bluuebunny/crossref_metadata_2025 huggingface dataset:
Design Guidelines for Truck Lanes on Mexican Two-Lane Roads
Authors: Mendoza Alberto , Mayoral Emilio
Published: January 2019

The results of a research project undertaken by the Mexican Transport Institute and the Freight Transportation and Distribution Systems Department of the Autonomous University of Querétaro for generating design recommendations in adding lanes for trucks on Mexican two-lane, two-way roads are presented. Implementation of additional lanes traditionally has been considered among the most efficient low-cost improvements on specific grades (longer than 800 m and steeper than 3 percent). This paper discusses the problem of improving traffic operations on composite grades (a series of consecutive grades with different gradients) that are located in rolling or mountainous terrain by implementing added lanes in both directions. This can be done in a series of appropriate subsegments. Basically, these subsegments are in places that lack the necessary passing sight distance. The longest traffic platoons usually occur in these places.
Washington State's Stormwater Management Program
Authors: Schaftlein Shari
Published: January 2019

To comply with state and federal laws, the Washington State Department of Transportation developed a Stormwater Management Program. The program included an outfall inventory and retrofit program, a Highway Runoff Manual (HRM), and stormwater research. Field crew inventoried sites where highway stormwater runoff is collected and discharged to surface water, ground water, and municipal storm sewers. Pipes, ditches, and stormwater structures that provide quantity and quality control were inventoried. The screening assessment for potential water pollution problems was made via observation and sampling kit. The sampling kit was found to be ineffective at identifying illicit connections. Inventoried sites were mapped using global positioning and geographic information system technology. Research was conducted on sites to determine watershed characteristics, potential environmental effects, and Best Management Practice (BMP) retrofit options. A computer data base of information is maintained to facilitate stormwater management activities. A prioritization scheme was developed to identify priority sites for retrofit, based on the following factors: receiving water body, beneficial uses, pollution loading, percent highway drainage, cost-pollution benefit, and values trade-off. The HRM was developed to direct stormwater management for existing and new state highways, rest areas, park-and-ride lots, and ferry terminals. Water quality and quantity issues for construction and maintenance are addressed by meeting the minimum requirements of the manual. Thirteen research projects have been funded to evaluate experimental BMPs, to determine BMP pollutant removal efficiencies, and to assess the costs and benefits of retrofitting outfalls. Research included bench-scale work, field projects, and a department survey.
Adjustment of Regional Regression Equations for Urban Storm-Runoff Quality Using At-Site Data
Authors: Barks C. Shane
Published: January 2019

Regional regression equations have been developed to estimate urban storm-runoff loads and mean concentrations using a national data base. Four statistical methods using at-site data to adjust the regional equation predictions were developed to provide better local estimates. The four adjustment procedures are a single-factor adjustment, a regression of the observed data against the predicted values, a regression of the observed values against the predicted values and additional local independent variables, and a weighted combination of a local regression with the regional prediction. Data collected at five representative storm-runoff sites during 22 storms in Little Rock, Arkansas, were used to verify, and, when appropriate, adjust the regional regression equation predictions. Comparison of observed values of storm-runoff loads and mean concentrations to the predicted values from the regional regression equations for nine constituents (chemical oxygen demand, suspended solids, total nitrogen as N, total ammonia plus organic nitrogen as N, total phosphorus as P, dissolved phosphorus as P, total recoverable copper, total recoverable lead, and total recoverable zinc) showed large prediction errors ranging from 63 percent to more than several thousand percent. Prediction errors for 6 of the 18 regional regression equations were less than 100 percent and could be considered reasonable for water-quality prediction equations. The regression adjustment procedure was used to adjust five of the regional equation predictions to improve the predictive accuracy. For seven of the regional equations the observed and the predicted values are not significantly correlated. Thus neither the unadjusted regional equations nor any of the adjustments were appropriate. The mean of the observed values was used as a simple estimator when the regional equation predictions and adjusted predictions were not appropriate.
Design Example for Bridge Pier Scour Measures Using Toskanes
Authors: Burns R. S. , Fotherby L. M. , Ruff J. F. , Carey J. M.
Published: January 2019

Toskanes were developed as an alternative scour countermeasure where riprap is not feasible or available in large sizes. The Toskane design procedure is based on results of a hydraulic model study of several different piers and abutments. Toskanes can be fabricated in sizes to meet the design requirements. One example of installing Toskanes at a bridge with a pier and vertical abutments is presented. Criteria are provided to size the Toskane. Techniques for installation are suggested and costs for the project are estimated.
Enhancement of the Culvert Outlet Scour Estimation Equations
Authors: Abt Steven R. , Thompson Philip L. , Lewis Todd M.
Published: January 2019

A study was conducted to simplify and broaden the procedures for estimating scour dimensions at culvert outlets. In addition, a means was sought to incorporate the influence of culvert shape, culvert slope, and culvert drop height into the scour prediction procedure. On the basis of a review of the literature and further analysis of existing outlet scour data, a general expression was developed relating the dimensions of scour to the culvert discharge, the hydraulic radius, time, and bed material gradation. Culvert-slope and drop-height coefficients were formulated and integrated into the outlet-scour prediction procedure. The results indicate that the 1983 HEC-14 scour calculation procedure can be more comprehensive and simplified for cohesionless materials.
Evaluation of Selected Pier-Scour Equations Using Field Data
Authors: Landers Mark N. , Mueller David S.
Published: January 2019

Field measurements of channel scour at bridges are needed to improve the understanding of scour processes and the ability to accurately predict scour depths. An extensive data base of pier-scour measurements has been developed over the last several years in cooperative studies between state highway departments, the Federal Highway Administration, and the U.S. Geological Survey. Selected scour processes and scour design equations are evaluated using 139 measurements of local scour in live-bed and clear-water conditions. Pier-scour measurements were made at 44 bridges around 90 bridge piers in 12 states. The influence of pier width on scour depth is linear in logarithmic space. The maximum observed ratio of pier width to scour depth is 2.1 for piers aligned to the flow. Flow depth and scour depth were found to have a relation that is linear in logarithmic space and that is not bounded by some critical ratio of flow depth to pier width. Comparisons of computed and observed scour depths indicate that none of the selected equations accurately estimate the depth of scour for all of the measured conditions. Some of the equations performed well as conservative design equations; however, they overpredict many observed scour depths by large amounts. Some equations fit the data well for observed scour depths less than about 3 m (9.8 ft), but significantly underpredict larger observed scour depths.
Clear-Water Scour around Bridge Abutments under Backwater Conditions
Authors: Sturm Terry W. , Sadiq Aftab
Published: January 2019

An experimental study was conducted of the depth of clear-water scour around the end of a square-edged bridge abutment terminating in the floodplain of a compound channel. The study's purpose was to improve current techniques of abutment scour prediction, which are based primarily on laboratory studies in rectangular channels. It is indicated that a discharge contraction ratio arising from a theoretical contraction scour analysis for equilibrium conditions can be used for explaining the effect of flow distribution on the local abutment scour depth in the case where significant backwater occurs from bridge contraction. The use of reference values of approach flow depth and velocity in the floodplain for undisturbed conditions without the bridge is shown to collapse experimental results for scour depth in both the case of a contraction with negligible backwater, and the case of a contraction with significant backwater in the bridge approach section.
Defining and Serving Clients for Pavements
Authors: Haas Ralph , Hudson W. Ronald
Published: January 2019

Total client satisfaction is a goal toward which any service or product provider, including pavement engineers, should strive. If this is to be achieved, the clients for pavements must be well identified, as should be the measures to be used for judging their satisfaction. The key sets of pavement clients are defined, in relation to the different classes of pavements, including roads, off-road areas, airfields, and railbeds. The means by which effective pavement management can serve clients is then addressed. Next, some possible measures of client satisfaction are identified, including ride quality, surface distress, structural adequacy, surface friction, surface drainage, noise, user delays, and life-cycle cost-effectiveness. The degree of importance for different client-measure combinations is suggested, as well. The technologies available for characterizing the measures are described briefly, and some examples are given. Finally, the results of a simple pilot study to determine the relative value of the measures of road user client satisfaction are related; they suggest that on a scale of 0 to 100, ride quality would contribute about 25 percent to overall customer satisfaction, surface distress nearly 20 percent, and all the other measures between about 5 and 10 percent each.
Institutional Issues in Implementation of Pavement Management Systems by Local Agencies
Authors: Amekudzi Adjo A. , Attoh-Okine N. O.
Published: January 2019

To optimize available funds in preserving the national transportation infrastructure, the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA) mandates that state and local agencies develop and implement various infrastructure management systems. One of these systems is a pavement management system (PMS). To comply with ISTEA, jurisdictions must implement a working PMS in order to continue to qualify for federal funds. Institutional issues that obstruct the implementation of PMS by local agencies are identified and analyzed. For effective implementation and continued use, PMS is viewed as both a new philosophy that must be incorporated into the overall organizational goals of an agency and a support tool for better decision making. Since pavement management is usually only one of several agency functions, the large expenditure of resources associated with PMS implementation is impractical for smaller agencies with limited budgets. This situation has lead to the abandonment of several PMS programs. Through a case study of the San Francisco Bay Area's Metropolitan Transportation Commission, strategies for the effective implementation and continued use of PMS are examined, as is the umbrella role of larger metropolitan planning organizations in successfully implementing PMS at local levels. Competing pavement budget requirements between local agencies are examined within the new context of ISTEA's comprehensive system. Finally, it is suggested that implementing PMS within the broader context of an overall infrastructure management apparatus is a strong incentive for optimizing the complete infrastructure system and achieving ISTEA's goal.
Development of Geographic Information System-Based Pavement Management System for Salt Lake City
Authors: Lee H.N. , Jitprasithsiri S. , Lee H. , Sorcic R.G.
Published: January 2019

Over the past 3 years, a major effort has been made toward making a pavement management system (PMS) functional in Salt Lake City, Utah. As part of this effort, a geographic information system (GIS) was developed to enhance the existing PMS. The GIS-based PMS (G-PMS) developed for Salt Lake City is presented. G-PMS was written in Map-Basic, the programming language of MapInfo, to provide pavement engineers at Salt Lake City with customized menus and pavement management functions. The G-PMS reads in the unified crack indexes based on the digital image processing algorithm, recommends the most appropriate maintenance strategies, and displays those strategies on a digital map. It also provides the functions to report estimated costs for each maintenance activity and conduct financial planning. The design and function of G-PMS are discussed in detail. G-PMS is being implemented for the public works department of Salt Lake City.
Adapting Local Agency Pavement Management Procedures to Develop a Simplified System for use by Smaller Cities in Washington
Authors: Sachs Paul , Sunde Dan
Published: January 2019

When Congress passed the Intermodal Surface Transportation Efficiency Act (ISTEA) in 1991, many larger local agencies in the state of Washington had already implemented a pavement management system (PMS). Larger cities and counties had adopted PMS procedures after the University of Washington, working with the Washington State Department of Transportation (WSDOT), modified the Washington State PMS in the late 1980s to accommodate local agencies. However, very few smaller cities in Washington state have adopted PMS procedures. Because ISTEA requires that all roads eligible for federal aid must be on a PMS, smaller cities that have even only a few segments or sections of Federal-aid roadways are required to have a PMS. In response to that need, the TransAid Service Center of WSDOT, working with a number of smaller cities, has developed a manual that is based on the computerized systems in the state yet can be filled out with pencil and paper. The simplified system should enable metropolitan planning organizations to use the manual system in comparing its results with those of any of the other existing computerized systems. It is WSDOT's intention that even if the management system requirements are suspended, as currently proposed, the simplified system will still be sent out to smaller cities. These agencies will be encouraged to develop projects for transportation improvement plans from the results derived from the simplified systems.
Toward Adapting HDM-III Model to Local Conditions: Lessons from a Case Study in Tanzania
Authors: Mrawira Donath , Haas Ralph
Published: January 2019

Drawing from a case study in Tanzania, a generic approach to the problem of the desirability and scope of recalibrating the HDM-III model for local application is presented. On the basis of the three key factors of locational sensitivity, parameter impact on the model output, and the availability of calibration resources, candidate parameters for calibration are recommended for the case region. The roughness progression factor was found to have the highest impact on the net present value (NPV) of life-cycle costs. The roughness-age, cracking progression, and pathole progression factors were found to be the next influential on the NPV, with elasticity values of 0.7 to 0.8. From these results the study recommended a priority list in allocating recalibration efforts. The study findings suggest that calibration of rutting, cracking initiation, and raveling can be given low priority where resources are constrained. Considerations in choosing the appropriate vehicle operating cost (VOC) model for local conditions are highlighted. The Brazil set of VOC relationships is recommended for many applications; however, recalibration for these equations is highly desirable. Recent changes in automotive technology (with increased engine power, higher gross vehicle weights and payloads, improved fuel efficiency and tire technology, etc.) are raising the question of obsolescence of the Brazil VOC relationships. This issue may pose the most important challenge to the next evolution of HDM-III.
Optimization Modeling for Enhanced Network-Level Pavement Management System
Authors: Mbwana John R. , Turnquist Mark A.
Published: January 2019

A new formulation of a network-level pavement management system (PMS) model is described, which includes the identification of specific network links in the optimization. This model uses Markov transition probabilities for pavement condition modeling, as have several previously developed PMS models. The incorporation of specific links into the model, however, allows much easier translation of network-level policies to project-level decisions than has been possible. This formulation also allows the easy incorporation of user costs as well as agency costs and can include a variety of specific constraints on the solution. A case study application to Nassau County, New York, illustrates the use of the model and allows a comparison of the model solution with current maintenance practices in the New York State Department of Transportation.
Description of Rehabilitation Scoping Process Used in Washington State Pavement Management System
Authors: Pierce Linda M. , Mahoney Joe P.
Published: January 2019

In the early 1980s the Washington State Department of Transportation (WSDOT) developed and implemented a pavement management system (PMS). Over the years, the PMS has evolved into a very useful documentation of the state highway system and an essential analysis tool for pavement design. The various elements of the Washington State Pavement Management System (WSPMS) will be discussed, as will the ways in which the WSPMS is used for the rehabilitation budgeting. Early in the development of the WSPMS, the system had a strong capability to identify the specific projects that required rehabilitation and when the rehabilitation was required. The weakness in the WSPMS was determining the required level of rehabilitation (overlay thickness). The process (referred to as scoping) currently used to estimate the overlay thickness using only the data in the WSPMS will also be discussed.
Development of New Network Optimization Model for Oklahoma Department of Transportation
Authors: Chen Xin , Hudson Stuart , Pajoh Masoud , Dickinson William
Published: January 2019

A new pavement network optimization model based on the Markov decision process (MDP) is presented. The new model is a global optimization model in which the entire network can be optimized without being divided into mutually independent groups. Current MDP models in use for pavement management use only one routine maintenance model for all types of rehabilitation and reconstruction treatments. The new formulation provides separate routine maintenance models for each type of treatment, which is more realistic than the currently available formulations. Methods for estimating pavement maintenance and rehabilitation benefits are described. These methods can be used for the optimization models with objectives of maximization when inadequate data are available to consider road user costs. The model has been applied to the network-level pavement management system for the Oklahoma Department of Transportation. Results of example runs are discussed.
Nevada's Approach to Pavement Management
Authors: Sebaaly Peter E. , Hand Adam , Epps Jon , Bosch Chuck
Published: January 2019

The Nevada Department of Transportation has a fully implemented pavement management system (PMS) at the network level and an extensive pavement evaluation system at the project level. Both systems use actual field performance data that are collected annually from pavement sections throughout the state. The PMS is being further developed to incorporate performance modeling, life-cycle cost analysis, and network optimization processes. Once fully developed the system will allow the engineer to select the best rehabilitation and maintenance alternative that can carry the pavement over the entire analysis period. The project-level evaluation process includes the use of nondestructive testing data and condition surveys from the PMS. The overall systems are summarized at both levels, and the individual steps that are involved within each system are described.
Deterioration Prediction Modeling of Virginia's Interstate Highway System
Authors: Sadek Adel W. , Freeman Thomas E. , Demetsky Michael J.
Published: January 2019

The development of deterioration models for Virginia's Interstate pavements with 7 years of distress data is described. Roadway sections were categorized by pavement type and geographic location, and stepwise regression was used to select the significant predictors of deterioration. Different model forms were examined in an attempt to identify the most appropriate one for fitting the data. The models were evaluated by checking their goodness-of-fit statistics and conducting a series of sensitivity analyses. To further assess the models’ accuracy, their predictions were compared against field-observed values. An analysis-of-variance (ANOVA) test was also conducted to compare the accuracies of two model forms and two model adjustment procedures. In general, the developed models provided an adequate fit and generated predictions that conform with accepted engineering judgment. Comparisons with field observations showed their accuracies to be quite reasonable, even for long-range predictions. Finally, the ANOVA results indicated that no significant differences existed between the two model forms tested or between the two adjustment procedures. Although the focus of the research was on developing models for Virginia, the concepts of the study are applicable to any deterioration model development effort.
Development of Pavement Performance Curves for Individual Distress Indexes in South Dakota Based on Expert Opinion
Authors: Jackson Newton C. , Deighton Richard , Huft David L.
Published: January 2019

Work done to develop pavement performance curves for use in the enhanced South Dakota Department of Transportation (SDDOT) pavement management system (PMS) is described. Pavement performance curves were developed for various new pavement sections as well as for a range of rehabilitation treatments. The performance curves were developed by using both individual and composite pavement indexes. Because of a lack of sufficient historical data the pavement performance curves could only be developed by using expert opinion. A pavement expert group was established and a questionnaire was developed to quantify their collective experience. The responses were then used to develop quite reasonable pavement performance curves by using individual and composite indexes developed for South Dakota. The resulting pavement performance curves are adequate for the beginning input into the enhanced SDDOT PMS. The pavement performance curves developed should be revised as sufficient historical pavement condition data become available.
Prediction of Pavement Remaining Life
Authors: Vepa T. S. , George K. P. , Shekharan A. Raja
Published: January 2019

The evaluation of remaining life is necessary to make optimal use of the structural capacity of in-service pavements. It simply represents the useful life left in the pavement until a failure condition is reached. Knowledge of remaining life facilitates decision making in regard to strategies for reconstruction-rehabilitation of roads, thereby leading to the efficient use of existing resources. Several methods proposed or used by various agencies to estimate the remaining lives of pavements are reviewed. They are classified under two categories: functional and structural. Making use of the Mississippi Department of Transportation pavement management system data base, survivor curves are developed for seven classes of flexible pavements with from thin to thick structures. By using these survivor curves a novel method for estimating remaining life is proposed. The reasonableness of the selected methods is examined by putting them to use in calculating the remaining lives of each of eight rigid and flexible pavement sections, all of them from the Mississippi global positioning system sections of the Strategic Highway Research Program–Long-Term Pavement Performance project (LTPP). With the structural details, falling weight deflectometer deflection data, and the distress information compiled from the LTTP information management system data base, the authors use two and four methods for rigid and flexible pavements, respectively, to determine the remaining lives. The remaining lives calculated by two methods for rigid pavements are comparable. Three of four methods for flexible pavements also generated comparable remaining lives. The authors were encouraged by the results and recommend that the survivor curve approach be explored further for network-level remaining life calculations. The reliabilities of various techniques currently available for the remaining life calculation are discussed.
Distress Prediction Models for Rigid Pavements for Texas Pavement Management Information System
Authors: Robinson Cristopher , Beg Muhammad Arif , Dossey Terry , Hudson W. Ronald
Published: January 2019

The development of distress prediction models for nonoverlaid portland cement concrete (rigid) pavements in Texas for the Texas Department of Transportation's pavement management information system is described. The regression models presented quantitatively predict distress level versus pavement age and are based on pavement condition data maintained by the Center for Transportation Research at The University of Texas at Austin. Models are available for the following distress types in continuously reinforced concrete pavement (CRCP): punchouts, portland cement concrete patches, asphalt patches, serviceability loss as measured by loss of ride score, transverse crack spacing, and crack spalling. Preliminary models are available for the following distresses in jointed concrete pavement and jointed reinforced concrete pavement: patches, corner breaks, faulted joints and cracks, spalled joints and cracks, transverse crack spacing, and slabs with longitudinal cracks. A sigmoidal regression equation was used for all distress types. Modifying factors to CRCP models, which are intended to capture the effects of structural, environmental, and traffic loading variables, are included. The models for CRCP represent a significant improvement from preliminary estimates made in 1993. The improvements to the models were made possible primarily by data collection efforts undertaken in the summer of 1994.
Data Analysis Procedures for Long-Term Pavement Performance Prediction
Authors: Kerali H. R. , Lawrance A. J. , Awad K. R.
Published: January 2019

The results of 3 years of research aimed at investigating data analysis methods used in the development of pavement performance relationships are reported. The research was part of the U.K. collaborative program linked to the U.S. Strategic Highway Research Program (SHRP), in particular the Long-Term Pavement Performance (LTPP) experiment. The development of pavement performance models usually concludes with the application of regression techniques to determine coefficients for model parameters. It is important to identify the model forms and the engineering or mechanistic principles to be used in the data analyses in the initial stages and then to censor any obvious anomalies in the data. This was applied to data on pavement rutting measured by the Transport Research Laboratory over a 20-year period in the United Kingdom. Engineering knowledge of rutting progression suggests a cubic model form, with the quadratic component representing typical performance in early pavement life. An attempt was made to derive a rutting model that took into account material properties, layer thickness, and aggregate types. The pavement structural number concept was applied as a proxy for pavement strength for the different pavement structures used in the test sites. The results of the analyses confirmed that material properties, layer thickness, and their combined effects influence rutting, but in ways that vary greatly. No simple model form was found to adequately predict rutting for a variety of pavement types, even with general categorical model forms.
Pavement Performance Modeling Using Canadian Strategic Highway Research Program Bayesian Statistical Methodology
Authors: Hajek Jerry J. , Bradbury Alison
Published: January 2019

An application of the Canadian Strategic Highway Research Program (C-SHRP) Bayesian statistical analysis methodology for the development of a pavement deterioration model for asphalt concrete surfaces containing steel slag aggregates is described. The asphalt concrete mixes containing steel slag have been used on major highways in Ontario since late 1970s. In 1992 their use was discontinued because of premature pavement deterioration. The purpose of the model was to facilitate timely scheduling of effective rehabilitation treatments for projects containing steel slag mixes. The Bayesian model combines information derived from field observations of 79 existing projects with information elicited from experts. The resulting model predicts the pavement deterioration in terms of a distress index, which is a function of age, the asphalt content of the mix, and traffic volume. The results suggest that the C-SHRP Bayesian statistical analysis approach is useful in that it provides an independent review and endorsement of prediction models by experts, it can increase the application scope, reliability, and predictive power of the models, and it facilitates the quantification and comparison of the influence and contribution of field data and expert judgment in the modeling process.
Deterioration Modeling for Unlaid and Overlaid Pavements
Authors: Livneh Moshe
Published: January 2019

Pavement management relies heavily on the ability to model and predict pavement condition accurately. The current deterministic deterioration models for use in the mathematical curve-fitting technique are evaluated, and a new universal deterioration model that can be used to improve some obstacles associated with the current models is introduced. The new procedure is applied to a family data file of various pavement sections possessing the same grouping variables. Then the prediction for each section within the family data file is performed by using its position relative to the family prediction curve. Information regarding the condition of the overlaid pavement in the future is needed for performing life-cycle analysis and developing optimal maintenance and rehabilitation strategies. Thus, deterioration curves for overlaid pavements are also needed. However, in some cases the existing data are not sufficient to construct these deterioration curves as a function of both the original pavement structure and the overlay characteristics. Thus, in these cases the deterioration curves are extrapolated from a new model recently obtained in Illinois. In that model the performance function is tied to major engineering parameters such as structural number, traffic load, age, and climatic conditions. The prediction methodology presented is being examined by Israeli pavement management system developers, and their preliminary results are very encouraging.
Load Transfer Characteristics of Roller-Compacted Concrete Pavement Joints and Cracks
Authors: Pittman David W.
Published: January 2019

The U.S. Army Corps of Engineers’ design procedure for roller-compacted concrete (RCC) pavements assumes that no load transfer is achieved at RCC joints or cracks. This is in contrast to the Corps of Engineers’ rigid pavement design procedure for airfields, parking areas, and open storage areas, where a 25 percent load transfer is assumed for all joints and cracks. The no-load-transfer assumption for RCC pavements is conservative and is based upon limited data that indicated that RCC pavement joints did not achieve a 25 percent load transfer. The purpose of this study was to identify common types of RCC pavement joints and cracks, to determine the load transfer characteristics of these joint and crack types at 12 RCC pavement test sites using the falling weight deflectometer and to indicate the effect of incorporating these load transfer characteristics within the corps’ RCC pavement design procedure. Thirteen RCC pavement joint and crack types were identified. The mean load transfer achieved at these joints and cracks varied from 4 percent to 32 percent, and was no less than 10 percent for the most common joints and cracks found. In two design examples comparing the existing corps RCC pavement design procedure with a modified version incorporating 10–15 percent load transfer, the design RCC pavement thickness decreased 8–17 percent.
Westergaard-Type Solution for Edge Load Transfer Problem
Authors: Ioannides Anastasios M. , Hammons Michael I.
Published: January 2019

On the prominent issue of edge load transfer in portland cement concrete pavements, common understanding has been that Westergaard's last contribution was the very cursory treatment contained in his 1948 paper. A recent examination of the archives at the U.S. Army Engineer Waterways Experiment Station, however, has brought to light a consulting report that Westergaard submitted to the Corps of Engineers in 1949 containing a detailed examination of the edge load transfer problem, prepared by his associate M. S. Skarlatos. To expedite dissemination of this information, the results of an investigation that sought to extend and refine the edge load transfer solution by Skarlatos using modern computational tools are presented. A comparison of this solution to earlier finite element solutions is also presented. Following the same approach as Skarlatos and Westergaard, closed-form equations are derived for the maximum deflection and maximum bending stress occurring on the unloaded side of an edge capable of load transfer. Together with Westergaard's 1948 free edge equations, the two unloaded side formulas effectively extend Westergaard's solutions to the case of the edge load transfer problem.
Curling Stress Equation for Transverse Joint Edge of a Concrete Pavement Slab Based on Finite-Element Method Analysis
Authors: Nishizawa Tatsuo , Fukuda Tadashi , Matsuno Saburo , Himeno Kenji
Published: January 2019

In the design of concrete pavement, curling stresses caused by the temperature difference between the top and bottom surfaces of the slab should be calculated at the transverse joint edge in some cases. However, no such equation has been developed in the past. Accordingly, a curling stress equation was developed based on stress analysis using the finite-element method (FEM). In this FEM analysis, a concrete pavement and its transverse joint were expressed by means of a thin plate–Winkler foundation model and a spring joint model, respectively. Multiregression analysis was applied to the results of the FEM numerical calculation and, consequently, a curling stress equation was obtained. After comparing the calculated results of the equation with curling stress equations developed in the past, it was confirmed that the equation was valid and practical.
Corner Stress Analysis of Jointed Concrete Pavements
Authors: Lee Ying-Haur , Lee Ying-Ming
Published: January 2019

Because corner breaks are one of the major structural distresses in jointed concrete pavements, the ILLI-SLAB finite-element program was used to analyze the critical corner stresses of concrete pavements under different loading conditions. Subsequently, the effects of a finite slab size, different gear configurations, a widened outer lane, a tied concrete shoulder, and a second bonded or unbonded layer were considered. Based on the principles of dimensional analysis and experimental designs, the dominating mechanistic variables were carefully identified and verified. The resulting ILLI-SLAB stresses were compared with theoretical Westergaard solutions to develop adjustment (multiplication) factors. A new regression technique (projection pursuit regression) was used to develop prediction models to account for these theoretical differences and to instantly estimate the critical corner stresses. A practical application example illustrating the use of the prediction models was also provided and carefully verified using the ILLI-SLAB program. The research findings can be used practically for various designs and analyses of jointed concrete pavements based on theoretical considerations. Not only can the use of these stress prediction models reduce the possibility of obtaining incorrect results due to the improper use of the finite-element model, but it can also reduce the complicated computation time significantly. Furthermore, the critical bending stresses can be conveniently, accurately, and—best of all—instantly calculated through the use of these stress prediction models.
Evaluation of AASHTO Rigid Pavement Design Model Using Long-Term Pavement Performance Data Base
Authors: Darter M.I. , Owusu-Antwi E. , Ahmad R.
Published: January 2019

The AASHTO design guide's rigid pavement equation that is used for thickness design was originally developed in 1960 at the conclusion of the road test. This equation predicts the number of axle loads for a given slab thickness and loss in serviceability. During the last 30 years, the original equation has been extended to include several additional design factors and has been used by many highway agencies for rigid pavement design. Due to the limited inference space of the original road test equation and the subjective nature of the subsequent extensions, there is considerable interest in determining the adequacy of the equation. The availability of the nationwide long-term pavement performance data has finally made an overall evaluation possible. The evaluation included determining the adequacy of predicting the number of heavy axle loads required to cause a given loss of serviceability. The results indicate that the original 1960 equation generally overpredicts the number of 80-kN (18-kip) equivalent single axle loads for a given loss of serviceability. However, extensions to the original model improve predictions considerably. These results were determined at the 50-percentile (mean) level. At a higher level of reliability such as 95 percent, the 1986 AASHTO model provides a conservative design for a majority of the pavement sections. However, several deficiencies that need to be improved still remain.
Case Study of Overlay Performance on Rigid Pavement in Bowie County, Texas
Authors: Mccullough B. Frank , Dossey Terry , Cho Yoon-Ho
Published: January 2019

A case study of flexible overlay performance on an old rigid pavement is presented. This special study was devised in cooperation with the Pavement Section of the Design Division of the Texas Department of Transportation to take advantage of a unique opportunity to study overlay effectiveness. Condition survey, roughness measurements, and deflection basins were taken before and after the removal of an old flexible overlay and after the construction of a new asphalt overlay. Subsequent analysis of the data shows that although the overlay restores the ride quality of a rigid pavement and eliminates dynamic loading caused by swelling subgrades, it can only slow, not reverse, fatigue in the underlying pavement structure.
Long-Term Performance of Recycled Portland Cement Concrete Pavement
Authors: Cross Stephen A. , Abou-Zeid Mohamed Nagib , Wojakowski John B. , Fager Glenn A.
Published: January 2019

Over the past years there has been an increasing interest in recycling construction materials, particularly hot-mix asphalt (HMA) and portland cement concrete pavements (PCCP). To this end the Kansas Department of Transportation (KDOT) participated in Demonstration Project 47, Recycling Portland Cement Concrete Pavement, by recycling a moderately D-cracked concrete pavement and monitoring the performance over a 10-year period. The recycled concrete pavement (RCP) aggregate was evaluated in four test sections consisting of two control sections, one test section of portland cement-treated base (CTB) with RCP aggregate, and one test section using RCP aggregate in the PCCP and CTB. An HMA shoulder using RCP as coarse aggregate was also constructed. The test sections were monitored over a 10-year period for performance including faulting, roughness, load transfer, and friction measurements. Faulting, roughness, performance level, and joint distress measurements from KDOT's 1995 pavement condition survey were used to compare the performance of the recycled sections with PCCP of similar age and traffic in the same area of the state. All test sections performed well, with the CTB and PCCP sections with RCP aggregates showing slightly more distress.
New Procedure for Evaluating Bond Strength of Concrete Reinforcement
Authors: Kachlakev Damian I. , Lundy James R. , Gillet Vincent , Le Bon Alain , Donon Yves , Martinand Cyril , Guerin Georges
Published: January 2019

The bond strength between concrete and reinforcement is critical to the performance of reinforced concrete structures, including continuously reinforced concrete pavements (CRCP). Unfortunately, a widely accepted test is not available for this critical property. Commonly used procedures apply the load to the reinforcing unit and the load is transferred from the unit to the concrete. Poisson's effects are induced in the reinforcement and a reduction in cross section results. The ensuing failure is not generally representative of the stress transfer mode between concrete and reinforcement in most structures. The proposed procedure obviates the Poisson's effects by applying the load directly to the concrete. Load is transferred to the steel in the vicinity of a preformed crack. Applicability of the procedure is demonstrated using a particular type of flat CRCP reinforcement; however, the procedure has been used on conventional steel and glass-fiber reinforced plastic reinforcement with equal success. The loading rate and instrumentation regime are adaptable to the needs of the researcher. Reinforced portland cement concrete specimens of various strengths were tested to evaluate the procedure and the reinforcement itself. The K-value was found to be satisfactory and comparable to conventional steel rebars. Also the mobilization of yield resistance ratios for the flat units were comparable to conventional steel reinforcing units.
Estimation of Dynamic Properties of Sand Using Artificial Neural Networks
Authors: Ni S. H. , Juang C. H. , Lu P. C.
Published: January 2019

Dynamic properties of soils are usually determined by time-consuming laboratory tests. This study presents a method for estimating dynamic soil parameters using artificial neural networks. A simple feedforward neural network with back-propagation training algorithm is used. The neural network is trained with actual laboratory data, which consists of six input variables. They are the standard penetration test value, the void ratio, the unit weight, the water content, the effective overburden pressure, and the mean effective confining pressure. The output layer consists of a single neuron, representing shear modulus or damping ratio. Results of the neural network training and testing show that predictions of shear modulus by the neural network approach is reliable although it is less successful in predicting damping ratio.
Performance of Mixed Bracing System in Deep Excavation of Stiff Soil
Authors: Sparacin W. G.
Published: January 2019

A braced excavation, 23 m deep x 213 m long, for Civic Center Station on the Los Angeles Metropolitan Transit Redline was nearing completion when high strut loads were measured at mid-depth. About four months after the excavation bottomed out and the base slab was cast, four strut-to-wale connections failed. The contractor was directed to install a sister level of braces and later sought compensation from the owner. An investigation into the contractor's claim used the finite element method and determined that the high loads could not have been anticipated from conventional theory, and that they were due both to mixing tiebacks and struts in the same excavation and to preloading the struts. The method and results of the investigation are summarized.
Earth Pressures Due to Compaction: Comparison of Theory with Laboratory and Field Behavior
Authors: Filz George M. , Duncan James M.
Published: January 2019

Compaction of backfill adjacent to stiff and unyielding structures induces earth pressures in the compacted fill that exceed normal at-rest earth pressures. A numerical method that can be used to calculate compaction-induced lateral earth pressures has been proposed by Duncan and Seed. The purpose of the study described in this paper is to evaluate the theory by comparing calculated and measured compaction-induced lateral earth pressures. The data for the comparisons is from values measured in backfills behind three stiff, unyielding walls: the instrumented retaining wall in the Transport and Road Research Laboratory in Crawthorne, England; the instrumented retaining wall in the Virginia Tech Geotechnical Laboratory in Blacksburg, Virginia; and the lock walls at Eisenhower and Snell Locks in New York state. The lock walls were found to be cracked, apparently by high earth pressures induced by compaction, and an extensive rehabilitation program was required. The measurements from all three walls confirm the existence of compaction-induced lateral earth pressures. For clean sand backfill, pressures calculated using the theory of Duncan and Seed are shown to be in reasonable agreement with measured values. Laboratory test data indicate that for moisture-sensitive silty sand backfill the applicability of the Duncan and Seed theory, which does not include considerations of pore water pressure development during backfill placement and compaction, depends on the degree of saturation of the backfill.
Identifying Failure through Locations of Acoustic Emission
Authors: Labuz J.F. , Dai S.-T. , Shah K.R.
Published: January 2019

Failure of such materials as dense or overconsolidated soil, rock, and concrete is associated with a zone of localized deformation, where the failure plane develops by a coalescence of damage in the form of pores and microcracks. As damage initiates and propagates, transient elastic waves are emitted from the sudden release of energy. These microseismic events are called acoustic emission (AE). The acoustic sources can be located through the first arrival of the waveform, the P-wave component, recorded by an appropriate data acquisition system. The source location can help identify the eventual failure plane well before it is visible. In this study, an acoustic emission system with eight channels of recording was used to monitor the failure process in rock specimens under uniaxial compression and four-point bend loading. Failure was controlled by conducting the experiments in a closed-loop, servo-hydraulic load frame. The sources were located using a nonlinear regression technique. From calibration studies, where artificial events were generated at known locations, an accuracy of 1 to 3 mm (about 1 to 3% of the travel distance) was demonstrated for laboratory specimens. For both loading configurations, a clustering of AE locations identified the zone of localized deformation prior to the limit load and before any visible sign of failure.