure using multiload-level deflections can estimate an excessive level of rutting quite well and thus improve the prediction quality of rutting potential in flexible pavements.
Network Pavement Evaluation with Falling-Weight Deflectometer and Ground-Penetrating Radar
Authors: Noureldin A. Samy , Zhu Karen , Li Shuo , Harris Dwayne
Published: April 2007

Nondestructive testing has become an integral part of pavement evaluation and rehabilitation strategies in recent years. Pavement evaluation employing the falling-weight deflectometer (FWD) and ground-penetrating radar (GPR) can provide valuable information about pavement performance characteristics and be a very useful tool for project prioritization purposes and estimation of a construction budget at the network level. Traditional obstacles to the use of the FWD and GPR in pavement evaluation at the network level used to be expenses involved in data collection, limited resources, and lack of simplified analysis procedures. Indiana experience in pavement evaluation with the FWD and the GPR at the network level is presented. A network-level FWD and GPR testing program was implemented as a part of a study to overcome those traditional obstacles. Periodic generation of necessary data will be useful in determining how best to quantify structural capacity and estimate annual construction budgets. Three FWD tests per mile on 2,200 lane-mi of the network is recommended annually for network-level pavement evaluation. The information collected will allow the equivalent of 100% coverage of the whole network in 5 years. GPR data are recommended to be collected once every 5 years (if another thickness inventory is needed) after the successful network thickness inventory conducted in this study. GPR data collection is also recommended at the project level and for special projects. Both FWD and GPR data are recommended to be used as part of the pavement management system, together with automated collection of data such as international roughness index, pavement condition rating, rut depth, pavement quality index, and skid resistance.
Friction Testing Method for Open-Grated Steel Bridge Decks
Authors: Zimmer Richard A. , Choubane Bouzid , Holzschuher Charles R.
Published: April 2007

For more than four decades, most of the testing methods and studies for the determination or quantification of friction and texture properties have been concerned primarily with concrete and asphalt paved roadways. However, since the focus of such methods has been mainly on paved roads, other traveled surface types, although part of roadway systems, have been overlooked or simply not addressed directly. As travel safety and efficiency are gaining importance to state agencies, it is imperative to include the atypical travel surfaces, such as bridges with open-grated steel decks, in an appropriate measurement program. To this end, the current study was initiated to identify an appropriate method for measuring the friction characteristics on steel bridge decks. An appropriate standardized test method would provide information that can be effectively used in state road safety and management programs. This method would also provide a tool to ensure that all travel surfaces are constructed and maintained with appropriate friction properties. All the results obtained during this investigation indicated that ASTM E-274 can be appropriately used to assess friction characteristics on both paved surfaces and open-grated steel bridge decks. Such information is critical to support informed highway planning and policy and decision making. In addition, the study findings can be used as a basis to revise the current ASTM standard to include open-grated steel bridge decks.