bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Geometric Characteristics on Head-On Crash Incidence on Two-Lane Roads in Connecticut
Authors: Zhang Chen , Ivan John N.
Published: January 2019

Negative binomial generalized linear models were used to evaluate the effects of roadway geometric features on the incidence of head-on crashes on two-lane rural roads in Connecticut. Six hundred fifty-five highway segments—each with a uniform length of 1 km and no intersections with signal or stop control on the major road approaches—were selected for analysis. Head-on crash data were collected for these segments from 1996 through 2001. Variables found to influence the incidence of head-on crashes significantly were speed limit, sum of absolute change rate of horizontal curvature, maximum degree of horizontal curve, and sum of absolute change rate of vertical curvature. Three models were estimated with different combinations of these four variables, and the performance of the models was tested by using Akaike's information criterion. The number of crashes was found to increase with each of these variables except for speed limit. Variables such as lane and shoulder width were not found to be significant for explaining the incidence of head-on crashes. The results suggest that to reduce the incidence of head-on crashes on two-lane roads, it is more effective to reduce the number and degree of horizontal and vertical curves than to widen the pavement.
Crash Reduction Factors for Deer-Vehicle Crash Countermeasures
Authors: Knapp Keith K.
Published: January 2019

A detailed critical evaluation of deer–vehicle crash (DVC) countermeasure safety analyses was completed during the past 3 years. Previous summaries of this literature did not focus on the adequacy or rigor of these analyses and generally repeated recommendations or based them on the exaggerated and sometimes incorrect safety impact conclusions presented in past documents. A comparison of past safety analysis designs and documentation with generally accepted transportation safety research standards was completed for 16 potential DVC countermeasures. The countermeasures were grouped into one classification system on the basis of the general safety result trends of past research and another system that used categories defined for the safety strategies used in the implementation of the AASHTO Strategic Highway Safety Plan. All but two of the DVC countermeasures were grouped into the AASHTO categories of “tried” and “experimental.” The proper implementation of wildlife fencing and crossings consistently resulted in DVC reductions, and these were categorized as proven strategies. The majority of the DVC countermeasures reviewed are used in the field, but their actual safety impact had rarely or never been studied. The study of other countermeasures produced conflicting safety analysis results. The use of past research results to develop valid DVC countermeasure crash reduction factors is not considered advisable given the safety analysis approaches used and the results produced. Research needs for the countermeasure categories are suggested to guide the activities needed to achieve this goal.
Determination of Events Leading to Sport Utility Vehicle Rollover
Authors: Blower Daniel , Woodrooffe John , Green Paul , Matteson Anne , Shrank Michael
Published: January 2019

To determine the major event pathways that result in sport utility vehicle (SUV) rollover, researchers at the University of Michigan Transportation Research Institute examined SUV rollover cases selected from the National Automotive Sampling System crashworthiness data system files for 1999 to 2001. Selected SUVs included the Ford Explorer, Jeep Cherokee, Chevrolet Blazer, Toyota 4-Runner, and GMC Jimmy for model years 1989 to 2001. Researchers coded up to six pre-rollover events, along with the stability of the vehicle (tracking or skidding) after each event. In addition, crash avoidance and recovery maneuvers were recorded, along with the rollover initiation type, location of rollover initiation, direction of roll, number of quarter turns of roll, location of roll, and surface condition at rollover initiation. Approximately 34% of SUV rollovers began with a loss of control caused by tire saturation, and about 75% of the loss-of-control cases were on icy, wet, or snowy roads. Of the SUVs that ran off the road as the first event, 47% returned to the road before rolling over, and of these, 76% were tracking (presumed under control) before initial road departure. Between 40% and 49% of SUV rollover crashes experienced yaw instability while still on the roadway before roll. These rollovers may be addressed by electronic stability control devices if such devices can increase the control limits of the vehicle.
Evaluating Abdominal Injury in Impacts with Workstation Tables
Authors: Parent Daniel , Tyrell David , Perlman Benjamin , Matthews Peter
Published: January 2019

In rail passenger seating arrangements with workstation tables, there is a risk of serious thoracic and abdominal injury. Strategies to mitigate this injury risk are being developed through a cooperative agreement between the U.S. Federal Railroad Administration and the Rail Safety and Standards Board of the United Kingdom. The approach to developing the protection strategies involves collision investigations, computer simulations of the occupant response, and full-scale testing. During the train collision in Placentia, California, on April 23, 2002, many occupants hit workstation tables. The investigation indicated the likely modes of injury caused by the impact, the most traumatic being damage to the liver and spleen. A MADYMO computer simulation was created to estimate the loads and accelerations imparted on the occupants that brought about these injuries. Two experiments were designed and executed on a full-scale impact test with an occupant environment similar to the Placentia collision. These experiments incorporated advanced anthropomorphic test devices (ATDs) with increased abdominal instrumentation. The THOR (test device for human occupant restraint) ATD showed a more humanlike impact response than did the Hybrid III Railway Safety ATD. The full-scale test results are used to refine a MADYMO model of the THOR ATD to evaluate improved workstation tables. The occupant protection strategy that will be developed requires that the table remain rigidly attached to the car body and includes a frangible edge with a force–crush characteristic designed to minimize the abdominal load and compression. MADYMO simulations of this table design show a significantly reduced risk of severe abdominal injury.
Informing Healthy Transport Policies
Authors: Egan Matt , Petticrew Mark , Ogilvie David
Published: January 2019

Transport is an important determinant of health, and the health impact of transport interventions requires robust evaluation. Systematic reviews provide a rigorous tool for locating, appraising, and synthesizing evaluative evidence. Some systematic reviews use meta-analysis techniques to synthesize data, but other systematic reviews do not. This paper addresses some methodological and practical issues associated with conducting systematic reviews on the health impact of transport interventions. By using as case studies recently conducted reviews on topics such as the health impact of new roads and the effectiveness of interventions in promoting modal shift, the paper outlines many of the challenges faced by systematic reviewers in this field. It then describes some research synthesis techniques available to systematic reviewers and discusses some of the strengths and weaknesses of these techniques. Systematic literature reviews on the health impact of specific transport interventions can be used to inform decision making. However, reviews of such complex interventions require an innovative approach to the methodologies of systematic reviews and research synthesis.
Can We Trust the Results of Meta-Analyses?
Authors: Elvik Rune
Published: January 2019

Every meta-analysis involves a number of choices made by the analyst. These choices may refer to, for example, estimator of effect, model for analysis (fixed effects or random effects), or the treatment of varying study quality. The choices made can affect the results of the analysis. Every meta-analysis should therefore include a sensitivity analysis, designed to probe how choices made as part of the analysis affect its results. This paper describes a systematic approach to sensitivity analysis in meta-analyses. An index intended to summarize the results of a sensitivity analysis, the robustness score, is developed. The robustness score varies from 0 to 1. A value of 1 indicates that the results of a meta-analysis are robust; they are not at all affected by the choices made by the analyst. It is proposed that every meta-analysis include a sensitivity analysis for (a) the potential presence of publication bias, (b) the choice of estimator of effect (if relevant), (c) the possible presence of outlier bias (a single result having decisive influence on the summary estimate), (d) statistical weighting of individual estimates of effect, and (e) assessment of study quality. A recently reported meta-analysis of studies that have evaluated the effects on road safety of daytime running lights for cars is used as a case to explain the proposed approach to sensitivity analysis.
Elasticity of Demand for Barged Corn Shipments on the Upper Mississippi River–Illinois Waterway
Authors: Dager Chrisman A. , Bray Larry G. , Murphree C. Michael , Leibrock Charlotte Ann
Published: January 2019

Qualitative evidence is presented to contend that the predominant response of waterway grain shippers on the Upper Mississippi River-Illinois Waterway to increases in barge shipping costs is most likely to be modal shift. Even so, modal shift faces serious constraints, moderating its ability to substitute for barges as waterway shipping costs rise. In addition, empirically derived estimates of demand price elasticities for barge transport are offered on four reaches of the river system. The elasticities are moderately inelastic, ranging from −0.7 to −0.3.
Long-Term Forecasting of World Grain Trade and U.S. Gulf Exports
Authors: Wilson William W. , Koo Won W. , Taylor Richard , Dahl Bruce
Published: January 2019

Important changes occurring in the world grain trade will affect the spatial distribution of grain flows and affect large-scale transportation projects. Most important among these are developments in ethanol and in Brazil and China. This paper develops a spatial optimization model based on a long-term competitive equilibrium to make projections in the world grain trade and shipments from individual ports to 2025. Results indicate that world trade should increase by about 47%, with the fastest growth occurring in imports to China and Pakistan and the slowest growth in Japan and the European Union, traditionally large markets. Most increases in terms of volume are expected in soybeans (49%), followed by corn (26%). Most of the U.S. export growth is expected through the barge system to U.S. ports on the Gulf of Mexico, with negligible growth through the Pacific Northwest and lakes. Although a multitude of reasons explain this expected trend, one is the growth in ethanol concentrated in the western states, which will require shifting production to meet demand. As a result, the exportable surplus from these regions will decline, and much of the growth in exports will be through the U.S. Gulf and from Argentina and Brazil, particularly northern Brazil, through spatial competition. Reflecting the impacts of growth in demand as well as international and intermodal competition, these results provide insight for transport project planners about the long-term growth in exports from particular origins and routes.
Who Gains from and who Pays for Channel Deepening?
Authors: Grigalunas Thomas A. , Opaluch James J. , Chang Young Tae
Published: January 2019

Port dredging to accommodate larger vessels can create substantial national economic benefits. However, how affected individual states fare economically with dredging is often unclear and can be an important issue. The benefits and the costs to Delaware residents of dredging—with the recent proposed deepening of the Delaware Bay and River main federal channel as a case study—are examined. Benefits include ( a) lower transportation costs that residents might receive on imported goods, ( b) profits that residents would realize if cost savings (e.g., on refinery products) were not passed forward to Delaware users, ( c) project costs that residents would bear as federal taxpayers, and ( d) benefits that residents would realize if the use of dredged sediments for planned beach renourishment created savings to the state. Sensitivity analyses are used to reflect uncertainty in outcomes. The estimated net present value to Delaware today of all future annual quantifiable benefits and costs ranges between $15,528,393 and $14,195,700 over 50 years at 5.875%. Stated another way, the quantified net benefits for Delaware imply a benefit-cost ratio between 2.07 and 1.89. Hence, for every dollar of the $7.5 million that Delaware would pay as a nonfederal cosponsor, estimated quantifiable net benefits to the state are $2.07 to $1.89. Some benefit and cost estimates are vehemently debated between interested parties, and not all benefits and costs can be quantified.
Geographical Characterization of Ship Traffic and Emissions
Authors: Wang Chenfeng , Corbett James J.
Published: January 2019

The Commercial Marine Vessel Traffic and Air Emissions Model (CMV-TAEM) estimates and geographically represents offshore vessel traffic and emissions based on actual shipping activities. The CMV-TAEM has three modules: ship traffic, ship emissions, and policy analysis. The model establishes empirical ship traffic network on the basis of ship observations derived from the International Comprehensive Ocean-Atmosphere Data Set and shipping activity records. Geographical representations of ship traffic intensities and emissions can be produced through the math-ematic manipulation of matrices of ship traffic network, shipping activity, and ship characteristic data. Overall, although seasonal changes are apparent, the global ship traffic pattern does not change much annually. The ship traffic pattern changes regionally, with a net increase in some areas and net decrease in others. Multiple-year observations are combined to make traffic patterns for major shipping lanes smoother and clearer. Results indicate that 84.5% of global ship traffic occurs north of the equator and two-thirds of global ship traffic within 200 nautical miles of the shore. About 10% of global ship traffic occurs in U.S. coastal waters; shipping along the East Coast accounts for more than one-fifth of the U.S. coastal traffic. Adequate data are available to determine ship activities and ship attributes and to implement the model.
Oil Spills in Maritime Transport
Authors: Boilé Maria , Theofanis Sotirios , Mikiki Foteini
Published: January 2019

Maritime transport plays a vital role in the economic growth and global competitiveness of the regions that it serves. It offers an enormous potential for sustainable and environmentally friendly transport. The international maritime community, however, is faced with a major challenge: to protect the marine environment from pollution related to oil spills. A parallelism between resolutions adopted by national and international bodies and the oil spill incidents that triggered them is presented. The focus is on reviewing records of maritime casualties associated with massive environmental pollution. It is an attempt to shed light on how these incidents affect the formulation and implementation of the global marine environment protection policy as well as the role of the International Maritime Organization in dealing with these problems.
Observations of Driver Time Gap Acceptance at Intersections in Left-Turn Across-Path–Opposite-Direction Scenarios
Authors: Chan Ching-Yao , Ragland David R. , Shladover Steven E. , Misener James A. , Marco David
Published: January 2019

Intersection collision warning systems can potentially reduce the number of collisions and associated losses. A critical design aspect of these systems is the selection of warning criteria, which represent a set of conditions and parameters under which the decision and the timing to issue warnings are determined. Proper warning criteria allow the generation of timely signals for drivers while minimizing false and nuisance alarms. The paper describes the development of a methodology to observe and analyze the selection of time gaps exhibited by driver behaviors in a real-world setting. The data collection procedures and analysis techniques are explained for left-turn across-path–opposite-direction scenarios, which constitute more than a quarter of crossing path crashes at intersections. Exemplar data sets from an urban, signalized intersection are used to illustrate methods of deriving time gap acceptance behaviors. The extracted information can serve as the basis for selecting gap acceptance thresholds in warning criteria, and the demonstrated methodology can be applied in the development of intersection collision warning systems.
Probabilistic Approach for Validation of Advanced Driver Assistance Systems
Authors: Gietelink O. J. , De Schutter B. , Verhaegen M.
Published: January 2019

This paper presents a methodological approach for validation of advanced driver assistance systems. The methodology relies on the use of randomized algorithms that are more efficient than conventional validation that uses simulations and field tests, especially with increasing complexity of the system. The methodology first specifies the perturbation space and performance criteria. Then, a minimum number of samples and a relevant sampling space are selected. Next, an iterative randomized simulation is executed; then the simulation model is validated with the use of hardware tests to increase the reliability of the estimated performance. The proof of concept is illustrated with some examples of a case study involving an adaptive cruise control system. The case study points out some characteristic properties of randomized algorithms with respect to the necessary sample complexity and sensitivity to model uncertainty. Solutions for these issues are proposed as are corresponding recommendations for research.
Simulation-Based Evaluation of Advanced Traveler Information Systems
Authors: Balakrishna Ramachandran , Koutsopoulos Haris N. , Ben-Akiva Moshe , Ruiz Bruno M. Fernandez , Mehta Manish
Published: January 2019

Traveler information has the potential to reduce travel times and improve their reliability. Studies have verified that driver overreaction from the dissemination of information can be eliminated through prediction-based route guidance that uses short-term forecasts of network state. Critical off-line tests of advanced dynamic traffic assignment–based prediction systems have been limited, since the system being evaluated has also been used as the test bed. This paper outlines a detailed simulation-based laboratory for the objective and independent evaluation of advanced traveler information systems, a laboratory with the flexibility to analyze the impacts of various design parameters and modeling errors on the quality of the generated guidance. MITSIMLab, a system for the evaluation of advanced traffic management systems, is integrated with Dynamic Network Assignment for the Management of Information to Travelers (DynaMIT), a simulation-based decision support system designed to generate prediction-based route guidance. Evaluation criteria and requirements for the closed-loop integration of MITSIMLab and DynaMIT are discussed. Detailed case studies demonstrating the evaluation methodology and sensitivity of DynaMIT's guidance are presented.
Framework for Inspection, Maintenance, and Replacement of Corrugated Steel Culvert Pipes
Authors: Meegoda Jay N. , Juliano Thomas M. , Ratnaweera Prasanna , Abdel-Malek Layek
Published: January 2019

A framework for inspection, rehabilitation, and replacement of corrugated steel culvert pipes (CSCP) is developed. It is expected to lead to developing a culvert information management system (CIMS), wherein justification and need are based on recent Governmental Accounting Standards Board (GASB) requirements. The CIMS will assist in evaluating infrastructure assets and facilitate comparing present costs of preserving infrastructure. Benefits include long-term savings from adopting optimized preventive maintenance strategies. CSCP condition states are used to express the extent of deterioration. Rehabilitation options and recommendations are given for deteriorated CSCPs. These options will be incorporated into the proposed CIMS, which uses survival probabilities based on the CSCP condition state during the previous year. Survival probabilities within Condition States 1, 2, and 3 are computed on the basis of corrosion research data. However, implementing the proposed CIMS requires field data for CSCPs or laboratory tests that mimic field conditions. The proposed CIMS can analyze decisions to inspect, rehabilitate and replace, or do nothing at both project and network levels. At the project level, inspection or rehabilitation and replacement costs are compared with failure risks and costs. At the network level, associated costs are optimized to meet the annual maintenance budget by prioritizing CSCPs needing inspection and rehabilitation and replacement. The proposed CIMS can also be used to estimate the required annual budgetary allocation for a stipulated planning horizon and to maintain or improve the aggregate condition state of the CSCP network or to maintain or improve the total highway CSCP network asset value, thereby meeting GASB 34 requirements. The optimum sequential path in the annual decision-making process may then be determined using a combination of operations research tools.
Guidelines for Using Late Merge Traffic Control in Work Zones
Authors: Beacher Andrew G. , Fontaine Michael D. , Garber Nicholas J.
Published: January 2019

The late merge traffic control strategy has been proposed as a way to improve flow at work zone lane closures by maximizing queue storage space and creating more orderly merging. The late merge instructs drivers to use all lanes to the work zone taper and then take turns proceeding through the work zone. There is little information available on when the late merge should be used, however, and a limited understanding of the factors that influence its performance. This paper discusses the results of a simulation study of the late merge concept using microscopic traffic simulation. The late merge concept was evaluated by comparing it with traditional traffic control, through a full factorial analysis. Results of the computer simulations showed that the late merge produced a statistically significant increase in throughput volume versus the traditional merge for the three-to-one lane closure configuration across all combinations of analysis factors. Although the two-to-one and three-to-two configurations did not show significant improvement in throughput overall, it was found that as the percentage of heavy vehicles increased, the late merge did foster higher throughput volumes than traditional traffic control. The results of the simulations indicate that the late merge may not provide as much of a benefit as previous studies had indicated and that the area of application for the late merge may be limited to situations where heavy vehicles constitute more than 20% of the traffic stream.
Night Work Specification of Nova Scotia, Canada
Authors: Kennedy Gerard
Published: January 2019

This paper describes the development and implementation of a specification for nighttime highway construction and maintenance projects in Nova Scotia, Canada, with the details of the specification and the lessons learned during its use on projects in the years 2002, 2003, and 2004. Increasing traffic volumes and the demand from the motoring public to minimize delays at work zones throughout North America have led to the scheduling of some highway maintenance and construction activities during nighttime hours. That has also been the experience in Nova Scotia. The first edition of the specification was developed by compiling information from many sources. A literature search, discussions with most American state and Canadian provincial agencies, and research data from TRB and other sources were used in the development of the specification. This specification has been revised each year on the basis of further research and practical experience with its use. It has been used on nighttime highway projects in Nova Scotia since 2002.
Effect of Time and Foggy Conditions on Subjective Visibility
Authors: Munehiro Kazunori , Tokunaga Roberto A. , Asano Motoki , Hagiwara Toru
Published: January 2019

In dense fog, the visibility of retroreflective traffic control devices is vital for driving safety. However, few studies have addressed the visibility of such devices in fog during a 24-h period (daytime, evening, and nighttime). This study measures the subjective visibility of the latest traffic control devices under various visibility conditions. An experiment was performed during a 2-month period in 2003 under natural fog at a test road 200 m long and 7.5 m wide in Eastern Hokkaido, Japan. Visibility conditions varied by daytime, evening, and nighttime and by weather condition factor (clear, cloudy, and dense fog). Thirteen kinds of traffic control devices were used as targets: two types of pavement markings, three of delineators, four of warning signs, and four of chevrons. Various newly developed materials were tested, and color and size were varied. The 20 women who participated in the experiment were required to make subjective judgments within a few seconds of the visibility of each target and their feeling of safety, assuming that they were driving on that section at 50 km/h. Results showed that daytime fog had a major negative effect on subjective visibility evaluations, while nighttime fog did not have as great a negative effect as that in daytime. However, the subjective visibility values of targets under the nighttime cloudy condition were worse than those under the daytime dense fog condition. Also, subjective visibility values for target objects made of highly reflective materials or incorporating fluorescent colors were high under both daytime fog and nighttime fog conditions.
Characterization and Environmental Management of Storm Water Runoff from Road Salt Storage Facilities
Authors: Fitch G. Michael , Bartelt-Hunt Shannon , Smith James A.
Published: January 2019

The Virginia Department of Transportation (DOT) is responsible for maintaining more than 57,000 mi of roadway; a major part of that responsibility is implementation of Virginia DOT's anti-icing program. In FY 2003, the agency purchased more than 570,000 tons of sodium chloride; this salt is stored at nearly 300 locations statewide. This study's objectives were to assess the quantity and quality of salt-contaminated water generated from storm water runoff at Virginia DOT's road salt storage facilities and to evaluate management and treatment alternatives to reduce costs and better protect the environment. For the first objective, data concerning detention pond surface area and volume, runoff area, and several key water quality constituents were collected from 45 randomly selected sampling sites. Chloride concentrations were significantly greater than those specified in state and federal regulatory guidelines, with values routinely exceeding 2,000 mg/L. The quantity of storm water collected was higher than anticipated, with approximately 60 megagallons (MG) of contaminated runoff water generated in an average rainfall year. For the second objective, two alternatives to Virginia DOT's disposal practices were examined: management strategies to reduce the volume of salt-contaminated storm water runoff generated at each facility, and treatment of runoff to remove salt and subsequent release of runoff back to the environment. Currently, the agency disposes of salt water by one of three methods at an average cost of $0.13 per gal. If Virginia DOT used a mobile ultrafiltration and reverse osmosis system, the cost would be cut by more than half. For a statewide annual treatment volume of 58.6 MG, an annual cost savings of $1.9 to $4.3 million would result.
New Methodology for Shape Classification of Aggregates
Authors: Al-Rousan Taleb , Masad Eyad , Myers Leslie , Speigelman Cliff
Published: January 2019

Aggregate shape characteristics play a major role in determining the structural and functional properties of asphalt mixes. A comprehensive, statistically based methodology for the analysis and classification of the shape characteristics of both fine and coarse aggregates is presented. These characteristics are form (three dimensions of coarse aggregates), angularity, and surface texture. The methodology was developed by measuring the distribution of the shape characteristics of aggregates from a wide range of sources and varying sizes. The limits for the classification groups were determined with the use of a cluster analysis. The new methodology offers several advantages over current methods used in practice. It is based on the distribution of shape characteristics in an aggregate sample rather than on average indices of these characteristics. The coarse aggregate form is determined with the use of a three-dimensional analysis of particles, which allows particles to be distinguished between flat, elongated, or flat and elongated particles. The fundamental gradient and wavelet methods were used to quantify angularity and surface texture, respectively. The classification methodology can be used to evaluate the effects of different processes, such as crushing techniques and blending, on aggregate shape distribution. It also lends itself to the development of aggregate specifications on the basis of the distribution of shape characteristics.
Unbound Aggregate Rutting Models for Stress Rotations and Effects of Moving Wheel Loads
Authors: Kim In Tai , Tutumluer Erol
Published: January 2019

The latest research findings on stress rotations caused by moving wheel loads and their effects on permanent deformation or rut accumulation in pavement granular layers are presented. Realistic pavement stresses induced by moving wheel loads were examined in the unbound aggregate base and subbase layers, and the significant effects of rotation of principal stress axes were indicated for a proper characterization of the permanent deformation behavior. To account for the rutting performances of especially thick granular layers, a comprehensive set of repeated load triaxial tests was conducted in the laboratory. Triaxial test data were obtained and analyzed from testing aggregates under various realistic in situ stress paths caused by moving wheel loading. Permanent deformation characterization models were then developed on the basis of the experimental test data to include the static and dynamic stress states and the slope of stress path loading. The models that also considered the stress path slope variations predicted the stress path dependency of permanent deformation accumulation best. In addition, multiple stress path tests conducted to simulate the extension–compression–extension type of rotating stress states under a wheel pass gave much higher permanent strains than those of the compression-only single path tests. The findings indicated actual traffic loading simulated by the multiple path tests could cause greater permanent deformations or rutting damage, especially in the loose base or subbase, when compared with deformations measured from a dynamic plate loading or a constant confining pressure type laboratory test.
Application of Dynamic Cone Penetrometer in Pavement Construction Control
Authors: Abu-Farsakh Murad Y. , Nazzal Munir D. , Alshibli Khalid , Seyman Ekram
Published: January 2019

A comprehensive testing program was conducted to evaluate the potential use of the dynamic cone penetrometer (DCP) in the quality control–quality assurance procedure during the construction of pavement layers and embankments. The laboratory tests were conducted on different materials prepared inside two test boxes measuring 1.5 m x 0.9 m x 0.9 m (5 ft x 3 ft x 3 ft) located at the Louisiana Transportation Research Center (LTRC). The field tests were performed on different highway sections in Louisiana. In addition, nine test sections were constructed and tested at the pavement research facility site of the LTRC. In all laboratory and field tests, DCP tests were carried out in conjunction with the plate load test (PLT). Also, falling weight deflectometer (FWD) tests were carried out on the field sections. California bearing ratio (CBR) laboratory tests were performed on samples collected from the tested sections. Regression analysis was carried out on the collected data to correlate the DCP penetration rate with the three reference tests used in this study (PLT, FWD, and CBR). Further field tests were conducted to verify the developed regression models. The results showed that the developed models yielded good predictions of the measured FWD moduli and CBR values. This suggests that these models can be used reliably to evaluate the stiffness and strength of pavement materials.
Variation of Resilient Modulus with Soil Suction for Compacted Subgrade Soils
Authors: Yang Shu-Rong , Huang Wei-Hsing , Tai Yu-Tsung
Published: January 2019

The variations of resilient modulus with the postconstruction moisture content and soil suction for cohesive subgrade soils were evaluated. In particular, the effects of relative compaction of the subgrade on the suction and resilient modulus were investigated. To simulate subgrade soils at in-service conditions, soil specimens were compacted at various relative compactions and optimum moisture content and then saturated to equilibrium moisture content to test for resilient modulus and soil suction. The filter paper method was used to measure the total and matric suctions of two cohesive soils. Test findings demonstrated that resilient modulus correlated better with the matric suction than with total suction. Matric suction was found to be a key parameter for predicting the resilient modulus of cohesive subgrade soils. A prediction model incorporating deviator stress and matric suction for subgrade soil resilient modulus was established.
Development of Surfacing Criteria for Low-Volume Roads in South Dakota
Authors: Wolters Angela S. , Zimmerman Kathryn A. , Huft David L. , Oien Paul A.
Published: January 2019

On a daily basis, local road agencies in South Dakota face the challenge of how to maintain low-volume roads cost-effectively. Specifically, agencies are faced with the decision of determining when it is most economical to maintain, upgrade, or downgrade a road's existing surface. To assist decision makers with maintenance and rehabilitation decisions, the South Dakota Department of Transportation (SDDOT) initiated a study in 2002 to investigate surfacing criteria for low-volume roads. The overall objective of this research is to create a process that allows users to compare the costs associated with different types of roads to provide assistance in deciding which surface type (hot-mix asphalt, blotter, gravel, or stabilized gravel) is most economical under a specific set of circumstances. In addition to incorporating economic factors into the analysis, the process allows the user to consider other noneconomic factors that are more subjective and difficult to quantify. The process used during this study is flexible enough to allow users to consider any combination of agency costs incurred by the agency for maintaining its roads, user cost factors such as vehicle operating costs or crash potential, and noneconomic factors such as politics and housing densities. The methodology was created with agency cost and user cost models developed on the basis of specific road section information supplied by various local agencies in South Dakota, average daily traffic and crash occurrence information supplied by the SDDOT, information obtained through a literature search, and input from members of the project's technical panel.
Evolution of Pavement Winter Roughness
Authors: Fradette Nicolas , Doré Guy , Pierre Pascale , Hébert Serge
Published: January 2019

The functional service level of roads is quantified in terms of roughness. This parameter considers every road surface defect that causes passenger vehicle discomfort. Roughness is measured by a quality index, the international roughness index (IRI). Roughness gives an overall appreciation of road profile quality without, however, permitting a deeper analysis. The overall value of the IRI does not discriminate between the two main factors responsible for winter deterioration of roughness: the subgrade differential heave and crack heaving (winter tenting). Differential heave is the result of variability in frost susceptibility of subgrade. This phenomenon can be detected by isolating the long wavelengths produced at the road surface from the longitudinal profile. Crack heaving is a superficial phenomenon greatly influenced by the application of deicing salts. By isolating the short wavelengths from the profile, it is possible to highlight the influence of this phenomenon on deterioration. The goal of this research is to establish, with the use of a filtering technique of road profile, the contribution of these two main factors to winter deterioration of roughness on five road sections in the Quebec City, Canada, area. This study will then allow for the development of a tool to determine the dominant factor for longitudinal profile deterioration and therefore the use of the best technique to rehabilitate roads.
Method for Automated Discontinuity Analysis of Rock Slopes with Three-Dimensional Laser Scanning
Authors: Slob Siefko , van Knapen Bart , Hack Robert , Turner Keith , Kemeny John
Published: January 2019

Three-dimensional (3D) laser scanning data can be used to characterize discontinuous rock masses in an unbiased, rapid, and accurate manner. With 3D laser scanning, it is now possible to measure rock faces whose access is restricted or rock slopes along highways or railway lines where working conditions are hazardous. The proposed method is less expensive than traditional manual survey and analysis methods. Laser scanning is a relatively new surveying technique that yields a so-called point cloud set of data; every single point represents a point in 3D space of the scanned rock surface. Because the density of the point cloud can be high (on the order of 5 mm to 1 cm), it allows for an accurate reconstruction of the original rock surface in the form of a 3D interpolated and meshed surface using different interpolation techniques. Through geometric analysis of this 3D mesh and plotting of the facet orientations in a polar plot, it is possible to observe clusters that represent different rock mass discontinuity sets. With fuzzy k-means clustering algorithms, individual discontinuity sets can be outlined automatically, and the mean orientations of these identified sets can be computed. Assuming a Fisher's distribution, the facet outliers can be removed subsequently. Finally, discontinuity set spacings can be calculated as well.
Formwork Pressure of Self-Consolidating Concrete in Tall Wall Field Applications
Authors: Tejeda-Dominguez Fernando , Lange David A. , D'Ambrosia Matthew D.
Published: January 2019

The growing interest in the use of self-consolidating concrete (SCC) for a wide variety of structural applications has initiated a reexamination of its properties and current construction practices and how they compare with those of conventional concrete. One property of interest is the formwork pressure of SCC and how it relates to that of conventional concrete. This work presents the results for three tall walls (28, 21.7, and 13 ft tall) cast slowly with SCC and a 10.6-ft-high column poured quickly by using the same concrete used in one of the walls. The research demonstrates that the pressure of SCC against the formwork drops quickly just after the concrete material is placed. Measurements from the walls poured slowly show that the maximum recorded pressure falls far below the hydrostatic pressure and is closely related to the pouring rate. The experiments also reveal that the formwork pressure exerted by SCC can be revitalized if the SCC is vibrated, even if stiffening is already in progress.
Properties of Crumb Rubber Concrete
Authors: Kaloush Kamil E. , Way George B. , Zhu Han
Published: January 2019

Crumb rubber is a material produced by shredding and commutating used tires. There is no doubt that the increasing piles of used tires create environmental concerns. The long-term goal of this research is to find means to dispose of the crumb rubber by placement of the rubber in portland cement concrete and still provide a final product with good engineering properties. The Arizona Department of Transportation and Arizona State University have initiated several crumb rubber concrete (CRC) test sections throughout Arizona over the past few years. Laboratory tests were conducted to support the knowledge learned in the field and enhance the understanding of the material properties of CRC. Concrete laboratory tests included compressive, flexural, indirect tensile strength, thermal coefficient of expansion, and microscopic matrix analyses. The unit weight and the compressive and flexural strengths decreased as the rubber content in the mix increased. Further investigative efforts determined that the entrapped air, which caused excessive reductions in compressive strength, could be reduced substantially by adding a deairing agent. The higher tensile strains at failure observed from the tests were indicative of more ductile, energy-absorbent mix behavior. The coefficient of thermal expansion test results indicated that CRC was more resistant to thermal changes. The CRC specimens tested remained intact after failure and did not shatter as a conventional mix did. Such behavior may be beneficial for a structure that requires good impact resistance properties. If no special considerations are made to maintain higher strength values, the use of CRC mixes in places where high-strength concrete is not required is recommended.
Influence of Cement Composition on Expansions Observed in Standard and Modified ASTM C1260 Test Procedures
Authors: Rangaraju Prasada Rao , Sompura Ketan R.
Published: January 2019

This paper presents the results of a laboratory study conducted to determine the influence of cement composition on the expansions observed in standard and modified ASTM C1260 tests. Also, the effectiveness of selected mitigation measures for alkali—silica reactivity was studied by using a modified ASTM C1260 test. Two different cements with substantially different alkali levels were used in combination with a Class F fly ash and a Class C fly ash. The results obtained from tests with 89 different sources of fine aggregate were analyzed. The results from this study indicate that cement composition has a distinct influence on the expansion levels observed in the ASTM C1260 study. For a majority of the aggregates tested in this study (88%), the use of a specific cement low in alkali content resulted in higher expansion than a cement with a relatively higher alkali content, regardless of the level of reactivity of the aggregate in the standard ASTM C1260 tests. Class F fly ash was found to be more effective than Class C fly ash in reducing the expansions in the modified ASTM C1260 tests. However, the cement used in the mixture influenced the percent reduction in expansion offered by both Class F fly ash and Class C fly ash. The use of low-alkali cement with Class F and Class C fly ashes yielded larger reductions in percent expansion.
Performance and Uniformity of Self-Compacting Concrete
Authors: Abou-Zeid Mohamed Nagib , Roushdy Mohamed Samir
Published: January 2019

Self-compacting concrete (SCC) can be achieved by adjusting mix proportions and incorporating adequate admixtures, such as viscosity-modifying (VM) admixtures, with no vibration. Yet, the impact of the mix proportions and the role played by the VM admixtures as opposed to those played by superplasticizer admixtures are not fully understood. There also seems to be no unique means for assessment of such concrete, and the correlation between various tests needs further work. This study aims to achieve a better understanding of the influence of mix proportions on the properties of SCC. Twenty-six mixtures were prepared with various water-to-cementitious material ratios, fine aggregate-to-coarse aggregate ratios, and admixture dosages. Fresh concrete tests, including slump flow, L-box, U-box, and hardened concrete tests, including hardened density, compressive and flexural strength, as well as the rebound hammer tests, were performed. The uniformity of SCC properties among the column specimens was examined. The results revealed that adjustment of the mix proportions has a major impact on the fresh and hardened properties of SCC. The fresh concrete tests were found to correlate well with one another, and the SCC strength was comparable to that of reference concrete made with mechanical vibration. Yet, the components of the SCC examined exhibited a remarkable uniformity of properties. Further work that should involve large specimens in which concrete properties are evaluated in various locations is needed.
Effect of Curing Temperature on Hardened Concrete Properties
Authors: Hale W. Micah , Bush Thomas D. , Russell Bruce W. , Freyne Seamus F.
Published: January 2019

Often, concrete is not mixed or placed under ideal conditions. Particularly in the winter or the summer months, the temperature of fresh concrete is quite different from that of concrete mixed under laboratory conditions. This paper examines the influence of supplementary cementitious materials on the strength development (and other hardened properties) of concrete subjected to different curing regimens. The supplementary cementitious materials used in the research program were ground granulated blast furnace slag (GGBFS), fly ash, and a combination of both materials. The three curing regimens used were hot weather curing, standard curing, and cold weather curing. Under the conditions tested, the results show that the addition of GGBFS at a relatively low replacement rate can improve the hardened properties for each curing regimen. This improvement was noticeable not only at later ages but also at early ages. Mixtures that contained both materials (GGBFS and fly ash) performed as well as and, in most cases, better than mixtures that contained only portland cement in all curing regimens.
Bimodal Use of High-Speed Rail Lines
Authors: Guirao Begoña , Menéndez José Manía , Rivas Ana
Published: January 2019

Over the past decades, bimodal operation of conventional rail lines-the use of a rail line to carry both passengers and goods-has been studied and put into practice in railway engineering and planning efforts. However, the growing construction of high-speed rail lines in Europe has sparked serious controversy about the possibility of introducing bimodal services on this type of track. This controversy encompasses not only technical issue but also acceptability and economic issues. So far, little has been published about it. Bimodal use of high-speed rail lines is now practically nonexistent in Europe, and national governments do not have the necessary information on the feasibility of the system. The first Spanish high-speed railway started to run in April 1992 between Madrid and Seville and, until now, has been used to transport only passengers. The future Spanish high-speed network will be centered in Madrid and will cover more than 2,000 km over the next 15 years. Its operation with bimodal criteria is starting to be discussed as a way to reap maximum benefit from the high investment costs. This paper presents and analyzes the results of the first study on the acceptability of and the potential demand for bimodal use of a Spanish high-speed rail line. The term “acceptability” is used to describe the prospective judgment of measures to be introduced in the future. The target group for the study was a sample of users of the corridor of this high-speed rail line. As part of the study, more than 3,000 valid questionnaires were collected, and more than 50 companies interviewed.