bluuebunny/crossref_metadata_2025 huggingface dataset:
Treatment Modalities of Obesity
Authors: Hainer Vojtĕch , Toplak Hermann , Mitrakou Asimina
Published: January 2008

The prevalence of obesity is increasing in both developed and developing countries, with rates reaching ∼10–35% among adults in the Euro-American region. Obesity is associated with increased risks of cardiovascular diseases, type 2 diabetes, arthritis, and some type of cancers. Obesity significantly affects the quality of life and reduces the average life expectancy. The effective treatment of obesity should address both the medical and the social burden of this disease. Obesity needs to be treated within the health care system as any other complex disease, with empathy and without prejudice. Both health care providers and patients should know that the obesity treatment is a lifelong task. They should also set realistic goals before starting the treatment, whereas keeping in mind that even a modest weight loss of 5–15% significantly reduces obesity-related health risks. Essential treatment of obesity includes low-calorie low-fat diets, increased physical activity, and strategies contributing to the modification of lifestyle. Anti-obesity drugs facilitate weight loss and contribute to further amelioration of obesity-related health risks. A short-term weight loss, up to 6 months, is usually achieved easily. However, the long-term weight management is often associated with a lack of compliance, failures, and a high dropout rate. Regular physical activity, cognitive behavioral modification of lifestyle, and administration of anti-obesity drugs improve weight loss maintenance. Bariatric surgery is an effective strategy to treat severely obese patients. Bariatric surgery leads to a substantial improvement of comorbidities as well as to a reduction in overall mortality by 25–50% during the long-term follow-up. Obesity treatment should be individually tailored and the following factors should be taken into account: sex, the degree of obesity, individual health risks, psychobehavioral and metabolic characteristics, and the outcome of previous weight loss attempts. In the future, an evaluation of hormonal and genetic determinants of weight loss could also contribute to a better choice of individual therapy for a particular obese patient. A multilevel obesity management network of mutually collaborating facilities should be established to provide individually tailored treatment. Centers of excellence in obesity management represented by multidisciplinary teams should provide comprehensive programs for the treatment of obesity derived from evidence-based medicine.
Is Type 2 Diabetes an Operable Intestinal Disease?
Authors: Rubino Francesco
Published: January 2008

Type 2 diabetes, which accounts for 90–95% of all cases of diabetes, is a growing epidemic that places a severe burden on health care systems, especially in developing countries. Because of both the scale of the problem and the current epidemic growth of diabetes, it is a priority to find new approaches to better understand and treat this disease. Gastrointestinal surgery may provide new opportunities in the fight against diabetes. Conventional gastrointestinal operations for morbid obesity have been shown to dramatically improve type 2 diabetes, resulting in normal blood glucose and glycosylated hemoglobin levels, with discontinuation of all diabetes-related medications. Return to euglycemia and normal insulin levels are observed within days after surgery, suggesting that weight loss alone cannot entirely explain why surgery improves diabetes. Recent experimental studies point toward the rearrangement of gastrointestinal anatomy as a primary mediator of the surgical control of diabetes, suggesting a role of the small bowel in the pathophysiology of the disease. This article presents available evidence in support of the hypothesis that type 2 diabetes may be an operable disease characterized by a component of intestinal dysfunction.
The Risk–Need–Responsivity Model of Assessment and Human Service in Prevention and Corrections: Crime-Prevention Jurisprudence
Authors: Andrews D.A. , Dowden Craig
Published: January 2008

The general personality and social psychology underlying the Risk–Need–Responsivity (RNR) model of rehabilitation recognizes the importance of the personal, interpersonal, and relatively automatic sources of control over human behaviour as well as the power of cognitive-social-learning approaches to interpersonal influence in many social settings. In terms of both prediction and intervention, the RNR model has impressive but limited research support and is widely implemented, albeit with mixed support in routine correctional practice. This article suggests that RNR and the psychology that underlies it may also assist justice agencies and the courts through crime-prevention jurisprudence (CPJ). Always in the context of ethical, legal, just, and otherwise normative interventions, the first task is to help keep low-risk cases low risk and not interfere with existing strengths. The second task is to identify moderate and higher-risk cases and arrange crime-prevention activities consistent with ethical, legal, and just applications of the principles of RNR. Not the least of the benefits is the provision of an evidence-based set of crime-prevention practices as well as a language system that will facilitate inter-agency and intra-agency communication both within and outside of the justice, court, and correctional systems.
Understanding Risk in the Context of the Youth Criminal Justice Act
Authors: Maurutto Paula , Hannah-Moffat Kelly
Published: January 2008

Increasingly, risk assessments are being adopted throughout the criminal justice system in Canada, and they are playing a significant role in the preparation of pre-sentence reports. Over the past five years, nine of Canada's jurisdictions have adopted the use of risk assessments for the preparation of youth pre-sentencing reports (PSR). While ample theoretical knowledge about risk exists, there are noticeably fewer empirical studies of how risk frameworks (re)shape and (re)organize local institutional decision-making practices or of what the socio-political effects of these processes are. Drawing on interviews, case law review, and analyses of risk-assessment documents, this article considers the implications of using risk assessments in the preparation of youth pre-sentencing reports (PSRs). In particular, attention is paid to the tensions between emerging risk practices and the emphasis on proportional sentencing under the Youth Criminal Justice Act (YCJA).
Modeling Household Vehicle Transaction Behavior
Authors: Mohammadian Abolfazl , Rashidi Taha H.
Published: January 2008

Household vehicle ownership analysis is an important and emerging topic in transportation research. Transportation researchers are interested in examining policy scenarios that can decrease the number of vehicles in a household fleet or encourage alternative transit. Many researchers have studied aspects of vehicle ownership and developed various aggregate and disaggregate models in different frameworks, including hazard-based duration models. Duration models can model the competing nature of vehicle transactions in a household and predict the timing of a change in vehicle ownership. Competing duration models are used to analyze the household vehicle ownership decision. Three vehicle transaction decisions (purchase, trade, and disposal of a vehicle) are considered. Dynamic variables that represent the state of the household and household location characteristics, an exogenous logsum variable representing maximum utility of vehicle class and vintage choice, and time-varying covariates (e.g., number of adults and household income) are considered in the model. Independent hazard models for each outcome and a competing hazard model are developed and compared.
Day-to-Day Travel Variability in the Commute Atlanta, Georgia, Study
Authors: Elango Vetri Venthan , Guensler Randall , Ogle Jennifer
Published: January 2008

Traditional travel diary surveys collect 1 or 2 days of travel data from participant households. Although useful in determining the overall average travel behavior of a regional population, cross-sectional travel diary surveys provide little insight into intrahousehold and intraperson trip variability. Longitudinal surveys are generally preferred for examining travel variability. The objective of the research is to examine the intrahousehold travel variability in the Commute Atlanta, Georgia, study, a Global Positioning System–based instrumented-vehicle monitoring study that collected vehicle trips from approximately 500 vehicles in 260 representative households. The research effort uses 2004 travel data collected for the Commute Atlanta study, in which the average variability or deviation in the number of trips by a household was 3 trips/day. Demographic variables (e.g., household size, household income, vehicle ownership, number of children, number of workers, and number of students) significantly affect the day-to-day variability in the total number of household trips per day. The variability due to seasonal effects is controlled by separately analyzing travel data during specific months in spring, summer, and fall. Results indicate that demographic variables have a significant effect on the day-to-day variability of the household number of trips when the variability associated with seasonal effects is excluded. Vehicles identified by participants as being used always or occasionally for business or commercial purposes have travel patterns different from those of other vehicles, and their presence in the sample will significantly bias analytical results in the analysis of longitudinal data. Commercial use vehicles are excluded from travel variability analysis, and the argument is made that households with such vehicles must be treated as an independent sample in future travel diary data collection and longitudinal studies.
Application of Constrained Enumeration Approach to Multimodal Choice Set Generation
Authors: Hoogendoorn-Lanser Sascha , Bovy Piet , van Nes Rob
Published: January 2008

Collected data often include only information about chosen routes. To gain insight into travelers’ route choice behavior or to predict route shares, one must know the set of alternatives from which travelers have chosen their routes. An alternative approach to choice set generation in mixed multimodal networks is presented. This new algorithm—a run-based, constrained enumeration method that uses branch-and-bound techniques—is suitable for both estimation and prediction. One key characteristic of the algorithm is a set of constraints that reflects observed travel behavior. The proposed algorithm for choice set generation can be applied to a complete multimodal network at once. However, by exploiting knowledge about the structure of multimodal trips, the separate application of the algorithm to partial networks and consecutive concatenation of subroutes into complete door-to-door routes substantially reduce computation times without resulting in incomplete choice sets. This algorithm for choice set generation has been calibrated for and successfully applied to a real-size, mixed multimodal transport network in the Netherlands. A comparison of generated choice sets with reported chosen and known alternatives indicated that the algorithm can generate these alternatives, with high coverage levels as a result. This result clearly indicates that this constrained enumeration approach meets the requirements for choice set generation and thus offers interesting perspectives for route choice analysis and the prediction of route shares. Furthermore, the separate application of the algorithm to partial networks and the consecutive concatenation of subroutes into complete door-to-door trips substantially do not result in incomplete choice sets.
Gender Role–Based Differences in Time Allocation
Authors: Cao Xinyu , Chai Yanwei
Published: January 2008

Previous studies on daily time allocation have shed light on individuals’ trade-offs regarding time allocation within a fixed time budget. However, the interpersonal interactions of time allocation with a social network are far from understood, largely because of limited research in this area. Furthermore, few studies have focused on the residents of China, whose population is the largest in the world and whose culture is different from that of Western countries. Structural equation models are applied to data collected from 261 households in Shenzhen, China, to investigate the time allocation of male and female household heads on weekdays and weekend days. The results clearly show the household activity roles of Chinese residents: men dominate out-of-home activities, but women dominate in-home activities. Some insightful interpersonal interactions of activity participation between household heads also is offered.
Population Synthesis for Microsimulating Travel Behavior
Authors: Guo Jessica Y. , Bhat Chandra R.
Published: January 2008

For the forecasting of activity-based travel demand, the representativeness of the base-year synthetic population is critical to the accuracy of subsequent simulation outcomes. To date, the conventional approach to synthesizing the base-year population has been based on the iterative proportional fitting procedure. Two issues associated with this conventional approach are discussed: the first is often termed as the zero-cell-value problem, and the second is related to the inability to control for statistical distributions of both household- and individual-level attributes. Then, a new population synthesis procedure is presented that addresses the limitations of the conventional approach. The new procedure is implemented into an operational software system and used to generate synthetic populations for the Dallas–Fort Worth area in Texas. Validation results indicate that the new procedure can produce a synthetic population that more closely represents the true population than the conventional approach can.
Measuring Sustainable Accessibility
Authors: Cheng Jianquan , Bertolini Luca , le Clercq Frank
Published: January 2008

Transport is one of the most significant sources of unsustainability in urban regional areas. This challenge is stimulating urban planners and decision makers to incorporate the concept of sustainability into their policy design at various levels. Despite its successful implementation in several sectors and wide recognition in academic and professional debate, sustainability is still not that evident in day-to-day regional planning practice. Interpretable measures integrating accessibility and sustainability and linking them with policy-making practice are relatively scarce. This paper aims to take some steps toward measuring sustainable accessibility, which in turn is intended to help regional planners define the potential problems and design possible alternatives at the strategic planning level for a sustainable regional transport and land use system. The proposed methodology for such measurement consists of the concept of conflicts in the planning process, job opportunity modeling, and sustainability and spatial conflict analysis. The Amsterdam urban region in the Netherlands is taken as a case study. Sustainable accessibility is measured in an integrated geographic information system environment, followed by corresponding policy implications for strategy design. The experimental study demonstrates that the indicator of sustainable accessibility can be incorporated into the process of strategic policy design.
Oil Independence
Authors: Greene David L. , Leiby Paul N. , Patterson Philip D. , Plotkin Steven E. , Singh Margaret K.
Published: January 2008

Oil independence has been a goal of U.S. energy policy for the past 30 years, yet the term has never been rigorously defined. A rigorous, measurable definition is proposed: to reduce the costs of oil dependence to less than 1% of gross domestic product in the next 20 to 25 years, with 95% probability. A simulation model incorporating the possibility of oil supply disruptions and other sources of uncertainty is used to test whether two alternative energy policy strategies—business as usual (BAU) and an interpretation of the strategy proposed by the National Commission on Energy Policy (NCEP)—can achieve oil independence for the United States. BAU does not produce oil independence. The augmented NCEP strategy comes close to achieving oil independence for the U.S. economy within the next 20 to 25 years, but more effort is needed to achieve full independence. The success of the strategy appears to be robust regardless of how the Organization of the Petroleum Exporting Countries responds to it. Expected annual savings are estimated to exceed $250 billion per year by 2030.
In-Vehicle Glance Duration
Authors: Horrey William J. , Wickens Christopher D.
Published: January 2008

In general, the unsafe conditions that are likely to produce a motor vehicle crash reside not at the mean of a given distribution (in other words, under typical conditions), but rather in the tails of the distribution. For example, an unusually slow response to a traffic obstacle, rather than an average response, may result in a collision. Although that situation means that crashes are the exception and not the norm, it has implications for how safety-critical data are approached and handled. In this current paper, experimental data collected in a driving simulator are used to demonstrate how an analysis of the average glance durations to an in-vehicle display might lead to different conclusions about safety compared with an alternative analysis of the tail end of the distribution. In addition, a model of crash risk based on the distribution of in-vehicle glances is described, as well as several characteristics of the traffic environment.
Evaluation of Driver Deceleration Behavior at Signalized Intersections
Authors: El-Shawarby Ihab , Rakha Hesham , Inman Vaughan W. , Davis Gregory W.
Published: January 2008

This study analyzes field data gathered from 60 test subjects to characterize driver deceleration rates at the onset of a yellow-phase transition on high-speed signalized intersection approaches using an in-vehicle Global Positioning System. The driver rate of deceleration is analyzed for five yellow-phase trigger times to stop line (1.6, 2.7, 3.3, 4.4, and 5.6 s) as drivers approach the intersection at a speed of 72 km/h (45 mph). Results of the study, based on a sample of 821 deceleration events, indicate that driver deceleration rates range between 1.51 and 7.47 m/s2 (5–24.5 ft/s2) with a mean value of 3.27 m/s2 (10.7 ft/s2). Mean deceleration rates varying from 2.2 m/s2 (7.2 ft/s2) for the longest time to stop line (5.6 s) to 5.9 m/s2 (19.4 ft/s2) for the shortest time to stop line (1.6 s) demonstrate that drivers use more time to decelerate if they are sufficiently away from the intersection. Statistical analyses were used to investigate the effects of the time to stop line, gender, age group, and grade on the average deceleration rates. Results demonstrate that male drivers appear to show slightly higher rates of deceleration when compared with female drivers. This difference increases as the trigger time to stop line decreases. Younger drivers (younger than 40 years old) and older drivers (60 years of age or older) exhibit greater deceleration rates when compared with drivers in the 40- to 59-year age group.
Information Technology Used to Evaluate Nontraditional Traffic Monitoring Systems
Authors: Guo Jianhua , Smith Brian L. , Zhang Guimin
Published: January 2008

A new approach to traffic data collection, known as link monitoring systems–systems that “mine” location data from existing infrastructure (such as cellular telephone networks or fleet management systems) to estimate link speeds and travel times–is emerging. In general, these systems are being developed and operated by private firms, which then seek to sell the data to transportation agencies. To make sound purchasing decisions, agencies must evaluate the quality of the data that they are considering purchasing. The research effort described in this paper developed and field-tested a link monitoring system evaluation procedure. This procedure is based on the use of state-of-the-art information technology resources, namely, geographic information systems and Global Positioning Systems (GPS), to provide a flexible, thorough, and fair evaluation methodology. The methodology consists of four steps. Step 1 is baseline data collection, which includes study site investigation, route design, and probe vehicle runs. Step 2 is data reduction, involving GPS data postprocessing, spatial processing, and travel time and link speed derivation. Step 3 is temporal match, and Step 4 deals with comparisons, including accuracy quantification and temporal traffic condition comparisons. The paper illustrates the procedure based on an evaluation of the Airsage link monitoring system in Hampton Roads, Virginia. In this evaluation, 147,000 GPS points that supported comparisons with over 1,000 link and time data records provided by the Airsage system were collected.
Quantum-Frequency Algorithm for Automated Identification of Traffic Patterns
Authors: Venkatanarayana Ramkumar , Smith Brian L. , Demetsky Michael J.
Published: January 2008

Knowledge of the normal traffic flow pattern is required for a number of transportation applications. Traditionally, the simple historic average has been considered as the best way to derive the traffic pattern. However, this method may often be significantly biased by the presence of incidents. One solution to avoid this bias is through visual inspection of the data by experts. The experts could identify anomalies caused by incidents and thereby identify the underlying normal traffic patterns. Three main challenges of this approach are (a) the bias introduced because of subjectivity, (b) the additional time required to analyze the data manually, and (c) the increasing sizes of the available traffic data sets. To address these challenges and also to exploit the potential of information technology, new data analysis tools are essential. In this research, a new tool, the quantum-frequency algorithm, was developed. This algorithm can aid in the automated identification of traffic flow patterns from large data sets. The paper presents the algorithm along with its theoretical basis. Finally, in the case study presented in the paper, the algorithm was able to identify a reasonable traffic pattern automatically from a large set of archived data. When compared with the historic average, it was found that the pattern identified by the quantum-frequency algorithm resulted in 39% lower cumulative deviation from the pattern identified manually by experts.
Data Collection Time Intervals for Stochastic Short-Term Traffic Flow Forecasting
Authors: Guo Jianhua , Williams Billy M. , Smith Brian L.
Published: January 2008

The specification of time intervals for data collection is a fundamental determinant of the nature and utility of the resulting traffic condition data streams. In the context of short-term traffic flow forecasting, the establishment of the data collection time interval should play a key role in determining the corresponding appropriate forecasting approach. The data collection time interval provides the forecasting horizon for one-step-ahead forecasting. Nevertheless, the need for more rigorous understanding of the effects of data collection time interval specification within the context of short-term traffic flow forecasting is not well recognized. By contrast, it has been common practice in previous research to select the data collection time interval and forecasting approach without explicit consideration of time interval effects or systematic evaluation of available forecasting methods. A stochastic seasonal autoregressive integrated moving average plus generalized autoregressive conditional heteroscedasticity (SARIMA+GARCH) structure proposed in previous work holds promise in providing accurate point forecasts and reasonable forecasting confidence intervals. In this paper, a spectrum of data collection time intervals is tested with an online forecasting algorithm developed based on the SARIMA+GARCH structure to determine the applicable data collection time intervals for this structure. In this test, both the forecast accuracy and the validity of the forecasting confidence intervals are investigated. This work serves as an important step toward establishing a short-term traffic condition forecasting framework that identifies appropriate forecasting approaches for candidate data collection time intervals based on the functional requirements of specific applications.
Evaluating Highway Capacity Investments Using a Geographic Information Systems-Based Tool
Authors: Ozbay Kaan , Yanmaz-Tuzel Ozlem , Mudigonda Sandeep , Bartin Bekir
Published: January 2008

This paper presents an interactive computer tool based on geographic information systems (GIS) and developed for the evaluation and analysis of full marginal costs (FMC) of highway transportation in New Jersey. The first part of the paper is concerned with the implementation of a trip-based FMC estimation methodology in the GIS environment. A constrained k-shortest-path algorithm is proposed to estimate the trip-based FMC of a trip along not only the shortest travel time path but also a set of feasible paths between each origin-destination (O-D) pair that can be attractive to the travelers. The second part of the paper deals with estimation of various transportation cost categories, including vehicle operation, congestion, accident, air pollution, noise, and maintenance. This estimation uses New Jersey-specific data. The methodology is then implemented in ArcGIS, with the use of Visual Basic and C-programming language. The developed GIS-based tool not only estimates FMC between a selected O-D pair but also compares complete and partial networks to assess short-term impacts of infrastructure investments on the FMC. The proposed tool will help planners to calculate true trip costs between different O-D pairs for various user-defined scenarios of various demand and supply changes.
Fuzzy Optimization Approach
Authors: Murat Y. Sazi , Kikuchi Shinya
Published: January 2008

The fuzzy optimization approach is known to be useful for multiobjective and multiconstraint decision situations in which the objectives and constraints are approximate. Although many transportation problems are in this category, the actual application of fuzzy optimization has been rare so far. This paper introduces the fuzzy optimization technique and tests this approach by applying it to setting the signal timing, in which the values of the parameters are not well defined. Three existing signal-timing models are reformulated into the fuzzy optimization approach to accommodate the uncertainty in the parameter values of the models. The results are compared with those obtained from the traditional formulation of the three models. The models tested are the Highway Capacity Manual approach, Webster's method, and Akcelik's method. For average delay and fuel consumption in general, the results obtained from the fuzzy optimization approach are found to be smaller than those obtained using the traditional approach of the three models. This study finds that the fuzzy optimization approach can be useful for transportation problems when objectives and constraints are many, when the boundary values of the constraints are not well defined, and when the goodness of the solution is based on acceptability or best compromise.
Adaptive Seasonal Time Series Models for Forecasting Short-Term Traffic Flow
Authors: Shekhar Shashank , Williams Billy M.
Published: January 2008

Conventionally, most traffic forecasting models have been applied in a static framework in which new observations are not used to update model parameters automatically. The need to perform periodic parameter reestimation at each forecast location is a major disadvantage of such models. From a practical standpoint, the usefulness of any model depends not only on its accuracy but also on its ease of implementation and maintenance. This paper presents an adaptive parameter estimation methodology for univariate traffic condition forecasting through use of three well-known filtering techniques: the Kalman filter, recursive least squares, and least mean squares. Results show that forecasts obtained from recursive adaptive filtering methods are comparable with those from maximum likelihood estimated models. The adaptive methods deliver this performance at a significantly lower computational cost. As recursive, self-tuning predictors, the adaptive filters offer plug-and-play capability ideal for implementation in real-time management and control systems. The investigation presented in this paper also demonstrates the robustness and stability of the seasonal time series model underlying the adaptive filtering techniques.
Prediction of Coarse Aggregate Performance by Micro-Deval and Other Soundness, Strength, and Intrinsic Particle Property Tests
Authors: Lang Alexander P. , Range Peter H. , Fowler David W. , Allen John J.
Published: January 2008

Aggregate samples were collected from the majority of the U.S. states, as well as several Canadian provinces, and subjected to micro-Deval, Los Angeles abrasion, magnesium sulfate soundness, Canadian freeze-thaw, aggregate crushing value, absorption, specific gravity, and particle shape characterization testing to determine whether a correlation exists between laboratory aggregate tests and observed aggregate field performance. Performance ratings were assigned to each aggregate on the basis of the type of distress observed and years of service in the field in hot-mix asphalt and portland cement concrete applications. Numerical and qualitative analyses were performed to evaluate the success of separating good performers from fair and poor performers, with the micro-Deval test alone as well as the micro-Deval test combined with other tests. Furthermore, attempts were made to determine whether a correlation exists between any two tests. The tests that most consistently correlated well with field performance, either alone or in combination with other tests, were micro-Deval, Canadian freeze-thaw, absorption, and specific gravity. Several correlations indicated specific loss limits, which appeared to correctly isolate good performers from the rest. The limits found from correlation of test results and field performance are believed to be effective in identifying good performing aggregates; how-ever, care should be taken in using the limits to exclude aggregates without further consideration because good performers with higher losses were identified. Each agency should develop criteria, including a performance history versus micro-Deval loss, for each aggregate to develop a database that provides accurate performance forecasting.
Soil Suction and Behavior of Chemically Treated Clays
Authors: Petry Thomas M. , Jiang Cheng-Ping
Published: January 2008

Expansive clay soils have caused significant damage throughout the world. Chemical stabilizing agents have been used to reduce the swell of expansive clay soils, but the effect of chemical treatment on the matric and osmotic suction of soils has not been investigated previously. Two subject soils were chosen to study soil suction and the behavior of chemically treated clay. One soil, with high swell potential, was from Irving, Texas. The other soil, with moderate swell potential, was from Slater, Missouri. Hydrated lime and KIS (a proprietary solution containing potash and ammonium lignosulfonate) were used as chemical stabilizers. Select physical and chemical properties of these soils before and after reacting with chemical stabilizers were determined. Total suction, matric suction, and osmotic suction were determined with the use of a dewpoint potentiometer (WP4) and an electrical conductivity probe. Matric suction arises from capillary forces, soil texture, and adsorption forces of clay. Osmotic suction results from the balance of salt concentrations in soil water. When the soils reacted with chemical stabilizers, the osmotic suction increased because of the ion concentrations in the soil. Practical methods were used to determine the osmotic and matric suction of natural soils and of chemically treated soils. Soil suction was correlated with other clay soil properties. Practical methods to separate soil suction parameters were used, and the validity of soil suction to predict chemically treated clay behavior was found to be problematic.
Rapid Chemical Stabilization of Soft Clay Soils
Authors: Rafalko Susan D. , Filz George M. , Brandon Thomas L. , Mitchell James K.
Published: January 2008

Since World War II, the military has sought methods for rapid stabilization of weak soils for support of its missions worldwide. Over the past 60 years, cement and lime have been the most effective stabilizers for road and airfield applications, although many nontraditional stabilizers also have been developed and used. The most effective stabilizer to increase the strength of two soft clay soils within 72 h for contingency airfields to support C-17 and C-130 aircraft traffic needed to be determined. The treatment of one clay with cement resulted in relatively high unconfined compressive strengths (UCS), whereas treating the same clay with quicklime and calcium carbide resulted in lower UCS. The treatment of another clay with higher plasticity resulted in similar UCS for cement, quicklime, and calcium carbide. Secondary stabilizers, including sodium silicate, superabsorbent polymers, a superplasticizer, and an accelerator, were ineffective in increasing the UCS of a soil treated with cement, quicklime, or calcium carbide.
Cement Stabilization of Aggregate Base Material Blended with Reclaimed Asphalt Pavement
Authors: Guthrie W. Spencer , Brown Ashley V. , Eggett Dennis L.
Published: January 2008

The effects of reclaimed asphalt pavement (RAP) content and cement content on the strength and durability of recycled aggregate base materials typical of the I-84 pavement reconstruction project performed in Weber Canyon near Morgan, Utah, were investigated. The laboratory work was based on a full-factorial experimental design, including five RAP contents, five cement contents, and three replicate specimens of each possible treatment. Measurements of unconfined compressive strength (UCS) and final dielectric value in the tube suction test (TST) were used to assess material strength and durability, respectively. These data, together with dry density measurements, were evaluated through an analysis of variance (ANOVA). The results of the ANOVA performed on the UCS data indicate that UCS decreases from 425 to 208 psi as RAP content increases from 0% to 100% and increases from 63 to 564 psi as cement content increases from 0.0% to 2.0%. Similarly, the final dielectric value decreases from 14.9 to 6.1 as RAP content increases from 0% to 100% and decreases from 14.0 to 5.8 as cement content increases from 0.0% to 2.0%. Increasing RAP contents generally correspond to decreasing dry densities. With design criteria requiring 7-day UCS values between 300 and 400 psi and final dielectric values less than 10 in the TST, the results of this research suggest the use of RAP contents in the range of 50% to 75% and a cement content of 1.0% for this material.
Concrete Sludge Powder for Soil Stabilization
Authors: Zhang Jinxi , Fujiwara Tadashi
Published: January 2008

Concrete sludge is an industrial waste produced from ready-mixed concrete plants. Every year, a large quantity of concrete sludge is produced in Japan. At the same time, practical, large-scale disposal options for the concrete sludge are limited, and the cost of disposal is high. Furthermore, the disposed concrete sludge may cause serious environmental and land use problems. A new way to recycle the concrete sludge and reuse large amounts of it is much desired. An innovative technology to cost-effectively recycle concrete sludge and use the recycled material in road construction was developed. Experiments were conducted to study the suitability and effectiveness of the dried sludge powder as a soil stabilizer to improve the load-bearing strength for a clay soil with high moisture content. The tests results showed that adding dried sludge powder to the selected soil with high moisture content can significantly decrease the water content, plasticity index, and frozen heave of the soil while greatly improving the load-bearing strength. The stabilizing effectiveness of the dried sludge powder is greater than that of quicklime in early stages. However, to obtain the best benefit and the best construction quality, some measures should be taken.
Evaluation of the Impact of Fines on the Performance of Lightly Cement-Stabilized Aggregate Systems
Authors: Ashtiani Reza Salehi , Little Dallas N. , Masad Eyad
Published: January 2008

The impact of increasing fines content on the performance of unbound (unstabilized) and lightly stabilized aggregate systems was evaluated. The aggregate systems analyzed varied in amount of mineral fines, the moisture state during curing and at the time of testing, and the amount of portland cement used to stabilize the blend. The evaluation was based on measurements of anisotropic resilient properties, permanent deformation, and unconfined compressive strengths of aggregate systems. In addition, the nonlinear anisotropic resilient properties of the aggregate blends were used in a finite element program to determine critical pavement responses. Aggregate systems with higher fines content were, as expected, more sensitive to moisture than control systems with standard fines content. The increase in the fines content in the unbound systems when molding moisture was wet of optimum dramatically diminished the quality of performance. However, the aggregate systems with higher fines benefited considerably from low percentages of cement stabilizer. It was found that with the proper design of fines content, cement content, and moisture, the performance of the stabilized systems with high fines content can perform equivalent to or even better than the systems with standard fines content. This was clearly evinced by enhancing the resilient properties (increase in stiffness and decrease in anisotropy), decreasing the rate and magnitude of permanent deformation, and increasing compressive strength. The beneficial use of mineral fines will result in benefit to the aggregate industry.
Performance Analysis of Coordinated Traffic Signals during Transition
Authors: Cohen David , Head Larry , Shelby Steven G.
Published: January 2008

Coordinated traffic signals can improve progression and delay times by switching timing plans as traffic conditions change. As cycle and split changes shift capacity where needed, signals shift offsets to maintain or to reestablish progressive flow. Signal offsets dictate, for each main-street green phase, where that green starts in each cycle with the intention of promoting nonstop green waves. To start it earlier or later at a given signal, the options are to shorten one or more intermediate phases or to lengthen one or more intermediate phases (or the main-street phase itself or both phases). Such phase time changes may create a temporary lack of capacity or impose extra delay time. Controllers from all vendors offer transition options to choose from that are differentiated by the amount of offset correction possible per cycle, whether they use a short or a long cycle, and by the distribution of time added to or subtracted from the set of phases. Common transition methods include dwell, maximum dwell, add, subtract, and shortway—all of which were recently incorporated into the CorSim actuated–controller logic. A transient profile analysis method is introduced and demonstrated with a model of a major arterial in Tucson, Arizona, and an additional hypothetical network model. The resulting transient profiles highlight the performance transition behavior that occurs during traffic signal plan transition and that contrasts with assertions previously reported in the literature.
Application of Diamond Interchange Control Strategies at Closely Spaced Intersections
Authors: Tian Zong , Urbanik Thomas , Gibby Reed
Published: January 2008

Signalized diamond interchanges are one of the most common interchange types in U.S. urban areas. Special signal control strategies have been developed for diamond interchanges to address their unique traffic flow and geometric characteristics such as tight spacing and one-way cross streets. The application of diamond interchange signal control strategies on a site consisting of six closely spaced intersections in Reno, Nevada, is documented. These intersections represent or closely resemble a standard diamond interchange. Advance control strategies are derived on the basis of diamond interchange signal control schemes. Simulation results of the timing strategies indicate significant reductions in the number of stops; however, no significant change is found for overall travel time and delay for the study site. Because the proposed control strategies emphasize maximum progression between closely spaced paired signals, the external approaches normally experience increased delay and stops. The proposed control is considered more efficient than the existing control because of significant reduction in stops and much improved driving experience and drivers' expectations. Public reaction to the new timings has been positive. Similar applications could be easily adopted at other locations with similar site characteristics. The proposed control enhances the knowledge of traffic signal control and coordination for closely spaced intersections.
Models for Quantitative Assessment of Video Detection System Impacts on Signalized Intersection Operations
Authors: Tian Zong , Abbas Montasir
Published: January 2008

Various models are presented for quantitative assessment of the impacts of video detection system applications at signalized intersections. The models are developed mainly to address the occlusion issue, one of the unavoidable phenomena associated with video detection systems. Two types of occlusion scenarios and their potential impacts on intersection operations are analyzed on the basis of typical parameter values and detection setup. Also addressed are the limitations of video detection systems in providing advance detection. Occlusion in video detection systems can result in missing detections, false detections, and increased detector presence time and thus may affect intersection operations under actuated control. It is found that missing detections due to occlusion to the following vehicles are generally less than 5% when the approach volume is less than 600 vphpl and the proportion of trucks is less than 5%. At this traffic volume level, additional phase extension time caused by occlusion is generally less than 3 s. To minimize false detections due to occlusion to adjacent lanes, the horizontal offset between the camera and the travel lane should be at the minimum, with an ideal mast-arm mounting and positioning to the division line between the lanes. Because of limitations on the achievable camera height and mounting angle, it is found to be difficult to use one camera to satisfy the required advance detection for speeds over 50 mph. The study does not address the impacts of physical limits of video detection systems such as pixel size, grayscale depth, lighting, and shadows.
Input–Output and Hybrid Techniques for Real-Time Prediction of Delay and Maximum Queue Length at Signalized Intersections
Authors: Sharma Anuj , Bullock Darcy M. , Bonneson James A.
Published: January 2008

Vehicle delay and queue length are quantitative measures of intersection performance. The technological advancement in the field of vehicle sensors and traffic controllers has reached a point where it has enabled efficient measurement of these performance measures. Two techniques are presented for real-time measurement of vehicle delay and queue length at a signalized intersection, and these automated delay and queue estimates are compared with manually ground-truthed measurement. These techniques were evaluated at an instrumented intersection in Noblesville, Indiana. The root-mean-square error by both techniques was below 0.7 veh-s for estimation of average delay and less than 0.15 vehicle for estimation of average maximum queue length, both on a cycle-by-cycle basis.
Implementation of Lane-by-Lane Detection at Actuated Controlled Intersections
Authors: Smaglik Edward J. , Bullock Darcy M. , Sturdevant James R. , Urbanik Thomas
Published: January 2008

Previous work with lane-by-lane detection has shown efficiency gains during periods of moderate to low volume, as well as a decrease in overall intersection delay when lane-by-lane detection is compared with traditional movement-based detection. This research extends that work with the implementation of lane-by-lane detection at the Indiana Department of Transportation's test bed intersection in Noblesville, Indiana. Over a 3-week period with traditional movement-based detection, green interval lengths, volume-to-capacity (v/c) ratios, and cycle lengths were computed for all eight phases. Detection and controller settings were changed to implement lane-by-lane detection on the multilane movements at the test bed, and the same measures of effectiveness were calculated for 3 weeks of lane-by-lane detection. During free operation with low to moderate volume, statistically significant decreases in green durations and cycle times, as well as statistically significant increases in v/c ratios, were observed on movements with lane-by-lane detection. These implementation results corroborate previous simulation results.
Recasting Dilemma Zone Design as a Marginal Cost–Benefit Problem
Authors: Sharma Anuj , Bullock Darcy M. , Peeta Srinivas
Published: January 2008

One control objective at high-speed isolated intersections is to provide safe phase transition by minimizing the occurrence of high-speed vehicles in the dilemma zone before the phase is terminated. An upper limit for extending the green (maximum green time) is used to avoid an indefinite extension of the main-street green. Currently, the maximum green times are chosen by using engineering judgment. This approach does not explicitly consider the trade-offs between safety and delay and hence often results in both unsafe and inefficient performance at the intersection under medium to heavy traffic volumes. The dilemma problem is recast as one of minimizing the number of vehicles entering the upstream decision conflict zone (DCZ). An economic evaluation approach is proposed to maximize both safety and efficiency at the intersection by considering the problem in terms of marginal costs and benefits. Traffic conflicts are used to estimate potential safety benefits, and the induced delay cost is used to estimate the cost accrued on side-street traffic that is associated with extending a competing phase. This approach allows the implementation of logic that minimizes DCZ exposure instead of the current approach of absolute protection until the maximum green time is reached, at which time no consideration is given to dilemma zone exposure when the phase is terminated. This approach handles efficiently and safely the periods of moderate demand volumes when current dilemma zone protection frequently encounters maximum green time exposure.