bluuebunny/crossref_metadata_2025 huggingface dataset:
Alternative Futures for Integrated Transportation and Land Use Models Contrasted with Trend-Delphi Models: Portland Oregon Metro Results
Authors: Conder Sonny , Lawton Keith
Published: April 2007

Since completing a trend-delphi–based regional forecast and transportation plan in 1996, the Portland, Oregon, Metro has developed an integrated transportation and land use model (MetroScope). The model is being used to explore several regional growth management options as well as to produce a new regional forecast and transportation plan. Comparing MetroScope results with the previous forecast reveals that integrated transportation and land use models may produce different results in regard to trip length, vehicle kilometers traveled, traffic congestion levels, mode and route choice, and employment and household locations. Compared with trend models, integrated models robustly respond to alternative land regulation and transportation investment policy options, allowing planners and officials an opportunity to evaluate the differences in land use and transportation arising from different policy choices. Moreover, the integrated models produce far more data on factors such as real estate prices, tenure choice, residential and nonresidential real estate output, land consumption, redevelopment, and density.
Incorporating Nonmotorized Mode and Neighborhood Accessibility in an Integrated Land Use and Transportation Model System
Authors: Waddell Paul , Nourzad Firouzeh
Published: April 2007

A model of residential location estimated as part of a larger integrated land use and transportation model development effort in the Wasatch Front area of Utah is presented. Main contributions are testing of the effects of neighborhood and regional accessibility on residential location, controlling for housing and neighborhood characteristics, and using a spatially disaggregate model. Results are relevant to the assessment of policies related to land use and transportation interaction, and the methods significantly advance our ability to examine neighborhood-scale effects on location choice.
Uncertainty Propagation in an Integrated Land Use-Transportation Modeling Framework: Output Variation via UrbanSim
Authors: Pradhan Anant , Kockelman Kara Maria
Published: April 2007

The effect of uncertainty in the land use component of a partially integrated land use–transportation modeling system called UrbanSim is examined. Outputs from the land use model (LUM) act as inputs for a traditional four-step travel demand model (TDM), and travel times from the traffic-assignment stage of the TDM are fed forward into the subsequent years’ LUM. This work examines the propagation of uncertainty across model stages as well as at each model stage over time. A factorized design approach is used to model uncertainty in demographic inputs (which include aggregate growth rates and mobility rates) to the land use model, as well as uncertainty in various model parameters. Results suggest that although several model inputs may affect model outputs in the short run, only those inputs that have a cumulative effect are likely to have a significant impact on outputs in the long run. Results also suggest that uncertainty in model outputs may increase for the first few years for which the model is run, as modified inputs send shocks through the urban system. However, the level of uncertainty appears to come down in later years, as households, jobs, and developers respond to changed input conditions.
Validation of Flexible Pavement Structural Response Models with Data from the Minnesota Road Research Project
Authors: Mateos Angel , Snyder Mark B.
Published: April 2007

A dynamic load test study was performed on instrumented asphalt and concrete pavement test sections at the Minnesota Road Research facility. Test variables included different types of vehicles (featuring various axle groupings, load levels, and tire pressures) operating at various speeds over different structural sections. Four flexible pavement sections were selected for inclusion, and the primary structural response measured was horizontal strain at the bottom of the asphalt layer. The test data suggest that the structural response of the four sections to varying loads was linear when other test parameters were held constant. The pavement sections also exhibited a pronounced viscoelastic behavior in response to changes in vehicle speed and load rate. This behavior was attributed mainly to the asphalt concrete layer. Changes in tire pressure did not significantly affect pavement behavior. The test data were used to validate a multilayer linear elastic pavement structural model. Sub-grade and base moduli inputs were back calculated from falling weight deflectometer data, and the asphalt modulus was determined experimentally from measured strain. This model adequately reproduced the strain distribution observed at the bottom of the asphalt layer under the passage of moving vehicles with certain limitations: the longitudinal strain asymmetry due to viscoelastic effects could not be reproduced, and the modulus of the asphalt layer had to be readjusted for temperature and vehicle speed. Also, it was not possible to calibrate or fit the model to observed longitudinal and transverse strains simultaneously because the pavement behaved more stiffly longitudinally than transversely.
New Relationships Between Falling Weight Deflectometer Deflections and Asphalt Pavement Layer Condition Indicators
Authors: Xu Bing , Ranjithan S. Ranji , Kim Y. Richard
Published: April 2007

New relationships have been identified between the layer condition indicators of flexible pavements and falling weight deflectometer (FWD) deflections. Synthetic databases were generated using dynamic finite element analysis with nonlinear material models. The sensitivity of various deflection basin parameters (DBPs) to layer conditions was comprehensively examined on the basis of the developed databases. Three types of layer condition indicators were identified in the study, including DBPs, effective layer moduli, and stresses and strains. The DBPs identified from the sensitivity study were used in developing new relationships between the selected condition indicators and FWD deflections by applying regression and artificial neural network techniques. Even though these relationships include the complicated dynamic effect of FWD loading and nonlinear behavior of unbound materials, the time to obtain results from these procedures is insignificant, thus making the procedures suitable for field implementation.
New Condition Assessment Procedure for Asphalt Pavement Layers, Using Falling Weight Deflectometer Deflections
Authors: Xu Bing , Ranjithan S. Ranji , Kim Y. Richard
Published: April 2007

Nondestructive condition assessment criteria were developed for application in conjunction with the condition evaluation indicators that are estimated based on falling weight deflectometer (FWD) deflections. Data obtained from state departments of transportation and DATAPAVE 2.0 were used in developing these criteria. To account for the effects of pavement structure and temperature on FWD deflection analysis, structure and temperature correction procedures based on synthetic databases were applied. Also, a deflection prescreening procedure was established to identify and correct any irregular deflection basins potentially arising from measurement errors. All the calibrated predictive procedures, structure and temperature correction procedures, and prescreening algorithms were incorporated into the user-friendly deflection analysis program with graphical interface, Asphalt Pavement Layer Condition Assessment Program, or APLCAP.
Automated Dynamic Cone Penetrometer for Subgrade Resilient Modulus Characterization
Authors: Rahim Ashraf M. , George K. P.
Published: April 2007

Subgrade soil characterization, expressed as resilient modulus ( M R), is crucial for pavement design. For a new design, M R is generally obtained by conducting repeated triaxial tests on reconstituted and undisturbed cylindrical specimens. Because of the test’s complexities, in situ tests are desirable, if reliable correlation is established. This study investigated the viability of using the automated dynamic cone penetrometer (ADCP, abbreviated as DCP) for subgrade characterization through correlation between DCP index (penetration per blow) and M R. The sensitivity of DCP results to changes in subgrade stiffness, expressed in modulus values, was also investigated. Twelve as-built subgrade sections, reflecting a range of typical Mississippi subgrade materials, were selected and tested with DCP. Undisturbed samples were extracted with a Shelby tube and tested in a repeated triaxial machine for M R. After other soil physical properties were determined, the soil was classified according to AASHTO procedure. DCP tests were repeated atop the subgrade through drilled holes after construction of pavement layers. Falling weight deflectometer (FWD) testing was conducted near the DCP test locations. Results suggest two relationships, for fine-grain and for coarse-grain soils, in correlating the DCP index to laboratory M R. Other physical properties helped improve the robustness of the regression models. For model verification, the DCP and M R tests were repeated and produced good agreement between predicted and actual M R values. The DCP index before and after pavement layer’s emplacement suggests subgrade stiffness enhancement, owing to pavement overburden, which agrees with FWD-backcalculated moduli.
Performance of Pavements Subject to Higher Truck Weight Limits in Virginia
Authors: Freeman Thomas E. , Clark Trenton M.
Published: April 2007

A study was mandated by Virginia’s General Assembly to determine if pavements in the southwest region of the state carrying vehicles operating under higher allowable weight limit provisions have greater maintenance and rehabilitation requirements than pavements bound by lower weight limits elsewhere. Detailed field surveys were conducted at 18 in-service pavement sites representing the range of roadway and traffic conditions found on Southwest Virginia’s primary and secondary highways. Traffic classification and weight surveys, an investigation of subsurface conditions, and comprehensive structural evaluations were conducted at all sites. The results were used to estimate the cost of damage attributed only to the net increase in allowable weight limits. Consistent with results of more comprehensive research conducted by and for other highway agencies, the authors found that pavement damage increased drastically with relatively small increases in truck weight for all vehicle classes affected by Virginia House Bill 2209. The cost of structural damage to mainline pavements attributable to the net weight increase in the seven affected counties alone was estimated at $28 million over 12 years. Costs for necessary improvements to roadway geometry, reduced service lives of bridges, increased motorist delays through work zones, and the safety implications of heavier vehicles operating in mountainous terrain were not included in the estimate. The report highlights the experience of one state highway agency with increasing political pressures to raise legal load limits.
Determination of Test Spacing in Pavement Evaluation
Authors: Chou Y. J. , Zou Yunyi
Published: April 2007

Highway engineers must conduct pavement evaluations before making rehabilitation decisions. Deflection tests performed at a uniform spacing are often used for structural evaluation purposes. The spacing between adjacent tests is often determined empirically. For pavements with large variability, more tests are needed. Variability is usually measured by the coefficient of variation ( CV). Several methods of determining test spacing were reviewed. A new method is proposed to calculate the test spacing based on the equivalent coefficient of variation ( CVe), which considers not only the variance but also the autocorrelation among the pavement responses. The new parameter CVe is more sensitive to test spacing than is the CV.
Index for Evaluating Initial Overlay Smoothness with Measured Profiles
Authors: Fernando Emmanuel G.
Published: April 2007

An index was developed for evaluating the acceptability of initial overlay smoothness based on surface profile measurements. The proposed index predicts the change in overlay service life due to differences between the target surface profile assumed in the design and the as-built profile. From theoretical considerations, the change in overlay life, based on reflection cracking, was found to be a function of the fracture characteristics of the overlay mix and the variability in vehicle dynamic loading due to unevenness in the surface profile. The index for evaluating initial overlay smoothness was applied using profile data from actual overlay projects. Using the final surface profile, the index is applicable to projects where the overlay thickness is more than 64 mm or where surface preparations, such as milling to grade or in-place recycling, are used to correct or remove existing surface distress. Implementation of the proposed index in a smoothness specification will require the use of surface profilers and the simulation of vehicle dynamic loads from measured profiles.
Correlation Between Longitudinal Roughness and User Perception in Urban Areas
Authors: La Torre Francesca , Ballerini Lorenzo , Di Volo Neri
Published: April 2007

Pavement management in urban areas requires the identification of appropriate roughness indicators and of related acceptability thresholds. The use of the international roughness index (IRI) is not suitable for urban areas owing to a number of problems. The available length of homogeneous sections is often much shorter than the typical 320 m used in the World Bank experiment that led to the IRI classification. The speed is considerably lower than the 80 km/h considered for the IRI quarter car model. Also, the type of paving materials used in urban areas can be considerably different than the ones used in rural areas, resulting in a different type of roughness (as in the case of stone pavements). Furthermore, the acceptability levels in urban areas need to be defined according to the different perception of the user and additional environmental constraints. Within the Interazione Ambiente Sicurezza nel Progetto delle Infrastrutture Viarie project funded by the Italian Research and University Ministry, an extensive study has been conducted to define a roughness index suitable to represent urban streets and to identify acceptability thresholds. For this purpose, a number of urban sections with different pavement surfacing and age have been identified, and on each section the profile has been measured. To identify user perception toward the different pavement conditions, a rating procedure has been defined, and a panel rating has been performed on each section.
Development of New Profile-Based Truck Dynamic Load Index
Authors: Chatti Karim , Lee Doseung
Published: April 2007

A new roughness index called the dynamic load index (DLI) is developed for the purpose of identifying pavement profiles that are likely to generate high dynamic truck-axle loads. The DLI is calculated as a weighted index of variances of the profile elevation in the frequency ranges of 1.5 to 4 Hz and 8 to 15 Hz. The first frequency range corresponds to truck body bounce, and the second frequency range corresponds to axle bounce. The analysis showed a very good relationship between the DLI and dynamic load. The DLI was tested on a range of road profiles from in-service pavements, and it was found that for any particular value of ride quality index (RQI), the DLI can cover a wide range of values, and this variation in DLI was found to correlate well with dynamic load, as predicted by a truck simulation program. This was not the case for the international roughness index, which gave a low coefficient of correlation with dynamic load for the same range of profiles. Therefore, the new index can differentiate between profiles that generate high dynamic loads and those having the same RQI but generating low dynamic loads. Most importantly, the use of the DLI negates the need for running a truck simulation program. This makes it possible for a state highway agency to decide whether a particular pavement with a given surface profile needs smoothing (to extend its service life) based on the DLI value.
Modeling Individuals’ Activity-Travel Rescheduling Heuristics: Theory and Numerical Experiments
Authors: Joh Chang-Hyeon , Arentze Theo , Timmermans Harry
Published: April 2007

Previously, a theory of activity-travel rescheduling decisions was developed. This theory left open the problem of how individuals deal with the combinatorial problem of a very large solution space. Based on the argument that an appropriate algorithm should also be interpreted as a representation of an actual decision-making process, such an algorithm for activity-travel rescheduling is proposed here. Details are described, and a numerical illustration is provided to explore the face validity of the proposed algorithm.
Do You Go to the Movies During Your Lunch Break?: Trip-Context Data-Based Modeling of Activities
Authors: Kuhnimhof Tobias , Wassmuth Volker
Published: April 2007

Specific information about travelers’ activities is often vital for transportation planners. For example, in modeling destination choice should only those attractions where a desired activity can be pursued be included? Destination choice modeling may improve when more specific activity information is available, especially for leisure trips. Destinations for leisure trips can be places to visit people, cinemas, and restaurants. In surveys, however, respondents are often asked to categorize their trips into generic purposes such as work, shopping, or simply leisure, without specifying the leisure activity. Hence, there is often a gap between trip-purpose information elicited from respondents and specific activity information, which would enhance destination modeling. A model is presented that bridges this gap with respect to leisure activity engagement. Common experience provides an idea of who is likely to conduct a particular leisure activity and at what time. The approach taken here was to quantify this likelihood by evaluating a data set of more than 20,000 leisure trips that provided specific activity information. This provided the calibration for the model IRMA, which simulates a specific activity for each trip based on trip-context data. IRMA was applied to model activities for leisure trips in a data set from Tuebingen, Germany. The result of the application of IRMA was consistent with common experience and provided vital activity information that helped to improve destination choice modeling. The approach to infer activity information from available trip data has proven useful in bridging the gap between information that is needed and information that is available.
Responses to Centre Street Bridge Closure: Where the “Disappearing” Travelers Went
Authors: Hunt J. D. , Brownlee A. T. , Stefan K. J.
Published: April 2007

An ongoing topic of interest in urban transportation engineering is the impact of changes in road network capacity on the amount of vehicle travel in an urban area. In many cases, the debate focuses on potential increases in vehicle travel that occur with increases in road capacity—the phenomenon of “induced demand.” Some studies have also looked at the effects of reductions in roadway capacity and found that, in many of these cases, reductions in vehicle travel occur, generally confirming that a relationship exists between roadway capacity and vehicle travel. Additional information is provided on this subject in a North American context. The city of Calgary, in Alberta, Canada, is a major urban center with a population of over 850,000 and a downtown employment of over 100,000. Centre Street Bridge is a major road bridge across the Bow River that connects downtown Calgary to the residential area in the northern part of the city. The bridge carries over 34,000 vehicles per day, with heavy peak-period flows. In August 1999, the Centre Street Bridge was closed to car and truck traffic for 14 months for major repairs. A detailed study was undertaken of changes in traffic and in transit and pedestrian flows that took place in weekday travel patterns during the closure. This included both analysis of observed count data before and during the closure and an interview survey with over 1,300 car users of the Centre Street Bridge and the other bridges serving the north side of the downtown. The major findings of this study are summarized here. Particular emphasis is placed on explaining what happened to the vehicle trips that used the bridge before the closure.
Drivers’ Route Choice Behavior: Analysis by Data Mining Algorithms
Authors: Yamamoto Toshiyuki , Kitamura Ryuichi , Fujii Junichiro
Published: April 2007

Decision trees and production rules, which are among the methods used in knowledge discovery and data mining, are applied to investigate drivers’ route choice behavior. These methods have an advantage over artificial neural networks, another data mining method often used in analysis of travel behavior: they facilitate determination of the relationships between the explanatory variables and the choice. Specifically, the C4.5 algorithm, which produces a decision tree and a set of production rules from the tree, is applied here. Two surveys were carried out to collect data on drivers’ route choice behavior between two alternative routes on expressway networks. The two data sets include the expected minimum, maximum, and average travel times along each alternative route, as indicated by the respondent as well as his or her sociodemographic attributes. The results of the analyses suggest that different expected travel times influence route choice in different cases and that a maximum or average travel time determines route choice in some cases regardless of other attributes. The results of a comparison analysis between the C4.5 algorithm and discrete choice models indicate the superior ability offered by the former in representing drivers’ route choice.
Travel Behavior Analysis of South Perth Individualized Marketing Intervention
Authors: Goulias Konstadinos G. , Broeg Werner W. , James Bruce , Graham Colin
Published: April 2007

The Western Australia Department for Planning and Infrastructure has initiated a unique information provision program to decrease the use of cars and increase nonmotorized transport. The program contains a component in South Perth that uses individualized marketing techniques to inform travelers about alternatives to the private automobile. Data about this program have been collected in the past 3 years, offering the opportunity to assess the program’s success. Regression analysis has been used to estimate the effect of information provision on program participants’ travel behavior for mobility and, more specifically, mode choice. Program participants, persons who agree to receive and use information, when compared with a variety of other groups consistently use the car as driver the least and appear to have increased their nonmotorized trip making. The findings here are extremely encouraging, and programs like this should be considered in other urban settings.
Structural Model of Automobile Demand in Korea
Authors: Chung Jin-Hyuk , Lee Dongkyu
Published: April 2007

Automobile demand has been widely and extensively investigated because of its effects on many related fields such as travel behavior, public policy and management, and transportation impact analysis. Although its importance has been well perceived in the field of transportation, the models developed frequently emphasize short-term forecasting, and interactions and simultaneity among the endogenous variables are rarely investigated. In addition, a large number of existing models adopt simple regression methods with time-series data. However, the approach may produce inconsistent estimates due to simultaneities of many other endogenous variables. A structural equation model has been constructed to estimate aggregated automobile demand with data from Korea. The model framework includes several endogenous and exogenous variables. The findings show significant interrelationships and simultaneities among automobile demand, driver population, and road length, and all exogenous variables strongly affect the endogenous variables as well. The model can be used as a basis for forecasting future automobile demand.
Exploratory Analysis of Fixed Commitments in Individual Activity—Travel Patterns
Authors: Frusti Teresa , Bhat Chandra R. , Axhausen Kay W.
Published: April 2007

The presence of fixed commitments in the activity—travel patterns of individuals is examined. Data obtained from a 6-week travel diary survey undertaken in Germany are used in the empirical analysis. The results provide several important insights into the determinants of fixed commitments.
Structural Equation Models of Day-to-Day Activity Participation and Travel Behavior in a Developing Country
Authors: Chung Jin-Hyuk , Ahn Yongsung
Published: April 2007

A series of structural equation models are presented that capture relationships among sociodemographics, activity participation (time use), and travel behavior for each day during a week in a developing country (Korea). Complex and strong relationships among the endogenous and exogenous variables are explained. In addition, results are similar to findings in the existing literature in developed countries such as European countries and the United States. It is temporarily concluded that there are similar relationships between sociodemographics and travel behavior in developing and developed countries. It is also confirmed that activity patterns are significantly different on weekdays and weekends. Furthermore, during weekdays there are some day-to-day variations in the patterns of activity participation and travel behavior. Finally, the relationships among sociodemographics, activity participation, and travel behavior from the direct, indirect, and total effects in structural equation model systems are presented and explained. This study may contribute to an understanding of travel behavior in developing countries.
Analysis of Lifestyle Choices: Neighborhood Type, Travel Patterns, and Activity Participation
Authors: Krizek Kevin J. , Waddell Paul
Published: April 2007

Activity-based travel modeling has begun to make significant progress toward a more behavioral framework for simulating household travel behavior. A significant challenge remains in the need to address the interaction of daily activity and travel patterns with longer-term household choices of vehicle ownership, residential location, and employment location. The choices often depend on one another and jointly define the lifestyle of the household. These choices are likely to evolve over the course of the life cycle as households are formed; as children are born, raised, and ultimately depart to form their own households; and as retirement and old age change patterns of residence, work, and travel. A framework is developed for analyzing household choices relating to three dimensions of lifestyle: travel patterns (including vehicle ownership), activity participation, and residential location (neighborhood type). With cluster analysis on data from the Puget Sound Transportation Panel, nine classifications of lifestyle are uncovered. These clusters demonstrate empirically how decisions of residential location reinforce and affect daily decisions related to travel patterns and activity participation. The applicability of these lifestyle clusters for land use transportation planning is discussed.
History Dependency in Daily Activity Participation and Time Allocation for Commuters
Authors: Kasturirangan Krishnan , Pendyala Ram M. , Koppelman Frank S.
Published: April 2007

The role of history dependency in explaining activity-travel patterns of commuters is investigated. Specifically, the extent to which one day’s activity engagement affects activity frequencies and activity durations of the next day is examined. The analysis uses 2-day activity survey data collected in 1996 in the San Francisco Bay area. Models of daily activity engagement and time allocation are estimated as a function of the previous day’s activity pattern to understand day-to-day dependency in activity engagement. Results from the model estimation effort are used to draw conclusions about the extent to which history dependency exists (within a 2-day time frame) in modeling different activity types. The results suggest there is a strong positive history dependency in activity engagement between days within a 48-h time frame.
Household Activity Rescheduling in Response to Automobile Reduction Scenarios
Authors: Doherty Sean T. , Lee-Gosselin Martin , Burns Kyle , Andrey Jean
Published: April 2007

Forecasting the enduring and wider implications of emerging travel demand management and automobile reduction policies has proved to be a challenging task. Travel behavior researchers point to the need for more in-depth research into the underlying activity-travel scheduling processes as a means to improve the ability to do so. The objective of this research is to explore the household rescheduling and adaptation process to vehicle reduction scenarios. Descriptive results from two, small-sample, in-depth experiments are presented. The first experiment focused on households’ response to a fuel prices increase, whereas the second focused on the response of two-vehicle households to long-term removal of one vehicle from the household. Results indicate that households are aware of a broad range of possible adaptation strategies, including not only mode changes but also a wide variety of changes in activities, planning, and longer-term lifestyle changes. When people were asked to actually implement such stated strategies under realistic conditions, a much more elaborate behavioral response was elicited. This included multiple rescheduling decisions involving several activities and household members over the course of a day or even several days. Thus, even relatively straightforward stated response strategies often lead to interconnected primary and secondary effects on observed activities and travel, realized through a sequence of rescheduling decisions over time and space and across household members. These results suggest that an explicit accounting of rescheduling decision sequences in forecasting models would enhance their behavioral validity and accuracy.
Pile Monitoring with Fiber Optic Sensors During Axial Compression, Pullout, and Flexure Tests
Authors: Glisic Branko , Inaudi Daniele , Nan Claire
Published: April 2007

A full-scale on-site test represents an ideal way to check a hypothesis and to determine the real behavior of structures, especially in cases in which some uncertainties cannot be reduced otherwise. To perform the test successfully it is necessary to monitor the parameters that representatively describe the structural behavior. In the case of piles, axial compression, pullout, and flexure tests cover all load combinations that may appear in service. To assess the foundation performance at a semiconductor production facility, two sets of piles with three piles in each set were tested. The monitored parameters were average strains, registered in several segments over the whole length of each pile using long-gauge fiber optic sensors. This type of sensor, combined in appropriate topologies, gives rich information concerning the piles’ behavior and soil properties. The monitoring method is presented and its performances through the results of the tests are discussed. This method allowed the determination of the Young modulus of the piles, the occurrence of cracks, the normal force distribution, and the ultimate load capacity in the case of axial compression and pullout tests, as well as the curvature distribution, horizontal displacement, deformed shape, and damage localization in the case of the flexure tests. Moreover, the pile–soil friction distributions, the quality of soil, and the pile tip force were estimated. The advantage of the presented method resides in the use of long-gauge sensors, which are insensitive to local structural defects like crack openings or air pockets and allow the collection of data on a global structural level and not on a local material level.
Pore Pressure Response of Liquefied Sand in Full-Scale Lateral Pile Load Tests
Authors: Ashford Scott A. , Weaver Thomas J. , Rollins Kyle M.
Published: April 2007

Several full-scale lateral pile load tests were performed at Treasure Island in the San Francisco Bay in sand liquefied by controlled blasting. Cyclic lateral loads were applied to the foundations with displacements up to 225 mm. Piezometers were installed adjacent to, and at a distance up to 4.2 m in front of, the deep foundations. Excess pore pressure ratios observed during testing are presented for the purpose of providing insight into the behavior of liquefied soil in response to laterally loaded piles. Observed excess pore pressure ratios show that soil in the loading path of the foundations experienced a phase transformation at distances as great as 4.2 m. The soil behavior in response to lateral foundation movement is presented based on interpretation of the measured excess pore pressure response.
Laboratory Evaluation of the Soil Stiffness Gauge
Authors: Sawangsuriya Auckpath , Bosscher Peter J. , Edil Tuncer B.
Published: April 2007

A new alternative geotechnical field testing device called the soil stiffness gauge (SSG), also known as GeoGauge™, exhibits particular promise for monitoring in situ soil stiffness during construction quality control. However, there has been only limited research on this device regarding its characteristics and limitations. The results of laboratory testing and a finite-element analysis (FEA) of the SSG are presented. Based on the FEA and the SSG measurement in the test box, the radius of measurement influence extends to 300 mm. For two-layer materials with different stiffness, the SSG starts to register the stiffness of an upper-layer material of 125 mm or thicker. The effect of the lower layer, however, may continue to be present even at an upper-layer material thickness of 275 mm, depending on the relative stiffness of the layer materials. Caution needs to be exercised in interpreting the results from the SSG when it is used on multilayer systems, especially those with geosynthetic separators. The presence of a geosynthetic separator between the layers may cause a stiffness decoupling of the layers.
Temperature Monitoring and Compressibility Measurement of a Tire Shred Embankment: Winnipeg, Manitoba, Canada
Authors: Shalaby Ahmed , Ahmed Khan Riaz
Published: April 2007

Lightweight fill, used to replace granular fill on a weak subgrade, is of particular interest to road construction. Scrap tires benefit from their lightweight and thermal insulation properties and hydraulic conductivity. Road construction with scrap tires provides a means of disposing of the tires and helps reduce the instability of construction over soft and frost-susceptible soils. However, most research has been focused on using 150-mm or smaller shreds as a lightweight fill in road construction, and there is a lack of technical data on the use of large-size shredded rubber tires. A large-size tire shred embankment, constructed to provide access to a gravel pit near the city of Winnipeg, Manitoba, Canada, is described. The thermal and mechanical behavior of large-size tire shreds is examined by conducting field temperature monitoring and laboratory and field compressibility testing. The thermal behavior of the tire shreds, established from on-site automated temperature measurements, has shown the thermal coefficient of the tires to be 0.2832 W/m·°C. In the compressibility analysis, three sizes of shred (300 mm, 150 mm, and 50 mm) are examined. The elastic modulus of the shredded tires is determined as a function of the bulk density of tires. A model is used to predict and verify the compressibility of the tire shred embankment based on the laboratory testing of tire compressibility.
Uncertainty in Load and Resistance Factor Design Phi Factors for Driven Prestressed Concrete Piles
Authors: McVay Michael C. , Birgisson Bjorn , Nguygen Thai , Kuo Ching L.
Published: April 2007

A database of 156 prestressed concrete piles was gathered to evaluate load and resistance factor design (LRFD) phi factors for eight AASHTO axial pile prediction methods. The majority of the piles had standard penetration test (SPT) data, with limited cone penetration test and laboratory information. In estimating the LRFD phi factors, variability associated with load test capacity estimation, as well as soil parameter assessment by means of in situ tests, was considered. Using an advanced first-order second-moment method, the LRFD phi factors were computed considering all variability (model, load testing, and soil parameters), as well as just the model (i.e., one of the eight AASHTO methods). Current AASHTO LRFD phi factors are shown to be high for some methods (i.e., α-Tomlinson and Meyerhof) and low for others (i.e., Schmertmann SPT). A number of prediction models are recommended for cohesive and cohesionless soils, as well as methods for determining soil parameters from in situ tests.
Use of Ground-Penetrating Radar Data for Rehabilitation of Composite Pavements on High-Volume Roads
Authors: Maser Kenneth R.
Published: April 2007

Applications of ground-penetrating radar (GPR) to composite pavements were studied on sections of Interstate highway: I-495 near New York City, I-95 in New Haven, and I-90 in Chicago. The sections, which ranged in length from 4 to 15 mi, needed to be evaluated for asphalt thickness and condition of the underlying concrete in order to plan and carry out rehabilitation and reconstruction programs. Given the high traffic volumes on these roads, lane closures to allow for direct pavement evaluation were unacceptable, and GPR was chosen as the data collection method. The GPR data were collected at normal driving speeds without interference to traffic and were coordinated with mileposts and other structures to ensure ground control for location referencing. The data were then analyzed to produce graphical plots and tabular spreadsheets of asphalt thickness. Contour plots were also produced showing locations of likely deterioration in the underlying concrete. The GPR thickness results were evaluated for reliability through correlation with data from core samples. The results of each survey were used as input in planning and scoping the subsequent rehabilitation work. The project objectives, equipment used, data analysis methodology, results obtained, use of the GPR data, and correlations with available core data are described.
Performance of Piles Supporting Integral Bridges
Authors: Arsoy Sami , Duncan J. M. , Barker R. M.
Published: April 2007

Cyclic lateral load tests simulating 75 years of bridge life were performed on an H-pile, a pipe pile, and a prestressed reinforced concrete pile by applying over 27,000 displacement cycles. The data from the tests indicate that steel H-piles loaded on the weak axis are the best pile type for support of integral abutment bridges. Concrete piles are not recommended for integral bridge support because, under repeated lateral loads, tension cracks progressively worsen and significantly reduce vertical load carrying capacity of these piles. Steel pipe piles are stiffer than H-piles loaded on the weak axis, and therefore induce higher stresses in the abutment where they are embedded.
Analytical Validation of Pullout Loading Capacity of Suction Piles in Clay
Authors: Cho Y. , Bang S.
Published: April 2007

An analytical solution for the estimation of the ultimate pullout loading capacity of suction piles has been developed by considering two potential failure modes (i.e., the soil tension failure and the pile pullout failure). The analytical solution has been used to identify the dominant failure mode under various circumstances. Finally, the validation of the analytical solution has been made through comparisons with the laboratory model tests results.
Dynamic Stress Response of Concrete Pavements to Moving Tandem-Axle Loads
Authors: Kim Seong-Min , Won Moon C. , Frank McCullough B.
Published: April 2007

The dynamic stress response of concrete pavements subjected to moving tandem-axle loads of constant amplitude and harmonic and arbitrary variations was investigated. The concrete pavement was modeled using a plate of infinite extent on a viscoelastic foundation. Formulations were developed in the transformed field domain using ( a) a double Fourier transform in space and moving space for moving loads of constant amplitude and for the steady-state response to moving harmonic loads and ( b) a triple Fourier transform in time, space, and moving space for moving loads of arbitrary variation. The effects of viscous damping, velocity, load frequency, and phase between front- and rear-axle loads on the maximum stress and the stress distribution were analyzed. Without viscous damping, the effects of velocity and frequency, within practical ranges, on the stresses are negligible; however, with viscous damping, those effects are significant. Since materials used in various pavement layers possess damping characteristics, wheel load stresses can vary considerably because of velocity and load frequency. The increase in wheel load variations and corresponding concrete stresses can be significant if the roughness of the pavement surface is not controlled. The difference in the phase angles between front- and rear-axle loads can considerably increase the maximum stress; therefore, the use of tandem-axle loads and dynamic analyses is necessary to obtain the accurate stresses because the phase effect cannot be obtained with single-axle loads or static analyses.
Evaluation of Subbase Friction for Typical Korean Concrete Pavement
Authors: Chan Suh Young , Woo Lee Seung , Soo Kang Min
Published: April 2007

The frictional force between concrete slab and subbase is accompanied by horizontal slab movements induced by variation of temperature and moisture in the concrete slabs. The frictional force is exerted in the opposite direction from the horizontal slab movement and causes stress in the slab. Rational evaluation of subbase friction is important in configuring joint sealing, slab thickness, and reinforced steel. Determination of the subbase friction is also required as an input for the recently developed concrete-pavement-construction program HIPERPAV. Lean concrete has been widely used as the typical subbase for jointed concrete pavement in Korea. Generally, polythene sheet is placed between the lean concrete subbase and the concrete pavement slab as a friction reducer. In addition, an asphalt bond breaker may be used as an alternative friction reducer in some cases. Three series of push-off tests were conducted to study the characteristics of subbase friction for this typical Korean jointed concrete pavement system under three different subbase conditions (I, test slab directly cast on lean concrete subbase; II, polythene sheet placed between test slab and lean concrete subbase; and III, 4-cm asphalt bond breaker placed between test slab and lean concrete subbase). For each series, tests were performed under various conditions (rate of movement, slab thickness, number of movement cycles) to investigate the influence of these potential factors on the development of subbase friction.
Improving Reliability of Pavement Loading Estimates with Pavement Loading Guide
Authors: Hajek Jerry J. , Selezneva Olga , Jiang Jane Y. , Mladenovic Goran
Published: April 2007

The development of the Long-Term Pavement Performance (LTPP) Pavement Loading Guide (PLG) was initiated to improve the reliability of traffic load estimates for the LTPP sections that do not have measured axle load data. The PLG contains extensive traffic data obtained from the LTPP database that may constitute the best available source of traffic data at the national level, a user-friendly graphical interface, and guidelines intended to help the user with the development of axle load spectra. Because of these features, the PLG will also facilitate traffic projections for general pavement design and management purposes. The uncertainty associated with estimating annual axle load spectra was quantified by assuming that the measured data do not exist and must be estimated. The estimated data were obtained by using axle load spectra obtained at similar sites in the same jurisdiction and utilized prototype PLG software. The difference between the estimated and the measured traffic loads was quantified by expressing axle load spectra in terms of equivalent single-axle loads. The results show that reasonable traffic load estimates can be obtained by judiciously selecting replacement traffic data. Although the PLG can reduce uncertainty of traffic forecasts and facilitate traffic forecasting, surrogate data can never replace site-specific data.
Effect of Traffic Load Estimates on Pavement Design
Authors: Shekharan Raja A. , Ostrom Barbara K.
Published: April 2007

The intention of various design procedures is to provide a means to arrive at a suitable structural configuration of pavement to last the expected traffic loading. Many factors—pavement structure, soil properties, climatic effects, required condition of pavements, and traffic—are inputs in pavement design as the best estimates. There is an inherent variability in these factors, which affects the reliability of the design. The variation in traffic load under constant volume is evaluated as a factor in the design process, specifically the procedure suggested in the AASHTO Design Guide. When the AASHTO Design Guide procedure is used, the traffic loading parameter is varied over a range while other factors are maintained as constants. The variation in reliability for a given slab thickness or structural number is determined for various levels of traffic load inputs in the form of different vehicle mixes, and the trends are documented. This study establishes the variation in reliability with traffic loads that can serve as a guide regarding the accuracy of traffic load input, not only for pavement design but also for traffic data collection activities. The use of reliability curves for the estimation of service lives and remaining lives of pavements is illustrated.
Analyzing Heavy Goods Vehicle Data Collected on Main Road Network in Greece
Authors: Mintsis George , Taxiltaris Christos , Basbas Socrates , Patonis Photis , Filaktakis Anastasios
Published: April 2007

The work described concerns the first major study on heavy goods vehicles operating on the trans-European links in Greek territory. The study period coincides with a period in which major development in the national road network took place that required the support by specific studies concerning pavement design, road management, and toll collection. Data were collected at seven specific sites on the main axes of the main national roads. A total of about 3,053,116 records at all sites were collected concerning all vehicle categories. Data were collected using permanent weigh-in-motion (WIM) instrumentation with either rigid or flexible sensors. In addition, comparison measurements were taken from high-speed and low-speed WIM systems to examine the validity of the above systems to be used in law enforcement for overloaded vehicles. Analysis of the data revealed that the initial sets included a series of counts that were not reliable. False data were detected by imposing various physical or technical filters. The consistency of the remaining good-quality data was examined by using simple analysis techniques. In the final stage of the work much emphasis was given in the development of a comprehensive database of WIM measurements. This database is unique for the Greek national road network and is a necessary step in order to provide useful information and support future actions in the area of pavement design and maintenance.