bluuebunny/crossref_metadata_2025 huggingface dataset:
In, Out, Within, and Through: Geography of Truck Freight in the Lower 48
Authors: Chin Shih-Miao , Hwang Ho-Ling , Greene David L.
Published: April 2007

The 1993 Commodity Flow Survey (CFS) proved that most freight transport on U.S. highways is interstate. The nation’s highway system functions principally to link the economies of states to form an integrated national economy rather than to serve the economies of individual states. Data from the 1997 CFS allow comparisons with the 1993 data to determine ( a) whether the predominant pattern of interstate shipments continues as a stable phenomenon; ( b) how fast the within-, from-, to-, and through-state components of truck freight are growing; and ( c) whether important regional trends are evident. The shipment of freight by truck in the United States was even more predominantly interstate in 1997 than in 1993. In 1997, interstate shipments made up 76 percent of the total tonmiles shipped by truck; in 1993 it was 73 percent. The proportions of truck freight shipments originating from, destined to, passing through, or occurring entirely within a state vary significantly from state to state. Individual state distributions remained relatively stable from 1993 to 1997, with the exceptions of dramatic increases in interstate truck ton-miles in small New England states and substantial but less-dramatic increases in border states, such as New York, Michigan, Washington, California, Texas, and Florida. These findings could have important implications for highway revenue allocations because trucks carrying freight play a significant role in damage to highway pavements and structures.
Are Households with Interrupted Phone Service Like Those with No Telephone Service?: Comparison Using Public-Use Microdata Set and Nationwide Personal Transportation Survey
Authors: McGuckin Nancy , Ann Keyes Mary , Banks David
Published: April 2007

Research suggests that households with interrupted telephone service can be used as a proxy for households with no telephone service to help mitigate the inherent frame bias in a random digit-dialing (RDD) sample. If a sufficient quantity of households with a history of interrupted service can be surveyed, some researchers suggest that probability weights can be calculated to account for the households not covered by the telephone survey. For the weighting of households with interrupted telephone service to serve the purpose of representing households without any service, these two groups should be similar. The analysis presented compares the demographic and travel characteristics of people with a history of interrupted telephone service [from the 1995 Nationwide Personal Transportation Survey (NPTS)] with those who are tabulated as having no telephone service in the 1990 census. This research shows that there are significant differences between the two groups—for example, people who report interrupted telephone service are more likely to own their home, have more workers in the household, and have more vehicles available than are people in households without telephone service. And although both groups are poor, the people with interrupted service are slightly less poor than those with no service at all. For the NPTS, and perhaps other surveys, the large significant differences between these two groups suggests that simply adjusting the weights for the households with interrupted telephone service who complete the survey may not be a sufficient strategy to mitigate the noncoverage of households without telephone service for a nationwide RDD survey.
Clearinghouse Approach to Sharing Geographic Information Systems-Transportation Data
Authors: Dueker Kenneth , Butler J. Allison , Bender Paul , Zhang Jihong
Published: April 2007

Updating and maintaining geographic information systems—transportation (GIS-T) data is proving difficult. Different database formats needed to support diverse applications lead to inconsistencies and inaccuracies and to duplication in updating. A clearinghouse approach is recommended for the collection and dissemination of new transportation features. This clearinghouse allows users to control the selection and segmentation of transportation features to update existing GIS-T databases to meet the needs of various private and public applications. Dayforward updating is recommended as the most appropriate technique for supporting existing systems without having to impose a new data model or a common identification schema. This approach is advantageous in that it is based on collecting data about new or changed transportation features once and uses the data many times to update existing databases. Four case studies are proposed as proof of concept and to pilot the day-forward GIS-T data-sharing clearinghouse concept.
Asset Management and Pavement Management: Using Common Elements to Maximize Overall Benefits
Authors: Cowe Falls Lynne , Haas Ralph , McNeil Sue , Tighe Susan
Published: April 2007

The public and private sectors have been managing their assets in some form for many years. Recently, however, the concept of asset management has been formulated to draw more explicitly on the principles of business, technology, economics, and other disciplines in a systematic and integrated way. This strategy offers cost-effective and responsive advantages in managing the public’s assets. Other management systems, particularly pavement management, have preceded the current interest in asset management by several decades. Accordingly, it is useful to assess whether there are common elements between asset management and pavement management and, if so, whether the experience gained from pavement management implementation and operation can be of benefit. In a generic sense, asset management has extensive commonalities with its component systems such as pavement management. However, asset management has some issues to resolve in progressing from a framework to an operational reality. A number of ways or areas in which asset management system development and implementation can benefit from pavement management operational experience are presented. Finally, some technical, economic/technical, and institution and user opportunities for innovations and advancements in asset management systems are identified.
Guidelines for Probabilistic Pavement Life Cycle Cost Analysis
Authors: Tighe Susan
Published: April 2007

To select the most appropriate pavement design for a given situation, it is necessary to understand how the pavement properties and in-service conditions relate to performance and life cycle cost. A given design may be most appropriate on one type of road and least appropriate on another type of road. This design selection is further complicated by the advent of new design methodologies, materials, and construction delivery techniques. Life cycle economic analysis is an important tool for comparing alternative treatment strategies. A life cycle analysis can use a deterministic approach, which incorporates a single point value, or it can use a probabilistic approach, which includes a mean, variance, and probability distribution. The probabilistic approach is better suited to describing the uncertainty associated with engineering. The Canadian Strategic Highway Research Program Canadian Long-Term Pavement Performance database and data provided by the Ministry of Transportation of Ontario were used in this analysis. Most construction variables are generally believed to be best described by a normal distribution. However, a lognormal probability distribution is better suited to describing these variables. This best fit is based on both a mathematical examination and a comparison of similar variables such as stocks and real estate values. It is also shown that thickness is a probabilistic variable that should be combined with the cost and incorporated into pavement life cycle costing. Ignoring the lognormal nature of these variables introduces bias into a life cycle cost analysis and does not reflect the true overall cost.
Counting Roundabouts: A Model to Obtain Detailed Roundabout Turning Movements
Authors: Al Kathairi Abdulla Salem , Mufti Rasin K. , Garib Atef M. , Williams Bradlee F. , Bierce Eric
Published: April 2007

To determine whether a roundabout or an intersection would work best at a particular location, it is important to know the number of vehicles making each turning movement. Methodologies have been developed for analyzing roundabout levels of service without knowing the detailed turning movements. To analyze whether a roundabout or signalized intersection would work better in a specific location, however, the detailed turning movements are needed. A methodology to determine existing turning movements at roundabouts with minimal labor is presented. Using only four persons, a typical four-leg roundabout can be counted, and all turning movements (including U turns) can be accurately estimated. The study to update the Master Transportation Plan of Abu Dhabi—the Capital of the United Arab Emirates—provided the opportunity to develop and test this approach. The roundabout counting methodology starts with procedures to count traffic volumes, including identification of specific movements to be counted. The counts are then entered into a model, which initially estimates all turns using percentages of vehicles exiting at various locations. The model then iteratively adjusts the turns until all entry and approach values match the counted values. Adjustment coefficients have been added into the process and calibrated, and the model has been successfully applied to obtain reliable turning movement estimates for three-, four-, and five-leg roundabouts. The model has been tested using data where all turns were known in advance and has proven to be quite reliable.
Using the Minnesota Accelerated Loading Facility to Test Retrofit Dowel Load Transfer Systems
Authors: Embacher Rebecca A. , Snyder Mark B. , Odden Trevor D.
Published: April 2007

The Minnesota Accelerated Loading Facility (Minne-ALF) is a laboratory-based, linear-loading, pavement test stand that simulates the passage of heavy loads moving at speeds up to 65 km/h over small, full-scale pavement test slabs. Moving wheel loads are simulated using a rocker beam controlled by hydraulic actuators. In this study, the passage of 40-kN single wheel loads was simulated at a rate of 172,800 loads per day. Demonstration tests were performed to ( a) determine the effects of selected design and construction variables on retrofit dowel load transfer system performance, ( b) measure the variability of Minne-ALF test results, ( c) demonstrate the general usefulness of the Minne-ALF, and ( d) identify the need for any additional test system modifications. Concrete slabs specimens were cast and dowels were installed in slots across cracks and formed joints. Test variables included joint face texture, repair backfill material, and dowel material and length. Test outputs included measurements of load transfer efficiency and differential deflection across the joint or crack. The effect of joint or crack face texture was great when the joint or crack remained tight. Load-carrying performance was improved by using Speed Crete 2028 in place of Minnesota Department of Transportation specification 3U18 (preproportioned bag mix) concrete backfill with similar joints and dowel bars. Load transfer was unaffected by the use of stainless steel–clad, fiber-reinforced plastic or grout-filled tubes in lieu of epoxy-coated structural steel dowel bars. Additional testing is recommended to examine the effects of dowel length and materials. This test program demonstrated the usefulness of the Minne-ALF; additional testing is planned.
Effect of Bearing Stiffness and Skew Angle on Performance of Precast Concrete Bridge
Authors: Green Tanya , Yazdani Nur , Spainhour Lisa , Cai Chun S.
Published: April 2007

Reinforced elastomeric bearing pads generally support precast concrete bridge girders. The condition of these bearing pads and the pad-bridge interface defines the support boundary conditions of the bridge super-structure. The interface between bearing pads and bridge girders affects the performance of the superstructure and the substructure. The pads are designed to carry vertical loads and to accommodate horizontal movements of the bridge girders. A study was conducted to determine the effects of various parameters on bridge superstructure performance and to compare the girder performance with simple support conditions corresponding to the current Florida Department of Transportation design. A parametric study on the interaction of the support boundary conditions and bridge girders was performed. The parameters studied included the skewness of the bridge and the effect of the bearing stiffness on the bridge system. A finite element model of a bridge superstructure containing Florida bulb tee 78 girders was created using ANSYS software. The model was subjected to an HL93 truck load according to the AASHTO load and resistance factor design specifications. The results indicate that pads with higher bearing stiffness are beneficial to bridges with higher skew angles. However, the reductions in deflections and stresses are smaller for increasing skew angles.
Experimental and Numerical Evaluation of Braced-Chain Eyebar Bridge
Authors: Laman Jeffrey A. , Lee Min-Suk , Boothby Thomas E.
Published: April 2007

Braced-chain eyebar bridges were common variations on the suspension bridge in the nineteenth century. The particular integration of a suspension system (eyebar chains) with the truss system (single diagonals and fabricated verticals) used at English Center, Pennsylvania, represents an important step in the evolution of the suspension bridge through its developmental stages in the late nineteenth century. The bridge, which spans 91.4 m (300 ft), was constructed in 1891 and was placed on the National Register of Historic Places in 1978 as a rare short-span suspension bridge. Because of the complex, apparently dual structural system of the bridge, identification of the bridge response to loading using analytical techniques was considered inadequate. Results of controlled load testing consisting of strain response measurements in selected suspension and truss components of the bridge are presented, and the interaction of the bridge truss and suspension systems is discussed. Field-measured response and predicted response derived from analytical models are compared and discussed. The Lower English Center Bridge is also evaluated for capacity of current legal loads considering the strength limit states.
Diagnostic and In-Service Testing of Transit Railway Bridge
Authors: Chajes Michael J. , Shenton Harry W. , Finch William W.
Published: April 2007

Results of a diagnostic load test and in-service monitoring of a steel through-girder bridge are presented. The bridge currently has a low load rating that is controlled by the flexural capacity of the steel deck trough. The diagnostic load test was conducted using the regularly scheduled transit trains, with no interruption to the daily service. A total of 16 strain transducers were mounted to the bridge girders and trough; five dynamic train passes were recorded. The largest tensile and compressive stresses recorded in the edge girder were 33.5 MPa and 23.4 MPa, respectively; the largest tensile and compressive stresses in the deck trough were 25.9 MPa and 27.9 MPa, respectively. The test results showed the effective width of the deck trough to be 2.89 m for a single axle and 5.19 m for a 2.74-m spaced axle pair. An in-service monitoring system was also placed on the bridge to record the stress cycles experienced by the bridge over a 1-week period. During the in-service monitoring period, 163 trains crossed the bridge with an associated 1,456 axles. The mean peak tensile stress in the deck trough caused by locomotives crossing the bridge was 26 MPa with a standard deviation of 1.8 MPa. The test results showed that the peak deck trough strains due to live load were only 15 percent of the computed values used in the rating. As a result, the bridge load rating can safely be increased, and the current speed restrictions can be lifted.
Concrete Bridge Decks Reinforced with Fiber-Reinforced Polymer Bars
Authors: Bradberry Timothy Ernest
Published: April 2007

Corrosion of metallic reinforcement is a primary cause of reinforced concrete bridge deck deterioration. A potential innovative solution to this problem is to eliminate this corrosion by using nonmetallic fiber-reinforced polymer (FRP) bars. FRP bars consist of continuous fibers of glass (GFRP), aramid (AFRP), carbon (CFRP), or a combination of these (hybrid FRP), impregnated with and bound by a resin matrix through a pultrusion, braiding, or weaving manufacturing process. Each of these fiber types is linearly elastic to failure. Characteristics of FRP bars include electrochemical inertness, high tensile strength, low weight, low elastic modulus (primarily GFRP and AFRP), and low shear strength. For increased bridge deck service life, electrochemical inertness is the most important characteristic of FRP bars. The structural design of a concrete bridge deck with FRP top mat reinforcement is presented. The deck is supported on five prestressed concrete Type C beams. The 200-mm (8-in.) nominal-depth deck is designed for self-weight, bridge rails, overlay, MS18 (HS20) wheel loads, and bridge rail impact loads. The continuous beam analysis with distribution of force effect is based on AASHTO distribution formulas. The discussion includes required flexural strength, limits on calculated crack width, FRP bar bond stress characteristics, durability, and shear strength of the concrete deck reinforced with embedded FRP bars.
Performance of Glass Fiber-Reinforced Polymer Deck on Steel Girder Bridge
Authors: Chajes Michael J. , Shenton Harry W. , Finch William W.
Published: April 2007

Because of the continued deterioration of U.S. bridges combined with the increasing cost of bridge maintenance, the U.S. bridge inventory continues to experience a backlog of structurally deficient bridges. One potential solution is the implementation of new high-performance materials. Because of their many beneficial characteristics, including being lightweight, having high strength- and stiffness-to-weight ratios, and being corrosion resistant, advanced polymer composites represent one such alternative. In 1999 the Delaware Department of Transportation rehabilitated a deteriorated concrete slab-on-steel girder bridge by removing the concrete slab and replacing it with a lightweight glass fiber-reinforced polymer (GFRP) deck. In the rehabilitation, the existing abutments were slightly modified and the original steel girders were retained. On July 28, 1999, a diagnostic load test of the bridge was performed using a fully loaded 10-wheel dump truck. The test included stationary load cases, semistatic load passes, and dynamic load passes. The details of the GFRP slabon-steel girder bridge as well as the bridge performance as determined from the field load test are presented.
Experimental Characterization of Metallic Dampers for Seismic Retrofit of Highway Bridges
Authors: Chen Genda , Bothe Eric R. , Ger Jeffrey J. F.
Published: April 2007

The seismic effectiveness of metallic dampers as vibration isolators and energy dissipation devices as well as the dynamic performance of high rocker bearings are investigated experimentally. The scope of the study includes optimizing the metallic dampers for maximum dissipation of energy, characterizing full-scale metallic dampers, and understanding the seismic behavior of a small-scale bridge with dampers. Three fullscale dampers, two of straight and one of linearly tapered rods, were fabricated and tested under a progressive cyclic load. Test results consistently show that the tangential stiffness of the metallic dampers does not degrade significantly as the number of loading cycles increases even though slack in the test fixture exists. For practical applications, a 10 percent damping ratio is recommended for the design of metallic dampers composed of straight rods, although a significantly higher ratio can be used for tapered dampers. Finally, a small-scale damper was fabricated and installed in an approximately one-tenth-scale steel-girder bridge model. The model was mounted on a shake table and tested under harmonic and earthquake loads. The test results indicated that the metallic damper is an effective isolator that can prevent energy transmission from the substructure to the superstructure of a bridge. They also show that high rocker bearings are stable even at the table acceleration of 0.54 g ( g =9.8 m/s2).
Fatigue Assessment of Traffic Signal Mast Arms Based on Field Test Data Under Natural Wind Gusts
Authors: Chen Genda , Wu Jingning , Yu Jiaqing , Dharani Lokeswarappa R. , Barker Michael
Published: April 2007

In recent years, several states including Missouri, Wyoming, California, and Texas experienced fracture failures of traffic signal mast arms. Almost all the failures are associated with the propagation of defects or cracks. It is therefore imperative to evaluate existing mast arms using a simple yet accurate procedure. A statistical methodology is proposed to predict the fatigue life of signal mast arm structures on the basis of field-measured strain data. The annual occurrence of various stress levels is determined using the historical wind speed data in the vicinity of a mast arm structure and the strain readings of the structure under specific wind gusts. For each stress level, the crack initiation and propagation lives are estimated with the strain-life approach and the Paris crack-growth-rate model. They are combined to account for variable stresses by means of Miner’s rule and the root-mean-square model, respectively. The stress concentration factor around the arm-post connection is determined using a finite element model. The parameters in the life prediction models are determined with ASTM flat tension and compact tension tests. The proposed methodology was applied to a 12.8-m (42-ft) long octagonal mast arm and a 16.5-m (54-ft) long circular mast arm in Missouri. It is concluded that signal structures in perfect condition will not crack under natural wind gusts during their service life. However, the 16.5-m-long arm is likely to be vulnerable to tiny defects around the weld connection, but the 12.8-m-long arm is safe unless a visible crack exists.
Advanced Technology and Integrated Public Transit: San Gabriel Valley Smart Shuttle Field Operational Test
Authors: Giuliano Genevieve , Moore James E. , O’Brien Thomas
Published: April 2007

Results of the San Gabriel Valley Smart Shuttle (SGVSS) field operational test (FOT) are presented. Results are drawn from a comprehensive evaluation of the FOT conducted over a 3-year period. The SGVSS attempted to integrate services of three local municipal public transit operators and a regional fixed-route operator via networked computer-assisted dispatching, automated vehicle location, and mobile data terminals. The integrated system was never fully deployed. The history of the project is described, and an analysis of the FOT is presented. Outcomes are explained by the following: ( a) origination of the project in a different location and with a different service concept, ( b) time and budget constraints imposed by the original FOT, ( c) limited commitment on the part of some project participants, ( d) lack of clear project goals and objectives, ( e) software and hardware technical problems, and ( f) problems with contracting and management. The FOT provides many insights into the challenges of service integration. Lessons learned are described.
Development of Canadian Architecture for Intelligent Transportation Systems
Authors: Borges Helena , Knapp Geoffrey , Eisenhart Bruce
Published: April 2007

Under the guidance of a steering committee of public- and private-sector representatives from the Canadian transportation industry, the development of the Canadian Intelligent Transportation System (ITS) Architecture was initiated in August 1999. In general, the Canadian effort subsumes all of the U.S. National ITS Architecture work and extends and modifies it to provide new services and areas of coverage and to reflect differences between the nations and the existence of new and different stakeholders. Since there is much commonality between the technical definitions of the two architectures, it is important to understand the explicit relationships. The development of the Canadian ITS Architecture is examined, and the differences between the architectures of the United States and Canada are illustrated. The development included an extensive review of other relevant ITS architecture and standards initiatives. On the basis of the review and significant ITS stakeholder input, an initial draft ITS architecture framework was developed that defined the user services, user subservices, and market packages applicable to Canada. After a review by ITS stakeholders, the revised ITS architecture framework was used to develop definitions of both the physical and the logical architectures of the Canadian ITS Architecture. The follow-up support activities anticipated for the Canadian ITS Architecture are reviewed, and the potential for iterative development with the U.S. National ITS Architecture is examined.
Evaluation Framework for Dynamic Vehicle Routing Strategies Under Real-Time Information
Authors: Hu Ta-Yin
Published: April 2007

Dynamic vehicle dispatching and routing strategies are important aspects of commercial vehicle operations applications of intelligent transportation systems technologies. One possible operational benefit of real-time information is the ability to reroute commercial vehicles efficiently according to current traffic conditions. A dynamic evaluation framework in which dispatching and routing strategies for individual vehicles can be tested in a realistic traffic simulation environment is developed. The simulation-assignment model, DYNASMART, is applied to evaluate such strategies in a traffic network. Numerical experiments conducted in the Taichung network are presented to investigate dynamic vehicle dispatching and routing strategies under real-time information supply strategies and to assess the effectiveness of such strategies in a dynamic perspective.
Scanning Electron Microscopy and Other Techniques to Investigate Low-Strength Concrete
Authors: Cross W. M. , Duke E. F. , Kellar J. J. , Johnston D. P.
Published: April 2007

Fracture surface scanning electron microscopy (SEM), X-ray microcomputed tomography (X-ray CT), microhardness testing, contact angle goniometry, and foam drainage testing were used to investigate the cause of low compressive strength concrete in South Dakota. SEM indicated that air voids were collecting in the vicinity of aggregate surfaces. These voids reduced the area over which stress could be transferred from the paste to the aggregate. Also, SEM showed that paste between the air voids was of poor quality. X-ray CT corroborated the SEM findings concerning the air void distribution, whereas microhardness testing indicated that the paste in higher-strength samples was three times as hard as the paste in low-strength samples. Air bubbles may attach to the aggregate surfaces due to the aggregate becoming hydrophobic when airentraining admixtures were used in the concrete. Contact angle goniometry confirmed this phenomenon as model aggregate surfaces had contact angles between 10 and 40 degrees for all admixtures tested, and model aggregate treated with vinsol resin–based air-entraining agents exhibited significantly lower (by 5 to 20 degrees) contact angles. Finally, examination of three-phase foams produced by mixing cement, air-entraining admixture, and water showed that vinsol resin–based foams had larger bubble sizes and kept more water within the foam than did nonvinsol resin-based admixtures.
Lightweight Fly Ash-Plastic Aggregates in Concrete
Authors: Jansen Daniel C. , Kiggins Michael L. , Swan Christopher W. , Malloy Robert A. , Kashi Mohsen G. , Chan R. Andrew , Javdekar Chitra , Siegal Charles , Weingram Joshua
Published: April 2007

The potential of using a synthetic lightweight aggregate (SLA) in concrete is examined. The aggregates are manufactured through thermal processing using plastic to encapsulate and bind fly ash particles. Nominal maximum-size aggregates of 9.5 mm were produced with fly ash contents of 0 percent, 35 percent, and 80 percent by total mass of the aggregate. The plastic used was high-density polyethylene, and the fly ash had a carbon content of 12 percent. An expanded clay lightweight aggregate and a normal-weight aggregate were used as comparison. Gradation, specific gravity, and absorption capacity are reported for the aggregates. Five batches of concrete were made with the different coarse aggregate types. Volume fractions of cement, water, fine aggregates, and coarse aggregates were kept the same for comparative purposes. Mechanical properties of the concrete determined included density, compressive strength, elastic modulus, splitting tensile strength, fracture toughness, and fracture energy. Salt-scaling resistance, a concrete durability property, was also examined. Compressive and tensile strengths were lower for the synthetic aggregates than for the normal-weight and expanded clay lightweight aggregates; however, comparable fracture properties were obtained. Relatively low compressive modulus of elasticity was found for concretes with the SLAs, although high ductility was also obtained. As fly ash content of the SLAs increased, all properties of the concrete were improved. Excellent salt-scaling resistance was obtained with the SLA containing 80 percent fly ash.
Roller-Compacted Fiber Concrete Pavement Foundation with Recycled Aggregate and Waste Plastics
Authors: Sobhan Khaled , Mashnad Mehedy
Published: April 2007

A laboratory investigation was conducted to evaluate the performance of a moderate-strength roller-compacted concrete (RCC) made from reclaimed crushed concrete used as aggregate, Class C fly ash, and wasteplastic fibrous reinforcement. The motivation for evaluating this primarily waste composite is to develop a high-quality foundation layer for a conventional flexible or rigid pavement while attempting to address such crucial issues as the ever-increasing solid waste disposal problem, rapidly depleting landfill spaces, and conservation of natural resources. A summary is given of the findings of materials characterization studies with the following objectives: ( a) to evaluate the effectiveness of recycled high-density polyethylene strips in stabilizing the tensile crack propagation through the brittle cementitious matrix; ( b) to determine the strength and toughness characteristics of the composite; and ( c) to suggest performance-based mixture design proportions for recycled aggregate, fly ash, cement, and recycled plastic fibers. Because an RCC pavement slab will be subjected to repeated tensile stresses under traffic loads, the study focused on instrumented split tensile and flexural tests to evaluate the performance of the foundation material. Results indicate that a mix containing only 8 percent cement and 92 percent recycled materials can achieve 28-day compressive strengths of up to 14 MPa and split tension strength of 1.5 MPa. It is found that the plastic fibers can improve the toughness characteristics significantly in split tension and moderately in flexure. Therefore, the new cement-bound composite made primarily from recycled products offers promise as an alternative material for construction and rehabilitation of highway pavements.
Laboratory Testing, Data Analysis, and Interpretation Procedures for Distressed Concrete Pavements
Authors: Sutter Lawrence L. , Van Dam Thomas J. , Peterson Karl R. , Dewey George R.
Published: April 2007

In recent years, there has been an increased awareness of materials-related distress (MRD) in portland cement concrete pavements. This research presents a protocol for identifying possible causes of MRD. The protocol is part of a series of guidelines prepared for the detection, analysis, and treatment of MRD in concrete pavements. The guidelines have been applied to a number of pavements, and the result of one study is presented. Laboratory results indicate that the subject pavement experienced a number of possible distress mechanisms and that no clear single cause exists. The guidelines were found to be useful in steering analyses without stopping at the first distress mechanism identified, thereby allowing for examination of all other possibilities. The guidelines will be most useful to engineers trying to correlate visual assessment and performance with the results of laboratory analyses.
Evaluation of High-Performance Concrete Pavement in Newport News, Virginia
Authors: Ozyildirim Celik
Published: April 2007

Three concrete mixtures were placed in a jointed plain concrete paving project in Newport News, Virginia, to reduce the shrinkage and improve the flexural strength of the concrete. Two mixtures contained ground-granulated blast furnace slag; one contained a 50-mm nominal maximum size (NMS) aggregate, and the other a 25-mm NMS aggregate. The third mixture contained Class F fly ash with a 25-mm NMS aggregate. Increases in maximum aggregate size are expected to provide concretes requiring less paste, less cementitious material, and less water, resulting in reduced shrinkage, and to provide a better interlock when cracks occur. Such improvements are expected to lead to better performance, with a long service life and reduced maintenance. The contractor, producer, FHWA, and Virginia Department of Transportation worked closely to fabricate the test sections. Test results from the laboratory and field indicated that all three mixtures can provide satisfactory strength, low permeability, and dimensional stability. The test sections are in excellent condition after 2 years of service in the westbound lane and 6 months of service in the eastbound lane of I-64.
Concrete Roughness Characterization Using Laser Profilometry for Fiber-Reinforced Polymer Sheet Application
Authors: Maerz Norbert H. , Chepur Poornima , Myers John J. , Linz Justin
Published: April 2007

The failure of a reinforced concrete member strengthened with fiberreinforced polymer (FRP) laminates may be caused by crushing of concrete, rupture of FRP laminates, or delamination of the FRP sheet. Therefore, the effectiveness and failure mode of FRP sheets applied to beams and columns is related to the degree of adhesion of the epoxy to the concrete surface. When a peeling or delamination failure can be avoided, a more effective engagement of the FRP sheet occurs, which results in more efficient use of the material. One of the principal factors affecting the bond behavior between the concrete and epoxy is the roughness of the concrete substrate. To prepare the bond surface, sand blasting or grinding is typically used to roughen the concrete. To that end, a portable device has been developed to measure the roughness of concrete surfaces. This device can be used as a quality-control tool to characterize surface roughness and identify when an adequate surface preparation has been attained. The method uses laser striping and image analysis. The method was tested on six slabs of sandblasted concrete, which were sandblasted to varying degrees of surface roughness, and a series of nine plastic model concrete surface profiles.
Comprehensive Activity Travel Pattern Modeling System for Nonworkers with Empirical Focus on Organization of Activity Episodes
Authors: Bhat Chandra , Misra Rajul
Published: April 2007

A comprehensive continuous-time framework is proposed for representation and analysis of the activity travel choices of nonworkers. An econometric formulation is also presented for one component of the comprehensive framework that focuses on the organization of activities in the nonworker’s daily activity travel pattern. In conclusion, an empirical analysis using activity travel data from the 1990 San Francisco Bay Area travel diary survey is discussed.
Estimating Employment Generation by Federal-Aid Highway Construction Projects
Authors: Anderson William P. , Lakshmanan T. R. , Kuhl Brenda
Published: April 2007

A model developed for the estimation of direct and indirect employment generated by expenditures on federal-aid highway improvement projects is reported. Data from the Federal Highway Administration’s Form 47 database is combined with input-output data from the Transportation Satellite Accounts to generate employment estimates for 14 distinct categories of highway improvement, making it possible to adjust employment estimates for shifts in the distribution of federal-aid expenditures across improvement types.
Benefits and Costs of Jointed Plain Concrete Pavement Design Features
Authors: Gharaibeh Nasir G. , Darter Michael I.
Published: April 2007

Highway agencies currently use a wide variety of alternative design features for jointed plain concrete pavement (JPCP). These features have evolved over time based on previous field performance, research studies, and designs of other agencies. A methodology for evaluating the benefits and costs of various JPCP design features is presented here. The methodology is based on predicting key distresses and smoothness, applying a performance-based maintenance and rehabilitation policy, and then computing the life-cycle costs of the evaluated design relative to a reference design. The methodology was applied to limited case studies of selected JPCP design features for illustration (slab thickness, base type, permeable drainage layer, joint spacing, load transfer at transverse joints, and widened slabs). The effects were studied for two climatic zones (wet freeze and wet no freeze) and two traffic levels (medium and heavy). Construction costs were estimated with the results from a nationwide survey of contractors, and future costs were estimated with prediction models of distress and smoothness based on nationwide databases. Results from the case studies indicate that the general methodology is reasonable and can be used by pavement designers to evaluate a set of potential JPCP designs at a given project site to achieve the lowest life-cycle costs over the long term.
Construction and Performance of Alternative Concrete Pavement Designs in Wisconsin
Authors: Crovetti James A. , Bischoff Debra
Published: April 2007

The design and performance of concrete pavement test sections constructed in Wisconsin in the summer of 1997 to validate the constructability and potential cost-effectiveness of alternative concrete pavement designs incorporating variable dowel strategies and slab thicknesses are described. To reduce the number of dowel bars across the transverse joints and remain consistent with dowel bar installation equipment currently used within the state, four alternative dowel patterns were examined. Test sections were constructed with alternative dowel materials including fiber-reinforced polymer (FRP) composite dowels, solid stainless steel dowels, and hollow core mortar-filled stainless steel dowels as well as a variable slab thickness. Postconstruction monitoring including deflection testing, joint distress surveys, and ride quality surveys have been done. Observed joint distress including minor spalling, chipping, and fraying is mainly due to joint saw cut operations. No transverse joint faulting or slab cracking has been observed. Deflection testing to date indicated general uniformity of foundation support in all test sections. Deflection testing has also been done across transverse joints to quantify deflection load transfer efficiency. Joint tests in the fall of 1997 and 1998 indicated reduced load transfer efficiencies in all test sections compared with control sections, most notably in the FRP composite dowel test sections and the placement alternative with three dowels in each wheelpath. Ride quality surveys indicated general uniformity among sections.
Repair of Ultrathin Whitetopping Pavements
Authors: Wu Chung-Lung , Tayabji Shiraz , Sherwood James
Published: April 2007

Since its inception in 1991, ultrathin whitetopping (UTW) has moved beyond the experimental stage and has become a viable pavement rehabilitation alternative. Development of the mechanistic design procedure in 1997 represented a milestone in the development of this technology. Over 150 UTW pavements have been built in the past decade. With the use of UTW rapidly increasing, the next logical step in the development of this technology is to develop UTW repair and rehabilitation techniques. How does one repair UTW pavements? Can conventional concrete pavement rehabilitation materials and methods be used for UTW pavements? Construction of the UTW test sections at the FHWA Turner-Fairbank Highway Research Center, subjected to accelerated loading tests, provided an excellent opportunity for evaluating potential UTW pavement repair methods. These test sections were constructed in April 1998 and were subjected to accelerated load testing with FHWA’s accelerated loading facility (ALF) from May 1998 until November 1999. Some UTW panels exhibited distresses, with corner cracking being the most prominent. After discussions with state agency staff and industry representatives, panel removal and replacement was selected to repair some of the distressed panels of these test sections. The repair work was done in April 2000 and the repaired test sections were load tested with ALF from May to August 2000. Based on the results of ALF testing, it was observed that panel removal and replacement is an effective method for UTW pavement repair. Guidelines for UTW pavement repair by this method are proposed. A strong bond between the concrete and asphalt layers, even for distressed (cracked) panels, was observed. The time required for UTW panel repair was also documented and can be used for planning UTW repairs.
Overlay Performance in Canadian Strategic Highway Research Program’s Long-Term Pavement Performance Study
Authors: Tighe Susan , Haas Ralph , Li Ningyuan
Published: April 2007

The Canadian Long-Term Pavement Performance (C-LTPP) study, initiated in 1989, involves 65 sections in the 24 provincial sites that received rehabilitation comprising various thicknesses of asphalt overlays. The effects of the various alternative rehabilitation treatments on pavement performance in terms of roughness progression under comparative traffic loading, climate, and subgrade soil conditions are described. Roughness trends are the main subject of the C-LTPP study. Progression of roughness for thin overlays (30 to 60 mm) is significantly higher on a national basis than for medium (60 to 100 mm) and thick (100 to 185 mm) overlays. Factor effects, including climatic zone, subgrade type, and traffic level were also evaluated. Some findings are that ( a) in wet, high-freeze zones, thinner overlays show a higher rate of roughness progression than thicker overlays, regardless of subgrade type; ( b) in dry, high-freeze zones, roughness progression for medium and thick overlays is relatively small; ( c) in wet, low-freeze zones, thinner overlays combined with a fine subgrade show the highest rate of roughness progression; ( d) traffic in terms of equivalent single-axle loads (ESALs) appeared to have a limited effect for all the preceding factors—this was attributed largely to all the traffic essentially falling into one level and to the designation of 200,000 ESALs per year as the boundary between low and high traffic levels. In conclusion, the C-LTPP experiment has provided valuable information on roughness trends after only 8 years of observations. The methodology developed in this study for pavement roughness evaluation can be applied to performance trends analysis of other measured LTPP data.
Effect of Fine Aggregate Angularity on Compaction and Shearing Resistance of Asphalt Mixtures
Authors: Stakston Anthony D. , Bahia Hussain U. , Bushek Jared J
Published: April 2007

The effect of fine aggregate angularity (FAA) on the densification characteristics of asphalt mixtures was evaluated with the Superpave® gyratory compactor (SGC). Aggregates from three different sources used in production of Superpave mixtures in Wisconsin were studied. From each source, a fine gradation and a coarse-shaped gradation were included. To vary the FAA values of the fine aggregates, the proportions of the manufactured sand to the natural sand from each source were varied and the same overall gradations were maintained. A range of FAA values between 40 and 48 for the sources was achieved. All other mixture variables were kept constant, and the mixtures were compacted in an SGC equipped with a special device called a gyratory load plate assembly to measure the densification and the shear force required for compaction of each mixture. Densification data were analyzed to estimate the effect of the FAA on densification to 92% of theoretical maximum density ( Gmm), which is assumed to represent resistance of the mixture to construction compaction, and to densification above 92% Gmm, which is assumed to represent mixture resistance to traffic. Results indicate a consistent trend of higher resistance to compaction with higher FAA values. Mixtures with higher FAA require higher compaction effort, as measured by densification rate and shear force required for gyrating. Resistance to densification above 92% Gmm, which is assumed to represent traffic, shows inconsistent trends. For one source of aggregates, the increase in FAA resulted in less resistance to densification and shear distortion above 92% Gmm. Results indicate that the sensitivity of mixture response variables to change in FAA values is highly dependent on the source of the aggregates and on gradation. Therefore, it is recommended that mixture design be based on limits of densification characteristics instead of a target FAA value for all mixture types.
Comparison of Fundamental and Simulative Test Methods for Evaluating Permanent Deformation of Hot-Mix Asphalt
Authors: Zhang Jingna , Cooley L. , Kandhal Prithvi S.
Published: April 2007

Rutting has long been a problem in hot-mix asphalt (HMA) pavement. Through the years, researchers have used different kinds of fundamental and simulative test methods to estimate the rutting performance of HMA. It has been recognized that most fundamental tests are very complex and simulative tests are generally easy to perform. A comparative study of two fundamental tests [repeated shear at constant height (RSCH) and repeated load confined creep (RLCC) tests] and one simulative test [asphalt pavement analyzer (APA) rut test] is documented. A comparison and correlation of various parameters (permanent deformation or strain, slopes, and intercepts from linear or power law regressions) from these three test results were conducted. The analysis data indicated that the two fundamental tests had significant correlation with APA rut tests. The relationship between the deformation rates and the correlation between initial deformation from the RSCH and RLCC indicate similar deformation behavior of HMAs under RSCH and APA loading conditions. Based on the observed relationships and the existing guidelines for interpreting RSCH permanent shear strain and RLCC permanent strain, preliminary guidelines were recommended for evaluating rut resistance on the basis of APA rut depth. Compared with the existing APA criteria developed by the Georgia Department of Transportation, the acceptable rut depth criteria generated from this study are reasonable and applicable.