bluuebunny/crossref_metadata_2025 huggingface dataset:
Liquefaction and Lateral Spread Evaluation and Mitigation for Highway Overpass Structure: Cherry Hill Interchange, Davis County, Utah
Authors: Price Bradford E. , Stilson Marc , Hansen Michael , Bischoff Jon , Leslie Youd T.
Published: April 2007

Transportation structures constructed in areas of significant seismic hazards are subject to lateral and vertical movements that can threaten the integrity of structures built on liquefiable subsoils. This case history summarizes the geology, analysis methods, mitigation requirements, and proposed quality control for the Cherry Hill Interchange project in Davis County, Utah. A liquefaction and lateral spread liquefaction hazard during the design earthquake has been identified that threatens failure of the proposed bridge. Cone penetration tests were determined to be a cost-effective method for supplementing standard penetration test borings to gain sufficient subsurface information for the liquefaction and lateral spread analysis. A cost-effective solution for protecting the bridge from the hazard has been developed using geotechnical principles combined with recent developments in liquefaction mitigation. The cost of the mitigation is a minor percentage of the overall project cost but is anticipated to protect the bridge from collapse and save lives.
Swelling Potential of Kansas Soils: Modeling and Validation Using Artificial Neural Network Reliability Approach
Authors: Najjar Yacoub M. , Basheer Imad A. , Ali Hossam E. , McReynolds Richard L.
Published: April 2007

Determination of the swell potential of a troublesome soil can only be made possible through the use of systematic methods for identifying, testing, and evaluating that potential. For proper evaluation of the severity of swelling for such soils, an accurate soil swell potential assessment method is warranted. To address this key issue, a two-phase research study was performed to develop combined artificial neural network and reliability-based soil swell prediction models. In Phase 1, a reasonable-sized database representing 514 swell soil tests retrieved from over 51 different projects in Kansas was used to develop both neural network–based (NNB) and statistical-based (SB) swell potential prediction models. Direct comparison of results obtained showed that NNB models provide significant improvements in prediction accuracy over their SB counterparts. In the second phase, predictions obtained using the developed NNB models along with the available experimental database were used to produce reliability (probability) factor matrices, which are used to assign a specific confidence level to predictions obtained via NNB models in order to classify the soil under consideration as a swelling or nonswelling type.
Benefits of Split Intersections
Authors: Bared Joe G. , Kaisar Evangelos I.
Published: April 2007

As urban and suburban intersections become more congested, a likely remedy for recurring traffic jams is grade separation in the form of diamond or tight diamond interchanges. A more economical intersection configuration to relieve congestion has been built overseas. The major highway is separated into two-directional, one-way roads comparable to an at-grade diamond junction known as the split intersection. The split intersection facilitates smoother flows with less driver delay, mainly by reducing the number of required signal phases from four to three. The success of converting to the split intersection has been analyzed by using deterministic methods that showed increased capacity and noticeable reduction in delay. The analysis methodology relies on a microsimulation technique to predicate previous claims and provide economic benefits. Comparisons of vehicular delay between the single and the split intersection revealed substantial savings in travel delay, particularly for higher entering volumes and higher left-turning movements. The findings provide guidance to planners and designers on the expected benefits of converting a four-lane by four-lane single intersection to the split intersection.
Predicting Operating Speeds on Tangent Sections of Two-Lane Rural Highways
Authors: Polus Abishai , Fitzpatrick Kay , Fambro Daniel B.
Published: April 2007

Prediction and estimation of speeds on two-lane rural highways are of enormous significance to planners and designers. Estimation of speeds on curves may be easier than prediction of speeds on tangent sections because of the strong correlation of speeds with a few defined and limiting variables, such as curvature, superelevation, and the side-friction coefficients between road surface and tires. On tangent sections, however, the speed of vehicles is dependent on a wide array of roadway characteristics, such as the length of the tangent section, the radius of the curve before and after the section, cross-section elements, vertical alignment, general terrain, and available sight distance. Few studies have dealt with this issue because a considerable database is necessary to identify any significant trends and substantial modeling effort is required. Research analyzed the variability of the operating speeds on 162 tangent sections of two-lane rural highways, and models were developed for prediction of operating speed based on the geometric characteristics available. A one-model approach was used initially. Because of the low R2 values, a family of models was developed that better predicted operating speeds.
Effects of Horizontal Curvature on Driver Visual Demand
Authors: Wooldridge Mark D. , Fitzpatrick Kay , Koppa Rodger , Bauer Karin
Published: April 2007

A consistent design allows drivers to perform safely the task of driving, allowing attention or capacity to be dedicated to obstacle avoidance and navigation. A measure of the consistency of a design is the amount of visual information needed by a driver to maintain an acceptable path on the roadway. Vision occlusion is a technique that measures driver visual demand on a roadway. It allows a more direct evaluation of the effects of various geometric elements on the driver. Studies of the effects of variations of curve radius, deflection angle, spacing, and sequences revealed several relationships between roadway geometry and visual demand. Curve radius and its reciprocal were found to be significantly related to visual demand in both on-road and test track studies. Small changes in visual demand were also found between types of curve pairs (S and broken back) with differing spacing between the curves. Visual demand was found to be a promising measure of effectiveness for use in studies of design consistency.
Turn Lane Storage Length Design: Theory for the Practitioner
Authors: Gattis J.L.
Published: April 2007

Transportation engineers use statistical distributions to determine the needed storage lengths of auxiliary left- and right-turn lanes. The theory behind the common design approach is reviewed. Field data are used to show shortcomings with the common design approach, and other storage length design perspectives and trade-offs are discussed. With this information, design engineers can better understand the relative strengths of various approaches and be more comfortable with a degree of flexibility in turn-lane storage length design.
Design of Roundabouts in France: Historical Context and State of the Art
Authors: Thai Van May-Jeanne , Balmefrezol Pascal
Published: April 2007

First appearing in the French highway code in 1983, roundabouts have multiplied greatly throughout France, to the currently estimated 17,000. The success of roundabouts is explained, first, by the ideal safety conditions that this type of intersection presents and, second, by the advantages roundabouts provide in speed reduction, suitability to traffic, and break effect. The growth of roundabouts in recent years has allowed better understanding of this type of layout and has enabled all uses to be tested. The rules for designing and sizing have developed to favor the construction of roundabouts that are smaller and thus easier to fit into the urban environment. Vulnerable users (pedestrians and cyclists) are catered to better. New configurations are appearing that combine traffic lights and roundabouts, and these should be investigated in depth. Furthermore, it appears that the roundabout is subject to fashion and that many changes are planned to the roundabout—forgetting that it is not always the best solution. Also, it is important to remind designers and architects of the conditions under which the roundabout actually is an adequate solution for the site in question.
Importance of Vehicle Costs, Fuel Prices, and Fuel Efficiency in Hybrid Electric Vehicle Market Success
Authors: Santini Danilo J. , Patterson Philip D. , Vyas Anant D.
Published: April 2007

Toyota’s introduction of a hybrid electric vehicle (HEV) named “Prius” in Japan and Honda’s proposed introduction of an HEV in the United States have generated considerable interest in the long-term viability of such fuel-efficient vehicles. A performance and cost projection model developed entirely at Argonne National Laboratory (ANL) is used to estimate costs. ANL staff developed fuel economy estimates by extending conventional vehicle modeling done primarily under the National Cooperative Highway Research Program. Together, these estimates are employed to analyze dollar costs versus benefits of two of many possible HEV technologies. Incremental costs and fuel savings are projected for a Prius-type low-performance hybrid (14.3-s 0 to 60 mph acceleration, Z60 time) and a higher-performance “mild” hybrid vehicle (11-s Z60 time). Each HEV is compared with a U.S. Toyota Corolla with automatic transmission (11-s Z60 time). The base incremental retail price range, projected a decade hence, is $3,200–$3,750, before considering battery replacement cost. Historical data are analyzed to evaluate the effect of fuel price on consumer preferences for vehicle fuel economy, performance, and size. The relationship among fuel price, the level of change in fuel price, and consumer attitude toward higher fuel efficiency also is evaluated. A recent survey on the value of higher fuel efficiency is presented and U.S. commercial viability of the hybrids is evaluated using discount rates of 20 percent and 8 percent. The analysis, with its current HEV cost estimates and current fuel savings estimates, implies that the U.S. market for such HEVs would be quite limited.
VMT-Mix Modeling for Mobile Source Emissions Forecasting: Formulation and Empirical Application
Authors: Bhat Chandra R. , Nair Harikesh S.
Published: April 2007

A fractional split model is proposed and implemented that predicts the vehicle miles traveled (VMT) mix on links as a function of the functional roadway classification of the link, the physical attributes of the link, the operating conditions on the link, and the attributes of the traffic analysis zone in which the link lies. The fractional split model is a useful formulation for VMT-mix analysis because it accommodates boundary values of fractional VMT in a vehicle class, is easy to estimate using commonly available econometric software, and is easy to apply in forecasting mode to predict the VMT mix on each link of a network. The empirical analysis applies the fraction split model structure to estimate a VMT-mix model for the Dallas–Fort Worth metropolitan region in Texas. The results of model evaluation also are presented.
Assessing Impacts of Improved Signal Timing as a Transportation Control Measure Using an Activity-Specific Modeling Approach
Authors: Hallmark Shauna L. , Fomunung Ignatius , Guensler Randall , Bachman William
Published: April 2007

Metropolitan areas in nonattainment for transportation-related air pollutants rely on transportation control measures (TCMs) to reduce emissions and meet clean-air goals. However, since traditional transportationrelated air quality models use emission rates based on average speeds, only TCMs that either increase or decrease vehicle activity to speeds in which emissions are lower show reductions in output of air pollutants. In recent years, transportation air quality analysis has shifted to an activityspecific modeling approach that correlates emissions to vehicle operating mode. With an activity-specific approach, the emission reduction potential of a TCM can be evaluated by its ability to decrease time spent in modes in which emissions are disproportionately elevated. Signal timing improvements are attractive TCMs for traffic flow improvement. However, with traditional modeling, they may greatly decrease extremes in modal activity yet not show significant emission reduction if only moderate changes in average speed are realized. The benefits of using activityspecific modeling for evaluation of improved signal coordination as a TCM are described. A brief overview of the development of an activityspecific carbon monoxide emission rate model is provided, data collection for on-road vehicle activity estimates is briefly outlined, and a comparison of traditional emission modeling versus activity-specific modeling is provided to estimate the air quality benefits from improved coordination at a study intersection. Results for the study intersection indicate that more significant reductions in carbon monoxide emissions are realized using an activity-specific approach than with traditional methods.
Requirements for Evaluating Traffic Signal Control Impacts on Energy and Emissions Based on Instantaneous Speed and Acceleration Measurements
Authors: Rakha Hesham , Van Aerde Michel , Ahn K. , Trani Antonio
Published: April 2007

The evaluation of many transportation network improvements commonly is conducted by first estimating average speeds from a transportation or traffic model and then converting these average speeds into emission estimates based on an environmental model such as MOBILE. Unfortunately, recent research has shown that certainly average speed and perhaps even simple estimates of the amount of delay and the number of stops on a link are insufficient measures to fully capture the impact of intelligent transportation system strategies such as traffic signal coordination. In an attempt to address this limitation, the application of a series of multivariate fuel consumption and emission prediction models is illustrated, both within a traffic simulation model of a signalized arterial and directly to instantaneous speed and acceleration data from floating cars traveling down a similar signalized arterial. The application of these multivariate relationships is illustrated for eight light-duty vehicles, ranging in size from subcompacts to minivans and sport-utilities using data obtained from the Oak Ridge National Laboratory. The objective is to illustrate that the application of these instantaneous models is both feasible and practical and that it produces results that are reasonable in terms of both their absolute magnitude and their relative trends. This research is one step in a more comprehensive modeling framework for dealing with the impacts of intelligent transportation systems on energy consumption and vehicle emissions. Other steps include analyses of traffic diversion and induced demand and validation of the estimated fuel consumption and emissions using direct on-road measurements.
Future World Oil Prices and the Potential for New Transportation Fuels
Authors: Birky Alicia K. , Maples John D. , Moore James S. , Patterson Philip D.
Published: April 2007

World petroleum demand is projected to continue increasing after the world enters the 21st century. The Energy Information Administration (EIA) forecasts low world oil prices for the indefinite future despite an expected 54 percent rise in consumption by the year 2020. In its reference case, EIA also assumes an 80 percent increase in Organization of the Petroleum Exporting Countries (OPEC) oil production over the same time period. In contrast to this, a popular world oil market projection model demonstrates that OPEC could increase its production profitability significantly by substantially slowing the rate of its expanded production. However, OPEC’s potential market control also is influenced by the prospective availability of fuels produced from natural gas, especially remote unconventional natural gas resources. The unconventional natural gas resource is potentially enormous compared with all other fossil fuels combined. Considerations of energy security, greenhouse gas curtailment, emissions control, and cost will act to dictate widespread production and use of these unconventional reserves. Estimates are provided for the amount of alternatives that might be available at various oil prices. Because of cost considerations, much of this added production is likely to occur outside the United States.
From Here to Efficiency: Time Lags Between Introduction of New Technology and Achievement of Fuel Savings
Authors: Mintz Marianne M. , Vyas Anant R.D. , Wang Michael Q. , Stodolsky Frank , Cuenca Roy M. , Gaines Linda L.
Published: April 2007

The energy savings of new technology offering significant improvements in fuel efficiency are tracked for more than 20 years as vehicles incorporating that technology enter the fleet and replace conventional lightduty vehicles. Two separate analyses are discussed: a life-cycle analysis of aluminum-intensive vehicles and a fuel-cycle analysis of the energy and greenhouse gas emissions of double versus triple fuel-economy vehicles. In both efforts, market-penetration modeling is used to simulate the rate at which new technology enters the new fleet, and stock-adjustment modeling is used to capture the inertia in turnover of new and existing current-technology vehicles. Together, these two effects—slowed market penetration and delayed vehicle replacement—increase the time lag between market introduction and the achievement of substantial energy savings. In both cases, 15 to 20 years elapse before savings approach these levels.
Comparison of Low-Fidelity TRANSIMS and High-Fidelity CORSIM Highway Simulation Models with Intelligent Transportation System Data
Authors: Rilett L. R. , Kim Kyu-Ok , Raney Bryan
Published: April 2007

In recent years there has been increased emphasis in the transportation modeling field on replacing macroscopic supply functions with simulation models. For example, the highway supply relationship in the Transportation Analysis and Simulation System (TRANSIMS) is based on a low-fidelity microsimulation model. How the TRANSIMS low-fidelity highway simulation module compares with a high-fidelity model and with empirical observations from intelligent transportation system (ITS) implementation projects has been examined. A section of Interstate 10 in Houston, Texas, was used as a test bed and ITS data were obtained for calibration and validation purposes. For comparison, the high-fidelity CORSIM model, which is used extensively in North America for operational analyses, was calibrated and tested with the same data. The two models did equally well at replicating the baseline volume data. In addition, the mean travel time output from the calibrated TRANSIMS model tended to be about 20 percent greater than the mean travel time from the calibrated CORSIM model. In general, the observed travel times were found to lie between the simulated values from the TRANSIMS and CORSIM models. More important, the link and corridor travel time variability appeared to be significantly less than the observed travel time variability. It is hypothesized that this difference may affect certain measures of effectiveness, such as automobile emissions, that will be used by transportation planners.
Assessment of Rural Intelligent Transportation System Wireless Communications Solutions
Authors: Yang Qingyan , Sisiopiku Virginia , Arnold Jim A. , Pisano Paul , Nelson Gary G.
Published: April 2007

Rural transportation systems have different features and needs than their urban counterparts. To address safety and efficiency concerns in rural environments, advanced rural transportation systems (ARTS) test and deploy appropriate intelligent transportation systems (ITS) technologies, many of which require communication support. However, wireless communication systems that currently serve urban areas often are not available or suitable in rural environments. Thus, a need exists to identify communication solutions that are likely to address successfully the needs and features of ARTS applications. Current and emerging wireless communications systems and technologies have been systematically assessed with respect to rural ITS applications. Wireless communication functions associated with rural ITS functions are first identified. Then requirements for applicable communication technologies in the rural environment are defined. Existing and emerging wireless communication systems and technologies are reviewed and evaluated by a systematic process of assessing rural ITS wireless solutions. Finally, recommendations for future research and operational tests are offered. The analysis results are expected to benefit rural ITS planners by identifying suitable wireless solutions for different rural contexts.
Estimating an Origin-Destination Table Under Repeated Counts of In-Out Volumes at Highway Ramps: Use of Artificial Neural Networks
Authors: Kikuchi Shinya , Tanaka Mitsuru
Published: April 2007

A method is proposed that applies an artificial neural network model to estimate an origin-destination (O-D) matrix for a freeway network for which the data on inflow and outflow at the ramps are gathered regularly. This problem is the same as estimating the elements of an O-D table, given that many sets of data about the right-hand column total (trip production) and the bottom row total (trip attraction) are available. A neural network model is developed to emulate the stimulusresponse process on the freeway traffic, in which the stimulus is the inflow at the entrance ramps and the response the outflow at the exit ramps. After the neural network of a particular structure is trained by many sets of data (e.g., sets of daily volumes), the weights of the neural network are found to represent the ramp-to-ramp volume expressed in the proportion of the in-flow at the corresponding ramps. The model is applied to estimate a ramp-to-ramp O-D table for the Tokyo expressway network. The result is compared with the actual O-D table obtained from a survey. The model is found to be useful not only for estimating the O-D volume with much less data than for the traditional method, but also for verifying the existence of a pattern in the traffic flow.
Dynamic Estimation of Origin-Destination Travel Time and Flow on a Long Freeway Corridor: Neural Kalman Filter
Authors: Suzuki Hironori , Nakatsuji Takashi , Tanaboriboon Yordphol , Takahashi Kiyoshi
Published: April 2007

A model was formulated for estimating dynamic origin-destination (O-D) travel time and flow on a long freeway with a neural Kalman filter originally developed by the authors. The model predicts O-D travel times and flows simultaneously by using traffic detector data such as link traffic volumes, spot speeds, and off-ramp volumes. The model is based on a Kalman filter that consists of two equations: state and measurement. First, the state and measurement equations of the Kalman filter were modified to consider the influence of traffic states for some previous time steps. Then artificial neural network models were integrated with the Kalman filter to enable nonlinear formulations of the state and measurement equations. Finally, a macroscopic traffic flow simulation model was introduced to simulate traffic states on a freeway in advance and predict traffic variables such as O-D travel times, link traffic volumes, spot speeds, and off-ramp volumes. The new model was compared with a regression Kalman filter in which the state and measurement equations are defined by regression models. The numerical analysis indicated that the new model was capable of estimating nonlinearity of dynamic O-D travel time and flow and helped to improve their estimation precision under free-flow traffic states as well as congested flow states.
Performance Evaluation of Neural Networks in Concrete Condition Assessment
Authors: Martinelli D. R. , Shoukry Samir N.
Published: April 2007

A neural network modeling approach is used to identify concrete specimens that contain internal cracks. Different types of neural nets are used and their performance is evaluated. Correct classification of the signals received from a cracked specimen could be achieved with an accuracy of 75 percent for the test set and 95 percent for the training set. These recognition rates lead to the correct classification of all the individual test specimens. Although some neural net architectures may show high performance with a particular training data set, their results might be inconsistent. In situations in which the number of data sets is small, consistent performance of a neural network may be achieved by shuffling the training and testing data sets.
Knowledge Acquisition, Verification, and Validation in an Expert System for Improved Traffic Safety
Authors: Herland Lisa , Möller Björn , Schandersson Rein
Published: April 2007

KLOTS (knowledge-based local traffic safety support) is a Swedish expert system that provides advice on traffic safety problems and countermeasures in urban areas. The system is briefly described and the processes of knowledge collection, verification, and validation used in its development are explained. The user defines a safety problem with input forms. The result from the system is an analysis and a list of countermeasures, each with specific comments that reflect the problem. The principle of presenting a list instead of a single solution is intended to make the user more active in the process of finding an appropriate countermeasure. In practice, KLOTS may be used for providing advice, testing solutions, and making checks. It also may be used for educational purposes. The knowledge in KLOTS was obtained from experts during interviews and is structured in the form of rules for evaluating each problem specified. Development of the system has indicated that the experts must have recent practical experience of traffic safety problems. Presenting real-world cases to the experts and asking them to explain how they would solve them has proved to be the most successful interview technique. It has been possible to achieve a consensus among experts. Extensive testing, verification, and validation are carried out before new versions of KLOTS are released. Both end user validation and knowledge verification are described. Development and widespread use of the system show both the feasibility of constructing knowledge-based systems for traffic safety and a demand for such systems.
Determining the Overall Value of Implemented New Technology in Transportation: Integrated Multiple Objective-Attribute Methodology
Authors: Mattingly Stephen G. , Jayakrishnan R. , McNally Michael G.
Published: April 2007

Two existing techniques are integrated and a methodology for evaluating transportation projects, especially complex projects that involve new technologies, is created. While integrating the multiattribute value function technique with the analytic hierarchy process, a new scaling approach is introduced through use of a linear scaling proxy. Additionally, the approach identifies an overall worth for a project. This overall worth provides decision makers with a quantitative value they can use to compare different projects or to estimate and compare hypothetical results. The methodology is demonstrated in a sample problem. The methodology’s application to the Anaheim field operational test is then described. Often, evaluations fail to look at all the potential areas a project may affect. This methodology simplifies the process for including institutional issues in the final results of an evaluation.
Performance Evaluation of Composite Prestressed Concrete Slab Bridges
Authors: Peterman Robert J. , Ramirez Julio A.
Published: April 2007

The results from a research project that evaluated the long-term performance of bridges constructed with composite prestressed concrete panels are summarized. The particular construction system investigated used full-span prestressed concrete panels that would be typical for bridges with spans of 12 m (40 ft) or less. A full-scale bridge specimen was constructed and subjected to 5 million cycles of service loading and 48 weeks of durability exposure cycling. This was done to assess the potential for delamination as well as the resistance to chloride-induced reinforcement corrosion. The exposure cycling greatly accelerated the rate of penetration of chlorides, producing concentrations in the deck that exceeded those from bridges that had been in service for nearly 40 years. The results from this study showed that long-term composite behavior can be achieved in these structures by applying a raked finish to the top surface of the prestressed panels. Corrosion measurements revealed the need to modify the positive-moment connections at interior piers to provide a more durable structure.
Use of High-Performance Concrete for Bridge Abutments: A Case Study
Authors: Miller R. , Baseheart T. M. , Sprague R.
Published: April 2007

As part of an FHWA program to use high-performance concrete (HPC) in bridges, the state of Ohio constructed an adjacent box girder HPC bridge. HPC was used both for the prestressed and precast girders and for the cast-in-place abutments. The abutment mix was primarily designed for durability by using a low water-to-cementitious material ratio and pozzolanic materials. Before construction, laboratory trial mixes were run by using the actual material that was to be used in the abutments. After verifying the suitability of the mix in the laboratory, a few large trial batches were made at the ready-mix concrete plant to verify the plastic and hardened properties of the mix. During construction of the bridge, several problems occurred. Just before construction began, the coarse aggregate failed the state inspection and a new source of coarse aggregate had to be found. Unfortunately, HPC is sensitive to changes in aggregate, but there was no time to create trial batches before construction began. As a result, the mix had to be adjusted during construction. Soon after the initial abutment pours were made, differential shrinkage cracking was found. This was due to problems with inadequate curing. After a few tries, the mix problems were corrected and proper curing eliminated most of the cracking. Specific recommendations for quality control are made on the basis of the experience gained.
Responses of Plain and Steel Fiber-Reinforced Concrete Beams to Temperature and Mechanical Loads: Experimental Study
Authors: Alavizadeh-Farhang Ali , Silfwerbrand Johan
Published: April 2007

To study the structural responses of plain and steel fiber-reinforced concrete pavements under combined mechanical and thermal loads, two test series have been conducted with plain and steel fiber-reinforced concrete beams. The magnitude and duration of the differences in the induced stresses caused by traffic load and a positive nonlinear temperature gradient (the top surface was warmer than the bottom surface during the day) may lead to some relaxation of thermal stresses and subsequently increase the load-carrying capacity. Considering the loss of support contact in the interior part of the concrete pavement, the experimental study of combined loading with restrained concrete beams may provide some insight and an indication of whether the superposition of stresses is a proper approach. The beams were subjected to solely thermal, solely mechanical, and combined thermal and mechanical loads while the rotation of the beam at supports was prevented. The results of tests conducted with both plain and steel fiber-reinforced beams showed that the superposition of stresses under combined loading before cracking gave a satisfactory estimation of the load-carrying capacities. The results also showed that the effect of relaxation of stresses due to short-term thermal loads was not noticeable in the load-carrying capacity achieved in tests with combined thermal and mechanical loads. On the contrary, a tendency for reduction of the load-carrying capacity was observed at higher thermal gradients. In addition, the overall structural responses of steel fiber-reinforced concrete beams under mechanical load and a nonlinear temperature gradient combined were similar to the responses of plain concrete beams up to the cracking stage. However, the release of thermal stresses due to cracking and the considerable residual load-carrying capacity after cracking were the most important observations for steel fiber-reinforced concrete beams.
High-Performance Steel Bridge Design and Cost Comparisons
Authors: Barker Michael G. , Schrage Steven D.
Published: April 2007

High-performance steel (HPS) is a relatively new and promising material for steel girder bridges. Several studies have been conducted regarding HPS, its properties, and its potential future use. The many benefits of HPS include its increased strength, the lighter structures that can be built with HPS, the possibly lower cost of bridges built with HPS, the ease of fabrication of bridges with HPS because of better weldability, and the significantly greater ductility and toughness of HPS compared with those of conventional steels of similar strength. Several bridges that have been completed with HPS are now in service and have met or exceeded expectations. Six alternative designs and cost comparisons for a two-span steel girder bridge are presented. The design alternatives include three homogeneous designs with HPS 485W (HPS 70W) girders, two conventional designs with 345W (50W) girders, and a design with a hybrid 345W/HPS 485W (50W/HPS 70W) girder. The results show that although the homogeneous HPS girder designs reduce the steel weight significantly, the additional cost of the HPS material tends to outweigh the benefits of the reduced steel weight. However, the hybrid design demonstrates considerable and definite savings in terms of both steel weight and total costs.
LARSA 2000: Seismic Analysis of Bridges with Seismic Isolation and Energy Dissipation Devices
Authors: Tsopelas Panos , Karakaplan Ali
Published: April 2007

During the past decade the need to perform nonlinear static and dynamic analyses on bridge structures has increased significantly. Nonlinear dynamic analysis has become the approach that is used when protective systems such as base isolators and isolation systems are present in the bridge structure. The commercial computer programs available that are used for these types of analyses and that can be understood and used by structural bridge engineers have been far from adequate. Recently, the research community has produced a number of useful computer programs. Among these are the IDARC-Bridge and 3D-BASIS family of programs from the State University of New York at Buffalo. Bridge engineers are not usually familiar with the available computer codes primarily used by researchers, and it is generally known that these programs are not user friendly. Prediction of the nonlinear dynamic responses of bridge structures has presented other challenges. These range from the volume of input and output to the computational effort needed to obtain solutions. The increase in computer speed and the use of faster-solution algorithms have drastically reduced the time needed to perform iterative nonlinear dynamic analysis. Use of the Microsoft Windows-based standardized graphical user interface with the ability for the seamless exchange of data between programs makes the volume of input and output manageable. The implementation of 3D-BASIS-ME—type nonlinear base isolators and isolation systems and the analysis methods used in the family of Microsoft Windows-based software LARSA, with which bridge engineers have become familiar over the years using a wide range of applications for bridges and buildings, are presented.
Parametric Study on Behavior of Stress-Laminated Southern Pine Bridge Decks
Authors: Yazdani Nur , Kadnar Joy O. , Kainz James A. , Ritter Mike
Published: April 2007

Stress-laminated timber bridge decks have gained popularity in the United States in recent years. As with all wood exposed to the environment, wood for these decks must be treated with preservatives. There has been reluctance to build chromated copper arsenate (CCA)-treated wood bridges because of concerns about dimensional stability. Because no research has been undertaken to investigate the use of CCA-treated southern pine stress-laminated bridge decks, a good resource for economical rural bridges has remained untapped. The objective of the present study was to evaluate the performance of various wood preservatives on stress-laminated southern pine bridge decks. A total of nine decks with seven different preservatives were built and exposed to the environment for more than 2 years. Force levels in prestressing rods and wood moisture contents from each deck were continuously monitored. It was found that the short-term variations in the rod stress levels are less for decks with oil-type preservatives than for decks with CCA preservatives. The long-term performances of decks with both preservative types were found to be similar. The anchorage effect on deck performance was found to be negligible.
Urban Design Considerations for the New Woodrow Wilson Memorial Bridge: Competition-Winning Design for Metropolitan Washington, D.C.
Authors: Rosales Miguel , Gottemoeller Frederick
Published: April 2007

Bridges are prominent features of many landscapes. They are justifiably called on to meet public objectives beyond their transportation function. It becomes the responsibility of the designer to determine what these requirements are and whether the proposed design is really addressing all of the dimensions of the problem, including objectives that may not express themselves in the form of number of lanes, minimum clearances, and other physical criteria. Public requests for structures that emulate historical bridges or architecture are especially difficult considering the modern demands on the structure and the modern materials and techniques that are available. Techniques used to incorporate contextual and urban design concerns into the design of a major contemporary bridge are described. The project addresses the public’s desire for landmark bridges without resorting to imitation of historical precedents. It is the winning entry in the recent international design competition for the new Woodrow Wilson Memorial Bridge in the Washington, D.C., Metropolitan area, submitted by a team led by the Parsons Transportation Group. The aesthetic and urban design considerations that guided the design for the bridge are described by the team’s architect-urban designers.
Field Performance of Integral Abutment Bridge
Authors: Lawver Andrew , French Catherine , Shield Carol K.
Published: April 2007

The behavior of an integral abutment bridge near Rochester, Minnesota, was investigated from the beginning of construction through several years of service by monitoring more than 180 instruments that were installed in the bridge during construction. The instrumentation was used to measure abutment horizontal movement, abutment rotation, abutment pile strains, earth pressure behind abutments, pier pile strains, prestressed girder strains, concrete deck strains, thermal gradients, steel reinforcement strains, girder displacements, approach panel settlement, frost depth, and weather. In addition to determining the seasonal and daily trends of bridge behavior, live-load tests were conducted. All of the bridge components performed within the design parameters. The effects from the environmental loading of solar radiation and changing ambient temperature were found to be as large as or larger than live-load effects. The abutment was found to accommodate superstructure expansion and contraction through horizontal translation instead of rotation. The abutment piles appeared to be deforming in double curvature, with measured pile strains on the approach panel side of the piles indicating the onset of yielding.
AASHTO’s Load and Resistance Factor Design Specifications for Transverse Braces: Adverse Effects on Integrity and Durability of Reinforced Concrete Deck Slabs
Authors: Burke Martin P. , Seif Joseph S.
Published: April 2007

The transverse bracing provisions (diaphragms, cross-braces, crossframes, and so on) of the 1998 AASHTO load and resistance factor design (LRFD) bridge design specifications for the design of deck-type highway bridges are examined. This examination suggests that implementation of these provisions not only will have an adverse effect on the integrity and durability of reinforced concrete deck slabs, and consequently on life-cycle bridge costs; implementation of such provisions also has the potential to affect the desirability of steel bridge construction adversely. Instead of avoiding the use of midspan braces, as implied by LRFD provisions, it is urged that midspan braces be more generally recognized as primary elements of complex superstructure structural systems and thus be sized and spaced to function not only as transverse flange braces but also integrally with concrete deck slabs to distribute vehicular loads laterally. Such a practice not only will yield more efficient higher-quality structural systems capable of functioning effectively for 100 years or more, thus doubling their presently expected lives, but it will also help extend the service lives of the more vulnerable reinforced concrete deck slabs.
Optimization of Tack Coat Application Rate for Geocomposite Membrane on Bridge Decks
Authors: Donovan Erin P. , Al-Qadi Imad L. , Loulizi Amara
Published: April 2007

One of the critical components of the U.S. civil infrastructure, bridges, has rapidly deteriorated in the past two decades and is in need of maintenance and rehabilitation. Geosynthetics may have the potential to provide a long-term solution to some of the problems that are present in these bridges, mainly, chloride intrusion into bridge decks. When installed properly, geosynthetics can act as both a moisture barrier and a stress absorption layer. However, the tack coat application rate is critical, as an excessive amount can cause eventual slippage, whereas too little may result in debonding. A new geocomposite membrane that comprises a low-modulus polyvinyl chloride layer sandwiched between two layers of nonwoven geotextile has recently been introduced for use in highway systems for water impermeation and strain energy absorption. A laboratory testing program was conducted to determine the optimum asphalt binder tack coat application rate that needs to be applied in the field. To accomplish this, a fixture was designed to allow the application of cyclic shear loading at the geocomposite membrane interface when used as an interlayer simulating a concrete bridge deck overlaid with the geocomposite membrane and a hot-mix asphalt (HMA) overlay. The study concluded that 1.75 kg of PG 64-22 binder per m2 is an optimum value to achieve excellent bonding and minimum slippage potential. For the upper surface in contact with a wearing surface mix, a tack coat application rate of 1.5 kg/m2 may be used. When the geocomposite membrane was included between concrete and HMA, failure occurred after a much larger number of applied loading cycles than the number of loading cycles to failure when the geocomposite was absent. In addition, the slope of shear stress versus the number of loading cycles at failure was much greater when the geocomposite was absent.
Construction Considerations for Repair of Bridges with Externally Bonded Fiber-Reinforced Plastic Material
Authors: Shahawy Mohsen , Beitelman Thomas E. , Chaallal Omar
Published: April 2007

A recent advancement in the field of structural rehabilitation consists of fiber-reinforced plastic (FRP) composites used to strengthen structural elements. Since a significant portion of the infrastructure in North America is in need of a rapidly applied strengthening and rehabilitation solution, much interest in this method has developed. FRP systems provide the advantage of increasing ductility and shear and flexural strength, whereas they are lightweight and can be applied relatively quickly and easily. Guidelines that the engineer can use to recommend construction specifications involved in FRP applications are provided. The results are based on numerous field applications and will help provide an efficient and proper repair method.
Road Safety in Tunnels
Authors: Lemke Kerstin
Published: April 2007

Roads in tunnels differ from comparable open-road sections in many respects. For most drivers a tunnel is an unusual driving environment in the road network that might even cause stress. A safety analysis was carried out to estimate average accident rates and accident cost rates for different cross sections of tunnels on German roads. The analysis is based on all the available accident data for German freeway and highway tunnels reported to police. Personal injury accidents and material-damage-only accidents were analyzed separately. The findings indicate that accident rates are lower for roads in tunnels. Moreover, accidents with severe personal injury and material damage are less frequent on roads in tunnels. However, the fear of a maximum credible accident still remains.
Floating Car Road Weather Information Monitoring System
Authors: Pilli-Sihvola Yrjö
Published: April 2007

A new method of gathering information employs a motor vehicle that travels along Route E18 in Finland. This mobile monitoring station gathers information about driving conditions and transmits video images of different places along this section of roadway. The information is transferred in real time to the Finnish National Road Administration road weather information system. The mobile road weather-monitoring vehicle was developed to improve the gathering of information on weather and driving conditions on the road network and to provide more accurate data. The monitoring equipment measures the temperature and humidity of the air and the surface temperature as well as friction of the road surface. This information is positioned in the equipment using a satellite-based Global Positioning System. The measurement takes place while the vehicle is driven in normal traffic. The functioning of the measurement system was tested in 1998–1999. The weather parameters measured by the mobile monitoring station correspond to information provided by stationary stations. The accuracy of the friction measurements is sufficient for defining driving conditions, but it is not quite as good as that of special friction-measuring instruments.
Automatic Vehicle Location System in Urban Winter Maintenance Operations
Authors: Roosevelt Daniel S. , Hanson Robert A. , Campenni William M.
Published: April 2007

The Virginia Department of Transportation installed Global Positioning System units in 80 trucks operating in two adjacent maintenance areas in the urban area near Washington, D.C. The units report real-time information about the location of the vehicles and their plowing and chemical-spreading activity. The installation is for a pilot test of an automatic vehicle location system that has continued over three winters. The primary purpose of the pilot test is to evaluate the system’s effect on ( a) the contract administration of snow removal and ice control, ( b) the provision of information concerning road conditions to the public and media, and ( c) the management and performance of snow removal and ice control activities. The methodology used to perform the evaluation is summarized, the results obtained are presented, and the problems encountered with the installation and implementation of the system are detailed.