bluuebunny/crossref_metadata_2025 huggingface dataset:
Typology of Motorcycle Crashes: Rider Characteristics, Environmental Factors, and Spatial Patterns
Authors: Kim Karl , Boski Joseph , Yamashita Eric
Published: April 2007

Research was conducted on motorcycling and alcohol-impaired motor-cycling in Hawaii to develop a crash typology. The investigation expanded the scope of rider characteristics analysis by examining the combined effects on motorcycle crashes of rider behavior (helmet use, speeding, actions taken before a crash, etc.), environmental factors (urban versus rural locations, roadway alignment, etc.), and spatial patterns. The crash typology was used to derive logistic regression models for explaining alcohol-involved crashes, single-vehicle crashes, and injury outcomes (including fatalities) associated with motorcycle crashes. The logistic models allowed comparisons of the relative importance of various rider characteristics, temporal and environmental correlates associated with motorcycle crashes, and the associated crash types and injury outcomes. Finally, a spatial cluster analysis was also performed with both geographic information system and spatial analytical tools. The analysis suggests that overall behavioral and temporal factors are more significant predictors of alcohol-involved crash patterns than environmental or roadway features. The findings are qualified in terms of the usefulness of the methods to motorcycle safety researchers and relevance to motorcycle safety initiatives in the state of Hawaii.
Factors in Truck Crashes on Roadways with Intersections
Authors: Daniel Janice , Tsai Chuck , Chien Steven
Published: April 2007

Accident prediction models have been used to identify factors that may contribute to crashes at a particular location. Models have been developed separately for highway locations and for intersections. Few accident prediction models have been developed specifically for truck crashes on roadways affected by traffic signals. On arterial roadways with a large number of intersections, it is difficult to isolate the relationship between accidents and specific geometric features, including intersections, because of the proximity of many of these elements to each other. For this reason, an accident prediction model that treats intersections as a geometric feature on the roadway may allow for both the impact of the intersection and of the geometric features of the adjacent roadway segments to be accounted for in one model. By using a database developed for truck accidents in New Jersey for 1998 and 1999, an overall analysis of truck accidents at signalized intersections along US-1 in New Jersey was performed. A Poisson regression and negative binomial model approach was used, and an accident model for estimating accidents on arterial roadways influenced by signalized intersections was determined.
Development of a Carrier Selection Method for Intrastate Compliance Review in Wisconsin
Authors: Smith Robert , Juni Emil
Published: April 2007

A method was developed for ranking intrastate carriers in Wisconsin to enhance the selection of carriers for Wisconsin’s intrastate compliance (comprehensive safety) review program. The federal SafeStat methodology for identifying interstate motor carriers that have poor safety records cannot be used in Wisconsin because of the lack of carrier size data. Missouri’s intrastate SafeStat methodology, which does not require carrier size data, was used as the starting point in developing Wisconsin’s methodology. The methodology involves merging a ranking of carriers based on historical inspection data (the total out-of-service rate) with a ranking based on total crashes. The validation based on crashes per carrier for a subsequent period showed a similar pattern for the before and after crash rates by percentile group. The overall level of crashes for the after period, however, was substantially lower because of the statistical phenomenon of regression to the mean (RTM). The methodology is also limited by the lack of exposure data for the carrier crash data. To account for RTM, an empirical Bayesian method for estimating RTM was proposed and applied to a before-and-after analysis of intrastate carrier crashes in Wisconsin. The method provided estimates of the after-period crash rates that were much better than the naive assumption of no change in the crash rate. An improved fit for the RTM estimates is likely if more homogeneous groups of carriers were created on the basis of grouping by carrier size.
Pedestrian Location Identification Tools: Identifying Suburban Areas with Potentially High Latent Demand for Pedestrian Travel
Authors: Vernez Moudon Anne , Mitchell Hess Paul , Matlick Julie , Pergakes Nicholas
Published: April 2007

Planning tools were developed for local and state agencies to identify locations with latent demand for pedestrian travel that are currently underserved with pedestrian infrastructure. Prior research in the Puget Sound showed that approximately 20% of the suburban population lives in dense, compact areas with latent demand for pedestrian travel. The tools are designed to enable agencies to target capital investments in nonmotorized infrastructure to areas with the highest potential for pedestrian trips. They are a first step toward delineating suburban pedestrian zones. After a review of existing methodologies to identify areas with pedestrian travel demand, two tools were developed that use geographic information system software. One tool benefits from highresolution parcel-level data with specified land use attributes. The other tool, however, relies on commonly available census block data and aerial photography. It is more labor intensive than the first tool and requires familiarity with reading urban form and development patterns. The tools identify locations with potential for pedestrian travel based on two attributes. First, the locations contain land uses that are functionally complementary, that is, commonly linked by travel. The land uses are dense residential development (travel generators) and retail areas and schools (travel attractors). Second, these land uses are also spatially complementary, that is, sufficiently close to each other to be linked by walking.
Policy for Sustainable Low-Volume Rural Roads in Costa Rica
Authors: Lopez Maria Lorena
Published: April 2007

The main issues that have been addressed in the Costa Rican government’s policy for low-volume rural roads are discussed. As in most developing countries, providing good roads to support the growing demand for agricultural and tourism activities has been a great challenge, especially in times of important budget limitations. The Costa Rican experience is shared in the hope that it can prove useful in other countries, because its impact has not been limited to just providing better roads; it is also helping to motivate widespread citizen participation and to improve technical and organizational capabilities of the local governments. Because the majority of the rural roads are managed by local governments, whose administrative and technical capacity has been limited in the past, the central government, through the Ministry of Public Works and Transportation, has developed a comprehensive policy based on simple technology transfer programs and regulations for these organizations, while at the same time inducing a method of investment planning that requires organized citizen participation. The program, called Participative Road Conservation, has become the center of the government’s policy. Some of the highlights of the program are presented. The strategy of the program has been to give straightforward guidelines in organizational issues of road maintenance at the local government level (including the local road committees), basic technical standards to be followed, and planning methodologies. One of the fundamental principles of the program is the sharing of responsibilities for adequate road maintenance, including financial contributions, among the communities, the local government, and the central government. This policy for sustainable rural roads is making a change in the road maintenance culture of the country. It has required educational programs concerning the importance of roads, the correct way to build and maintain them, adequate control of the work, and so forth. Once the community is involved in planning and rehabilitating a road, it is more likely that the road will not be allowed to deteriorate again. Even children are involved in a program of school patrols. The financial reforms that have been made in Costa Rica to attend to the needs of the national and municipal road systems are also addressed.
Sustainability of Rural Road Network Given Changing Demands of Rural Agriculture: Evidence from Texas
Authors: Prozzi Jolanda , Harrison Robert , Prozzi Jorge A.
Published: April 2007

Over the past two decades, the changing transport demands of agriculture and rural industry and the strategic rail decisions that resulted in the abandonment of many rural rail links have had severe impacts on rural road infrastructure. As larger and heavier trucks haul products over longer distances on rural pavements, the financial ability of the state and local governments to maintain and improve the rural road network has been diminishing. Clearly there is a need to recognize the significance of the agriculture–transport relationship and to determine the impacts on rural roads associated with major agricultural traffic generators to ensure the sustainability of rural road networks. Evidence of the increased truck volumes associated with industrialized agriculture and strategic changes in the rail industry is provided through a case study of the grain industry, with specific emphasis on the production and consumption of corn in Texas. A methodology is suggested to quantify the impacts of increased truck volumes and axle loads on rural pavements that were not designed or built to accommodate more and heavier axle loads. It is believed that a simple methodology to quantify pavement damage can be invaluable to demonstrating rural maintenance needs and to informing rural transport investment decisions.
Applying Pavement Preservation Concepts to Low-Volume Roads
Authors: Zimmerman Kathryn A. , Peshkin David G.
Published: April 2007

As the challenges associated with managing a low-volume road network increase, agencies have realized the benefits associated with the use of pavement management tools for the road network. One of the benefits of the use of these tools is the ability to illustrate quickly and effectively the impacts of various pavement preservation strategies (such as worst-first repair) on overall network conditions. As a result, agencies are in a better position to communicate the needs of the road network to individuals responsible for the allocation of funds. In some cases, agencies have successfully lobbied for additional funds to support their road management efforts. The benefit of pavement management tools in supporting the preservation of the low-volume road network is illustrated by their use in evaluating the long-term impact of various funding strategies, the cost-effectiveness of pavement preventive maintenance programs, and various cost analyses that can be used to enhance road system management. Information from a variety of transportation agencies is used for this illustration. For instance, a summary is presented of the use of pavement management information to compare a worst-first repair strategy with a strategy that includes pavement preservation techniques. Examples are provided of the types of presentations that can be given to top management to illustrate these effects. In addition, the cost-effectiveness of pavement preservation programs is illustrated by showing the reduction in life-cycle costs and the overall benefits provided to the agency through the implementation of preventive maintenance programs.
Regional Network Analysis of Primary-Industry Truck Traffic on Public Roads in New Zealand by Using Geographic Information Systems
Authors: Douglas Robert A.
Published: April 2007

Industrial forestry activities in New Zealand are now in a phase of unprecedented growth: the annual cut will double from 18 million m3 to well over 30 million m3 a year during the next 5 years. Given that most of the wood is taken from forest to mill or port by road in New Zealand, including a portion of the trip on public highways, the impacts of the doubling in logging truck traffic will be significant and severe. New Zealand’s roads have, for the most part, thin-sealed, unbound pavements. New Zealand’s second-largest industrial sector is tourism. Pavements and tourists will feel the impact of the looming increase in logging truck traffic unless steps are taken to anticipate the changes in traffic volumes and patterns. There is the complicating factor that the dairy industry too is now expanding rapidly with associated increases in raw milk tanker traffic. There is some friction between the forest industry and the dairy industry over which will be responsible for the increased strengthening, rehabilitation, and maintenance of roads. Research is under way to use regional network analysis and geographic information systems to predict the increases in heavy-truck traffic and changes in its distribution on public roads. This is the first step toward devising measures to mitigate the impacts and is a precursor to the implementation of pavement management. A unique opportunity exists in southern New Zealand: cooperation between forest operators and government agencies in the Otago and Southland region of the South Island of New Zealand on large-scale projects, providing the environment needed to examine such large, landscape-scale problems.
Improved Erosion Control Selection for Steep Slopes with the USDA Forest Service Erosion Control Selection Guide
Authors: Rivas Todd
Published: April 2007

Low-volume forest roads are a significant source of erosion and can be challenging and expensive to control because of the steep (greater than 50% slope gradient) slopes. Most erosion control documents lack guidance on treatment selection, emphasize temporary erosion control, and do not adequately address steep slopes. To address the deficiency, the U.S. Department of Agriculture Forest Service San Dimas Technology and Development Center created the USDA Forest Service Erosion Control Selection Guide. The primary focus of the guide is technical information to assist long-term erosion control treatment selection on steep slopes, particularly road cut and fill slopes. This guide is a synthesis of information encompassing erosion control fundamentals, erosion and sediment yield prediction models, treatment parameters, erosion control treatments, selection tips, installation tips, and additional resources. Treatments include grading, seeding, mulch, soil amendments, rolled erosion control products, soil bioengineering, and biotechnical stabilization. Significant advantages of the guide include general treatment selection guidance, inclusion of permanent treatment methods, and consideration of steep slopes. The guide is limited because of the complex nature of erosion; it does not address nontechnical issues, and it may need updating as new information becomes available. Despite these limitations, the guide is a valuable new tool for reducing erosion and sediment yield on steep slopes of low-volume roads.
Challenges and Strategies for Local Road Safety Training and Technology Transfer
Authors: Knapp Keith , Walker Donald , Wilson Eugene
Published: April 2007

A significant increase in the safety of transportation networks in the United States and throughout the world will require the direct involvement of local jurisdictions (e.g., counties, townships, villages, and cities). In 1998, approximately 4 out of 10 fatalities in the United States occurred on collector and local roadways. Local road agencies need to have the skills to identify, evaluate, and mitigate safety concerns. Effective local road safety training, technology transfer, and resources are essential. A number of challenges need to be met to complete these tasks, but current local road safety training and technology transfer programs and strategies also offer opportunities. Some of these challenges are identified and discussed, and several current and potential programs and strategies for local road safety training and technology transfer are described. Relevant results from a recent FHWA and AASHTO international scan tour on the management and organization of comprehensive highway safety programs are also presented and used to support the suggestions provided. A synopsis of the relevant discussions from a recent workshop on highway safety workforce development, sponsored by FHWA, AASHTO, TRB, and ITE, is also offered. The objective is to initiate discussion about the need for and development of a comprehensive and cost-effective local safety training and technology transfer program.
Durable Roadside Protective Structures for Low-Volume Roads
Authors: Tom Joe G. , Weiss Charles A. , Malone Philip G. , Virostek Andrew
Published: April 2007

Data compilations on accidents nationwide show that 30% of all traffic fatalities and 16% of all injuries occur when a vehicle goes into a ditch or strikes a fixed obstacle on the roadside. Highway traffic barriers and crash cushions are not economical for use on low-volume roads, even though they could be helpful in reducing fatalities and injuries. Sand-filled barrels and metal barriers that undergo controlled deformation are relatively expensive and require significant investments in placement, inspection, maintenance, and repair. A crash cushion design based on scrap tires encased in foamed, fiber-reinforced concrete is being developed and can provide a versatile, low-maintenance safety barrier that is also resistant to vandalism. The composite scrap tire–and–concrete protective barrier uses a skeleton of scrap tires as an attachment point that can serve to lift, place, and anchor a mass of foamed, fiber-reinforced concrete in place on the roadside. The foamed, fiber-reinforced concrete crushes like wood under impact from tools or projectiles, so the modules are difficult to vandalize and can survive scrapes from graders or snow removal equipment. Module array can be developed on the basis of weight distribution in sand-filled barrel arrays. Potential uses for the barrier modules include protection of bridge piers, bridge railings, and obstacles on curves. The durability and economy of these units make them a practical option for use in improving safety on low-volume roads, especially in remote areas.
Field Evaluation of Method for Rating Unsurfaced Road Conditions
Authors: Soria Manoel H. A. , Fontenele Eliana B.
Published: April 2007

Research was conducted to evaluate the performance of a method for rating the surface condition of low-volume unsurfaced roads and eventually to adapt the method to the situation prevailing in the state of São Paulo, Brazil. The rating method selected as the basis for this experiment is the unsurfaced road condition index (URCI) developed by the U.S. Army Corps of Engineers. The field research comprised subjective evaluations and URCI determinations performed by a rating panel composed of seven members. Some of the main questions underlying the research are: Are the original URCI deduct values curves adequate for the south Brazilian region? If not, is it possible to construct deduct values curves similar to URCI’s? To what extent can a rating panel be used to construct and calibrate these curves? Five unsurfaced county roads were selected according to the criteria of maximum soil and conditions variability. From these roads 14 segments 300 m length were selected and divided into 140 sample units 30 m in length. The rating panel attributed scores for the section, for each sample unit, and for each distress found in the sample unit. It was concluded that the panel scores for distress and surface condition of sample unit and section do not agree with the URCI computed by the method and that there is some coherence between the subjective scores given to the sample units and the score given to the section composed of these sample units.
Study of Site-Specific Roughness Progression for a Bitumen-Sealed Unbound Granular Pavement Network
Authors: Hunt P. D. , Bunker J. M.
Published: April 2007

Pavement management systems assist engineers in the analysis of road network pavement condition data and subsequently provide input to the planning and prioritization of road infrastructure works programs. The data also provide input to a variety of engineering and economic analyses that assist in determining the future road network condition for a range of infrastructure-funding scenarios. The fundamental calculation of future pavement condition is commonly based on a pavement age versus pavement roughness relationship. However, roughness–age relationships commonly do not take into account the pavement’s historical performance; rather, an “average” rate of roughness progression is assigned to each pavement based on its current age or current roughness measurement. Results of a research project are documented; the project involved a comprehensive evaluation of pavement performance by examining roughness progression over time with other related variables. A method of calculating and effectively displaying roughness progression and the effects of pavement maintenance was developed. The method provides a better understanding of pavement performance, which in turn led to a methodology of calculating and reporting road network performance for application to the pavement design and delivery system in Queensland, Australia. Means of using this information to improve the accuracy of roughness progression prediction were also investigated.
Solution for Distressed Pavements and Crack Reflection
Authors: “Skip” Brown Norman R.
Published: April 2007

It is commonly accepted that cracks in aged asphalt pavements will reflect through seal coat and overlay applications. Pavement fabric placed under asphalt concrete overlays will slow this crack reflection, but not stop it. Nineteen years of experience working with the same fabric under a double chip seal has shown that using a modified technique, developed through trial and experimentation, adds substantial pavement life at a reduced cost over typical methods of repair used in the industry. In addition, pavement deterioration due to oxidation and stripping has been eliminated because air and water are unable to penetrate the surface. The subgrade dries out and regains its original strength, minimizing deflection under traffic loadings. This method reduces crack reflection by more than 90% over alternate methods. The reduction is due mainly to a regaining of the subgrade strength along with an increase in the flexibility of the surface through the use of a higher percentage of oil in the total mix. The most surprising aspect of this process is that alligatored pavement can be repaired without having to remove and replace the damaged pavement.
Simplification of HDM-4 Economic Models for Network-Level Gravel Road Management Systems
Authors: Burger A. F. , van der Gryp A. , van Zyl G. D. , Fourie H. G.
Published: April 2007

A description is provided of the procedure followed in the gravel road management system (GRMS) of the Provincial Administration: Western Cape (PAWC) for determining scheduled maintenance priorities and upgrade to paved standard priorities for gravel roads. An algorithm was developed that takes account of a number of factors to determine the costs and benefits of PAWC’s two maintenance strategies. Cost and benefit streams are further used in the calculation of the internal rate of return (IRR) for the different maintenance strategies. Prioritization in the GRMS is based on the calculated IRR, and the priority lists are further refined through a consultative process involving maintenance personnel, the community, and head-office decision makers. As part of the implementation of the algorithm, Highway Development and Management System version 4 (HDM-4) equations for the calculation of vehicle-operating cost (VOC) were simplified for application in the southern African context. Results are presented of a comparison between the output of the simplified HDM-4 equations with the output of HDM-4. Conclusions reached show that implementing the procedure described had a number of positive consequences. They include that the prioritization of projects is based on sound principles that result in the effective and responsible use of available funds. It was also concluded that the simplified HDM-4 VOC calculation results compare well with HDM-4 results.
Effect of Surfactant on Dry-Side Compaction of Silty Sand
Authors: Berney Ernest S. , Peters John F. , Newman J. Kent , Smith Donald M.
Published: April 2007

The use of surfactants with soil is an evolving practice that lacks a systematic theory to describe the mechanisms of behavior that influence the soil response. A technique has emerged from the theoretical modeling of partially saturated soils that allows near-optimum densities to be achieved with water contents well below optimum. The central theme of the model is a distinction between the intergranular stress caused by externally applied loads and the stress derived from internally distributed capillary stresses due to the presence of water menisci. A practical consequence of the theory is that resistance to compaction can be reduced by adding surfactant (soap) to the mix water to reduce the component of intergranular stress derived from capillary tension. The decrease in capillary tension permits greater dry-side compaction density and an increase in soaked California bearing ratio strength. Well-graded silty-sand data were used to compare the behavior of untreated specimens with that of specimens treated with a 4% by weight of water anionic surfactant. The treated specimens achieved dry densities near optimum with the use of 25% less total mix water. Differences in the California bearing ratio strength for the soaked and unsoaked specimens and comparison of specimens' swell during soaking support the concept that compaction was improved through reduction of capillary tension. This allows specified dry densities to be achieved using considerably less water, which is critical in arid environments, and translates into efficiency in cost and, more important for rapid military operations, in construction time.
Stabilization of Clay Soils with Nontraditional Additives
Authors: Tingle Jeb S. , Santoni Rosa L.
Published: April 2007

A laboratory experiment was conducted to evaluate the stabilization of low- and high-plasticity clay soils with nontraditional chemical or liquid stabilizers. Clay soil specimens were mixed with various stabilization products and compacted using a gyratory compaction machine to approximate ASTM D1557 moisture–density compaction. Each specimen was subjected to wet and dry testing following a 28-day cure. Twelve nontraditional stabilizers were evaluated, including an acid, enzymes, a lignosulfonate, a petroleum emulsion, polymers, and a tree resin. Additional specimens were stabilized with Type I portland cement and hydrated lime for comparison with traditional stabilizers under the same mixing, compaction, and curing conditions. Analysis of the test data consisted of determining the average strength, in terms of unconfined compressive strength, of three replicate specimens of each mixture. The average strength of the three replicates of each additive was compared with the average strength results of the remaining nontraditional additives, the traditional stabilization results, and a series of control specimens that were not stabilized. The experiment results indicate an increased strength of some nontraditionally stabilized specimens when compared with that of both the control series and the traditional stabilization alternatives. Other nontraditional stabilizers did not demonstrate significant increased strength compared with that of the control series for the conditions of this experiment. Many of the stabilized specimens were highly susceptible to moisture, indicating the potential for poor performance when exposed to adverse environmental conditions, whereas a few specimens demonstrated excellent performance when exposed to moisture. Specific product categories are recommended for stabilizing low- and high-plasticity clay soils.
Strength and Behavior of Materials for Low-Volume Roads as Affected by Moisture and Density
Authors: Paige-Green P.
Published: April 2007

The relationships among strength, moisture, and density in pavement subgrades and layerworks are well known, but they have particular significance in low-volume roads. In these roads, the specified density is frequently not achieved (quality assurance testing tends to be reduced), and moisture fluctuations are more severe with greater consequences. Traditional studies of the material strength for these roads in southern Africa are based almost entirely on the California bearing ratio (CBR), a test with inherent problems. The test is routinely carried out to identify whether the materials under consideration have the required soaked strengths (typically CBRs of 80% or 45% for bases of different standards) at the design compaction density. Studies of the CBR at different moisture contents and densities should be carried out to identify the implications of variations in these properties on the behavior of pavement materials. A simple technique to be carried out during conventional laboratory testing was developed. Aspects pertaining to this type of study were evaluated, and the findings were related to low-volume road behavior.
Use of Locally Available Soils on Subbase and Base Layers of Flexible Pavements
Authors: Ribeiro de Rezende Lilian , Camapum de Carvalho José
Published: April 2007

Lateritic soils are very abundant in the region of the Federal District of Brazil. If this material could be used in low-volume roads, it would be possible to avoid some environmental problems. Alternative techniques were developed for the use of nonconventional materials as subbase and base layers of flexible pavements. To analyze the technical and economical viability of using local soils, two experimental highways were constructed. Each highway was divided into three sections with different materials in the subbase and base layers, such as fine lateritic soil, fine lateritic soil stabilized with lime, and a mixture of fine lateritic soil and crushed rock. The compaction characteristics were evaluated in laboratory tests. From the time the segments were constructed (in 1998 and 2000) until 2001, the stress–strain behavior of the paving structures was evaluated by in situ tests, such as the plate-bearing, Benkelman beam, and falling weight deflectometer tests. From the results, conclusions were drawn about which of the chosen materials showed the best performance in mechanical behavior.
Gravel Loss Characterization and Innovative Preservation Treatments of Gravel Roads: Saskatchewan, Canada
Authors: Berthelot Curtis , Carpentier Allan
Published: April 2007

Recent restructuring of Canadian transportation has significantly increased commercial truck traffic on many rural roads in Saskatchewan, Canada. This increased traffic is having a detrimental effect on performance of the approximately 175,000 centerline kilometers of gravel roads collectively managed by provincial road agencies. The depletion of quality aggregate sources in many Saskatchewan regions is a primary contributor to the detrimental performance. Preservation and optimization of gravel are therefore becoming critical in sustaining an effective and efficient rural road system. Saskatchewan road agencies spend tens of millions of dollars per year purchasing gravel for the gravel road system. Even minor improvements in gravel optimization could significantly reduce the amount of gravel required for an acceptable level of service and save millions of dollars per year for taxpayers. A study was undertaken to quantify typical gravel supply and demand characteristics in Saskatchewan, the factors influencing gravel loss, and innovative means of gravel road preservation. Several rural municipalities were interviewed on their gravel road preservation practices and gravel supply and demand. Test sections were constructed to evaluate relationships between gravel loss and heavy truck loadings and to investigate innovative gravel preservation techniques. The study determined that most rural municipalities suffer from aggregate shortages. Gravel with a larger top size took longer to break down, and higher gravel application rates reduced gravel displacement. Ionic stabilization of gravel roads improved gravel retention and reduced dust, and shoulder reclamation with commercial rock rakes could recover gravel from roadside slopes for reapplication to the road surface.
Design of Granular Pavements
Authors: Arnold Greg , Hughes David , Dawson Andrew R. , Robinson Des
Published: April 2007

The use of high-quality quarried crushed rock aggregates is generally required to comply with current specifications for unbound granular materials (UGMs) in pavements. The source of these high-quality materials can be a long distance from the site, resulting in high transportation costs. The use of more local sources of marginal materials or the use of secondary aggregates is not allowed if they do not fully comply with existing specifications. These materials can, however, be assessed for their suitability for use in a pavement by considering performance criteria such as resistance to permanent deformation and degradation instead of relying on compliance with inflexible specifications. The final thickness of the asphalt cover and the pavement depth are governed by conventional pavement design methods, which consider the number of vehicle passes, subgrade strength, and some material property, commonly the California bearing ratio or resilient modulus. A pavement design method that includes as a design criterion an assessment of the resistance to deformation of a UGM in a pavement structure at a particular stress state is proposed. The particular stress state at which the aggregate is to perform in an acceptable way is related to the in situ stress, that is, the stress that the aggregate is anticipated to experience at a particular depth in the pavement. Because the stresses are more severe closer to the pavement surface, the aggregates should be better able to resist these stresses the closer they are laid to the surface in the pavement. This method was applied to two Northern Ireland aggregates of different quality (NI Good and NI Poor). The results showed that the NI Poor aggregate performed at an acceptable level with respect to permanent deformation, provided that a minimum of 70 mm of asphalt cover was provided. It was predicted that the NI Good material would require 60 mm of asphalt cover.
Electric Arc Furnace Steel Slag: Base Material for Low-Volume Roads
Authors: Rohde Luciana , Peres Núñez Washington , Augusto Pereira Ceratti Jorge
Published: April 2007

The results of a study of the use of electric furnace slag as pavement aggregates are presented. Slag is generated as waste during steel production in industrial plants that use electric arc furnaces. Tests for the following were carried out to determine the characteristics of the aggregate: grain size distribution, soundness, Los Angeles abrasion, compaction, California bearing ratio, resilient modulus, and expansion. To use the slag as a granular layer, its grain size distribution had to be corrected. This procedure increased the bearing capacity and workability of the material. Evaluation of the expansion potential showed that the slag must be stocked in the open air for at least 4 months before it can be used in pavement construction. After correction of the gradation, the slag presented a resilient modulus that exceeded those of traditional granular materials; its use resulted in thinner and cheaper pavements. The results of the study led to the conclusion that the use of electric arc furnace slag as pavement material is possible and that it provides remarkably good technical quality and economic advantages.
Optimizing Low-Volume Road Network Performance Through Improved Management, Design, and Construction
Authors: Van Zyl G. D. , Henderson M. G. , Fourie H. G.
Published: April 2007

The Provincial Administration of the Western Cape in South Africa is responsible for 18,900 km of proclaimed roads, of which 10,500 km are unsurfaced. A formal gravel road management system has been in operation since 1989 that assists in prioritizing projects for regraveling and upgrading gravel roads to surfaced standards. Because of fund limitations for upgrading gravel roads to surfaced roads, there is a need to optimize performance of the gravel road network and maximize use of knowledge and latest research results for southern Africa. Staff shortages and loss of in-house expertise made external assistance necessary to improve service to road users. Processes formalized, implemented, and planned for this purpose included ( a) upgrading the gravel road management system to quantify benefits, prioritize activities, and select maintenance and improvement measures; ( b) appointing consulting engineers in each district to help manage borrow pits, materials design, training, construction supervision and quality control, maintenance planning and control, and performance monitoring; ( c) communication about project priorities, construction programs, work methods, construction team performance, and activity costs; and ( d) development of an operational web-enabled system to manage all activities related to unsurfaced roads. Within 1 year, a remarkable difference in gravel road performance was observed without a significant reduction in productivity. Total transportation costs were lowered with only a marginal increase in agency costs. Continuous communication among system operators, design engineers, project managers, and construction teams is considered one of the most important aspects in optimizing performance of the Western Cape low-volume road network. This study highlights the most important changes in management, systems, design, and construction and the practical innovations responsible for the successes achieved as a potentially valuable aid to those involved with providing and maintaining low-volume roads.
Chilean Structural Design Guide for Low-Volume Roads
Authors: Thenoux Guillermo , González Alvaro , Halles Felipe
Published: April 2007

The practical and theoretical principles used for development of the Chilean Structural Design Guide for Low-Volume Roads 2002 and the guide’s conceptual model and hypotheses are presented. The design guide is a simplified methodology for selection of different pavement structure alternatives for a variety of conditions (traffic, soil support capacity, and climate). The design guide provides solutions for four traffic ranges, six ranges of soil support capacity, and three climate conditions (dry, normal, and saturated). The design charts contain more than 150 solutions. Pavement structural design was solved by mechanistic analysis with the BISAR computer program and fatigue models developed in South Africa. The design guide may be considered an engineering application with upto- date research tools and results.
Improving Performance Through Consideration of Terrain Conditions: Soils, Drainage, and Climate
Authors: Birgisson Bjorn , Ruth Byron E.
Published: April 2007

Inadequate drainage of surface and subsurface water can have significant impact on pavement behavior and long-term maintenance costs. Interception of water before it infiltrates into the pavement foundation is essential unless the soils are truly free draining. Even then, there can be potential damage by frost action. Identification of seepage zones and surface runoff characteristics based on terrain conditions such as soils and geology can aid in the selection of a suitable road alignment and design to minimize future problems. However, most moisture–soil-related pavement performance problems are observed and corrected after construction of the facility. Case history examples of moisture damage were examined that relate to seepage from culverts, perched water tables, weathered zones in sedimentary rock, permeable glacial deposits, and ponded water. Construction defects and the effect of soil suction and exudation of water into the pavement structure were evaluated. With emphasis on inadequate surface and subsurface drainage conditions, ideas relating to improvements needed to correct deficiencies were developed.
Thermal Aspect of Frost-Thaw Pavement Dimensioning: In Situ Measurement and Numerical Modeling
Authors: Boutonnet Michel , Savard Yves , Lerat Patrick , St-Laurent Denis , Pouliot Nadia
Published: April 2007

The thermal behavior of pavements in winter has a major influence on their dimensioning. The Paris-based Laboratoire Central des Ponts et Chaussées and the Ministère des Transports du Quebec have models to forecast the propagation of frost, frost heave, and thaw events. They have developed a collaborative project to validate these models on an experimental pavement. This pavement was constructed in Quebec in 1998, and its thermal behavior was monitored for 3 years. Two pavements, one with a cement-treated base and one with a hot-mix asphalt pavement, were selected. Two test beds were constructed on each pavement. One test bed was thermally insulated by a layer of extruded polystyrene, and the second was not. The SSR, GEL1D, and CESAR–GELS thermal models; the site and the temperature conditions of the three winters; the pavement structures and their physical properties; the instrumentation setup; and the analysis and comparison of the results of the models among themselves and in relation to the observations conducted on the pavements were assessed. The models provided a satisfactory estimate of frost penetrations, with less than 10% deviation observed between the measured and calculated depths. The deviations between the results of the different models are explained by the differences between the modeling principles. The size and quality of the database constituted will make it possible to improve the thermal forecasting models through more in-depth studies.
Air Convection Embankment for Roadways: Field Experimental Study in Alaska
Authors: Saboundjian Steve , Goering Douglas J.
Published: April 2007

During 1996—1997, an experimental air convection embankment (ACE) was constructed in Fairbanks, Alaska, using very coarse [1- to 6-in (25- to 150-mm)], poorly graded, crushed rock fill material on top of icerich permafrost foundation. The highly permeable ACE installation was designed to test the cooling effectiveness of the ACE concept in an actual roadway project. Using thermistor sensor strings, temperature data were collected from the ACE test section and an adjacent control section. Results showed that the ACE technique can be used to generate a passive cooling effect. This effect manifested as a depression of mean annual temperature at the base of the ACE cross section compared with mean embankment surface temperatures. The data indicated that this thermal offset is on the order of 7°F (Δ = 4°C) for this installation. The measured data also showed that mean annual temperatures are generally near or above the freezing value in the upper portion of the ACE embankment but significantly below freezing at the base. The temperature offset caused a gradual cooling of the foundation soil beneath the embankment with maximum base temperatures that have decreased from more than 40°F (4.4°C) to near freezing during the 5-year measurement period. Within a few more years of operation, it is anticipated that the permafrost table will move up into the base of the ACE cross section, completely eliminating any seasonal thaw in the foundation soil below and thus preventing future subgrade thaw–consolidation.
Design and Construction of Rock Cap Roadways: Case Study in Northeast Washington State
Authors: Uhlmeyer Jeff S. , Pierce Linda M. , Lovejoy James S. , Gribner Mike R. , Mahoney Joe P. , Olson Gordon D.
Published: April 2007

In recent years, the Washington State Department of Transportation (WSDOT) has deviated from its normal policy of correcting frost heaving and thawing problems on state highways. WSDOT’s traditional approach for frost design rehabilitation has been to place a crushed stone base at least half the depth of the frost penetration. This approach has served WSDOT well on the majority of its highway system; however, other measures were sought to mitigate extensive frost-related problems in northeast Washington. To isolate the flow of water from the pavement structure, a capillary break using a free-draining aggregate or “rock cap: layer was used on projects during the last 5 years. The rock cap material was a maximum 75-mm (3-in.) material with 0% to 15% passing a 12.5-mm (1/2-in.) sieve. The open-graded nature of the rock cap provides a positive drainage blanket so that excess water can be eliminated from the roadway structure, and thus eliminates frost-heaving and thaw-weakening problems. However, constructing with a large stone material presents special construction considerations, particularly pertaining to the stability of the material. WSDOT’s construction experience is detailed, and rock cap performance in Washington State is summarized.
Resilient Moduli of Treated Clays from Repeated Load Triaxial Test
Authors: Puppala Anand J. , Ramakrishna Aravinda M. , Hoyos Laureano R.
Published: April 2007

Three chemical stabilization methods—sulfate resistant cement (Type V), low-calcium fly-ash (Class F) mixed with sulfate resistant cement (Type V), and ground granulated blast furnace slag—were used in a series of repeated load triaxial tests on clayey soil to assess the effectiveness of these three stabilizers in enhancing resilient modulus ( MR) properties of the soil. MR results were measured from repeated load triaxial tests conducted on both control and treated soils at optimum moisture content levels. Test results were analyzed to understand the potentials of each stabilizer on MR response of the soils and to study the effects of confining and deviatoric stresses on resilient response of the treated soils. Mechanisms for MR enhancements in treated soils were developed, and a series of flexible pavement design exercises was conducted to evaluate the impact of each stabilizer on the design thickness of the asphalt surface layer of pavements.
Performance of Rigid Pavement Rehabilitation Treatments in the Long-Term Pavement Performance SPS-6 Experiment
Authors: Hall Kathleen T. , Correa Carlos E. , Simpson Amy L.
Published: April 2007

The results of a study conducted to assess the relative performance of different jointed rigid pavement rehabilitation treatments, including the influence of pretreatment condition and other factors, are presented. The data used in the study were drawn from the Long-Term Pavement Performance Studies' Specific Pavement Study (SPS) SPS-6 and General Pavement Study (GPS) GPS-7B experiments. The rehabilitation treatments used in the SPS-6 experiment were minimal and intensive nonoverlay repair, 4-in. asphalt overlays with minimal and intensive preoverlay preparation, 4-in. overlays with sawed and sealed joints, and 4- and 8-in. asphalt overlays of cracked and seated concrete slabs. Overall, the rigid pavement rehabilitation treatments in the SPS-6 experiment could be ranked from most to least effective in the following order: 8-in. overlay of cracked or broken and seated pavement, 4-in. overlay (of either intact or cracked or broken and seated pavement, with or without sawing and sealing of joints and with either minimal or intensive preoverlay repair), concrete pavement restoration with diamond grinding, and concrete pavement restoration without diamond grinding. Concrete pavement restoration with diamond grinding yielded an initial posttreatment international roughness index (IRI) of 1.05 m/km, on average, whereas restoration without diamond grinding yielded no benefit in IRI and in fact tended to leave the pavement rougher than before. In the long term, both restoration and overlay treatments reduced long-term roughness, rutting, and cracking levels compared with those on the control sections, but the conditions of the restored test sections are approaching those of the control sections faster than those of the overlay sections.