bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of Repaired Sewers Under Earthloads
Authors: Law T. C. , Moore Ian D.
Published: April 2007

The trenchless rehabilitation of damaged rigid sewers has become a competitive alternative to conventional methods of pipeline replacement. However, buckling caused by fluid load is identified as the important limit state in the current pipe-liner design standard, while the contribution of the damaged rigid host pipe in the assessment of resistance to earth loads as well as disturbance to the liner (e.g., vehicle loads) is neglected. Fullscale testing in the laboratory is used to investigate the soil–host and pipe–liner interaction. Two host-pipe–liner systems are examined. The first system involves a liner that fits perfectly inside a host pipe. The second system features initial lack of fit between the liner and the host pipe, and gaps across the fractures in the host pipe, to investigate ungrouted repair of rigid pipe with severe damage. The test geometry and measurement scheme to evaluate local bending and movement at the fractures in the host pipe are described. Key parameters affecting local bending are identified, including initial lack of fit between the liner and the host pipe as well as the hoop stiffness of the host pipe. This recent research on repair of sanitary and storm water sewers is discussed in the context of culvert rehabilitation.
Reorienting World Bank Involvement with Urban Transport in Europe and Central Asia
Authors: Mitric Slobodan
Published: April 2007

Responding to an acute funding and supply crisis in urban public transport services during the past decade, the World Bank made eight loans benefiting about 20 cities in ex-socialist countries in Europe and Central Asia (ECA). The main strategy for the first five projects, now completed, was to make loans for fleet replacement and rehabilitation, conditional on restructuring publicly owned operators, increasing their fare revenue, instilling a greater discipline in subsidy payments, and attempting to bring private capital and skills into the sector. Services provided by publicly owned operators were improved and cost recovery from fares increased, but the funding gap still persists. In the last three projects, approved in the late 1990s, the focus shifted to attracting private operators under a competitive framework, creating markets in road maintenance, and accelerating traffic management. A strategic shift is now warranted, recognizing that increasing motorization and the consequent shifts in the modal split are of primary importance in ECA urban areas. A proposal is presented to extend market principles to the automobile as well, primarily through city-based road use charges. The new strategy continues to emphasize the creation of competitive markets, increased user charges, and sound funding for public transport services, subject to protection mechanisms for low-income and other vulnerable groups. Other building blocks of the strategy (e.g., investment agenda, capacity building, and knowledge-oriented activities) are derived directly from the preferred policy orientations.
Beijing–Tongjiang Expressway, People’s Republic of China: Development Impact Study
Authors: Ojiro Makoto , Pan Yuli , Shu Mingxin
Published: April 2007

The government of the People’s Republic of China is constructing a national trunk highway system, a 35,000-km network of interprovincial expressways, during 1991–2010. As part of this network, a priority 1,867-km Beijing–Tongjiang route in northeastern China has recently been completed, costing about 37 billion yuan. As a result, developmental impacts are beginning to emerge. An evaluation is presented of the impact of the new Beijing–Tongjiang route on transport services, economic activities, social services, and environmental and social issues. Changes in economic and social indicators were quantified by comparing ( a) before-and-after project conditions, ( b) the project area and a control area, and ( c) the project area situation and national or provincial trends. Recognizing the difficulty in isolating the expressway impact from other factors, the study concluded that the new route is associated with local economic development because of improved accessibility. Travel time has been reduced from 35 to 17 h for cars. Industrial plants have been built along the expressway, and tourism has developed along it. Some feeder roads upgraded along with expressway construction now serve 3.3 million rural residents in Liaoning Province.
Urban Road Transport in Asia’s Developing Countries: Safety and Efficiency Strategy
Authors: Jraiw Kim
Published: April 2007

Most of the world’s population and economic growth is occurring in the developing countries (DC) of the Asia-Pacific region. DCs will experience most of the world’s urban growth. Motor vehicles are growing at two to three times the population rate. Road safety and congestion are major concerns. As a consequence, DCs now face alarming urban road transport challenges, which are expected to continue for some years. The supply of transport services has not matched the increased demand, because of insufficient infrastructure development. No comprehensive strategy exists to address the safety and efficiency of the urban transport system. A review is presented of the development of an integrated road safety strategy to address such key concerns as the need to establish a national road safety council, transport data system, and road safety monitoring and enforcement system. An urban road transport strategy is introduced that has been developed to address the overall transport problem, including assessment, objectives, and implementation. The strategy encompasses a wide range of issues, in a comprehensive framework, to create a competitive and sustainable approach to address problems, improve institutional capacity, optimize resource use, and link the road system to community benefits and expectations. Government leadership and sponsor involvement are addressed.
Development of Design Vehicles for Hang-Up Problem
Authors: James French L. , Clawson Amy , Eck Ronald W.
Published: April 2007

Design vehicles were developed to evaluate the operation of low-ground-clearance, long-wheelbase, overhang vehicles on extreme hump or sag profile alignments. The literature review indicated that although formal studies had been conducted to develop design vehicles, these vehicles did not include the information needed to assess hang-up susceptibility on a particular vertical alignment. Relevant design vehicle dimensions for 17 vehicle types prone to hang-up were developed. Relevant dimensions included wheelbase, ground clearance, and front and rear overhang. These vehicles can be used in conjunction with the HANGUP software or other tools in designing vertical alignments that reduce the likelihood of hangup problems. Because they are based on representative samples of both field-collected and manufacturers' data and have been evaluated using the HANGUP software, the design vehicles are reasonable and have a rational basis. The proposed vehicles should receive broad review with an eye toward inclusion in appropriate design policies and guidelines.
Comparison of Operations of Single-Point and Tight Urban Diamond Interchanges
Authors: Jones Elizabeth G. , Selinger Matthew J.
Published: April 2007

Single-point urban interchanges (SPUIs) and tight urban diamond interchanges (TUDIs) are alternatives typically considered in locations where roadway right-of-way is constrained. The body of research comparing these two interchange types is limited, and operational comparisons are varied in their findings. It is believed that the traffic operation performance of these two interchange types does not differ significantly, which makes it challenging for transportation practitioners to select a preferred interchange type for a specific location. The operations of the geometrically similar SPUIs and TUDIs were compared using microscopic simulation analysis for a wide range of volume conditions. The analysis was conducted with CORSIM using optimum signal phasing and timing for both interchange types. Three specific test volume cases and five varying volume levels were developed for both interchange types to evaluate the interchanges over a range of capacity conditions. The 30 cases were analyzed using microscopic simulation, and results were summarized to compare the two interchange types. The findings show that for the geometric and volume conditions tested, the SPUI provides greater traffic operation performance than the TUDI. Over the range of tests, the SPUI provided higher average travel speeds, fewer phase failures, a lower percentage of stops, and a considerably higher capability to serve traffic. The results typically show that the TUDI will reach capacity conditions when the SPUI is operating at average conditions.
Multicriteria Decision-Making Model for Selection of Build-Operate-Transfer Toll Road Proposals in the Public Sector
Authors: Ababutain Abdulaziz Y. , Bullen A. Graham R.
Published: April 2007

Governments in many countries have recently begun privatizing infrastructure sectors. Some of the forces that have been driving this movement are a scarcity of public resources, increase in the demand for services, political trend toward privatization, and expansion of global capital markets. The build–operate–transfer (BOT) approach has played a growing role in the implementation of infrastructure privatization. Because of the types, uncertainty, and high risk of BOT projects, the selection process is crucial. To date, decision makers in the public sector have lacked a set of complete selection criteria or a systematic process to help them make quality selections. The main objectives are to understand the details of toll road projects so that ( a) major criteria and variables related to toll roads can be identified and ( b) an integrated decision-making process model can be developed as a framework to help the public sector make quality decisions. The methodology includes development of a multicriteria decision-making model based on the analytical hierarchy process and validated by a case study of the California Department of Transportation privatization program. The model makes the selection process clear and allows it to be traced back by all parties. That fact will likely encourage the private sector to bid on BOT projects. A framework is developed that will enable the public sector to make better decisions when selecting BOT toll road proposals and to also save decision makers time and effort.
Conceptual Framework for Defining and Developing an Integrated Asset Management System
Authors: Shufon John J. , Adams Louis H.
Published: April 2007

Interest in developing and implementing asset management systems has grown considerably during the past several years. Although asset management is defined in the literature, these definitions are generally all encompassing and fail to distinguish the asset management model from that of traditional infrastructure management systems. To assist those practitioners who are tasked with developing automated asset management systems, guidance is needed to better clarify what is meant by the term asset management. The work being done by the New York State Department of Transportation (NYSDOT) in defining asset management and enhancing its current program development process is described. The department’s asset management system is defined in relation to four precepts, and a conceptual design for an automated asset management system is presented. Central to the NYSDOT approach is a method of conducting trade-off analysis among the department’s four major goal areas—pavements, bridges, safety, and mobility. Excess user costs are discussed as the common measure to compare benefits of diverse projects such as a pavement project versus a mobility project. The goal of the NYSDOT approach is to better integrate decision making among program areas. It is concluded that while the NYSDOT approach may not be right for all transportation agencies, the idea that system development be carefully defined and properly scoped is important and should be considered as organizations endeavor to implement integrated asset management systems.
Engineer-in-Residence: Strategy for Increasing Relevance in Transportation Education
Authors: Pritchard Daniel , Beimborn Edward A.
Published: April 2007

Results are reported of the implementation of an engineer-in-residence concept in the Department of Civil Engineering and Mechanics at the University of Wisconsin–Milwaukee College of Engineering and Applied Science. This concept brings an experienced practitioner to campus specifically to mentor students and faculty in the application of engineering and management principles to real-life problems and to provide additional relevancy to the education process. Success of the concept is measured by evaluations completed by students and faculty. On the basis of the findings of these evaluations, the concept is a promising way to provide expanded relevancy to a transportation education program.
Urban Transportation Planning Education Revisited: Reading the Dials and Steering the Ship
Authors: Khisty C. Jotin , Kikuchi Shinya
Published: April 2007

Now, more than ever, the planning and management of transportation systems in the real world is beset by change and uncertainty. Under these conditions, the quality of transportation education continues to be a matter of concern for the profession because of continuing demands and commitments at several levels. From an academic standpoint, topics such as public involvement, strategic management of capital resources, soft systems methodology, and applied ethics need to be incorporated in the curriculum in more substantial ways. On the basis of the demands of professional practice, as suggested by hiring agencies, the political working of the real world also needs to be understood by entry-level graduates. These and other relevant issues, relevant particularly for a graduate-level course on urban transportation planning, are described and discussed. On the basis of the “Millennium State-of-the-Art and Future Directions White Paper” sponsored by the Committee on Transportation Education, students are expected to have a deeper knowledge and acquire greater skills in the following four topics: intermodalism and systemicity, soft systems methodologies, applied ethics, and communication. A sample course outline incorporating these suggestions based on a three-credit course offered at the Illinois Institute of Technology, Chicago, in 2001 is described. Finally, the composition of the class and the student course evaluation are discussed. Overall, the course was well received by students.
Resolving Conflict Between Mobility-Impaired Passenger Requirements and Freight Service on Mixed High- and Low-Platform U.S. Railroad Lines
Authors: Morlok Edward K.
Published: April 2007

The first objective is to explain the conflict that has emerged and is growing between ( a) requirements to make passenger trains accessible for passengers in wheelchairs and for other mobility-impaired travelers and ( b) requirements for general freight service on the same tracks on certain types of railroad lines. The second objective is to present two designs for railroad passenger car entranceways that appear to resolve this problem and that have additional benefits as well. The conflict emerges in situations in which high-level platforms are used (at stations) on tracks that are also used by freight trains, because such platforms intrude into the normal clearance envelope of freight trains. High-level platforms are now most commonly used in the northeastern United States, but more extensive use elsewhere is contemplated because of various benefits for passenger service. After the problem is presented, reviews are completed of previous evaluations of various generic approaches to providing platform-to-train access—in foreign railways and in rail transit contexts—to identify characteristics of effective solutions that are compliant with the Americans with Disabilities Act. Then two related new approaches designed for North American railroad conditions are presented. It is hoped that research into this problem will be encouraged along with testing and ultimately the deployment of technologies that will provide effective transport for mobility-impaired travelers on the railroads while maintaining characteristics necessary for freight service.
From Basic Rights to Full Access: Elements of Current Accessibility Practice in Developing Countries
Authors: Venter Christoffel J. , Rickert Thomas E. , Maunder David A. C.
Published: April 2007

Improving access to transport systems and mobility of people with disabilities is a necessary element of alleviating poverty in developing countries. A selected overview of the progress made toward achieving improved access is provided. It is based on an ongoing 3-year research program on access needs and approaches in a selection of developing countries in Africa, Asia, and Latin America. A generalized framework is suggested for describing the progress made across different countries. Many least developed countries are at the bottom of a continuum of activities in which issues of human rights and access to basic mobility are still paramount. Others, such as countries in Latin America, have made significant progress on access issues in major cities and are faced with challenges of expanding improvements to noncore areas and to less well-regulated modes. The framework is used to suggest some critical priorities for countries at various levels of development.
Departure Time Choice for Recreational Activities by Elderly Nonworkers
Authors: Okola Anna
Published: April 2007

A discrete choice analysis was performed to study the temporal preferences of elderly persons for recreational trips. Departure time choice studies for recreational activities helped in gaining an understanding of flexible travel behavior. Elderly persons form the fastest-growing age groups, and results from the 1995 Nationwide Personal Transportation Survey indicate an increase in travel by elderly persons. This study was the first part in a study of the interaction of age, emerging transport technologies, and activity participation. Modeling departure time choice for elderly persons is critical in understanding the travel needs of an aging population to provide adequate services and enhance efficacy of transport systems and user mobility. The study makes possible an analysis of the impacts on congestion, air quality, and associated mitigation efforts. Results of this study confirm that travel patterns for elderly persons are different from those of the general population; they prefer the earlier part of the day for recreational trips. The implications of increased daytime travel may include the need for additional emergency or incident response units, particularly in rural areas. This study may be used to gauge how to best offer alternative means of transport such that they will be most effective in meeting the demands of nonworkers for nonwork trips.
Arkansas Superpave® Seminars: Model Technology Transfer Partnership
Authors: Hall Kevin D.
Published: April 2007

Arkansas implemented the Superpave® asphalt mixture design system in 1997 for all state and federal highways. Local roadway agencies in Arkansas, including cities and counties, have historically used Marshall method–based mixes—typically by specifying the use of state mix in paving projects. In recent years, however, more Superpave-based mixtures are being used for local projects, leading to an acute need for information at the local level about specification and construction practices necessary for Superpave. A partnership of people representing academia, industry, local roadway agencies, and the state highway agency was formed to develop and present information to local agencies and consulting engineers on the use of Superpave for low-volume roadways. The goal of the partnership was to develop a series of Superpave seminars to provide vital technology transfer to local roadway personnel. Nine seminars were held throughout Arkansas, drawing more than 250 people from cities, counties, consulting engineering firms, and other interested parties. The seminar series proved to be a success. Keys to the success included a buy-in of all major stakeholders in the partnership; a funding strategy for development and execution that allowed attendees to participate at no cost; an informal, hands-on presentation seminar approach; and recognition of the realities of local roadway agency practices and the need to frame new technology within those practices. Attendee feedback was overwhelmingly positive and indicated a willingness to participate in future technology transfer activities.
Relationship Between Soil Stiffness Gauge Modulus and Other Test Moduli for Granular Soils
Authors: Sawangsuriya Auckpath , Edil Tuncer B. , Bosscher Peter J.
Published: April 2007

Recently, there has been a concerted effort to develop methods for direct measurement of soil stiffness, modulus, or both. A new field test device called the soil stiffness gauge (SSG), which is currently marketed as GeoGauge, shows potential to assess near-surface stiffness. A comparison is presented of moduli obtained from the SSG with moduli obtained from other tests on granular soils. The maximum singleamplitude dynamic force produced during the SSG measurement is determined to be 17.3 N. On this basis, an estimate of the shear strain amplitude produced from the SSG is made by finite element analysis. A plot of shear modulus versus shear strain amplitude on a medium sand obtained from different laboratory tests, including the SSG, is presented. The comparison of the SSG modulus with the moduli from other laboratory tests indicates that the SSG outputs a dynamic modulus corresponding to a strain amplitude approximately 20 times higher than the expected range and with a magnitude lower than it should be on the basis of the induced strain. Nevertheless, the SSG modulus is still higher than that from the resilient modulus test typically used for pavement design.
Use of Stiffness for Evaluating Compactness of Cohesive Pavement Geomaterials
Authors: Ooi Phillip S. K. , Pu Jianping
Published: April 2007

There has been a recent push toward adoption of in-place soil stiffness as a means of assessing compactness of pavement geomaterials. From a series of low strain GeoGauge stiffness measurements made under controlled laboratory conditions on compacted silts, the variation of stiffness with water content, dry unit weight, degree of saturation, volume change upon wetting, shear strength, and soil plasticity is discussed. In general, the GeoGauge stiffness is not directly related to dry unit weight, and it peaks dry of optimum and decreases upon wetting. Soil specimens with a large stiffness also tend to be stronger, but they also tend to swell more upon wetting, implying that the shrink–swell potential is not optimized if stiffness is. These results help advance the understanding of the role of stiffness in assessing compactness of cohesive geomaterials.
Axial and Lateral Load Performance of Two Composite Piles and One Prestressed Concrete Pile
Authors: Pando Miguel , Filz George , Ealy Carl , Hoppe Edward
Published: April 2007

Composite piles use fiber-reinforced polymers (FRPs), plastics, and other materials to replace or protect steel or concrete, with the intent being to produce piles that have lower maintenance costs and longer service lives than those of conventional piles, especially in marine applications and other corrosive environments. Well-documented field loading tests of composite piles are scarce, and this lack of a reliable database may be one reason that composite piles are not in widespread use for load-bearing applications. The purpose of this research is to compare the axial and lateral load behavior of two different types of composite test piles and a conventional prestressed concrete test pile at a bridge construction site in Hampton, Virginia. One of the composite piles is an FRP shell filled with concrete and reinforced with steel bars. The other composite pile consists of a polyethylene plastic matrix surrounding a steel reinforcing cage. The axial structural stiffnesses of the prestressed concrete pile and the FRP pile are similar, and they are both much stiffer than the plastic pile. The flexurel stiffness of the prestressed concrete pile is greater than that of the FRP pile, which is greater than the flexural stiffness of the plastic pile. The axial geotechnical capacities of the test piles decreased in order from the prestressed concrete pile to the FRP pile to the plastic pile. The prestressed concrete pile and the FRP pile exhibited a similar response for lateral load versus deflection, and the plastic pile was much less stiff in lateral loading.
Design of Fiber-Reinforced Polymer Composite Piles Under Vertical and Lateral Loads
Authors: Han Jie , Frost J. David , Brown Vicki L.
Published: April 2007

Conventional pile materials, such as steel, concrete, and wood, can encounter serious corrosion problems in industrial and marine environments. Deterioration of steel, concrete, and wood piling systems has cost the military and civilian marine and waterfront civil engineering communities billions of dollars to repair and replace. Fiber-reinforced polymer (FRP) composites have desirable properties for extreme environments because they are noncorrosive, nonconductive, and lightweight. Different types of FRP composite piles are currently under research investigation, and some have been introduced to the marketplace. FRP composites have been used as internal reinforcement in concrete piles; as external shells for steel, concrete, and timber piles; and as structural piles such as FRP pipe piles, reinforced plastic piles, and plastic fender piles. The different ways of constituting FRP composite piles result in different behavioral effects. Because FRP structural piles have anisotropic properties, low section stiffness, and high ratios of elastic to shear modulus, they have different behavior in load-displacement relations under vertical and lateral loads. Current design methods for conventional piles were examined to determine the validity for FRP composite piles, and some new design methods specific to FRP structural piles were developed from research work conducted by the authors.
Buried Corrugated Thermoplastic Pipe: Simulation and Design
Authors: Schafer B. W. , McGrath T. J.
Published: April 2007

The objective of this study was to demonstrate a computational method for assessing the allowable depth of fill over a buried thermoplastic profile wall (corrugated) plastic pipe and to compare the results with those of the recently adopted AASHTO design method. The computational method is demonstrated for a 1,500-mm (60-in.) diameter high-density polyethylene profile wall pipe but is applicable to all profile wall thermoplastic pipe that exhibits local buckling limit states. The computational model compares strain demands predicted from a two-dimensional plane strain finite element model of buried pipe in the embankment condition with strain capacity predicted from a three-dimensional finite element model of a pipe–soil segment undergoing thrust or positive and negative bending, or both. The strain demands indicate the dominance of thrust strains as opposed to bending strains in the overall behavior, particularly for intermediate to larger fill depths. In the examined profile the ultimate strain capacity is limited by local buckling for thrust strains and positive bending (crest in compression) and inward radial movement of the crest for negative bending (liner in compression). Predictions for depth of fill by the new AASHTO design method for thermoplastic pipe and the computational method agree within 10% of one another when uniform soil distribution is considered and within 20% of one another when a soft haunch and other soft soils are considered in the pipe–soil envelope.
Characterization of Transverse Cracking Spatial Variability: Use of Long-Term Pavement Performance Data for Continuously Reinforced Concrete Pavement Design
Authors: Selezneva Olga , Darter Michael , Zollinger Dan , Shoukry Sarmir
Published: April 2007

Mechanistic-empirical design procedures for continuously reinforced concrete pavement (CRCP) require characterization of variations in major design parameters so that a new or rehabilitated pavement can be designed for a desired level of reliability. Transverse cracking is an important CRCP design parameter affecting the prediction of crack width, crack load transfer efficiency, and critical stresses leading to longitudinal cracking and punchout development. The primary focus of this study was to investigate spatial characteristics of transverse cracking occurring in CRCP and to develop a theoretical model that would provide a means for systematic characterization of transverse crack spacing variability along the pavement length. Long-term pavement performance distress data were utilized to analyze transverse crack spacing characteristics for CRCP sections. From the results of the field data analysis, a theoretical model utilizing a Weibull distribution was developed to characterize the along-the-section transverse crack spacing frequency distribution. This theoretical model could be incorporated into the mechanistic-empirical procedures for CRCP structural design. The relationship between transverse crack spacing characteristics and punchout development and the location of the longitudinal cracks, which are a punchout precursor, were also analyzed using field survey data. Conclusions derived from field data analysis and the theoretical model presented here will be of interest to practicing engineers and researchers involved in CRCP design and performance modeling.
Estimation of Pavement Layer Thickness Variability for Reliability-Based Design
Authors: Jiang Y. “Jane” , Selezneva Olga , Mladenovic Goran , Aref Susanne , Darter Michael
Published: April 2007

Estimating the variability of key pavement design inputs is essential to reliability-based pavement design. The thickness of most pavement layers has a great impact on the outcome of practically all analyses of pavement performance. The within-section layer thickness variability is investigated here, as is the extent of the mean layer thickness deviation from its design thickness. Pavement layer thickness data (elevation and core measurements) from a large number of newly constructed flexible and rigid pavement sections in the Long-Term Pavement Performance (LTPP) program were examined. To determine the distribution type of the thickness data, a combined statistical test for skewness and kurtosis showed that ( a) thickness variations within a layer indicate a normal distribution for 86% of 1,034 layers and ( b) the mean thickness deviations from the design values may be assumed to be normally distributed for a layer having a given type and design thickness. The estimated thickness-within-layer variability values and the estimated typical thickness deviations derived from LTPP data may serve as benchmarks for use in pavement design reliability, construction quality assurance specifications, and other research studies. In addition, statistical comparisons of layer thickness variability indicators were made between the elevation and core layer thickness data to determine whether there are systematic differences between these two measuring methods. These results will be very useful to both researchers and practitioners who develop or use reliability-based pavement design procedures.
Eight-Year Field Performance of Secondary Road Incorporating Geosynthetics at Subgrade-Base Interface
Authors: Ai-Qadi Imad L. , Appea Alexander Kwasi
Published: April 2007

In June 1994 an instrumented 150-m-long secondary road pavement section was built in Bedford County, Virginia. This pavement section was composed of nine individual segments each 15 m long. The nine sections include three groups with aggregate base layer thicknesses of 100, 150, and 200 mm. Three sections from each group were stabilized with geotextiles and three were stabilized with geogrids at the base-subgrade interface. The remaining three sections were kept as control sections. As part of the structural analysis, deflection data parameters such as the base damage index and surface curvature index calculated from falling weight deflectometer (FWD) data were analyzed after being corrected for temperature variations from the time of construction until October 2001. Performance criteria such as rutting measurements were also collected over the whole period. A nonlinear exponential model was used to describe the development of rutting versus cumulative equivalent single-axle loads for the 100-mm base course. A linear elastic program incorporating constitutive material properties was used to calculate vertical compressive stresses, which were used with FWD deflections to predict rutting rates with a mechanistic equation. The rutting rate results confirmed the separation function of geosynthetics that prevented the migration of fines from the subgrade to the base course layer and the penetration of the aggregate base layer into the subgrade. Rutting results, deflection data, and service life analysis showed that geosynthetically stabilized sections significantly improved the performance of the 100-mm base course sections.
Strength Properties of Flexible Geogrids Under Indoor and Outdoor Ultraviolet Exposure
Authors: Hsieh Chiwan Wayne , Lin Chien Kuei
Published: April 2007

The outdoor ultraviolet (UV) light exposure program according to ASTM D5970 and the indoor UV fluorescent lamp device according to ASTM G154 were used to evaluate the UV degradation in test polyester geogrids. Eighteen months’ worth of data were obtained from the outdoor program. UV-A-340 lamps and exposure condition No. 7 were used for the indoor program. The outdoor exposure program was conducted at Pingtung, in southern Taiwan. The annual sunlight exposure energy was 4,263.50 MJ/m2. The accumulated annual UV-A and UV-B energies were 256.56 and 0.83 MJ/m2, respectively. The tensile strength of the test geogrids decreased as the outdoor exposure increased, but the decrease in the rate of tensile strength also lessened as UV exposure increased. Carbon black and antioxidants contained in the coating materials have a significant influence on the rate of degradation for the test geogrids; 2% carbon black and 1% antioxidant by weight are recommended. The proportions of average retained ultimate tensile strength for 1 month, 12 months, and 18 months of outdoor exposure were 88%, 71%, and 66%, respectively. The tensile strength half-life cycle due to UV exposure was greater than 18 months. Similar behavior was also observed for the elongation at break. However, no clear trend was found for strength at 5% strain due to UV exposure. The reduction factors due to 18 months of outdoor exposure varied from 1.27 to 1.99. The average reduction factor was about 1.60. The reduction in ultimate tensile strength under 180 h of UV exposure in the indoor UV exposure test program was very significant. However, the rate of lost tensile strength for the second and third 180-h UV exposure was very small. The average retained tensile strengths for the geogrids under 180-h and 540-h exposures were 81% and 77%, respectively. The effect of 540-h fluorescent light exposure on the tensile strength of polyester geogrids coated with polyvinyl chloride was equivalent to 151 days of outdoor exposure at Pingtung.
Validation of Approach and Climb-Out Times-in-Mode for Aircraft Emissions Computation
Authors: Rice Colin C.
Published: April 2007

The first aircraft emissions standards were proposed by the U.S. Environmental Protection Agency (EPA) in “Proposed Standards for Control of Air Pollution,” in 1972. Landing–takeoff cycles (LTOs), aircraft engine emissions factors, and times-in-mode (TIMs) were the basis of computing aircraft emissions. Discrete values were assigned to each TIM. No formal record of the derivation of these TIMs is available. Thirty years later, the same TIMs presented by EPA in 1972 are still used in developing aircraft emissions inventories. Today’s aircraft perform much differently than did aircraft from the past. A study was attempted to validate the TIM values currently used with radar data. A sample emissions inventory will be developed for Chicago O’Hare International Airport to show the impact of the proposed changes of TIMs.
Heavy Truck Dynamic Rollover: Effect of Load Distribution, Cargo Type, and Road Design Characteristics
Authors: García Lino O. , Wilson Frank R. , Innes J. David
Published: April 2007

The dynamic response of a five-axle tractor–trailer unit carrying loads of various weights was evaluated under actual operating conditions as the vehicle traveled along roadway curves with various radii. A data acquisition system (DAS) was designed and developed to record information for a vehicle moving at highway speeds. The DAS used sensors interfaced to a central processing unit. The test runs were performed over a total of 1,110 km of highway under three load configurations: empty, loaded with less than the truck load, and loaded with bottled spring water packed in boxes. Data on lateral, longitudinal, and vertical accelerations; steering activity; vehicle speed; and roll angle of the trailer were recorded. It was found that in most cases the average level of lateral acceleration exhibited on both the tractor and the trailer exceeded expected values calculated for the curves on the basis of geometric design characteristics. Comparisons of actual results with theoretical considerations confirmed this observation. Analyses of field data indicated that under certain motion and load conditions, the occasional peak lateral acceleration values generated were in the vicinity of rollover threshold values estimated for the instrumented vehicle. The results also showed that although the vehicle traveled at or below the posted speed limit in the majority of cases, lateral accelerations recorded for the trailer exceeded expected lateral accelerations under all load configurations. This suggests the need to consider establishing speed limits on curves that take into consideration the different responses of heavy trucks compared with those of smaller and lighter vehicles.
Numerical Modeling of Scour in Cohesive Soils Around Artificial Rock Island of Cooper River Bridge
Authors: Kassem Ahmed , Salaheldin Tarek M. , Imran Jasim , Chaudhry M. Hanif
Published: April 2007

A new laboratory-based methodology for prediction of the maximum scour depth in cohesive soil has recently been developed at the University of South Carolina. Because of the absence of field data, a computational fluid dynamics model, FLUENT, is used to test the scale effects associated with such a methodology. The numerical model was first verified against measurements obtained in the laboratory. The numerical results agreed satisfactorily with the measurements. Then, the numerical model was applied to the rock island protecting the main piers of the Cooper River Bridge, located in Charleston, South Carolina. The scour hole created around the island in the laboratory was scaled up and used in the numerical model. The computed bed shear stresses compared satisfactorily with those scaled up from the measurements and the shear stress at which the field sample begins to erode. It was found that the scour depth of 3.7 m represents the equilibrium state, which is similar to the results scaled up from the laboratory experiments. The numerical results showed that the scour depth of 36 m calculated by the HEC-18 approach is significantly overestimated.
Development of Trailer Attenuating Cushion for Variable Message Signs and Arrow Boards
Authors: Sicking Dean L. , Rohde John R. , Reid John D.
Published: April 2007

In 1993, FHWA adopted a policy that requires all roadside features placed within the clear zone to be evaluated according to the guidelines contained in NCHRP Report 350. Variable message sign trailers and arrow board trailers have never been tested under these safety evaluation guidelines. A full-scale crash test and a review of work zone accident studies clearly indicate that these trailers are a serious roadside hazard and they are struck in approximately 15% of all work zone intrusion accidents. An attenuating cushion that safely treats the full range of these trailers was developed. Two full-scale crash tests of the trailer attenuating cushion were conducted to verify that the new designs meet NCHRP Report 350 guidelines. The new safety treatments are believed to be relatively inexpensive to build and easy to deploy. The new systems should reduce the severity of many run-off-road crashes without a major increase in the cost of using variable message signs and arrow boards.
Box-Beam Burster Energy-Absorbing Terminal Bridge Pier Protection System
Authors: Rohde John R. , Sicking Dean L. , Reid John D.
Published: April 2007

A new box-beam burster energy-absorbing terminal (BEAT) bridge pier (BEAT-BP) protection system was successfully crash tested according to the safety performance criteria presented in NCHRP Report 350. The system comprises two BEAT crash cushions and a frame that envelops the bridge piers. Because of the close proximity to the piers, the system has a footprint significantly smaller than those of the other available options. Three crash tests were considered necessary to evaluate the BEAT-BP protection system and were conducted successfully: a pickup truck critical impact point (CIP) transition test at a bridge pier (Test Designation 3-21), a pickup truck CIP test at the connection between the crash cushion and the tubular frame structure (Test Designation 3-38), and a pickup truck end-on test for the crash cushion (Test Designation 3-31). A total of four crash tests were conducted, including one failed test (Test BP-2). The BEAT-BP protection system performed satisfactorily in all three required crash tests, meeting all evaluation criteria set forth in the guidelines of NCHRP Report 350.
Design and Testing of Tie-Down Systems for Temporary Barriers
Authors: Bielenberg Bob W. , Faller Ronald K. , Reid John D. , Rohde John R. , Sicking Dean L.
Published: April 2007

Two tie-down temporary barrier systems were developed and crash tested according to the safety performance criteria provided in NCHRP Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features. Both tie-down systems were designed to reduce barrier displacements and to retain deflected barriers on the bridge deck edge. The first system consisted of a steel tie-down strap concept for use with the Iowa F-shape temporary concrete barrier. At each barrier joint, the trapezoidal-shaped strap retained the vertical pin and was attached to the concrete bridge deck using two drop-in anchors. An acceptable fullscale vehicle crash test of the tie-down strap concept was conducted according to the Test Level 3 (TL-3) impact safety standards in NCHRP Report 350. The second tie-down system was developed for use with Iowa’s steel H-section temporary barrier. A new barrier connection was developed to simplify barrier attachment and to accommodate deviations in horizontal and vertical alignment. It consisted of two steel shear plates positioned within an opening on the adjacent barrier section and held in place with two steel drop pins. Four steel angle brackets were welded to the barrier’s base to allow for rigid attachment to the concrete bridge deck with drop-in anchors. Two full-scale vehicle crash tests were conducted on the steel H-barrier system according to TL-3 impact safety standards found in NCHRP Report 350. After an unacceptable first test, the system was successfully tested with minor design modifications.
Utilities in Highway Right-of-Way: Data Needs and Modeling
Authors: Quiroga Cesar , Pina Robert
Published: April 2007

Each year, thousands of new utilities are installed within the rights-of-way (ROWs) of highway facilities nationwide. With the proliferation of utilities within their ROWs, it is becoming increasingly difficult for transportation agencies not only to allow more utilities but also to deliver and manage their own transportation systems in a timely and efficient manner. A geographically referenced prototype model that ties the locations of utility facilities to a state highway network and that associates the positional data with details of utility facility ownership, service or commodity type, infrastructure size, material, and other pertinent characteristics is described. The inventory model can accommodate a variety of utility-related processes within a transportation agency, including utility permits, joint use agreements, and deliverables from subsurface utility engineering contracts. Common sources of utility facility data at a transportation agency are reviewed, and a geographic information system model that represents the locations of utility facilities within the highway ROW is described.
Freeway Quality of Service: Perceptions from Tractor-Trailer Drivers
Authors: Hostovsky Charles , Hall Fred L.
Published: April 2007

Trucks make up a significant and growing portion of the traffic on freeways. The perceptions of tractor-trailer drivers regarding the quality of service on freeways are the subject of this research, with a focus on the factors that are important to this group of road users. Perceptions were determined using the standard qualitative inductive analysis approach through a focus group with professional tractor-trailer drivers. The results were compared with quality-of-service focus groups held for urban and rural freeway commuters. Freeway conditions in general were the most frequently mentioned factors and encompassed a variety of considerations. The three variables that together describe traffic conditions—travel time (or speed), traffic density (or maneuverability), and traffic flow—were all mentioned with regard to quality of service. Likely the most significant finding is that it is not traffic density that matters to these drivers; rather it is traffic flow. It appears that there is a comfortable operating range of highway speeds in which not much braking and acceleration-related gear changing are required. Other important themes included weather, attitudes toward other drivers, and road rage (i.e., aggressive driving). Participants also responded to questions about regional differences in quality of service. Safety was an issue that transcended or overlapped many other issues.
Two-Stage Gap Acceptance: Some Clarifications
Authors: Brilon Werner , Wu Ning
Published: April 2007

Chapter 17 of the Highway Capacity Manual (HCM) 2000 provides a method for analyzing a two-stage priority process at unsignalized intersections, which provide a wide median in the major street. In the HCM itself, the method is described rather briefly. This briefness could give rise to misunderstanding, and practitioners might avoid using the procedure altogether. Therefore, the analytical background of the procedure and the correct application of the parameters are explained in greater detail. Moreover, graphical representations have been developed to replace the difficult formulas, significantly simplifying application in the field. The method also has some limitations, which should be taken into account in practical application. Thus, this paper is something like a comment on the method described in the HCM 2000, besides providing some enhancements that allow easier application in practice.