bluuebunny/crossref_metadata_2025 huggingface dataset:
New Procedure for Pavement Parameter Identification from Falling Weight Deflectometer Test
Authors: Al-Khoury R. , Scarpas A. , Kasbergen C. , van Gurp C.
Published: April 2007

A newly developed parameter identification procedure for pavement structures that uses the falling weight deflectometer (FWD) test is presented. The procedure involves the development of both forward and inverse models. The spectral element technique is used for the formulation of the forward model. The spectral element contributes to the efficiency of the procedure because ( a) it is able to describe a whole material layer by one element, which makes the system of equations very small, and ( b) it is able to describe the transfer functions of the system exactly. The latter assists in the development of an efficient objective function for the inverse model. Some aspects of the formulation of the inverse model are presented. Two case studies that address use of the procedure for FWD data harmonization and the accuracy and robustness of the procedure are examined.
Three-Dimensional Numerical Simulation of Asphalt Pavement at Louisiana Accelerated Loading Facility
Authors: Huang Baoshan , Mohammad Louay N. , Rasoulian Masood
Published: April 2007

A true mechanistic pavement design procedure should be able to correctly predict pavement response and the development of pavement distress (such as rutting and fatigue cracking) under various traffic and environmental conditions. A three-dimensional (3-D) numerical simulation procedure with realistic material models would be an effective tool that could be used to achieve such an objective. The results of a 3-D numerical simulation at the Louisiana Accelerated Loading Facility are presented. A 3-D finite-element procedure with moving wheel loads was developed for such analyses. Rate-dependent viscoplastic models were incorporated into the 3-D finite-element procedure. A creep model was used to predict rutting of the asphalt pavement. The results indicated that the 3-D finite-element procedure with viscoplastic models is capable of reflecting the pavement responses and predicting pavement rutting with reasonable accuracy.
Study of Rut-Depth Measurements
Authors: Chen Dar-Hao , Bilyeu John , Walker Deborah , Murphy Mike
Published: April 2007

Results obtained with the rut bar were compared with those obtained with other devices, and it was determined why the rut-bar measurements are different from field observations. Also, because it would be beneficial if the cause of the rutting could be identified from the shapes of the profiles collected by next-generation rut-bar vehicles, it was determined whether this is possible. Trenching data were collected for 10 different pavements located in Texas. Rut depths were measured with several devices before a trench was cut across the traffic lane. Careful measurement of each pavement layer was done to determine the amount of rutting in each layer. Although there may be 50 mm of rutting as measured with a straightedge, the rut bar sometimes measured no rutting. The rut bar yielded zero rut depth in 10 percent of cases in which ruts were deeper than 16 mm. This is mainly due to limitations of the current rut-bar setup, specifically, the sensor spacing and rut-bar length. A profile alone is still not adequate to determine the layer in which rutting occurred. Material-related problems such as bleeding yielded wide-basin rutting that appears to be base or sub-grade rutting, as observed from the profile alone. The profile has been found to be inadequate for determination of the major source of rutting except when there is a clear dual-wheel rut. This is a good indication that rutting is isolated to the asphalt concrete surface layer. The sensor spacing recommended for routine data collection is 100 mm. Analysis of the data shows that this spacing is 95 percent accurate and capable of capturing dual-tire ruts.
Seasonal Temperature Effects on Flexible Pavements in Tennessee
Authors: Marshall Chris , Meier Roger , Welch Michael
Published: April 2007

Beginning in 1996, four newly constructed flexible pavements in Tennessee were instrumented with automated weather stations and various in situ devices to measure temperature and moisture conditions throughout the pavement system. Since their completion, falling weight deflectometer (FWD) tests have been performed periodically to assess the seasonal changes in pavement response. The collected data were analyzed to establish correlations between the pavement layer moduli (back calculated from the FWD results by using MODULUS, Version 5.0) and the asphalt layer temperature. The use of the BELLS3 model to relate asphalt temperature to air and surface temperatures is also explored.
Effective Layer Temperature Prediction Model and Temperature Correction via Falling Weight Deflectometer Deflections
Authors: Park Dong-Yeob , Buch Neeraj , Chatti Karim
Published: April 2007

Surface deflections and backcalculated layer moduli of flexible pavements are significantly affected by the temperature of the asphalt concrete (AC) layer. The correction of these deflections and moduli to a reference temperature requires the determination of an effective temperature of the AC layer. In light of this, a new temperature prediction model for determination of the AC temperature on the basis of a database approach is presented, and temperature correction factors for AC modulus are developed. Temperature datum points ( n = 317) and deflection profiles ( n = 656) were collected from the six in-service test sites in Michigan. Temperature datum points ( n = 197) from three of the test sites were used to develop the temperature prediction model, and data from the remaining sites were used for validation. The temperature prediction model developed has an R2 value greater than 90 percent and an F-statistic significantly greater than 1.0. For further validation of the temperature prediction model, temperature datum points ( n = 18,444) from seven Seasonal Monitoring Program sites (Colorado, Connecticut, Georgia, Nebraska, Minnesota, South Dakota, and Texas) were obtained from DATAPAVE, version 2.0 (Long-Term Pavement Performance program database). The validation results suggested that the model could be adapted to all seasons and other climatic and geographic regions. The major improvements over existing models are that ( a) the model does not require temperatures for the previous 5 days, ( b) it takes into account temperature gradients due to diurnal heating and cooling cycles, and ( c) it needs fewer parameters than other published models. The effect of temperature prediction error on the performance prediction was also investigated.
Novel Approach to Pavement Cracking Detection Based on Neural Network
Authors: Cheng H. D. , Wang Jingli , Hu Y. G. , Glazier C. , Shi X. J. , Chen X. W.
Published: April 2007

The collection of pavement surface condition data is usually done by conventional visual and manual approaches, which are very costly, time-consuming, dangerous, labor-intensive, and subjective. These approaches have high degrees of variability, are unable to provide meaningful quantitative information, and almost always lead to inconsistencies in cracking details over space and across evaluations. A novel pavement crack detection approach based on neural network and computer vision, pattern recognition, and image-processing techniques is proposed. The thresholding approach is used to separate crack pixels from the background. The selection of the thresholds is critical to the performance of automated crack detection systems. Statistical values (mean and standard deviation) are used as the features, and they are used to train the neural network for selection of the thresholds. Because of the noise, the resulting images have some isolated spots that can be eliminated by a curve detector. Finally, Hough transformation is used to detect or classify all cracks in parallel. The experimental results have demonstrated that the cracks are correctly and effectively detected by the proposed method, which will be useful for pavement management.
Smoothness Models for Hot-Mix Asphalt-Surfaced Pavements: Developed from Long-Term Pavement Performance Program Data
Authors: Von Quintus Harold L. , Eltahan Ahmed , Yau Amber
Published: April 2007

The results of a study conducted to determine the relationship between changes in the surface distress of flexible pavements and incremental changes in the international roughness index (IRI) or ride quality by using Long-Term Pavement Performance (LTPP) program data are presented. The results of the regression analyses completed to identify those distresses found to be important and related to incremental changes in the IRI were obtained under the sponsorship of NCHRP Project 1-37A (Development of the 2002 Guide for the Design of New and Rehabilitated Pavement Structures). The results from the study have shown that selected distresses do have a significant effect on incremental changes in IRI with time and traffic. The results summarized can be used for the management, design, or evaluation of pavement structures.
Virtual Environment for Transportation Data Management System
Authors: Meng Chua Koon , McKeen Gordon , Burge John , Luger George
Published: April 2007

The New Mexico State Highway and Transportation Department has routinely been collecting traffic data and pavement nondestructive testing data (pavement surface deflections) and realized that unless a more efficient way to retrieve and review voluminous amounts of transportation data were developed, the highway engineer would be overwhelmed and some of the data would have to be ignored for practical reasons. The Virtual Environment for Transportation Data (VETD) management system was developed as a proof-of-concept software package to overcome this problem. The VETD management system is a comprehensive front-end software package that allows the user to easily locate and retrieve data files through a map and to visualize large data sets. The user can then invoke numerical or analytical tools to facilitate the decision-making process. The user can also call any off-the-shelf three-dimensional topographical software package to access the virtual-reality representation of the surrounding area associated with the data in question. The visualization routine is unique in that it allows charting of two-dimensional, three- dimensional, or radar-time plots even as the data are scrolled (dynamically accessed) from the database. The front-end package was designed to be easily interfaced with other software by allowing on-screen data to be parsed into other programs as text. This project was funded through the FHWA Priority Technologies Program and was managed by the New Mexico Division of FHWA.
Increasing Life Cycles of Pavement Structures by Lane Shifting
Authors: Parvini Mehdi
Published: April 2007

Increasing the life cycle of a system by adopting a proper operational policy is the most efficient way of improving the productivity of the system. Although a better design requires a higher initial cost, and a good maintenance program requires an ongoing expense, the cost of an optimum operation is often relatively low. Pavement systems are not an exception to this rule. A key factor in optimization of the operation of a pavement system is to let the pavement cross section deteriorate uniformly. Lane shifting is proposed as an effective operational policy to increase the efficiencies of pavement systems. The approach is based on the lateral transfer of wheel loads to reduce the damage due to load repetitions under the wheelpaths. On the basis of a parametric study, factors involved in the effectiveness of this strategy are determined and a methodology for a cost-benefit analysis is presented.
Mathematical Model for Calculation of Pavement Temperatures: Comparison of Calculated and Measured Temperatures
Authors: Hermansson Åke
Published: April 2007

A simulation model has been developed to calculate pavement temperatures during summer conditions. Data input into the model are hourly values for solar radiation, air temperature, and wind velocity. The levels of long-wave radiation incident to and outgoing from the pavement surface are calculated from the air and pavement surface temperatures, respectively. The portion of the incident shortwave radiation absorbed by the pavement surface is calculated from the albedo of the surface. By means of a finite-difference approximation of the heat transfer equation, the temperatures under the surface are calculated. Convection losses from the pavement surface are also calculated on the basis of wind velocity, air temperature, and surface temperature. The model is validated by using data from 12 different sections in the Long-Term Pavement Performance program. One set of parameter values for albedo, emissivity, long-wave counterradiation, and convection losses that gave a good correspondence for asphalt concrete and one set of parameter values that gave a good correspondence for cement concrete are given. The formulas used in Superpave to calculate maximum pavement temperatures are based on the assumption that there is an equilibrium when a maximum temperature is reached. Such an equilibrium assumption can strongly be questioned. The author instead suggests that the proposed simulation model can be used to calculate the maximum temperature of a pavement either by calculating the maximum solar radiation or, as suggested, by using weather data. Then, sets of calculation parameters are used for asphalt concrete and for cement concrete pavements, respectively. The parameters are obtained by analyzing several years of weather data and the corresponding pavement temperature information.
Advantages and Limits of Different Road Roughness Profile Signal-Processing Procedures Applied in Europe
Authors: Delanne Yves , Pereira Paulo A. A.
Published: April 2007

Three road profile signal-processing methods that give parameters or indices used for the detection of road unevenness in Europe are compared: international roughness index (IRI) analysis, power spectral density analysis, and constant percent bandwidth spectrum analysis. This comparison is carried out with road rideability prediction models, car vibration prediction models, and careful diagnosis and definition of rehabilitation work. The IRI meets the profiling needs with regard to the assessment of road condition, the road serviceability level, and the setting of priorities for planning for road maintenance and repair. This index is not suitable for specification of rehabilitation work or for diagnosis of possible problems with road sections. Power spectral density (PSD) analysis by the International Organization for Standardization’s Standard 8608 is a suitable method with regard to the evaluation of evenness level only if, on the basis of the averaging length, the road profile can be considered a stationary stochastic process and if a single regression line can be fitted. PSD is valuable for the detection of periodic defects in the road profile. Constant percent bandwidth spectrum analysis of consecutive segments along the section under investigation is well adapted to both the road serviceability evaluation and the diagnosis of possible problems with road sections.
Low-Temperature Binder Specification Development: Thermal Stress Restrained Specimen Testing of Asphalt Binders and Mixtures
Authors: Roy Sushanta D. , Hesp Simon A. M.
Published: April 2007

Results of low-temperature testing of Bow River asphalt binders and concrete mixtures, unmodified and modified with three commercially used polymers [diblock styrene-butadiene (SB), radial styrene-butadiene-styrene (SBS), and ethylene-vinyl acetate], are discussed. Thermal stress-restrained specimen tests, at a cooling rate of 10°C/h, were used to evaluate the performance of binders and mixtures. Binders were restrained as direct tension specimens with and without a sharp starter crack. Notching of the samples resulted in lower failure loads for all systems. But three of the four binders failed at warmer temperatures. The fourth binder, an exceptionally tough radial SBS-modified system, remained unaffected in this regard. Changes in failure temperatures ranged from 0°C (radial SBS) to +12°C (diblock SB). A comparison of binder results with those obtained for the mixture yields additional insights. It appears that there are differences between binder and mixture failure modes. The higher stress levels encountered in the mixture give rise to energy dissipating mechanisms that do not occur at the lower stress levels in the binder test. It is unlikely that a specification based on binder failure stress or strain will predict performance in polymer-modified systems. Three-point bend tests on notched asphalt binder or mastic beams may provide more realistic conditions for measuring materials properties. A compression test on the binder or mastic may be used to determine additional important parameters, such as Young’s modulus and yield stress in compression, which along with the failure properties, will likely produce an improved fracture mechanics-based low-temperature failure criterion.
Sample Preparation for Direct Tension Testing: Improving Determination of Asphalt Binder Failure Stress and Test Repeatability
Authors: Man Sze Ho Susanna , Zanzotto Ludo
Published: April 2007

During Superpave direct tension testing (DTT) of asphalt binders, the failure stress and failure strain values were found to depend strongly on the molecules of asphalt in the DTT mold forming a stable network. An asphalt specimen in which molecules have formed a network with aligned dipole moments has a higher DTT failure stress value. A sample preparation method based on this theory was developed. In this method, ceramic tiles holding the DTT molds were heated in an oven with controlled temperatures specific to the performance grade (PG) of the binder. These heated ceramic tiles provided a means for the poured asphalt to stay fluid and cool slowly and uniformly. The theory, detailed method development, and sample preparation procedure are described. With this method, the DTT failure stress of asphalt binder is higher than in samples prepared without controlled cooling. The variability of failure stress and failure strain values of the six specimens within the same run is usually less than 15 percent for the softer asphalt, for example, PG52–34, and somewhat higher for the harder asphalt, for example, PG64–28. The average results of the best four out of six specimens usually agreed with another run within 10 percent, regardless of asphalt type. Important considerations during preparation of DTT samples are discussed. The incorporation of these details for the sample preparation method in the DTT procedure will lead to better agreement of direct tension results among different laboratories.
Proposed Refinement of Superpave High-Temperature Specification Parameter for Performance-Graded Binders
Authors: Bouldin Mark G. , Dongré Raj , D′Angelo John
Published: April 2007

A semiempirical approach developed to predict the viscoelastic response of a binder in repeated creep recovery tests is described. This model provides an avenue to predict the rut resistance ( R) as a function of loading (time and load) and temperature from data at a single frequency or frequency sweeps when needed. Thus, it can be used to develop a grading procedure for asphalt binders that not only accurately captures the delayed elasticity of modified binders but also accounts for the effect of traffic speed and traffic loading. The current Superpave binder specification attempts to capture the relative high-temperature performance (i.e., resistance to rut) of a binder via the inverse shear loss compliance, 1/ J” or G*/sin δ, at 10 rad/s. This parameter represents an improvement over the absolute viscosity because it is measured at a defined rate of deformation and accounts to some degree for the viscoelasticity of the binder via the phase angle. The parameter would correctly predict the relative R for an ideally viscous ( R ∞ η) material or an ideally elastic material ( R = ∞). However, there is mounting evidence that at phase angles between 40° and 75°, the parameter may not fully capture the viscoelastic nature of many modified binders. Various authors have shown that the R of mixtures can be well described by models using data from dynamic creep experiments, in which the mix is subjected to a load followed by a relaxation period. More recently, Bahia proposed to capture their high-temperature performance by using a similar technique on neat binders.
Evaluation of Fatigue Criteria for Asphalt Binders
Authors: Anderson David A. , Le Hir Yann M. , Marasteanu Mihai O. , Planche Jean-Pascal , Martin Didier , Gauthier Gilles
Published: April 2007

The original SuperPave asphalt binder specification criterion for fatigue, G* sin δ, has received considerable criticism. Recently, a time sweep using the dynamic shear rheometer (DSR) has been proposed as an alternative test method for developing load-associated fatigue information for asphalt binders. This proposed test method is examined with respect to a phenomenon called edge fracture. Edge fracture is reported in the literature for steady state and oscillatory flow in DSR, but it has not been reported for asphalt binders. The modulus, when plotted versus number of cycles generated in a time sweep test, has the appearance typical of fatigue behavior; however, the actual response of the material depends markedly on the initial modulus of the material. The development of the modulus with repeated shearing is described with respect to flow of the asphalt binder at its circumference. The data are examined with respect to their validity as a measure of fatigue, and recommendations with respect to the use of time sweep data in a binder specification are presented.
Correlations Between Superpave Asphalt Stiffnesses and In-Service Pavement Performance
Authors: Galal Khaled A. , White Thomas D.
Published: April 2007

One of the primary concerns in the state of Indiana is the early appearance of flexible pavement distresses. Early distresses may result in pavement failure, shorter pavement service life, or both. The Strategic Highway Research Program–developed Superpave asphalt binder specifications are directed toward in-service pavement performance. Superpave binder tests and associated criteria were selected to control distresses that effect in-service hot-mix asphalt performance, specifically, permanent deformation, fatigue cracking, and low-temperature thermal cracking. The Indiana Department of Transportation was interested in whether or not the changes in in-service asphalt can be related to pavement distresses. Several factors were examined, including the type and severity of distresses as documented by pavement condition surveys. Also, Superpave asphalt binder tests were conducted on the original and the recovered in-service binders. One important aspect of the study was how the changes of inservice asphalts can be related to such distresses as permanent deformation, fatigue cracking, or low-temperature thermal cracking. This study documents the relationship among in-service asphalt binder stiffnesses, as characterized by complex shear modulus or binder stiffness ( G*), and in-service permanent deformation and cracking, as characterized by pavement maintenance management system deduct values. The study documents a poor relationship between in-service binder stiffness and in-service permanent deformation or rutting. The study also documents a good relationship between in-service stiffness and in-service cracking.
Quantitative Evaluation of Stripping Potential in Hot-Mix Asphalt, Using Ultrasonic Energy for Moisture-Accelerated Conditioning
Authors: McCann Martin , Sebaaly Peter
Published: April 2007

The ultrasonic moisture-accelerated conditioning process is a quantitative analysis to establish the moisture sensitivity of any given hot-mix asphalt (HMA) pavement. While in a water bath at a constant 60°C, a sample from an HMA mix is conditioned by ultrasonic energy for a specified period of time. The repeated cycle of compression then cavitation accelerates the detachment and displacement of the asphalt binder from the aggregate’s surface. The proportion of separated particles versus conditioning time has been statistically shown to have a unique linear relationship for each HMA mix. The test procedure was implemented on a variety of pavement mixtures and was found to distinguish among aggregate sources, different asphalt binders, specimens containing lime versus no lime, and variability in asphalt binder content. Simplicity of the ultrasonic moisture-accelerated conditioning process is attributed to the ease in which a sample is prepared and conditioned. Samples can be derived from pavement cores or used from briquettes after establishing the job mix formula. When submerged in the water bath and subjected to ultrasonic moisture-accelerated conditioning, the samples are subjected only to variables associated with moisture sensitivity: aggregate, asphalt binder, water, temperature, and energy.
Repeated Triaxial Testing During Mix Design for Performance Characterization
Authors: Carpenter Samuel H. , Vavrik William R.
Published: April 2007

The advancement of the Superpave gyratory compactor (SGC) has led to a recognized need for a simple test that preferably can be performed on SGC samples during mix design that would rank performance potential of the mixtures if used in a pavement. Although it has proved difficult to find one test that can rate mixture potential for rutting and fatigue cracking and modulus, a limited study was conducted on Illinois mixtures that provides evidence that a simple test performed during mix design has the potential to predict a diverse set of performance characteristics. The results are presented for 10 Illinois dense-graded mixtures of surface and binder (9.5 and 12.5 mm) gradations that were tested in an asphalt pavement analyzer (APA) and subjected to flexural beam fatigue, unconfined repeated load permanent deformation, and diametral resilient modulus testing. The mixtures were further subjected to a rapid triaxial test procedure using SGC compacted samples, as taken from the SGC machine, and tested at 50°C in a triaxial stress reversal mode. The triaxial testing provides data that predicts resilient modulus, APA rutting results, fatigue coefficients, and permanent deformation characteristics of accumulated strain at tertiary failure, loads to tertiary failure, and the exponent to the standard logarithmic permanent deformation curve. The excellent correlations obtained from this study provide direct evidence that this test protocol may provide a structural evaluation procedure to supplement the volumetric mix design process and warrants further study.
Variability of Asphalt Mixture Tests Using Superpave Shear Tester Repeated Shear at Constant Height Test
Authors: Romero Pedro , Anderson R. Michael
Published: April 2007

Analyses were conducted on data obtained from the Superpave shear tester using the repeated shear at constant height (RSCH) test. The data indicated that even under the most controlled experimental conditions, the resulting parameters showed high variability. Up to six replicate samples were tested using an extra shear linear variable differential transformer. The coefficient of variation of the permanent strain at 5,000 load cycles for six samples was between 10 and 20 percent in most cases. From the different options studied to decrease variability, the trimmed-mean method provided the greatest decrease in the coefficient of variation without affecting the mean of the results. In this method, five specimens are tested, the high and low values eliminated, and the remaining three are used to obtain the mean and standard deviation of the results. Since the suggested trimmed-mean method requires an increase in the number of samples tested to five, it is proposed that the number of load cycles used in the RSCH test be reduced for materials placed in low-volume roads.
Mechanistic Analysis of Asphalt Pavements, Using Superpave Shear Tester and Hamburg Wheel-Tracking Device
Authors: Wang Jian-Neng , Yang Chien-Kuo , Luo Tsair-Yi
Published: April 2007

A comparative evaluation of permanent deformation and moisture damage of asphalt mixtures using the Superpave shear tester and the Hamburg wheel-tracking device (HWTD) is presented. The damage analysis of simulated asphalt pavements is also included. The selected materials were a PG 64-22 asphalt binder and a sandstone aggregate with and without an antistripping additive. The repeated shear at constant height (RSCH) and HWTD tests were performed for the evaluation of permanent deformation. The results showed that the Superpave mixtures were less susceptible to permanent deformation than the Marshall mixture. The results of the HWTD tests performed at 40°C were consistent with those of the RSCH tests. Two permanent deformation models were compared to relate plastic strain accumulation with the number of load repetitions. The one selected for use in the Strategic Highway Research Program A-005 contract is generally better than the other model. For moisture susceptibility evaluation of these mixtures, the results of the AASHTO T283 tests were consistent with those of the HWTD tests at 40°C. The creep compliances calculated from the frequency sweep at constant height tests were applied to the KENLAYER program for pavement damage analysis. On the basis of the data analyses in this study, the simulated asphalt pavements are considered more of a material and mix design problem than a structural problem. The use of creep compliances of the above mixtures could not successfully predict the pavement performance in comparison with results of the RSCH and HWTD tests.
Effect of Mix Gradation on Rutting Potential of Dense-Graded Asphalt Mixtures
Authors: Kandhal Prithvi S. , Mallick Rajib B.
Published: April 2007

A study was conducted to evaluate the effect of mix gradations, both complying with and violating the Superpave restricted zone, on rutting potential of hot-mix asphalt. Superpave gyratory samples of mixes with granite, limestone, and gravel aggregates were used. The following gradations were used: gradation above the restricted zone, gradation through the restricted zone in close proximity to the maximum density line, and gradation below the restricted zone. Rut tests were conducted at 64°C with the asphalt pavement analyzer under 689-kPa contact pressure and 45.2-kg wheel load. Rut depths were measured at the end of 8,000 cycles. Repeated shear tests at a constant height were also conducted with the Superpave shear tester. Statistical analysis of rut data generally indicates a significant difference between rut depths obtained in mixes using different aggregate types and gradations. The gradations violating the restricted zone did not necessarily give relatively higher rut depths compared with the gradations in compliance with the zone.
Impact of Gradation Relative to Superpave Restricted Zone on Hot-Mix Asphalt Performance
Authors: Hand Adam J. , Epps Amy L.
Published: April 2007

Significant controversy has revolved around the Superpave gradation specifications, in particular the restricted zone, since the completion of the Strategic Highway Research Program (SHRP). Historically, dense-graded mixtures that encroach on the restricted zone had provided good performance prior to SHRP. However, current Superpave guidelines recommend that gradations passing through the restricted zone not be used. A synopsis of recent research related specifically to the impact of the Superpave restricted zone on performance of hotmix asphalt (HMA) is provided. The evolution and purpose of the Superpave restricted zone are presented, along with findings of both recently completed and ongoing research. Studies involving laboratory and full-scale accelerated performance tests of mixtures with gradations plotting above (ARZ), through (TRZ), and below the restricted zone were considered. The research reviewed clearly suggests that good performance can be achieved with fine-graded (ARZ and TRZ) mixtures and that no relationship exists between the Superpave restricted zone and HMA rutting or fatigue performance. It is suggested on the basis of this research that the restricted zone recommendation be eliminated from the Superpave volumetric mixture design specifications.
Applications of State Employment Data to Transportation Planning
Authors: Souleyrette Reginald R. , Plazak David J. , Strauss Tim R. , Andrle Stephen J.
Published: April 2007

A major problem in transportation modeling is the acquisition of quality employment data. Employment data are used in transportation planning to model the journey to work and other types of trips, but they rarely are collected solely for transportation purposes because of the large expense involved. Census data, on the other hand, are inexpensive but are collected only every 10 years (although the American Community Survey provides some continuous data). This presentation outlines and assesses a process to develop systems and protocols for using an already-collected set of detailed employment data for an alternative purpose, transportation planning. Tapping this source may provide an ongoing, economical, and annual source of important transportation data that allows planners to better model and predict transportation needs, from the commuter and the business perspective. A better understanding of travel patterns, in turn, helps planners to evaluate investments in fixed physical infrastructure and public transportation. The data set also has valuable uses in other fields, such as workforce development planning, economic development, land use planning, and social service delivery. The success of this project required intergovernmental cooperation from several key partners.
Proposed Framework for State-Based, Data-Driven Models for Improved Transportation Operations
Authors: Scherer William T. , Sadek Adel W. , Smith Brian L.
Published: April 2007

Numerous transportation analysis and modeling tools have been developed over the last 30 years, and the data collection for these models was a personnel-intensive process requiring significant resources. As a result, there typically were insufficient amounts of data to verify transportation models under diverse operating conditions. However, with the proliferation of sensors to support intelligent transportation systems, researchers now find themselves in a data glut and an information shortage. With this data overload, there is a need to shift the modeling focus toward a state-based modeling approach. Fundamental to this is the need to explore the question of what constitutes a parsimonious state definition that effectively captures the dynamics of a large-scale, regional transportation system. Discussed are a proposed framework for a state-based modeling paradigm and, specifically, two key concepts to this new approach: case-based reasoning and simulation for model generation.
Traffic Characteristics in the Arab Gulf Region: Case Study in Abu Dhabi, United Arab Emirates
Authors: Salem Al Kathairi Abdulla , Mufti Rasin K. , Garib Atef M. , Williams Bradlee F. , Karim Anwar
Published: April 2007

The municipality of Abu Dhabi is in the process of updating its long-range master transportation plan. The initial step in this process was to collect substantial data on existing transportation system characteristics. The extensive data-collection program made possible a comprehensive analysis of traffic characteristics for the first time in more than 20 years. Traffic characteristics in Abu Dhabi have changed significantly during this time. Recent changes in government working hours have caused a dramatic shift in peaking patterns. Some characteristics, such as the availability and performance of taxis, are unique. Other characteristics, such as general peak period factors, are typical of most Arab Gulf cities. Presented is an analysis of existing traffic characteristics in Abu Dhabi. Peaking patterns, vehicle classifications, vehicle occupancies, and other characteristics are analyzed and described. The characteristics that are unique to Abu Dhabi are identified. Characteristics transferable to other Gulf Cooperation Council countries are highlighted and discussed.
Toll Road Origin-Destination Travel Survey: Internet and Mail-Back Response Analysis and Implications for Future Surveys
Authors: Abdel-Aty Mohamed A. , Abdelwahab Hassan T.
Published: April 2007

Use of the Internet compared with mail-back respondents for an origindestination survey of Central Florida’s expressway system users is analyzed. Surveys were distributed by two methods: handing out of surveys to manual-payment and automatic coin machine (ACM) users, and mailing out of surveys to automatic vehicle identification (E-Pass) users. Data collection was primarily by prepaid business reply mail or by Internet. The survey achieved an overall response rate of 12.7 percent: 7.5 percent for manual and ACM users and 20.6 percent for E-Pass users. About 2.5 percent of these responses were made by the Internet. Although Internet response was not specifically requested, the web address was printed on the survey form, and analysis showed that this response method has great potential. The quality and completeness of the responses received via the Internet were much better than those of the responses received by mail; that is, there were fewer nonresponses to items, and they required on average only 6.7 min to finish. The results show that the odds of Internet response are much higher for young respondents (16 to 25 years old) and that the odds of Internet response have a decreasing trend with age. Finally, professionals and E-Pass users tend to have a higher preference for responding by using the Internet. Among the benefits of using the Internet method in this study were the ability to validate the responses and eliminate coding errors and to ensure that key questions in the survey were answered. It provided the possibility to include maps to help respondents identify the ramps they used. The Internet was cost-effective by eliminating printing, mailing, and coding expenses.
Dynamic Freeway Travel-Time Prediction with Probe Vehicle Data: Link Based Versus Path Based
Authors: Chen Mei , Chien Steven I. J.
Published: April 2007

Short-term travel-time prediction is very important to the real-time traveler information and route guidance system. Various methodologies have been developed for dynamic travel-time prediction. However, most existing studies assume that path travel time is the simple addition of travel times on the consisting links. Through simulation, it is shown that, under recurrent traffic conditions, direct measuring of path-based (or movement-based) travel time rather than link-based travel time could generate a more accurate prediction. Factors that would have an effect on the prediction accuracy are analyzed.
Integrated Platform for Managing Utilities Along Highway Corridors
Authors: Quiroga Cesar , Ellis Christopher D. , Shin Sang-Young
Published: April 2007

Continued proliferation of utilities along highway corridors is affecting the ability of transportation agencies to deliver and manage transportation facilities effectively. From a data-management perspective, two specific issues are of interest to transportation agencies: data needs, data compatibility, and coordination with utility companies; and platform and procedures to support a utility data management system that properly addresses the needs of the transportation agency. Described is the architecture of a prototype platform for the management of utility data that takes into consideration utility data characteristics and roadway network characteristics. The platform uses the Global Positioning System (GPS), the geographic information system (GIS), and Internet technologies. The model includes a GPS/GIS-based prototype to represent utility facilities located within a highway right-of-way and associated attribute data such as ownership, purpose, size, type, and shared and multiple uses. The model also includes a prototype Internet-based data entry procedure to facilitate the capture of utility data from a variety of utility entities.
Pavement Performance Analysis Applying Probabilistic Deterioration Methods
Authors: Tack Joseph N. , Chou Y. J.
Published: April 2007

The procedure used to determine whether performance differences exist among the Ohio Department of Transportation’s (ODOT’s) 12 districts is presented. Two performance measures were used: pavement condition rating deterioration trends and distributions. The methods used to develop the performance measures from existing pavement data are presented. Five years of actual pavement inspection data were supplied. The study was limited to divided highways with four or more lanes. To develop the deterioration trends, existing data were transformed into a probabilistic deterioration model using geographic information systems and relational database software. Monte Carlo simulation was used to establish deterioration trends and a Markovian deterioration envelope. Hypothesis testing was implemented to determine which districts were performing better or worse than the state as a whole. ODOT’s northeastern districts performed worse than the state average, and rural districts performed better than the state average.
Data Warehouse Digital Archiving Case Study: North Carolina Department of Transportation
Authors: Rasdorf William , Taylor Kent , Wikoff Larry
Published: April 2007

Data at state departments of transportation (DOTs) are numerous and varied. Large legacy data stores exist in many forms; are stored in a variety of media; and include such diverse items as text (calculations, forms, correspondence, specifications, and so forth), drawings, and photographs. Enormous collections of new data are continuously being created. Nearly all of the legacy data are in paper form. Even much of the newly collected data begins on paper, although most new data collection efforts are being converted to digital form. Given the current state, the key problems faced by state DOTs are how to find and acquire needed data, how to store it (warehouse), how to convert it to a useful form, how to relate it to other data (so that new analyses can be performed), how to manage it, how to access and use it, and how to archive it for both predicted and unexpected future needs. In another context, state DOTs are asking what to convert to digital form; what to do with data that are not in digital form; how to manage and access digital data warehouses; and how to maintain digital data in the face of continuous and drastic changes in hardware, software, and storage media. These questions are addressed in the context of a study conducted by the Traffic Survey Unit of the North Carolina Department of Transportation that led to some insightful and unexpected observations.
Performance Evaluation of Piezoelectric Weigh-in-Motion Sensors Under Controlled Field-Loading Conditions
Authors: Alavi Sirous H. , Mactutis Joseph A. , Gibson Scott D. , Thomas Papagiannakis A. , Reynaud David
Published: April 2007

A research study evaluating piezoelectric sensors used for collecting Weigh-in-Motion (WIM) data is summarized. The evaluation was sponsored by the Highway Innovative Technology Evaluation Center and consisted of testing the WIM sensors under controlled laboratory and fieldloading conditions in both asphalt concrete (AC) and portland cement concrete (PCC) pavements. The field evaluation of piezoelectric WIM sensors is emphasized. The AC installation was performed at the WesTrack test facility near Reno, Nevada, and the PCC installation was performed at a California Department of Transportation (Caltrans) Heavy Vehicle Simulator test site near Palmdale, California. In addition, a compatibility study of the response of the WIM sensors with different data acquisition systems was conducted at the WesTrack facility. Also, various types of grouts were used in the WIM installations. Results indicated that WIM sensor performance was most dependent on the ability of data acquisition systems to process the raw sensor output accurately.
Field Investigation of High-Performance Concrete Bridge Decks in South Carolina
Authors: Petrou Michael F. , Harries Kent A. , Schroeder Gerald E.
Published: April 2007

A high-performance concrete (HPC) mixture has been used on several bridge construction projects in the upstate region of South Carolina. The majority of these bridge decks, although not all, have experienced problems with early-age cracking both before being opened to traffic and immediately thereafter. The cracking exhibited in these bridge decks presents a significant obstacle to the widespread adoption of HPC materials for bridges in South Carolina. In an effort to determine likely causes of the cracking experienced in these concrete bridge decks, sight inspections were made of nine bridges in the Greenville-Spartanburg, South Carolina, area, and a thorough review of construction documentation from three of these sites was carried out. In addition, a review of the South Carolina Department of Transportation concrete specifications was conducted. It was concluded that observed cracking has two likely causes. Early-age shrinkage cracking resulted from a rich concrete mixture combined with poor curing practices. Load-induced cracking, appearing shortly after the spans were open to traffic, may result from the placement of relatively stiff decks on more flexible bridge superstructures. Improved on-site quality control and quality assurance are recommended for all aspects of mixing, placing, and curing when HPC is used. It is also recommended that a more appropriate HPC mix design be developed for use in bridge decks. Such a concrete mix would have enhanced durability characteristics and should not be a high-strength mix. Adoption of the eight FHWA performance criteria for HPC is recommended.
Comparative Study of AASHTO Load and Resistance Factor Design Distribution Factors for Slab-Girder Bridges
Authors: Puckett Jay A.
Published: April 2007

The distribution factors for slab-on-girder bridges in AASHTO load and resistance factor design (LRFD), and the work upon which they are based, were compared with results from an independent analysis based on the finite strip method. The primary objective of the current work offers an independent comparison of 352 of the same bridges used in the development of the AASHTO LRFD factors. The comparisons were limited to interior girders of slab-on-girder bridges, and the results were compared closely within reasonable deviation. Because of the importance of the AASHTO factors, this independent confirmation is documented. Moreover, statistics on the variability are helpful for calibration where analysis factors are involved.
Dynamic Loading of Bridges
Authors: Heywood Rob , Roberts Wayne , Boully Geoff
Published: April 2007

Management of the aging bridge infrastructure is demanding an increased understanding of all aspects of the performance of existing bridges. Loading models are an important consideration in the risk assessment of a structure. Quantifying the actual in-service dynamic response of a structure can make a significant difference in terms of keeping a bridge in service. Code-recommended allowances for dynamic effects range between 20 and 40 percent for major elements. Higher values are sometimes recommended for local effects. It is well understood that parameters including the unevenness of the road profile, the potential of frequency matching between heavy vehicles and the bridge, vehicle speed, and heavy-vehicle load levels all contribute to the dynamic response of a bridge to a single-vehicle event. Multiple vehicles increase the complexity even further. Recent new editions of bridge codes around the world tend to have diversified the methods and allowances for dynamic effects. These methods are compared, and then they are compared with a database of experimental responses measured in a range of structures in Australia and New Zealand during recent years. The results clearly illustrate the importance of each of the above parameters and that very large dynamic responses can be achieved, particularly in short-span structures.