bluuebunny/crossref_metadata_2025 huggingface dataset:
Laboratory and Field Evaluation of Cement Kiln Dust and Lime for Stabilizing Clayey Silt on Low-Volume Unpaved Roads
Authors: Légère Glen , Tremblay Hélène
Published: April 2007

The potential of cement kiln dust (CKD) and lime (quicklime) for stabilizing low-volume unpaved roads on sites dominated by cohesive soils was investigated. CKD, lime plus CKD, lime, and portland cement were tested at different mixtures and soil moisture contents in a clayey silt to determine the resulting unconfined compressive strength after three curing periods. In a field study, road sections were stabilized with CKD and with lime plus CKD, and then a gravel running surface was added. Soil penetration resistance increased after the treatment. Field results confirmed the laboratory results and helped identify the most effective treatment. Stabilization proved cost-effective for new roads in areas where gravel is difficult to obtain.
Full-Depth In-Place Recycling and Road Strengthening Systems for Low-Volume Roads: Highway No. 19 Case Study
Authors: Berthelot Curtis , Gerbrandt Ron
Published: April 2007

The province of Saskatchewan has the highest number of public roads per capita in Canada, totaling approximately 198,700 km. The Saskatchewan Department of Highways and Transportation manages approximately 26,100 km of these public roads. As with most public road agencies, the department has limited resources for managing this relatively large network of low-volume roads and therefore continually strives to research and implement more cost-effective and technically feasible solutions. Of particular concern are approximately 7,500 km of thin membrane surface (TMS) roads that are undergoing accelerated damage as truck traffic and loading increase. Although conventional TMS upgrading strategies are normally effective, there are potentially significant benefits to be gained with implementation of more cost-effective methods of road strengthening. Systems include granular soil strengthening and applications of different cement products, lime, various grades of fly ash, geotextiles, geogrids, natural and manufactured fibers, emulsified bitumen, tall oil, lignin, foamed bitumen, and synthetic ionic and cationic chemicals. Since 1999, in conjunction with Pavement Scientific International and in cooperation with the University of Saskatchewan and product suppliers, the department has constructed pilot projects on Highway No. 19 to identify, develop, and implement more cost-effective strengthening systems. The primary research objective is to investigate alternative road construction systems that will improve the load-carrying capacity and environmental durability of Saskatchewan TMS roads. Improved mechanistic engineering methods played a part in this initiative, and pilot project performance was monitored.
Ranking of Four Chemical and Mechanical Stabilization Methods to Treat Low-Volume Road Subgrades in Texas
Authors: Puppala Anand J. , Wattanasanticharoen Ekarin , Hoyos Laureano R.
Published: April 2007

Expansive soils encountered in North Texas exhibit low strength properties, as well as high swell and shrinkage characteristics. These soil properties often result in the poor performance of pavement infrastructures, particularly those built for low-volume traffic conditions. Pavement distress caused by differential heaving leads to pavement cracking and ponding problems. This causes riding discomfort for commuters and induces traffic delays due to the continual repair of the pavements. Hence, it is necessary to explore and develop new and alternate stabilization methods to improve stabilization of expansive soils. Laboratory investigations were designed and conducted on four local expansive soils stabilized with low-calcium Class F fly ash, Type V sulfate-resistant cement, ground granulated blast furnace slag (GGBFS), and lime mixed with fibers. Test results were analyzed and ranked by well-established scales to select the top-performing stabilizers. Results showed that the sulfate-resistant cement, followed by the lime with fibers and the GGBFS stabilization methods, provided effective stabilization of soft and expansive soils. Ranking assessments were performed, and a few important conclusions on stabilization mechanisms were drawn.
Cement Stabilization Mixed in Place for Rural Road Reconstruction in Austria
Authors: Haslehner Wolfgang
Published: April 2007

The Austrian state territory, with a total area of about 84,000 km2, is served by a road network of approximately 200,000 km, including about 35,000 km of highways, expressways, and federal and provincial roads. The balance of about 165,000 km are roads at the local community level and finally rural roads (approximately 100,000 km) outside village boundaries. In the future, new roads will be built principally to finalize development plans. The maintenance of the Austrian rural road network has been the major task of road agencies over the last 10 years and will be of significant importance in the future. In view of the growing need for economical methods for rural road reconstruction, the use of mixed-in-place cement stabilization with existing pavement materials (recycling of milled material) is considered to be an economical and resource-saving approach. Practical experience was gained with the preparatory work required (inspection of the existing pavement and suitability testing) and the different stages of construction work. The resulting increase of the load-bearing capacity has been proven by measurement. Additional measurements will be carried out in the future (Benkelman beam, falling weight deflectometer). Application conditions and especially limitations were evaluated. A simple comparison of costs shows that the economic benefit of the presented method depends highly on local conditions, such as the costs of material, transportation, and materials deposit.
Development of Mix Design Criteria for 4.75-mm Superpave® Mixes
Authors: James Robert S. , Cooley L. Allen , Buchanan Shane
Published: April 2007

The Superpave® mix design system includes design criteria for a range of mixes with nominal maximum aggregate sizes (NMASs) between 9.5 and 37.5 mm. Many agencies in the United States have expressed an interest in using a 4.75-mm NMAS mix. Such a mix could provide benefits; that is, it should provide a very smooth riding surface, could be used for thin lift applications, could correct surface defects (leveling), could decrease construction time, could provide a use for manufactured screening stockpiles, and could provide a very economical surface mix for facilities with low traffic volumes. A study was done to establish the standard mix design criteria needed for 4.75-mm mixes. On the basis of the findings of the study, the recommended Superpave mix design criteria include a specified gradation control of 30% to 54% passing on the 1.18-mm (No. 16) sieve and 6% to 12% passing the 0.075-mm (No. 200) sieve. During design, the following were recommended: a design air void content of 4%, minimum voids in mineral aggregate (VMA) of 16% for all traffic levels, maximum VMA of 18% for mix designs with more than 75 gyrations, voids filled with asphalt (VFA) of 75% to 78% for mix designs with 75 gyrations and above, and VFA of 75% to 80% for mix designs with 50 gyrations. The results of the study showed that 4.75-mm NMAS mixes can be successfully designed. These types of mixes should provide economical mixes for low-volume roadways.
Use of Coral-Derived Aggregates for Construction of Low-Volume Roads
Authors: Bullen Frank
Published: April 2007

Many tropical island and coastal regions suffer from a paucity of recognized engineering aggregates. In these regions river gravel and old uplifted coral reef formations are often the only economically viable materials. Typically, the coral-derived material most widely available for use is termed coronous material, a land-based uplifted coral reef that may contain an abundance of plastic fines and that is usually easily excavated without the use of explosives. The shortage of traditional aggregates and the availability of the upraised reefs have promoted the study of the use of coral-derived aggregate as an alternative aggregate in pavement engineering works. Although coral-derived materials have been successfully used for pavement construction in the past, traditional engineering tests have generally indicated that it is a substandard product, and material from most pits does not pass typical specification tests. The material properties and the historical use of coronous materials in road construction are summarized, and a draft guide for the use of coronous materials in the road base and subbase for both sealed and unsealed road pavements is provided.
Implementing the Gyratory Mix Design System for Local Agency Projects in Iowa
Authors: Heitzman Michael , Tymkowicz Shane , Hinrichsen John , Engle Ed , Boell Brenda
Published: April 2007

A team of county, Iowa Department of Transportation, and asphalt paving contractors developed an implementation plan for the successful application of Superpave® by Iowa’s local public agencies. The plan is intended for use by engineers, technicians, and researchers interested in the implementation program and technical process used to develop the gyratory hot-mix asphalt design criteria for local agencies in Iowa. The plan identified seven activities. The mixture analysis activity is the focus and is the core of the implementation effort. The analysis studied the gyratory properties of mixtures prepared by use of the existing Marshall design (Marshall mixtures) with proven performance. The local agencies selected Marshall mixtures with good performance histories for the analysis. The mixtures were sampled directly behind the paving screed and were analyzed for gradation, compaction characteristics, and volumetric properties. The database contained data for mixtures from 92 local agencies from the 1999 and 2000 construction seasons. The first step in the compaction analysis was to normalize the data for comparison of groups of mixes. This step shifted the gyratory compaction envelopes to meet a specific set of criteria for the number of design gyrations. The next step in the analysis was to define the critical mixture properties. The critical mixture properties were founded on sound engineering principles with the recognition that routes with very low volumes should be designed for durability with a minor risk of fatigue or rutting failure. The final step weighed the impact of the selected criteria on maintenance of the material proportions of the currently acceptable mixtures.
Toward Fit-for-Purpose Certification of Road Additives
Authors: Jones D.
Published: April 2007

Chemical stabilizers and dust palliatives are widely used in road construction and maintenance to improve the characteristics and performance of available materials for lower dust levels, improved riding quality, reduced gravel loss, and improved all-weather passability. Numerous products are available to the road industry. However, the level of research and the usefulness of the findings differ from product category to product category. In many instances, no effort has been made to quantify the benefits and cost-effectiveness of additives over longer periods of time (e.g., 5 years), and little attempt has been made to compare the performance of treated roads with the performance of untreated roads for reduced gravel loss and reduced maintenance, the two most important factors in unsealed road management. Only limited information on material requirements and application techniques is available, whereas there is minimal information on rejuvenation. This lack of understanding has culminated in general skepticism in the road industry regarding chemical dust control and stabilization with so-called alternative stabilizers. The situation is aggravated by poor marketing, with many sales representatives having no engineering background, little understanding of the road industry, and insufficient information to provide adequate technical backup. Discussions with road authorities and consulting engineers indicated that a “fitfor-purpose” certificate for each product issued by an independent certification body would contribute to confidence in the use of the products. A certification system would also encourage suppliers to conduct appropriate product research. An internationally recognized certification body in South Africa was therefore approached about developing such a certification system, under the guidance of a steering committee with representation from road authorities, consulting engineers, product suppliers, and academia. Unsealed road additive certification is introduced, the development of control tests for certification is detailed, and a procedure for certification is proposed.
Impact of Assumed Versus Measured Vehicle Distributions on County Road Flexible Pavement Design
Authors: Timm David H. , Skok Eugene L.
Published: April 2007

Accurate characterization of traffic is critical to the design of pavement structures. At the low-volume road level, a common practice is to use assumed vehicle type distributions based on statewide or regional studies instead of measuring the traffic for a particular location. The impact of this practice was investigated, and equivalent single-axle loads determined from measured vehicle distributions on 29 county roads in Minnesota were compared with those calculated from assumed distributions. It was found that significant differences exist between the assumed distribution and the measured distribution. Additionally, the impact of using assumed distributions on the structural design of flexible pavements was investigated. With data collected from 21 different county roads in Minnesota, it was found that using assumed distributions can result in over- or under-designed pavements, with asphalt concrete thicknesses often deviating by more than 50 mm (2 in.). Based on the results, it was recommended that Minnesota counties begin to evaluate when more detailed traffic studies are warranted to improve their designs and use of resources.
Seasonal Load Response Behavior of a Thin Portland Cement Concrete Pavement
Authors: Burnham Tom
Published: April 2007

The mechanistic-empirical pavement design methods currently under development have demonstrated a need for seasonal material and load response behavior characterization. The seasonal dynamic load strain response of a thin [5-in. (127-mm)], low-cost, portland cement concrete pavement at the Minnesota Road Research Project was examined. Environmental and load-related factors to be considered in this type of study are described. For the truck speeds used, analysis found minimal effects on measured dynamic strain. Nonlinear temperature profiles in the slabs prompted the use of the temperature-moment concept in the analysis. For the approach side of the joint in the slabs, during periods with unfrozen base and subgrade layers, there is only a small increase in the dynamic strain response with decreasing temperature-moment. Average dynamic strain responses range from 50 to 80 microstrain, with little difference in magnitude between the 80,000-lb (355-kN) and 102,000-lb (453-kN) loadings. For the leave side of the joints in the slabs, there is a larger increase in dynamic strain response with decreasing temperature-moment. In addition, the 102,000-lb load response is nearly 60% larger than the 80,000-lb load response for large negative temperature-moments. Recommendations for improving dynamic load testing of pavements are given.
Implementation of the British Columbia Side Road Assessment Plan
Authors: Cowe Falls Lynne , Landers Shawn , Bekheet Wael , Fredrickson Reg
Published: April 2007

With more than 61,000 lane-km, the British Columbia side road network is an important economic asset to the province, providing access to a large resource-based economy. This network is composed of paved (25,000 lane-km) and unpaved (36,000 lane-km) sections of various geometric and construction standards and low traffic volumes. In the mid-1990s, the British Columbia Ministry of Transportation completed implementation of a comprehensive corporate pavement management application on its entire primary and secondary highway system. The ministry was also committed to extension of the system to all roads under its jurisdiction as part of its asset management practices to support formalized condition assessment and needs analysis processes. One of the obstacles facing the implementation of pavement management application on the side roads was the huge data collection cost, particularly in a time of governmentwide fiscal restraint. The side road data collection project was initiated with the objective of developing a data collection methodology and plan for the entire network by a combination of continuous and sampled approaches. The approach used to modify the existing U.S. Corps of Engineers data collection system for unpaved roads to conditions in British Columbia and the field verification trials that were completed before full-scale implementation are discussed. The data collection blueprint, which combines full and sampled coverage of the network with a road classification system, is also described. The results of the first data collection cycle and lessons learned are presented.
Calibration of Performance Models for Surface Treatment to Chilean Conditions: The HDM-4 Case
Authors: Hernán de Solminihac T. , Priscila Hidalgo S. , Mauricio Salgado T.
Published: April 2007

The HDM-4 (Highway Development Management) model used for pavement management activities must be adjusted to the specific conditions of a country or region where they are to be used by adjusting certain calibration factors. The results obtained from calibrating the cracking, raveling, potholing, rut depth, and roughness models contemplated in HDM-4 version 1.1 for surface treatments are presented and compared with the results obtained from equivalent models of HDM-III. In this task, the “windows” methodology was used, which consists of reconstructing the distress performance curve of a specific road category starting with observation of the condition of different roads with similar characteristics (such as traffic, pavement structural capacity, and climatic conditions) but of different ages. On the basis of the results obtained, recommendations for calibrating the performance models are proposed, and calibration factors more adequate for characteristics specific to Chilean surface treatments are established. On comparing the results of the calibrated models of HDM-III and HDM-4, it is concluded that both cases furnish similar values, and use of HDM-4 models is recommended because of their operating advantages and because they afford a greater flexibility, which allows them to more aptly adapt to a broader number of cases and situations.
Use of Foamed Tar for Construction of Flexible Pavement with Existing Unpaved Road Structure
Authors: Morton Bruce S. , Visser Alex T. , Horak Emile
Published: April 2007

Low-volume and unpaved roads constitute the majority of the road network throughout the developing and developed world. Upgrading these unpaved roads to conform to standards of low-volume flexible asphalt pavements is a costly exercise. In most instances, this involves constructing an entirely new pavement base. Recent technological advances in the field of deep in situ recycling have provided pavement engineers with an alternative to standard rehabilitation and reconstruction methods of flexible pavements. One such technique of stabilization is foamed tar treatment of inferior natural pavement materials through the application of deep in situ recycling to produce a stabilized base for lowvolume flexible pavements. Foamed tar technology and the concept of deep in situ recycling, and its advantages over current reconstruction methods, were reviewed. Health aspects relating to implementation of the stabilization process were addressed with respect to the use of gasifier tar in a controlled recycling environment. The engineering properties of foamed tar mixes were compared with existing stabilization techniques. A test section was constructed with particular attention to the flexibility of foamed tar for placement time, workability, and durability to environmental conditions. Performance testing results were analyzed. In conclusion, the benefits of foamed tar stabilization for developing an improved road network in a cost-effective manner were evaluated.
Road Asset Management System Implementation in Pacific Region: Papua New Guinea
Authors: Jusi Petri , Mumu Roy , Jarvenpaa Sirpa H. , Neausemale Barnabas , Sangrador Eduardo
Published: April 2007

The road network of Papua New Guinea includes 8,258 km of national classified roads and another 19,937 km of lesser-trafficked but equally important provincial roads. The value of the national road network is more than 5 billion Kina (US$1 billion). Maintaining this significant asset places a great responsibility on the government and the Department of Works (DOW). Sadly, insufficient attention has been given to maintaining the road network. There is no doubt that poorly maintained roads have a significant adverse effect on national economic growth, with an adverse effect on gross domestic product. In a developing country such as Papua New Guinea, there is always a need to provide a basic level of access to all areas of the country to be able to provide basic services for all the population (access to markets, administrative, health, education). A poorly maintained road network limits access and deprives rural populations of basic services. Therefore, DOW, with funds and guidance provided by the Asian Development Bank, has, with the assistance of a Finnroad consultant, developed a road asset management system (RAMS). RAMS is a tool for storing and presenting road data information, planning short-and long-term road maintenance, creating budgets, and maximizing economic returns of investments made for the road network. The government of Papua New Guinea has also established requirements for institutional reform and strengthening under its public sector reform program. Furthermore, responding to community and other stakeholder pressure, the government has committed itself to launching a road sector reform program.
Minnesota’s Experience with Thin Bituminous Treatments for Low-Volume Roads
Authors: Johnson Greg
Published: April 2007

Three surface treatments placed on aggregate-surfaced roads (doublechip seal, Otta seal, and oil gravel) were investigated through field trials for performance. A double-chip seal used a single-size aggregate applied to a layer of hot asphalt binder. After 6 years of service, the performance of the road has required only routine preventive maintenance. The surface has a few thermal cracks and no rutting. An Otta seal, which uses a thick layer of soft asphalt to which a dense graded aggregate is added, has proven successful. The use of a chip spreader is recommended for precise aggregate application during construction. A large top-size aggregate, 1 in. (25 mm) minus, gave a rough texture to the surface, but the performance has not been adversely affected. Because of the fines included in an Otta seal, usually a locally available aggregate can be used. In design and construction, the oil gravel surface is similar to hot-mix asphalt. All the projects had some problems with segregation, but most can be corrected during construction with proper handling techniques. One benefit of this treatment is that additional material stockpiled during construction can be used in subsequent maintenance activities on the road. All three of the surface treatments require a strong stable base to work properly. The treatments add no structural component to the road. Therefore, the condition of the road needs to be carefully evaluated before construction. The roads that performed the best had the best base stability.
Use of Railroad Flatcars in Cost-Effective Low-Volume-Road Bridges
Authors: Doornink J. D. , Wipf T. J. , Klaiber F. W.
Published: April 2007

The use of railroad flatcars (RRFCs) as the superstructure in lowvolume bridges has been investigated in a research project at Iowa State University. These alternative bridges should enable county engineers to replace old, inadequate county bridges for less money and in a shorter construction time than required for a conventional bridge. Capital saved can be used to improve other areas of secondary road transportation. A feasibility study completed in 1999 by the Bridge Engineering Center at Iowa State University determined that RRFC structures have adequate strength to support Iowa legal traffic loads. In a follow-up research project, two RRFC demonstration bridges with different substructures and RRFC lengths were designed, constructed, and tested to validate the conclusions of the feasibility study. Bridge behavior predicted by grillage models was supported by data from field load tests, and it was determined that the engineered RRFC bridges had live-load stresses significantly below the safe yield strength of the steel and deflections well below the AASHTO bridge design specification limits. Moreover, since analytical procedures were able to predict RRFC bridge behavior, it is possible to analyze each bridge to determine its adequacy for any state’s legal traffic loads or for roads with larger hauling loads, such as quarry or coal-hauling roads. From the results of this research, it has been determined that, through proper RRFC selection, connection, and engineering design, RRFC bridges can be a viable, economic alternative for low-volumeroad bridges.
Cost-Effective Structures for Off-System Bridges
Authors: Russo Francesco M. , Wipf Terry J. , Klaiber F. Wayne
Published: April 2007

Nearly half of the 587,000 bridges in excess of 6.1 m (20 ft) long on public roads in the United States are located off the Federal Aid System, are on local rural and urban roads or rural minor collectors, and are classified as off-system bridges. Approximately one-third of the off-system bridges are structurally deficient or functionally obsolete. The majority of states with large bridge populations are rural states with large percentages of structures owned by counties and other local agencies. Many of these bridges are on low-volume roads. Given the size of the deficient bridge population and the concentration of these bridges largely on locally owned networks, a recent NCHRP synthesis (NCHRP 32-08, Cost Effective Structures for Off-System Bridges) has explored the current practices regarding the maintenance, rehabilitation, and replacement of off-system bridges. The administrative aspects of off-system bridge ownership and management were explored, including sources and problems of funding, bridge asset management, design policies for off-system bridges, exploration of the environmental process, and discussions of interagency partnering and coordination problems. A significant body of work exists on effective bridge maintenance and rehabilitation. A significant discussion of bridge strengthening, including specific techniques used on low-volume-road bridges, was also examined. Concerning bridge replacements, the literature and owner survey were used to provide information on successful concepts currently being used. In addition to successful bridge replacement options, discussion of the use of standard plans, design aids, and software is promoted as leading to standard and efficient low-volume-road bridge replacements.
Beam-in-Slab Low-Volume-Road Bridge System
Authors: Konda T. F. , Klaiber F. W. , Wipf T. J.
Published: April 2007

Funding for the repair and replacement of structurally deficient and functionally obsolete bridges is a nationwide problem. This problem is magnified for the managers of low-volume-road (LVR) systems who have limited budgets; thus, innovative replacement alternatives are always being sought. The beam-in-slab bridge (BISB) is an alternative replacement bridge developed in Iowa. The bridge consists of W-beam sections spaced 24 in. (610 mm) on center, with concrete filling the void space between them. Spans up to 50 ft (15.24 m) can be constructed with this low-cost alternative. Field and laboratory testing confirmed that the system is capable of handling legal loads. Modifications to the BISB have been investigated to improve its structural efficiency to make it possible to use the system in longer spans. An alternative shear connector (ASC) has been developed to provide composite action in the BISB. The ASC consists of holes, either torched or drilled, through the web of the girder for the formation of concrete dowels that provide for composite action. Ongoing research promises more structural efficiency with the development of an arched formwork system, which will make possible wider girder spacings and reduced self-weight. Combining the ASC with the arched formwork should result in an essentially steel-free system that is relatively easy to construct. From initial results, it should be possible to construct spans up to 75 ft (22.86 m) to carry legal loads in Iowa with these modifications.
Impact of Innovative Technical Concepts for Load Unit Exchange on the Design of Intermodal Freight Networks
Authors: Kreutzberger E. D.
Published: April 2007

The best and most promising intermodal freight rail and barge networks, given new opportunities for designing networks, are identified. These opportunities have arisen because of numerous attempts at the end of the 20th century to introduce innovations in intermodal transport rapidly and to achieve a quality leap—a substantial improvement in the quality–cost ratio. The total effect had the appearance of an innovation wave. Most visible in Europe were hardware expressions such as new types of terminals, trains, barges, and storage and transport systems. Despite the low speed of implementation, achievement of a new level of effectiveness and efficiency of load unit exchange at nodes and link operations is expected. That would imply new conditions for network design. Thus, less promising networks could be improved, and some existing models would be superseded. An important aspect of this reorientation is the choice of bundling concepts by train and barge operators. Beginning with the expectation of new opportunities, an analysis will be done of networks innovative in the method of bundling flows and by realizing short load unit exchange times at nodes. The focus will be on the relationship between important bundling characteristics—network volumes, transport frequencies, scale of transport, and network layout. A typology of bundling concepts, mathematical formulation of bundling effects and, for rail transport, results of performance and cost calculations are presented. One result is that, given one daily service on each transport relationship, hub-and-spoke concepts have the lowest main modality costs for networks with medium-sized flows, and line concepts have the lowest for networks with small flows.
Impact of Differential Pricing on Barge Freight Transportation
Authors: O’Rourke Laurence
Published: April 2007

Through the Staggers Rail Act (1980) and the Railroad Revitalization and Regulatory Reform Act (1976), Congress deregulated railroad pricing to improve the financial health of the industry. Deregulation legalized differential pricing—the policy of charging customers different prices according to their willingness to pay. While the railroads have returned to profitability, shippers have been angered by railroad pricing strategies that are seen as abusive. Railroads have refused to quote rates to competing transportation facilities or have set prices to divert traffic onto the rail network. An economic measurement of the impact of differential pricing of rail services on barge transportation in the Ohio River Basin is provided by constructing a model to predict freight traffic volumes at barge terminals in the Ohio River Basin.
Parameters for a Roll On-Roll Off Marine Intermodal Service on Lake Superior
Authors: Stewart Richard D. , LaVoie Terry , Shutes Nathan
Published: April 2007

The feasibility of reestablishing roll on–roll off (RO–RO) service linking Thunder Bay, Ontario, and the Twin Ports of Duluth, Minnesota, and Superior, Wisconsin, was examined. An analysis of similar services both on the Great Lakes and overseas was undertaken. Previous operations on the same route on Lake Superior and short sea service in the Baltic region were analyzed, and the attributes of an appropriate vessel type, such as ice strengthened scantlings and adequate speeds, were determined. A route schedule for a typical vessel was developed. A profile of a suitable vessel was prepared, and the market availability of the vessels was assessed. Issues in terminal design and operation were applied to potential docks in the ports of call to determine the adequacy of shoreside facilities. Cost factors for vessel operations and terminal operations were determined, and a spreadsheet model was developed for future application. Potential revenue streams from vessel and terminal operations were also explored. Revenue generators included day passengers as well as trailers and containers. The feasibility of linking the RO–RO service to a larger intermodal system serving Canada and the United States was also assessed.
Freight Transport Restructuring in the Baltic States
Authors: Ojala Lauri , Queiroz Cesar
Published: April 2007

A brief outline of the restructuring of the freight transport sector in the three Baltic States (Estonia, Latvia, and Lithuania) is provided that focuses on the provision of logistics and freight-forwarding services in international transport and trade. The three countries have made significant progress in all areas of the transport sector in the past 10 years. During this period the private sector has taken over a large part of the transport sector. Despite the very positive development, continued efforts are needed to improve the transport sector further. Issues pertaining to national legislation are recognized to be of high priority in all three countries, but cooperation in customs issues between countries of the Commonwealth of Independent States is problematic. Also delays in border crossings, especially to and from Russia and Belarus, appear to be a common and persistent problem in the Baltic States. The general transport-supporting services and the performance of customs have improved substantially during the past decade. Entry of foreign operators, especially in international road-based transport and logistics services, has restructured the logistics market profoundly. It can be argued that the efficiency of the industry and the overall quality of services have improved substantially.
Frost Heave and Water Uptake Relations in Variably Saturated Aggregate Base Materials
Authors: Guthrie W. Spencer , Hermansson åke
Published: April 2007

The occurrence of frost heave in soils and aggregates can be attributed to the redistribution of water in the soil profile. Frost heave testing performed in this study on 71 variably saturated specimens of aggregate base material indicates that although the uptake of new water from outside the soil body is a primary source of moisture in the formation of segregation ice, internal water residing within the soil or aggregate structure can serve as an important supply of water to the freezing front. Frost heave concepts relating to unsaturated soil conditions were reviewed, and a laboratory methodology was employed to study the relationships between the physical properties of the specimens and their frost heave behavior. Degrees of saturation ranging from 45% to 84% were evaluated, and heave–uptake ratios as high as 2.24 were calculated. Ratios less than 1.09 suggest that sufficient porosity exists in the sample matrix to allow the formation of ice without causing frost heave; higher ratios designate samples that are nearly saturated and that undergo substantial upward redistributions of existing water during the initial freezing process, which gives rise to measurable heave even before additional water is imbibed by the sample. The entry of air into freezing soils and aggregates can play an important role in their frost heave behavior.
Effect of Off-Road Equipment on Flexible Pavements
Authors: Sebaaly Peter E. , Siddharthan Raj , El-Desouky Magdy , Strand Dan , Huft David
Published: April 2007

The South Dakota Department of Transportation sponsored a study to evaluate the effect of agricultural equipment on flexible pavements. One thin and one thick flexible pavement were instrumented at two locations and tested under agricultural equipment. Each section was instrumented with pressure cells in the base and subgrade, surface deflection gauges, and strain gauges at the bottom of the asphalt layer. Field tests were carried out during fall 2000, spring 2001, and summer 2001 to evaluate the impact of heavy equipment on flexible pavements under variable environmental conditions. Test vehicles included two types of Terra-Gators, a grain cart, and a tracked tractor. The field-testing program collected the pavement responses under five replicates of each combination of test vehicle and load level and under the 18,000-lb singleaxle truck. Data were examined for repeatability; the average of the most repeatable set of measurements was calculated and used in the analysis. The first part of the research evaluated the relative impact of the equipment defined as the ratio of pavement response under each combination of vehicle-load level over the pavement response under the 18,000-lb single-axle truck. The analysis of the pavement response ratios indicated that ( a) the tracked tractor is not more damaging than the 18,000-lb single-axle truck, ( b) Terra-Gators 8103 and 8144 are more damaging than the 18,000-lb single-axle truck only when fully loaded, and ( c) the grain cart is more damaging than the 18,000-lb single-axle truck only when loaded over the legal load limit. Data from the second part of the research showed that transporting the commodities using tridem-axle trucks caused far less pavement damage than transporting commodities on agricultural equipment.
Evaluation of Seasonal Effects on Subgrade Soils
Authors: Heydinger Andrew G.
Published: April 2007

One objective of the FHWA’s Long-Term Pavement Performance (LTPP) program is to determine climatic effects on pavement performance. The LTPP instrumentation program includes seasonal monitoring program (SMP) instrumentation to monitor the seasonal variations of moisture, temperature, and frost penetration. Findings from the SMP instrumentation are to be incorporated into future pavement design procedures. Data from SMP instrumentation at the Ohio Strategic Highway Research Program Test Road (US-23, Delaware County, Ohio) and other reported results were analyzed to develop empirical equations. General expressions for the seasonal variations of average daily air temperature and variations of temperature and moisture in the fine-grained subgrade soil at the test site are presented. An expression for the seasonal variation of resilient modulus was derived. Average monthly weighting factors that can be used for pavement design were computed. Other factors such as frost penetration, depth of water table, and drainage conditions are discussed.
Dissipation Pattern of Excess Pore Pressure After Liquefaction in Saturated Sand Deposits
Authors: Ha Ik Soo , Park Young Ho , Kim Myoung Mo
Published: April 2007

In liquefied areas, the amount of damage to a structure is mainly affected by the postliquefaction behavior of the liquefied ground. Understanding postliquefaction behavior requires understanding the dissipation pattern of excess pore pressure after liquefaction. It is difficult to measure pore pressures generated and dissipated during an earthquake because of the more-or-less randomness of earthquake events. Researchers have artificially generated liquefaction with sand samples in the laboratory and have simulated curves for the time history dissipation of excess pore pressure. To estimate variation in permeability during dynamic loading, which should be known for settlement predictions of the ground undergoing liquefaction, 1-g shaking table tests were carried out on five kinds of sands, all with high liquefaction potentials. During tests, excess pore pressures at various depths and surface settlements were measured. The measured curve of the excess pore pressure dissipation was simulated using the solidification theory. From analysis of the velocity of dissipation, the dissipation pattern of excess pore pressure after liquefaction was examined. Permeability during dissipation was calculated using the measured settlement and dissipation velocity, also used for estimating permeability during dynamic loading. The dissipation velocity of excess pore pressure after liquefaction had a linear correlation with the effective grain size divided by the coefficient of uniformity. The increase in the ground’s initial relative density played a role in shifting this correlation curve toward increased dissipation velocity. Permeability during liquefaction increased 1.4 to 5 times compared with the permeability of the original ground, the increase becoming greater as the effective grain size of the test sand increased and the coefficient of uniformity decreased.
Simplified Analysis of Unsteady Moisture Flow Through Unsaturated Soil
Authors: Aubeny Charles , Lytton Robert , Tang Dina
Published: April 2007

The moisture diffusion properties of unsaturated soils control the rate of infiltration of surface moisture into the soil mass and hence are critical to a wide variety of civil structures, including pavements, structures, retaining walls, and slopes. Because of the dependence of permeability on suction and the nonlinearity of the suction–moisture relationship, the analytical formulation for flow through unsaturated soils is highly nonlinear. An approximate linear analysis of this problem, which was originally proposed by Peter Mitchell, was investigated. One advantage of this approximate analysis is that it can provide the practical basis for measuring soil moisture diffusion characteristics in laboratory tests. A second advantage is that the linear formulation provides an analytical tool accessible to practitioners. Mitchell originally based his formulation on a relatively restrictive assumption on the permeability-versus-suction relationship. An approach to circumventing that restriction is proposed. The findings of a laboratory test program that uses Mitchell’s formulation to estimate a soil’s moisture diffusion characteristics are presented. Finally, some simple analytical predictions demonstrate the practical significance of the soil moisture diffusion properties.
Filter Paper Column for Measuring Transient Suction Profiles in Expansive Clay
Authors: Likos William J. , Lu Ning
Published: April 2007

An inexpensive experimental system for measuring suction profiles during transient moisture movement processes in unsaturated expansive clays was developed. The system relies on measurements of total suction using the noncontact filter paper technique at several stations along a onedimensional soil column. Performance of the system was demonstrated for a column of compacted Ca2+-smectite undergoing evaporation at the top boundary under ambient laboratory conditions for 91 days. The system was most applicable during latter stages of drying when the rate of moisture movement was slow enough to be adequately captured by the required 7-day measurement interval and the suction values are large enough to offset scatter. Final water content and suction profiles were determined gravimetrically and compared with values obtained from the filter paper measurements. Desiccation cracking did not significantly affect the accuracy of the filter paper system. The research forms an experimental basis to develop or verify theoretical models aimed at predicting moisture flux for in situ expansive soil subject to infiltration or evaporation processes.
Stability of Cut Slopes Against Shallow Failure: Evaluation by Neural Network Model
Authors: Matsuyama Hiroyuki , Ogata Kenji , Amano Kiyoyuki
Published: April 2007

The discrimination model for road cut slope stability was used to assess 216 cut slope locations on the Chuo Expressway. This model ranks the failure probability of slopes by the rainfall threshold (cumulative precipitation that causes the slope to fail) to identify slopes highly prone to collapse. Because of the complexity (nonlinearity) of the relationship between the factors relating to the cut slope failure and the precipitation that triggers a failure, it has been difficult to correctly evaluate the likelihood of failure for cut slopes. The developed model has overcome that difficulty by involving the neural network as the discrimination technique. The input data included the different factors (topography, soil properties and geology, surface layer status, change in state) in the stability investigation table prepared at the time of road slope inspection, with additional information such as catchment topography. The cut slope data were prepared, referring to a variety of information encompassing the failure history for 30 years after the commencement of service, the rainfall record at the time of failure, the maximum rainfall amount ever recorded, and the data on the status of slope protection around the time of failure. As shown by the discrimination results, the model accuracy (ratio of correct answers to number of slopes evaluated) was as high as approximately 80%, which allowed accurate determination of the amounts of rainfall inducing the failure of different slopes.
Antiterrorism Security and Surface Transportation Systems: Review of Case Studies and Current Tactics
Authors: Fink Camille N. Y.
Published: April 2007

The events of September 11, 2001, brought the issue of transportation security and terrorism to the forefront of policy and government. Public surface transportation systems are especially vulnerable because they are by nature open and accessible. They also serve large numbers of people in extensive networks. Case studies of transit systems and terrorist incidents offer examples of effective planning and response as well as gaps in security systems. Systems in London and Paris have experienced bombing attacks. Tokyo was the site of a chemical attack. Preparation against terrorist attacks involves assessments of vulnerabilities, mitigation of weaknesses in the system, and the development of effective response and emergency plans. Cost factors are a particular concern for transit officials. The use of design elements, closed-circuit television, training, and exercises, together with the establishment of close relationships with other local, state, and federal agencies, appears to be the most cost-effective security option.
Vulnerability Assessment Through Integrated Transportation Analysis
Authors: Hood Jacqueline N. , Olivas Tim , Slocter Chuck B. , Howard Barry , Albright David P.
Published: April 2007

Vulnerability assessment is the analysis of a system for weaknesses that could be exploited and the determination of the probability of an attack on those weaknesses. Transportation vulnerability assessment is concerned with our transportation system. Highway, bridge, airport, rail, transit, and intermodal infrastructure are part of our transportation system. Automobiles, trucks, airplanes, trains, and transit vehicles are part of our transportation system. People of all walks of life, in every city and state, are part of our transportation system. Vulnerability assessment includes people involved in all modes of our transportation system at all levels of government and the private sector. Because our responsibility is as extensive as it is essential and enduring, vulnerability assessment is critical if we are to use our resources to provide safe, secure, and reliable transportation. Described is the vulnerability-assessment process in use in New Mexico and its relationship to integrated transportation analysis.