bluuebunny/crossref_metadata_2025 huggingface dataset:
In Situ Test for Hydraulic Conductivity of Drainable Bases
Authors: Randolph Brian W. , Steinhauser Edward P. , Heydinger Andrew G. , Gupta Jiwan D.
Published: August 2018

The development and use of an in situ hydraulic conductivity test for drainable bases under existing pavements is presented. Six highway test sections were constructed by the Ohio Department of Transportation to test the drainage characteristics and durability of four unbound and two stabilized base materials. The in situ test was then used to determine the field hydraulic conductivity of the highway test section bases. This test uses an approach to Darcy's law called the direct velocity technique. A standpipe is placed in a cored hole in the pavement to establish steady-state horizontal flow through the base toward the edge drains. Two probes along a radial flow line measure differential pressure and electrical resistance in the water. An electrolytic solution injected at the standpipe is used to determine the water velocity as the median resistance is noted at each probe. The in situ hydraulic conductivity is calculated by dividing the discharge velocity by the hydraulic gradient. The in situ test provided results that compare favorably with published values from carefully controlled laboratory tests. It proved to work well for high-hydraulic-conductivity drainable bases, and it has the potential to be a valuable tool for condition assessment of bases under existing pavements.
Using Seasonal and Day-of-Week Factoring to Improve Estimates of Truck Vehicle Miles Traveled
Authors: Weinblatt Herbert
Published: August 2018

Procedures developed by FHWA for “factoring” short-duration traffic counts for seasonal and day-of-week variations in traffic volumes are capable of producing estimates of annual average daily traffic (AADT) that are quite accurate. Moreover, there is virtually no bias in these estimates, so AADT estimates for a set of road sections can be used to produce unbiased estimates of total vehicle miles traveled (VMT) for systems of roads. Unfortunately, corresponding procedures are not generally used for estimating AADT by vehicle class, and the less sophisticated procedures that are commonly used contribute to substantial overestimates of truck AADT and VMT. Current procedures apparently overestimate VMT by 25 to 40 percent for combination trucks and possibly more for single-unit trucks. Modified versions of the FHWA factoring procedure that are capable of producing substantially improved estimates of truck VMT and of AADT of combination trucks are presented. These procedures use seasonal and day-of-week factoring to reduce the errors in truck AADT estimates and to eliminate the upward bias in truck VMT estimates that result from the use of unfactored weekday classification counts.
Stream-of-Traffic Interview Truck Survey: Methodology and Recommendations on Traffic Volume Thresholds
Authors: atherly Deborah W. M
Published: August 2018

Truck survey methods vary in the response rates they generate and in their coverage, accuracy, and cost. Roadside intercept/interview surveys enjoy representation, coverage, and response-rate advantages compared with phone/mail surveys, but in practice they are frequently restricted to weigh stations, toll plazas, and similar controlled facilities. A roadside truck interview survey for Berks County, Pa. was conducted within the stream of traffic in conjunction with distribution of a postcard automobile survey. Over 1,000 interviews conducted throughout the county at five cordon locations representing key two-lane and four-lane roads were compiled. The sampling rate exceeded 22 percent, and valid response rates were approximately 98 percent. The information obtained was limited in detail but was sufficient to achieve the study objectives of estimating major internal-external, external-internal, and external-external truck movement patterns for Berks county. The study was not intended to identify internal-internal trips. The purpose, methodology, and advantages and disadvantages of the approach are discussed, and the focus is on the traffic congestion element. Surveys were conducted within a single lane in each direction, restricting traffic flows. At certain traffic volumes (roughly 200 vehicles per 15 min) delays became a significant problem, including several periods during which surveys were not conducted to alleviate traffic backups. The conclusion suggests using this parameter for applying the method to other locations.
Investment Selection Model for Multicommodity Multimodal Transportation Networks
Authors: Loureiro Carlos Felipe G. , Ralston Bruce
Published: August 2018

A Multicommodity Multimodal Network Design (MCMND) model is presented; the model is to be used as a planning tool for determining investment priorities for freight intercity networks. The MCMND model is designed to select the best set of investment options for a multimodal regional network, given a limited investment budget. The main component of the model comprises the solution of a nonlinear bilevel network design problem formulated to choose investments that minimize both the transportation costs incurred by users and the environmental impacts of less efficient modes of transportation. Investment options to be considered by the model involve the addition of new physical links to the network, the improvement of existing links, and the location of intermodal transfer facilities at specified nodes of the network. The representation of the multimodal network is at a level of detail appropriate for strategic planning for a large region. The demand for transportation services is fixed and exogenous to the model. Mode choice in shipping freight is modeled in combination with flow assignment, assuming that goods are shipped at minimum total generalized costs. A new path-based stochastic user equilibrium assignment algorithm is proposed to distribute trips over the multimodal network according to a logit-type model. The Tietê-Paraná Valley in Brazil was selected for the development of a pilot application of the MCMND model to assess its efficiency when dealing with large networks. This application also served to emphasize the importance of an interface between the MCMND model and a geographic information system in solving real-life problems.
State of the Practice of Information Technology at Marine Container Ports
Authors: Holguín-Veras José , Walton C. Michael
Published: August 2018

A glimpse into the state of the practice of information technology at marine container ports is provided. First, network representation is used to characterize the information process that takes place at marine container terminals. These network representations were used as a framework to analyze a survey on the state of the practice of information technology. The survey targeted a selected group of U.S. container terminals, which provided information on current practices. The first section of the survey, General Information, gathered information about the general characteristics of the terminal. The second section, Internal Activities of the Container Terminal, gathered information about the performance of the most important internal activities. The third section, Interactions Among the Parties Involved, focused on the interactions that take place among the different agents associated with either importing or exporting containers. The fourth section, About the Future, gathered the respondents' perceptions about the future of information technology. The information gathered was used to characterize current practices and to assess the level of market penetration of advanced devices such as electronic tags.
Traffic Analysis of Chicago River and Lock
Authors: Khisty C. Jotin , Johnson James A.
Published: August 2018

The vessel-carrying capacity of the Chicago River in Illinois is restricted by a lock, which separates the river from Lake Michigan. Vessels passing through the lock experience long delays during the summer months. An investigation and analysis of this system determined that although the system is now generally operating below capacity the peak periods during summer weekends approach capacity, and the situation is likely to deteriorate in the future. In addition, the river and lock have safety and traffic conflict problems that require attention. Recommendations to mitigate these problems are described.
Resolution of Land Use and Port Access Conflicts at Inland Waterway Ports
Authors: Lipinski Martin E. , Clarke David B.
Published: August 2018

During the last two decades urban redevelopment of waterfronts has accelerated. The historical significance of these areas coupled with their unique visual amenities has resulted in major renewal efforts in many cities. The competition between the waterway navigation industry and redevelopment interests for scarce waterfront land has resulted in conflicts. Congestion along the access routes to existing ports and terminals has affected the efficient movement of goods to and from the waterfront. The results of an investigation into waterfront redevelopment issues and port and terminal landside-access conflicts are presented. There are many complex forces at work that affect the use of and access to waterfront land. Some of these forces are economic and involve uses of the waterfront that are the “best and highest,” one example of which is river-boat gaming. The surveys and case studies conducted identified many conflicts that have occurred. Guidelines have been developed that address some of the problems that arise during the development of waterfront development projects and planning of adequate transportation access. Application of these guidelines by waterway transportation interests, urban planners, transportation engineers, and community officials may alleviate some of the conflict and enhance the planning process.
Technological Advancements in Hazardous Materials Evacuation Planning
Authors: Abkowitz Mark , Meyer Eric
Published: August 2018

The development and implementation of a methodology by which evacuation planners can assess the sufficiency of their current evacuation plan, identify inadequacies, and define and evaluate potential improvement strategies are discussed. Such goals are accomplished through innovative uses of information technology and the development of a modeling environment that builds on previous work by introducing more representative and efficient algorithms. The new evacuation planning methodology is subsequently applied to a fixed facility incident scenario to demonstrate its applicability to present practice. In this context, several important conclusions are reached, illustrating the importance of having this type of decision-support tool available. Advancements made to the state of the art are assessed and further research needs in this critical and emerging field are identified.
Wyoming Road Closure Gate
Authors: Mak King K. , ligh Roger P. B , Wilson William B.
Published: August 2018

Road closure gates are used to close certain highways when driving conditions become too hazardous under severe winter weather conditions. The Wyoming Department of Transportation (WYDOT) developed a new road closure gate design that had not been crash tested to determine whether it would meet nationally recognized safety standards. WYDOT sponsored a study at the Texas Transportation Institute to crash test and evaluate the new road closure gate design and, as appropriate, to improve the design from the standpoints of safety performance, cost, and practicality. The original road closure gate design was crash tested and failed to meet the guidelines set forth in NCHRP Report 350 and the 1985 AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals. The design was then modified and crash tested with successful results. The modified road closure gate design consists of a standard 8.84-m (29-ft)-high luminaire support pole structure with a mast arm and light standard, a four-bolt slip base breakaway base, a telescoping fiberglass-aluminum gate arm with an electric in-line linear actuator lift mechanism, and a gate arm bracket to restrict the lateral movement of the gate arm when it is in the up position. The road closure gate design has been adopted by WYDOT and accepted by FHWA for use on the National Highway System.
Dual-Support Breakaway Sign with Modified Fuse Plate and Multidirectional Slip Base
Authors: Reid John D.
Published: August 2018

Dual-support breakaway signs have been used across the country for more than 25 years and have been credited with saving many lives. A very important feature of this system is the ability of its support to swing up and out of the way when it is struck by an errant vehicle. Another critical feature of the sign system is its ability to withstand wind loads without causing structural damage to the system. A modified dual-support breakaway sign system that improves on both criteria is proposed. A dual-support breakaway sign with a multidirectional slip base performed acceptably during full-scale crash testing. The sign tested consisted of 4.8-m-tall, W6 × 9-wide flange posts with a sign 3.05 m wide by 2.44 m tall. The research indicated that the modified system does not pose any significant hazard for vehicles striking one of the supports at angles of up to 25 degrees. Changing the material of the fuse plate to an A572 Grade 50 steel creates a stronger connection that significantly improves the wind load capacity of the sign system. The proposed material for the fuse plate did not hinder the safety performance of the sign: the fuse plate performed as designed under full-scale testing.
Guardrail Runout Lengths Revisited
Authors: Wolford Dan , Sicking Dean L.
Published: August 2018

The guardrail runout length recommendations contained in AASHTO's Roadside Design Guide were reevaluated to determine optimal guardrail length of need. Encroachment data collected along Canadian highways were evaluated in a manner similar to that used with other encroachment data to reproduce the procedures contained in AASHTO's Roadside Design Guide. A cost-benefit analysis of extending guardrails was also conducted as an alternative procedure for defining appropriate guardrail runout lengths. Both analysis procedures indicate that the guardrail runout lengths recommended by the Roadside Design Guide are excessive. Highway agencies are advised to select one of the two new procedures for identifying appropriate guardrail runout lengths.
Reduced-Height Performance Level 2 Bridge Rail
Authors: Holloway James C. , Sicking Dean L. , Faller Ronald K.
Published: August 2018

The safety performance of a 737-mm (29-in.)-high open concrete bridge railing was evaluated. The evaluation included four full-scale crash tests, investigating two critical impact locations where structural failure was most likely to occur. Each impact location was evaluated with a single-unit truck and a ballasted pickup truck. The safety performance of the 737-mm-high open concrete bridge rail was shown to meet the Performance Level 2 requirements specified in the AASHTO Guide Specifications for Bridge Railings (1989).
Evaluation of Crossover and Partial Lane Closure Strategies for Interstate Work Zones in Indiana
Authors: Pal Raktim , Sinha Kumares C.
Published: August 2018

There are two main lane closure strategies for Interstate highway work zones, crossover and partial lane closure. Depending on the situation one or the other strategy may be more desirable. However, little research has been done to develop a systematic method for selecting appropriate lane closure strategies. The selection of appropriate lane closure strategies at Interstate highway work zones is discussed.
Investigation of Highway Work Zone Crashes: What We Know and What We Don't Know
Authors: Wang Jun , Hughes Warren E. , Council Forrest M. , Paniati Jeffrey F.
Published: August 2018

Emphasis on work zone safety and improving the identification of work zone problems has been increased by recent legislation and federal programs. There is a critical need for better data related to highway work zone safety. Results are presented of an investigation to (a) determine what is known about the magnitude of highway work zone crashes, (b) examine characteristics of highway work zone crashes using the Highway Safety Information System, (c) investigate how work zone accidents are reported on police accident report forms and within state accident report systems, (d) identify critical voids in the knowledge of the relative safety of work zones, and (e) examine possible ways to address unfulfilled information needs related to work zone safety. Deficiencies of data reporting practices and issues of data needs pertaining to work zone safety are discussed. Recommendations to improve data collection and fulfill information needs are presented, including suggested data elements to be added to police accident report forms.
Evaluation of Cold Mixes for Winter Pothole Repair
Authors: Prowell Brian D. , Franklin Alan G.
Published: August 2018

The performances of 13 proprietary cold-mix patching materials, 4 of which are currently approved under the Virginia Department of Transportation's Special Provision for High Quality Cold Patching Materials, were evaluated. Cold-mix patching materials are regularly submitted to the Materials Division for approval. The purpose of the evaluations was to determine which of the submitted materials were of the same caliber as the approved materials. The addition of materials of equal quality will promote competition in the competitive bid system. Three test sections were placed to evaluate the materials' performance. A standardized evaluation form and performance model were developed to rank the materials. The field performance results were compared with laboratory test results in an effort to develop a laboratory screening test. Design and quality control procedures were identified. These procedures were used to design a material that has performed well.
Evaluation of Pyrolized Carbon Black from Scrap Tires as Additive in Hot Mix Asphalt
Authors: Park Taesoon , Coree Brian J. , Lovell C. W.
Published: August 2018

The viability of using pyrolized carbon black (CBp) derived from waste tires as a reinforcing agent in asphalt mixtures was evaluated. Commercial carbon black (CB) has been previously shown to reduce the rutting resistance, temperature susceptibility, and cracking propagation potential of asphalt concrete. It was believed that CBp could produce similar benefits; this belief has been confirmed by this study. Different ratios of CBp and CB (5, 10, 15, and 20 percent by weight of asphalt) were blended with two grades of asphalt (AC-10 and AC-20). The Marshall method, the gyratory testing machine, the dynamic creep testing (confined), the indirect tensile testing, and the resilient modulus test were performed. The test results of CBp mixtures were compared with results of CB and conventional mixtures. The analyses of test results show that the typical performance of CBp-modified asphalt mixtures is improved with respect to commercial CB and conventional mixtures. The rutting potential and the temperature susceptibility can be reduced by the inclusion of CBp in the asphalt mixture. A CBp content of 10 to 15 percent by weight of asphalt is recommended for improvement of asphalt concrete.
Passenger Train Crashworthiness—Primary Collisions
Authors: Chatterjee Subhasish , arney John F. C.
Published: August 2018

The results of computer simulations of passenger train collisions in which train coaches with unoccupied, crushable end zones are used to dissipate the collision energy are presented. The proper design of these crush zones and the passenger compartment features are shown to result in a controlled distribution of the crush along the length of the impacting trains and a reduction of the accelerations to which trains' occupants are subjected. The main design parameters for these crushable zones are studied for a variety of train configurations, coach load versus deformation characteristics, and inter-coach gaps. It is shown that well-designed crushable zones can absorb collision energy in a predictable manner, reducing the probability of occupant injuries and fatalities.
Passenger Train Crashworthiness—Secondary Collisions
Authors: Chatterjee Subhasish , Carney John F.
Published: August 2018

Secondary collisions in passenger train crashes are considered and a companion paper dealing with primary collisions is followed up. The effects of crash pulse magnitude and duration, occupant flail distance, and the nature of the impacted surface are considered. The constitutive relationship for a Hybrid III dummy head satisfying the peak acceleration requirements of FMVSS208 is developed and used with the crash victim simulator MADYMO to investigate the impact response of train passengers seated in a unidirectional layout. It is shown that the design of the coach shell and the interior have to be integrated to obtain train designs that will minimize occupant injuries in the event of train collisions.
Effect of Pumping on Air Characteristics of Conventional Concrete
Authors: Lessard M. , Baalbaki M. , Aïtcin P.-C.
Published: August 2018

The stability of the air content of concrete during pumping has been the subject of a number of recent investigations. Because increasing volumes of concrete are placed with the aid of pumps and the durability of such concrete to freezing and thawing (ASTM C666) as well as the scaling resistance (ASTM C672) preoccupy engineers, a study concerning the stability of the air-void system of a concrete with 45 to 50 MPa compressive strength was carried out. The slump of the three tested concretes ranged between 85 and 115 mm. Three pumping setups were studied. In the first, the concrete was pumped horizontally; in the second the concrete was pumped upward and then downward. In the third, the vertical setup was used but a reduced section was placed at the end of the pump line, and the concrete was allowed to free fall a short distance. For each pump setup, the concrete was sampled before being placed in the pump and after leaving the pump. The results clearly show that when the concrete is pumped horizontally, the spacing factor (L) and the specific surface of the air-void system are barely altered. On the other hand, after pumping the concrete vertically without a reduced end section, it was impossible to obtain an L less than 230 μm, the maximum spacing factor allowed by Canadian standards (CSA A23.1) to ensure good frost durability. Furthermore, the specific surface of the air bubbles fell to 20 mm−1, which is inferior to the 25-mm−1 value recommended in Canadian standards. By placing a reduced section at the end of the vertical pump line, it was possible to enhance the air-void system but that procedure still fell short of ensuring a system that satisfies the air-void system recommended by Canadian standards to ensure proper frost durability. Although the pumped concrete mixtures did not always satisfy the requirements of CSA A23.1 regarding air-void systems, they satisfied the requirements of ASTM C666 (Procedure A) for resistance to freeze-thaw cycles. Freeze-thaw resistance in the presence of deicing salts was evaluated according to ASTM C672. After 50 frost cycles, all but one concrete exhibited mass losses that were lower than the maximum permissible limit of 0.50 kg/m2 required by BNQ 2621-900, the standard currently enforced in the province of Quebec. Placing a reduced section at the end of the pump line creates a light counterpressure in the descending section of the pump line, which allows the conservation of an acceptable air-void system. Considering the appreciable improvement in the preservation of air-void characteristics when a reduced section was placed at the end of the pump line, it was decided to proceed with further experimental work using four 90-degree elbows placed at the end of the vertically hanging pump line.
High Dosage Type-C Fly Ash and Limestone in Sand-Gravel Concrete
Authors: Abou-Zeid Mohamed Nagib , Wojakowski John B. , Cross Stephen A.
Published: August 2018

Alkali-silica reactions are a major cause of concrete deterioration. The reactions can lead to severe damage that may ultimately endanger the performance and safety of concrete structures. The use of fly ash as partial replacement of Portland cement and the use of some limestone in concrete mixtures were considered as two potential approaches to minimize the severity of the problem. Sand-gravel concrete mixtures were prepared by replacing 15, 25, and 35 percent, by weight of Portland cement, with an equal weight of ASTM Type C fly ash. In those mixtures, either 30 percent or 50 percent of the total aggregate was limestone. Concrete beams were prepared and the wetting-and-drying test was performed in accordance with Kansas Department of Transportation (KDOT) specifications. Also, freeze-and-thaw testing of concrete beams were performed on some selected mixtures. Results indicate that most of the fly ash concrete mixtures with 30 percent limestone do not fulfill the requirements of the KDOT specifications. The fly ash mixtures with 50 percent limestone yield better results; most of them meet the specifications. Results also show that increasing the fly ash dosage does not seem as effective as introducing limestone for alleviating alkali-silica reaction problems.
Developing High-Performance Concrete Mix for New York State Bridge Decks
Authors: Streeter Donald A.
Published: August 2018

The development and implementation of a more durable concrete mixture for bridge decks are described. The work began with review and evaluation of published results of research conducted by others and resulted in a new concrete mixture that has been designated Class HP for high performance. It has better handling and workability characteristics, improved resistance to chloride intrusion, and greater resistance to cracking, and it displays little or no surface scaling. Increased strength was not a primary concern in producing a high-performance concrete for bridge decks, but greater ultimate strength was nevertheless achieved. Class HP concrete is a modification of New York State's standard Class H concrete, incorporating two pozzolan substitutions for cement—20 percent Class F fly ash and 6 percent microsilica. On the basis of satisfactory laboratory testing, field trial, and field production it is being recommended for use statewide. Initial increases in cost are expected to be minimized as concrete producers and contractors become familiar with its mixing and placement. The first-cost increase will be easily offset by more than doubling service life expectancy. Further investigation is progressing to optimize performance of Class HP concrete in bridge decks and for its use in other concrete applications.
Snow Road Enhancement
Authors: Diemand Deborah , Alger Russ , Klokov Valeri
Published: August 2018

Snow roads are used extensively in areas where seasonal access to remote areas would otherwise be difficult or impossible for wheeled vehicles. Forestry operations in Scandinavia and Canada, petroleum operations in Alaska and Canada, and almost all activities in Antarctica make extensive use of this technology. Many techniques of preparing snow roads and runways have been used and studied, but the most intractable problems remain unsolved: how to extend the service life of the road as the warm season approaches and how to bridge damaged or transitional sections. Other, less important problems include sinkage of parked vehicles, damage to heavily trafficked areas, damage caused by fluid spills and infiltration by saltwater, and use limited to vehicles with low tire pressures. Research addressing these problems was conducted, and the preliminary results are encouraging. A short test section of road was constructed with geocells. This material is designed for use with sand or gravel but, instead, the cells were filled with packed snow. The resulting surface was very hard, stable, and resistant to damage by repeated passes by wheeled traffic. Paving blocks were also prepared by converting snow directly to ice by using very high compaction pressures in a hydraulic press. The material was very strong and was resistant to the infiltration of fluids of all kinds. The application of these two techniques would greatly reduce most problems encountered in the use of snow roads and runways.
Efficiency of Geosynthetic Lateral Drainage in Northern Climates
Authors: Lafleur Jean , Savard Y.
Published: August 2018

During winter the formation of ice lenses causes frost heave within frost-susceptible materials. The uneven spatial distribution of heave due to heterogeneity results in severe damage to the pavement. Fissures are created, favoring excess infiltration, especially during subsequent springtime thaw. The installation of drainage can be beneficial in reducing the amount of water present in road foundations. Some uncertainty, however, exists about the sources of water feeding the lenses and, therefore, the optimal location of the systems. To assess the efficiencies of deep lateral drainage systems, a full-scale test has been undertaken along an existing road constructed on a glacial till subgrade. Three 150-m-long vertical geocomposite systems were installed at depths ranging between 2 and 3 m. In situ monitoring included piezometers and frost indicators and measurements of flow rates and pavement heave. To obtain a point of comparison, the measurements started 1 year before drain installation. For the period of observation the freezing indexes ranged between 1432°C-day and 1558°C-day, and the maximum frost penetration was 2.5 m. The flow rates varied considerably with the seasons, ranging between 1 ml/sec/linear meter during winter and 10 ml/sec/m during the April thaw. Before drainage the heave values ranged between 50 and 150 mm. After installation they were reduced by a factor ranging between 10 and 50 percent.
Numerical Simulation of Geosynthetic-Reinforced Flexible Pavements
Authors: Wathugala G. Wije , Huang Baoshan , Pal Surajit
Published: August 2018

In traditional analyses of flexible pavements the linear elastic material behavior is assumed for pavement materials. However, pavement materials do not behave as linear elastic materials. They can be better modeled by using elasto-plastic constitutive relationships. The consequences of the assumption of linear elasticity in the prediction of the behavior of geosynthetic-reinforced flexible pavements are presented. The effect of the stiffness of geosynthetic reinforcements on pavement behavior is also studied. The behavior of a geosynthetic-reinforced flexible pavement is analyzed by the finite-element method with different constitutive models. The results of six analyses where E is Young's modulus [Case 1, linear elastic models with geosynthetics (Case 1a, E = 1 GPa; Case 1b, E = 100 GPa); Case 2, linear elastic models without geosynthetics; Case 3, elasto-plastic models with geosynthetics (Case 3a, E = 1 GPa; Case 3b, E = 100 GPa); and Case 4, elasto-plastic models without geosynthetics on the same pavement under the same load cycle] are presented and compared. Key observations and conclusions are as follows. The linear elastic analyses predicted tensile stresses in the crushed limestone layer although in reality this material cannot withstand tensile stresses. The vertical stresses directly under the load for all of the analyses were very close and were little smaller than those predicted by Boussinesq's equations. The linear elastic analyses showed only a small reduction in settlements when geosynthetics were added. In contrast, elasto-plastic analyses showed a large reduction in settlements, especially with stiffer geosynthetics. Previously published field data indicate an improvement in the pavement performance when geosynthetic reinforcements are introduced.
Pullout and Direct Shear Testing of Geosynthetic Reinforcement: State-of-the-Art Report
Authors: Mallick S. B. , Zhai H. , Adanur S. , Elton D. J.
Published: August 2018

The frictional characteristics of a soil-geosynthetic interface can be determined by direct shear and pullout tests. The direct shear test is commonly conducted according to ASTM standard D5321. However, at present there is no ASTM method for pullout testing of geosynthetics. During the past 10 years different researchers have obtained a wealth of information from direct shear and pullout tests of geosynthetics. A critical analysis of direct shear and pullout tests and an evaluation of the effects of fundamental material and testing parameters on test results are presented.
Dynamic Material Functions and the Structure of Asphalts
Authors: Stastna J. , Zanzotto L. , Kennepohl G.
Published: August 2018

A simple model of the complex modulus, based on the general principles for a linear response function, is presented. The model represents a generalization of the Maxwell model and it is indicated that the model well describes a relatively broad group of regular and modified asphalts. A discrete spectrum of no more than 10 relaxation times is obtained for all the asphalts studied. The spectra of modified asphalts indicate the presence of several relaxation times that can be related to the interface interactions of the base asphalt and the polymers used. It is indicated that the phase angle of the complex modulus contains valuable information about the structure of asphalts. An attempt to use this information for calculations of the molecular mass distribution is presented. A possibility to characterize asphalts by the so-called pseudospectra is also discussed.
Polymer-Modified Asphalt Cements Used in the Road Construction Industry: Basic Principles
Authors: Brûlé Bernard
Published: August 2018

Modified binders—obtained by adding thermoplastic macromolecular systems of plastomers or elastomers to traditional pure asphalt cements for road construction—have existed for more than 20 years. These products are still poorly understood scientifically. Significant research must be undertaken to better understand binder relationships between composition, structure, and properties, and the relationships between hot mix performance (rutting, fatigue, thermal cracking) and the characteristics of the modified binders as measured in the laboratory. The current state of knowledge regarding these issues is presented along with a discussion of the basic principles of bitumen-polymer compatibility, the mechanism for modification, and the effect of the components on the properties of the modified binders. Several specific problems related to the use of these products are presented.
Rheology of Asphaltic Binders and Their Effects on Asphalt Concrete
Authors: Jiang Rong-Bin , Lin Jyh-Dong , Lin Deng-Fong
Published: August 2018

The rheology of asphaltic binders and their effects on asphalt concrete are discussed with the intention of improving the correlation between conventional mix design results and pavement performance. Test results show that mineral fillers increase the viscosity and pseudoplasticity of asphalts but do not always decrease the tan 8, except apparently at a lower frequency or at a higher temperature. Mineral fillers are also hard to mix homogeneously and quickly with asphalts. All these effects become more pronounced with a continuously increasing filler to asphalt (F/A) ratio, and uses are limited to a lower F/A range unless the processing temperature is adjusted properly. The abnormal drop in tan δ improves for some modified asphalts (e.g., air-blown or polymerized asphalt).
On-Site Calibration Evaluation Procedures for WIM Systems
Authors: Papagiannakis A. T. , Senn K. , Huang H.
Published: August 2018

The feasibility of two methods for evaluating and calibrating weigh-in-motion (WIM) systems is explored. The first method uses a combination of test trucks and vehicle simulation models. The computer model VESYM was used for the simulations. The models for the test trucks were calibrated using acceleration measurements on board the vehicles. Although, this approach does not allow calculation of the discrete value of the dynamic axle load over WIM sensors, it can be used effectively in establishing the extent of variation at a particular WIM site. This information leads to an effective WIM system calibration method. The second method for calibrating WIM systems compares static and dynamic axle loads of vehicles through automatic vehicle identification (AVI). The AVI facilities developed for the Heavy Vehicle Electronic License Plate project on the I-5 corridor was used for this purpose. The static axle load of AVI-equipped vehicles was obtained from the Oregon Department of Transportation for two sites, Woodburn southbound and Ashland northbound. The WIM load data were obtained from Lockheed IMS for all the AVI-equipped WIM systems on the I-5 corridor. The data were analyzed to match AVI numbers, dates, and times of weighing. Time limits for traveling between sites were established to ensure that trucks could not stop and load or unload cargo between sites. Errors were calculated as the percentage difference between WIM and static loads for individual axles and axle groups. Calibration factors were derived to minimize the residual sum of squares of the errors.
Development of Portable Tester for Measuring Skid Resistance and Its Speed Dependency on Pavement Surfaces
Authors: Saito Kazuo , Horiguchi Takashi , Kasahara Atsushi , Abe Hironari , Henry John Jewett
Published: August 2018

Skid resistance is an important factor in a rational maintenance program for pavement surfaces. Therefore, the skid resistance of a road surface is monitored by maintaining skid resistance inventories; in addition, spot checks are made at high accident sites. The equipment, called the dynamic friction tester (DF tester), is a disc-rotating-type tester that measures the friction force between the surface and three rubber pads attached to the disc. The disc rotates horizontally at a linear speed of about 80 to 20 km/hr under a constant load, so the DF tester can measure the skid resistance at any speed in this range with a single measurement. At the same time, the results provide speed dependency of skid resistance that will be as close as possible to the results obtained by other testing modes. The DF tester can measure on flat as well as rutted surfaces, the depths of which are less than 6 mm. In that case, the coefficient of variation is found to be less than 10 percent. The long-term characteristics of the coefficient of friction were measured by the DF tester, the British pendulum tester and the mini-texture meter. The coefficient of friction increases moderately with the traffic service period (up to 35 weeks) and decreases with increasing speed. The test results showed a significant speed dependency on the coefficient of friction measured by the DF tester although there was a high relationship between the coefficient of friction of the DF tester and the British pendulum number at each point and at each measuring speed. A weak relationship was found between the coefficient of friction and the sensor-measured texture depth values produced by the texture meter. Results of the Permanent International Association of Road Congresses experiment to compare and harmonize texture and skid resistance measurements indicate that the DF tester is capable of reporting the friction component (F60) of the international friction index using the friction coefficient at 60 km/hr.
Use and Effects of Studded Tires on Oregon Pavements
Authors: Brunette Bruce E. , Lundy James R.
Published: August 2018

The use and effects of studded tires in Oregon are investigated, updating a 1974 report. Studded-tire use was surveyed, rut measurements collected, studded-tire traffic estimated, and pavement wear and damage analyzed. Studded-tire use in Oregon varies geographically. Half of the vehicles equipped with studs use them on all wheels, representing a significant change from 1974 practices. More than 23 percent of vehicles used studded tires in 1994. Studded-tire pavement wear coefficients were calculated and found to be half those reported previously. The coefficients for rigid and flexible pavements are 0.20 mm (0.008 in.) and 0.86 mm (0.034 in.), respectively, per 100,000 studded tire passes. Studded-tire wear will shorten pavement life on high-volume routes in Oregon. Asphalt pavements experiencing average daily traffic (ADT) volumes of 35,000 and 20 percent studded-tire use will reach the threshold rut in 7 years. Portland cement concrete (PCC) pavements experiencing 120,000 ADT and 20 percent studded-tire use will develop the threshold rut depth of 19 mm in 8 years. These estimates substantially reduce Oregon design life expectations for asphalt and PCC pavements. The estimated Oregon studded-tire damage for 1994 is $37 million for the state highway network, with similar damage for municipal and county roads. Alternatives are discussed to reduce the damage caused by studded tires, including a ban on studs, shortened use period, lightweight studs, user fees, and public education initiatives.
Calibrating Road Roughness Meters in Developing Countries
Authors: Bennett Christopher R.
Published: August 2018

Pavement roughness is an important characteristic monitored by many road agencies. It is used as an indicator of road performance and also for feasibility studies. In developing countries, the most common method of recording road roughness is the use of response-type roughness meters. These are instruments that measure the displacement of the vehicle chassis relative to its axle. Because vehicles respond differently to roughness, it is necessary to calibrate them against a standard roughness measure. Calibrating roughness meters against the international roughness index, profiling test sections, undertaking a calibration experiment, and analyzing the calibration data are addressed.
Vehicle Traction Performance on Snowy and Icy Surfaces
Authors: Lu Jian John
Published: August 2018

Snow and ice have been considered the main factors that contribute to reduced vehicle traction forces and potential traffic accidents during winter. To increase a vehicle's traction on snow and icy surfaces, studded and nonstudded winter tires have been used in cold regions. However, the use of studded tires causes significant pavement damage, such as accelerated pavement rutting and pavement marking damage. Since spring 1994, the Alaska Department of Transportation and Public Facilities has asked the Transportation Research Center at the University of Alaska Fairbanks to conduct a series of research studies related to vehicle traction performance on snow and icy surfaces in Alaska. One of the studies conducted in 1995 is summarized. The main objectives of the study were to evaluate (a) traction performance of used winter tires on roadways, (b) traction performance comparison of lightweight studded tires with other winter tires, (c) traction performance of vehicles with two front studded tires, and (d) effects of vehicle type on traction performance. Field tests were conducted on traveled roadways and in parking lots. The main traction performance measurements included stopping distances, maximum stopping deceleration forces, time necessary to reach a certain speed, and maximum starting acceleration forces.
Smart Traveler Automated Ridematching Service Lessons Learned for Future ATIS Initiatives
Authors: Golob Jacqueline M. , Giuliano Genevieve
Published: August 2018

An evaluation study of the Smart Traveler Automated Ridematching Service is reported. This advanced traveler information system (ATIS) demonstration used a fully automated Touch-Tone telephone system to offer real-time ride matching service for just 1 day or for conventional carpool arrangements. An innovative feature was an automated messaging system in which a computer was used to dial up and leave recorded messages with potential matches. The system failed to perform as intended, and problems were experienced with the generation of computer-based reports for monitoring purposes. The demonstration revealed a low level of use and a mismatch with the needs of the market. Lessons are drawn for future ATIS initiatives.
California Consumer Perceptions of Potential Intelligent Transportation System Innovations
Authors: Frayer Constance D. , Kroot Louise
Published: August 2018

The purpose of the present research was to gain insight into the public perception of existing transportation options and to then explore consumers' needs and wants of those systems and the likely acceptance of possible intelligent transportation system (ITS) initiatives. The selected ITS concepts were based on nationally defined user needs for ITSs. Focus groups were selected as the means of gathering this primary research conducted throughout the state of California. Two perspectives were studied: statewide, to gain broad insights, and smart card specific, for focused insight. There was conspicuous agreement throughout the state as to the feelings about existing transportation systems. Californians are angry that they have not been consulted about their transportation system and that its current state does not reflect their wishes and does not meet their needs. Consumers are open to ITS concepts, including information systems, alternative fuel-powered vehicles, and other high-technology improvements. They support improvements in the automobile system and useful public transportation. Convenience, safety, freedom, flexibility, and control in planning and executing their travel are what they expect within an integrated transportation system. Much is written about the cost-effectiveness of buses. The reality is that the majority of the people will never use public transit in its current state. Electronic fare payment systems were seen as the ultimate in convenience for current users. Integrated fare systems were considered a tool for beginning the improvement of public transportation for existing users and for breaking down barriers of confusion and the lack of connectivity to attract new users.
Using Nationwide Personal Transportation Survey Data to Indicate Electric Vehicle Market Potential in Rural Areas
Authors: Bernard Martin J.
Published: August 2018

The 1990 Nationwide Personal Transportation Survey included 10,381 rural households, that is, households that were not in metropolitan statistical areas and were in zip code areas with population densities of less than 386 persons/km2 (1,000 persons/mi2). An analysis of the survey data to determine how rural households use their household (nonfarm) vehicles and to describe the potential for some vehicles to be electric vehicles (EVs) is reported. A main step in the analysis is to aggregate the daily household trips by vehicle. The counterintuitive result is that rural household vehicle use in terms of kilometers per day is quite similar to that of metropolitan area households. Thus, the potential for rural households to acquire EVs is similar to that for metropolitan area households.
Multiclass Dynamic Traffic Assignment Model: Formulation and Computational Experiences
Authors: Lo Hong K. , Ran Bin , Hongola Bruce
Published: August 2018

To model the impact of advanced transportation management and information systems, especially route guidance and other traffic information systems, it is often necessary to develop traffic models that acknowledge the existence of different user classes and that acknowledge that each class may respond to traffic information differently. As a minimum the model should differentiate vehicles that receive real-time traffic information from those that do not. Most existing approaches that incorporate multiple user classes are based on simulation. Although there are advantages of doing so, their main disadvantage is lack of solution quality and property. Recognizing the importance of these, an analytic approach in which the solution properties and quality are well defined is developed. The users are divided into three classes: (a) fixed-route travelers, (b) stochastic dynamic user-optimal, and (c) dynamic user-optimal. The approach defines the property of each class and integrates each into one modeling framework through a variational inequality formulation. Subsequently, a solution algorithm for the formulation is provided and the results of the algorithm are verified through six scenarios.