bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of Performance Specification Approach for Pavement Foundations
Authors: Frost M. W. , Fleming P. R. , Rogers C. D. F.
Published: April 2007

Road foundations are currently designed using established empirical relationships and a recipe specification, according to which specified materials are laid and compacted using specified methods. Such an empirically based specification is unlikely to result in an efficient use of construction equipment or materials and does not allow the use of analytical design procedures. If a move to a performance specification can be adopted, functional subgrade and foundation material parameters can be used in design and compliance testing. This allows for the use of previously untried materials and provides assurance of the “as-constructed” performance of the pavement foundations. The philosophy adopted for a performance specification currently being researched in the United Kingdom is explained. The performance parameters to measure for both design and compliance testing, and when they should be measured, are detailed. The requirements of tests to measure the parameters are specified, and the techniques currently available are reviewed. Finally, selected results from field trials performed to evaluate the proposed specification are presented. Research has shown that techniques are available to allow for a move to a performance specification. However, the assessment of granular materials with large particle sizes requires further research. The trials revealed that adequate compaction of subbase can be achieved on a wider range of supporting materials than might be expected. Significant variability in test data was found for small areas of the same site containing similar subgrades; therefore, any target values set for compliance testing should be ideally both material and site specific.
Computer Simulation of Statistical Characterization of Aggregate Inhomogeneity in Asphalt Concrete
Authors: McCuen Richard H. , Azari Haleh , Shashidhar Naga
Published: April 2007

Recent developments in image analysis techniques have enabled the measurement of the precise locations of aggregate particles in sawed sections of asphalt cores. Statistical tests are applied to the asphalt core cross sections to quantify the inhomogeneity (segregation) of hot-mix asphalt cores. The Runs test uses the frequency of aggregate in the various layers of the hot-mix asphalt cores. The Quadrat test also uses the frequency of aggregate, but the test statistic is computed as the coefficient of variation of the number of particles in panels randomly located on the slice face of the specimen. The Average Depth test compares the average depths of aggregates of different gradation sizes. The methods differ in their ease of application and their ability to discriminate across levels of inhomogeneity. The value of computer simulation in assessing the power of the tests is demonstrated.
Distinct Element Method for Study of Failure in Cohesive Particulate Media
Authors: Ullidtz Per
Published: April 2007

Permissible stresses or strains in pavement layers constitute the empirical part of the mechanistic-empirical method. Whereas it appears to be possible to predict the actual stresses or strains under a load (the mechanistic part) reasonably correctly, there is much uncertainty with respect to the permissible values. Some of the possibilities that the distinct element method (DEM) raises for calculating permanent deformation and failure in pavement materials are explored. Because the study is limited to two dimensions and makes a number of assumptions that may not be strictly correct, the results should be considered as indicative of only some of the capabilities of DEM. After a brief description of DEM, tests to the failure of two different samples of elements are presented, with different element shape and size distribution and thus different resulting pore volume after compaction. For one of the samples, seven different stress paths were followed to failure (pure tension, uniaxial tension, pure shear, etc.). From this study, a nonlinear relationship between the permissible shear stress and the hydrostatic stress was deduced. Using this relationship as the basis for the kinetic equation in continuum damage mechanics can lead to cracking from the top of and the bottom of a slab. Finally, DEM is used to study the effect of repeated loading on permanent deformation and failure for one of the samples. The effect on permanent deformation was pronounced, whereas the effect on failure was much more uncertain, although there could be some indication of fatigue.
Evaluation of Dolomite and Related Aggregates Used in Bituminous Overlays for Indiana Pavements
Authors: West Terry R. , Choi J. C. , Bruner D. W. , Park H. J. , Cho K. H.
Published: April 2007

To allow vehicles to stop in a reasonable distance, adequate friction resistance is needed to prevent pavement slipperiness. In stone-masticasphalt surfaces, friction resistance is mainly caused by the interaction between aggregates exposed at the surface and vehicle tires. Performance of aggregates is reduced with time through wear and polishing by vehicular traffic. A method to investigate aggregate performance using physical, chemical, and petrographic factors was evaluated. The objective was to develop a laboratory test for Indiana dolomite, limestone, sandstone, and gravel aggregates to predict field friction resistance and to determine causes for the range of polish resistance of these aggregates. Dolomite and slag are specified aggregates for wearing surfaces for high-traffic roads in Indiana, but some limestones and crushed gravels may prove acceptable. Gravel sources were assessed on the basis of percentages of rock types included in the gravel. Initial friction values and polished values were determined in the laboratory using the British wheel and pendulum procedures, and field values were determined with the towed friction trailer (ASTM E274-97; average friction numbers), which yielded friction number smooth (smooth tire) and friction number ribbed (ribbed tire). Correlations between parameters predict friction resistance from laboratory test data. Also polished values of 25 may be equivalent to a friction number smooth of 27.7 and friction number ribbed of 30.7. Further refinement is required to establish performance specifications for individual aggregate selection.
Effect on Crashes After Construction of Directional Median Crossovers
Authors: Taylor William C. , Lim Inkyu , Lighthizer Dale R.
Published: April 2007

The purpose was to determine the safety impact of a program to replace bidirectional median crossovers with directional median crossovers on urban arterials. The state of Michigan has adopted this strategy to increase safety and reduce operational problems associated with the lack of storage space in bidirectional median crossovers. Eight arterial road segments were studied, varying in length from 1.17 km to 8.91 km, in which this change had been made. A total of 54 bidirectional median crossovers were replaced on these eight segments. The crash analysis showed an average of over 30 percent reduction in both total crashes and crashes involving at least one injured party. This reduction occurred almost exclusively at the locations in which the bidirectional median crossovers were replaced, with no significant change observed at crossovers that were not changed.
Wet and Wild: Developing and Evaluating an Automated Wet-Pavement Motorist Warning System
Authors: Collins Jason S. , Pietrzyk Michael C.
Published: April 2007

A fully automated motorist warning system developed for wet-pavement conditions was evaluated. The demonstration took place on one expressway interchange ramp where 69 percent of total recorded crashes had been classified as “run-off” crashes during wet-pavement conditions. However, fewer than one-half of all wet-pavement crashes occurred during rain. The potential solution was to develop an automated, dynamic motorist warning system to attract attention to the advisory speed limit signs and thus encourage motorists to reduce vehicle speed. A pavement sensor embedded in the roadway activated two flashing beacons located above the signs whenever moisture was detected. Infrared radar recorded vehicle speed at the site. Speeds and volumes were grouped into a matrix according to weather conditions and time periods, which were based on sunlight visibility and peak traffic hours. The reduction of the 85th-percentile speeds served as the first measure of effectiveness, and only “like” conditions were compared for system evaluation. In total, more than 27,000 wet-pavement vehicle speeds were compared before and after system activation. The average reduction in travel speed was 16 km/h (10 mph) during heavy rain and 8 km/h (5 mph) during light rain; the standard deviation for vehicle speed also was reduced after system activation. No run-off crashes were reported at the site after the first week of the evaluation period.
Evaluation of a Voice Interface Management System
Authors: Tattegrain-Veste H. , Bruyas M.P. , Bellet T. , Pachiaudi G. , Forzy J.F. , Martini D. , Baligand B. , Simoes A. , Carvalhais J. , Lockwood P. , Boudy J. , Damiani S. , Opitz M.
Published: April 2007

The final prototype of a centralized voice information system, developed under the framework of the European CeMVocAS (Centralised Management of Vocal Interfaces Aiming at a Better Automotive Safety) project, was evaluated. This system manages all types of voice messages to the driver (i.e., input and output voice flows to and from car telephone, radio, and driver assistance systems) to minimize their disruptive impact on the basic task of driving. Analysis of the results included evaluation of ( a) the part of the system responsible for determining the driver’s potential availability to receive voice messages [driving situation recognition unit (DSRU)] and ( b) the complete system (DSRU plus centralized voice interface management system). Results indicate that the system is quite robust in terms of vehicle, driver, and route variability; in addition, levels of system effectiveness, system efficiency, and user satisfaction were high.
Bus Stop–Environment Connection: Do Characteristics of the Built Environment Correlate with Bus Stop Crime?
Authors: Liggett Robin , Loukaitou-Sideris Anastasia , Iseki Hiroyuki
Published: April 2007

Can we understand why some bus stops are safe and others are crimeridden? Can we predict which features of the bus stop environment are likely to encourage or discourage crime? Can we design safer bus stops? These questions are addressed by exploring the relationship between environmental variables and bus stop crime. An earlier study used crime data, along with environmental indicators, for a sample of 60 bus stops in downtown Los Angeles. Crime rates were higher for bus stops near alleys, multifamily housing, liquor stores and check-cashing establishments, vacant buildings, and graffiti and litter. In contrast, good visibility of the bus stop from its surroundings and the existence of bus shelters contributed to lower crime rates. This earlier study was indicative but not predictive of the elements that contribute to bus stop crime. With the geographic and temporal expansion of the data (covering a larger city part over a longer time span), a series of regression models was generated that identify environmental predictors of bus stop crime. These models show that the most important predictor of crime is location. If the environment is controlled, undesirable facilities and litter result in higher crime rates, whereas visibility and many pedestrians lead to lower crime rates. The presence or absence of certain characteristics in the bus stop microenvironment can affect crime. Also, the appropriate design and layout of the physical environment can reduce opportunities for criminal actions.
Bus Rapid Transit Institutional Issues: The Route from Research to Experience
Authors: Miller Mark A. , Buckley Stephen M.
Published: April 2007

The institutional aspects of bus rapid transit (BRT) are investigated through a macroscopic examination and a survey of members of FTA’s BRT Consortium and several Canadian transit properties. The macroscopic examination resulted from a literature review, project team brain-storming meetings, and input from FTA’s BRT staff. Several dozen issues were identified and grouped into nine categories that formed the basis of the survey—intergovernmental and interorganizational; intratransit property; political; public relations and marketing; funding and finance; labor; safety and liability; planning and land use; and the physical environment. Specific issues were identified that, overall, are both the most important and most difficult to resolve—local and business community opposition to the removal of, or restrictions on, parking spaces for use; availability and acquisition of right-of-way or physical space; integration of multiple priorities, objectives, and agendas; concerns over longterm funding commitments to BRT; BRT effects on roadway operations; finding political champions to support BRT; gaining community support for transit-oriented development; and educating the public about BRT and managing perceptions and expectations. Although a small set of opinions was obtained, the investigation and analysis of survey responses was based on the insight and expertise of individuals who have experienced these institutional issues. This study should offer guidance to anticipate future problems and develop strategies to resolve them.
Bus Transit in the 21st Century: Some Perspectives and Prospects
Authors: Levinson Herbert S.
Published: April 2007

A broad overview is presented of the role and opportunities for bus transit in the 21st century. Drawing from the input of a millennium paper prepared by TRB’s Bus Transit Committee (Bus Transportation in the New Millennium—A Look Forward), bus transit’s past, its present status, and its future prospects are reviewed. Policy choices, likely dimensions of change, and various opportunities for improvements in service design, vehicles, bus technology, and management are identified. Bus transport will continue to provide important service to metropolitan America. Therefore, continued support at all levels of government is essential. Growing community concerns about traffic congestion, sprawl, air pollution, and sustainability; the progressive revitalization of cities and towns; and continued advances in transport technology argue for improved bus transit in the new century. A greater effort to establish more transit-friendly residential areas, employment centers, and shopping areas will further enhance the future of bus transit.
Potential Effects of Automatic Vehicle Location and Computer-Aided Dispatch Technology on Paratransit Performance: A Simulation Study
Authors: Fu Liping , Xu Yiqun
Published: April 2007

Automatic vehicle location (AVL) and computer-aided dispatch (CAD) systems have afforded a unique opportunity for public transit agencies to integrate these technologies in their paratransit systems for improved productivity and reliability. This opportunity has also prompted widespread interest in quantifying the benefits that can be attained from such technological enhancement. This research assesses the potential effects of AVL and CAD on the productivity and service reliability of a paratransit system. A simulation model that can realistically model AVL and CAD functionality is used in the investigation. Many cases representing variations in operating environment, such as service area, demand intensity, and proportion of real-time demand trips, are simulated for a sensitivity analysis under three assumed operational improvements—en route diversion, dwell time reduction, and periodic reoptimization. The results indicate that although AVL and CAD effectiveness varies from case to case, on average, these systems can help to substantially improve paratransit performance.
Equilibrium Model Based on a Microfoundation for Forecasting Dial-a-Ride Ridership
Authors: Benjamin Julian M. , Sakano Ryoichi
Published: April 2007

The demand and capacity of a van dial-a-ride service for elderly and disabled passengers are analyzed together. The service demand is based on a survey of an advanced public transit system for an elderly and disabled persons van service. Demand is estimated by the Poisson regression on individual demand and by aggregating over individuals in the market. Service supply is modeled in two ways—a deterministic queuing model and a regression model—and is estimated by using drivers’ manifest data. Market demand is compared with market supply derived from each method to identify the equilibrium level of ridership and travel time, which are used to measure the service quality. The model is used to predict a trade-off between ridership and travel time and to present this trade-off conveniently on a simple tabulation form. The service provider can use this form to determine combinations that maximize the management objective without engaging in simulation or estimation for all possible choices.
User Behavior Evaluation of an Intelligent Shared Electric Vehicle System
Authors: Barth Matthew , Todd Michael
Published: April 2007

Critical to any new transportation system technology is how users respond to the new technology or system. Various intelligent transportation system studies and demonstrations have shown that the greatest likelihood for success comes when users adjust their behavior and embrace the system. However, user behavior is often difficult to predict and is often overlooked as a critical component when introducing new transportation systems or technology. To better understand user behavior in shared vehicle systems, an intelligent shared electric vehicle system test bed has been developed at the University of California–Riverside (UCR), named UCR IntelliShare. Faculty and staff use this system, consisting of 15 shared electric vehicles and three stations, for their daily travel needs. The system technology includes smart cards, touch-screen registration kiosks, vehicle monitoring and tracking hardware, and sophisticated management software. With this test bed system, researchers can develop and implement new operating techniques, perform experiments in travel demand management, collect data for supporting models, and quantify the energy and emissions savings associated with the system. The user behavior aspect of the system is the focus of this study. Much information has been collected through user surveys and operational analysis. The surveys have provided good insight on user satisfaction and on how the system is used. The operational analysis has brought forth key results on trip characteristics and travel demand patterns. Initial results indicate that the UCR IntelliShare system may be temporarily producing approximately 15 percent more trips. Other results indicate that trips between stations are fairly well matched, requiring few relocations. Further, day-by-day travel patterns are relatively consistent; however, approximately 14 percent of the travel patterns deviate significantly. These results, along with calibrated simulation models, can be used to help design other shared vehicles systems before implementation, potentially reducing associated risks and liabilities.
Alternative-Fueled, Low-Emission Bus Purchases in North Carolina
Authors: Cook Thomas J. , Straten Eliza Anne
Published: April 2007

North Carolina Senate Bill 953 enacted April 14, 1999, established a goal to reduce nitrogen oxide and particulate matter emissions in North Carolina. The legislation mandates that 50 percent of all replacement and expansion transit and school bus purchases in specific counties after January 1, 2004, shall be alternative-fueled, low-emission buses. The estimated emissions and costs in purchasing and operating various alternative-fueled, low-emission transit buses between 2004 and 2009 are addressed. A 1999 current emissions baseline scenario was developed to provide a basis for comparing the estimated emissions from four hypothetical scenarios for 2009. One scenario, the 2009 baseline emissions scenario, estimates emissions in 2009 if North Carolina transit fleets continue to purchase only diesel-fueled buses operating at current levels of emissions. The remaining scenarios estimate emissions assuming that 50 percent of transit bus purchases between 2004 and 2009 will be alternative-fueled, low-emissions buses. Estimates of the costs to purchase and operate alternative-fueled, low-emission buses were developed corresponding to the four 2009 emissions scenarios. A rudimentary benefit-cost analysis was conducted to estimate the cost per ton avoided for each of the four U.S. Environmental Protection Agency criteria pollutants. The benefit-cost analysis indicated that emissions reduction from diesel engines could surpass those from current natural gas–powered buses at a fraction of the cost.
Feasibility of Using Precast Concrete Panels to Expedite Construction of Portland Cement Concrete Pavements
Authors: Merritt David , McCullough B. Frank , Burns Ned H.
Published: April 2007

As the number of vehicles on America’s roadways continues to grow at an unprecedented rate, pavements continue to deteriorate faster and require replacement. In urban and densely populated areas, however, pavement construction can cause traffic delays, thereby increasing user costs. A method for expediting pavement construction to reduce traffic delays and user costs is therefore needed. A feasible method for expediting construction of portland cement concrete pavements through the use of precast concrete panels is described. The main advantage of precast concrete panels is that they can be set in place and assembled quickly, allowing traffic back onto the pavement almost immediately. This allows pavement construction to be carried out in overnight or weekend operations, when traffic volumes are low, resulting in tremendous savings in user costs. The concept presented for precast concrete pavement should have the same, if not better, durability as conventional cast-in-place concrete pavements currently being constructed. Also, by incorporating prestressing, it is demonstrated that equivalent load repetitions and design life can be achieved with a significant reduction in pavement thickness over conventional pavements. Although the initial construction costs may be higher for precast pavements, the savings in user costs far outweigh any additional construction costs.
New Jersey’s Superpave Specification: The Next Generation
Authors: Weed Richard M.
Published: April 2007

Testing of New Jersey’s first acceptance procedure for hot-mix asphalt pavement designed by the Superpave method began in 1998 with the construction of a series of pilot projects. A distinct feature of the prototype specification was the use of a composite pay equation that expressed the pay factor as a function of average quality levels for air voids, thickness, and riding quality. Although the quality under this specification has ranged from good to excellent, a national survey recently conducted by the New Jersey Department of Transportation (NJDOT) suggests that pavement performance is more appropriately characterized by an additive function than by the average of the individual quality measures. A new pay schedule, developed from a combination of performance and analytical data and the opinion survey, produces larger bonuses for superior quality and larger pay reductions for poor quality. NJDOT engineers realized that the original rejectable-quality-level provision based on individual quality measures did not account for the combined effect of deficient quality in two or more quality measures. The use of a composite quality measure not only corrects these deficiencies but also makes it possible to key the pay equation more directly to performance while substantially reducing the complexity of the acceptance procedure as a whole. Consequently, the new procedure is closer to a true performance-related specification and is simpler to understand and apply than its predecessors. The new version of the specification was developed cooperatively through a task force representing NJDOT, FHWA, and several industry associations and is currently under test on a series of pilot projects.
Effect of Flat and Elongated Coarse Aggregate on Field Compaction of Hot-Mix Asphalt
Authors: Aho Brian D. , Vavrik William R. , Carpenter Samuel H.
Published: April 2007

It has long been believed that coarse aggregates that have a flat and elongated (F&E) shape are detrimental to the properties of hot-mix asphalt. Several attempts have been made to establish a relationship between these aggregate particles and performance. It is believed that decreased performance may result from either aggregate breakage or less than optimum particle orientation. The question of mixture performance is set aside, and the focus is on the construction effects in asphalt mixtures with high percentages of F&E aggregate. Research shows that for a given gradation and aggregate type, increasing the percentage of F&E will increase the amount of aggregate breakdown. One focus is to determine if the same relationship between percentage of F&E particles and breakdown that has been documented in laboratory settings can be observed in the field. The other focus is on a comparison of the aggregate breakdown caused by the gyratory compactor with the aggregate breakdown in the field.
Field Conditioning of Superpave Asphalt Mixes
Authors: Musselman James A. , Page Gale C. , Sholar Gregory A.
Published: April 2007

Failing volumetric properties (low air voids and voids in mineral aggregate) have been a common occurrence in the production of Superpave mixes in Florida and nationally. There are several potential causes of this problem including the effect of asphalt absorption as related to conditioning time. Research was done to determine ( a) whether the 2-h force-draft oven conditioning adequately simulates actual roadway conditions and ( b) how actual roadway conditions can best be simulated when the asphalt mixture is sampled and tested immediately following production at the plant. The results indicate the following: ( a) 3 h of conditioning during design best correlated with roadway conditions; ( b) a 1-h conditioning time at the asphalt plant resulted in maximum specific gravity values that best correlated with roadway conditions; ( c) 1 h of conditioning at the asphalt plant increased the air voids of the mix by 0.5 percent for absorptive materials and 0.25 percent for nonabsorptive materials; and ( d) conditioning had minimal effect on bulk density values.
Theory Behind Vibration-Based, Onboard Asphalt Density Measuring System
Authors: Edward Minchin R. , Randolph Thomas H. , Swanson David C.
Published: April 2007

For more than 25 years, the hot-mix asphalt paving industry has been searching for a device that can produce accurate, real-time asphalt density readings during the compaction process. A system was developed using data gathered from department of transportation (DOT) paving projects in five states and validated through testing on DOT projects in two other states. The results indicate that through a system of sensors, an onboard computer, and radio transmissions, the onboard density-measuring system provides accurate asphalt density readings in real time and transmits the information to remote locations while building and maintaining a file of all pertinent data on the asphalt compaction process. Insight into the asphalt paving process and results showing the relationship between the vibratory signature of a vibratory asphalt compactor and the density of the asphalt mat compacted are provided.
Statistically Based Methods for Verification Testing
Authors: Schmitt Robert L. , Hanna Awad S. , Russell Jeffrey S. , Nordheim Erik V.
Published: April 2007

State highway agencies currently use split-sample and independent-sample verification procedures for the purpose of comparing test results or verifying the contractor’s overall construction process in independent assurance (IA) programs and quality assurance (QA) construction specifications. Sampling procedures are reviewed, and new statistically based methods for developing comparison procedures in both IA programs and QA specifications are presented. The statistically based approach determines an appropriate mean difference between either split-sample test results or independent-sample verification results by recognizing sample size, field variability, and inherent risks. A practical application is given using collected field data from hot-mix asphalt (HMA) construction projects. State highway agencies and contractors will benefit from an understanding of the statistical concepts involved with split-sample and independent-sample comparison procedures and of what information an agency needs to determine if a contractor’s overall test results are accurate. The concepts and procedures presented can be applied to all areas of highway construction involving split-sample and independent-sample verification tests, such as base materials, concrete structures and pavements, and HMA pavements.
Derivation of Equation for Cost of Premature Pavement Failure
Authors: Weed Richard M.
Published: April 2007

With the continuing interest in performance-related specifications and the development of software packages to compute the appropriate level of payment associated with variable levels of quality, there is a need for a simple, easily understood method to validate the output of these computer programs. A standard validation procedure is to create realistic hypothetical cases that can be calculated readily by hand and then to compare the results with the output of the procedure under test. An equation is derived that can serve two extremely useful purposes: it can be used as a validation tool for software currently under development, or it can be used directly to establish pay schedules that award payment appropriate for the level of quality received.
Overview of National Wood in Transportation Program and Its Focus on Commercializing Proven Technology
Authors: Cesa Edward T. , Eriksson Merv , Tice Ed , Lemon Janet L.
Published: April 2007

A significant opportunity exists in the United States to improve local transportation networks and to assist in revitalizing local economies by using wood for bridges and other transportation structures. Modern timber bridge technology provides an opportunity to improve transportation infrastructure, particularly bridges on single- and double-lane rural roads. To address this issue, the U.S. Congress provided funding to the U.S. Department of Agriculture’s Forest Service in 1989 for a program called Wood in Transportation (WIT), formerly known as the National Timber Bridge Initiative. The program has three key components: ( a) demonstration projects, ( b) research, and ( c) technology transfer and information management. The current focus of the demonstration projects is on funding approximately four large-scale “commercialization” projects per year that result in the construction of three or more structures. The intended outcome of these projects is to develop structures that showcase WIT technology and provide useful design and cost information to potential users throughout the nation. These projects build on past knowledge gained from research and other previously funded projects. The successful completion of three commercialization projects is highlighted. The first one was in Yellowstone County, Montana, where three glued-laminated timber bridges were designed, fabricated, and installed in 1998. The second project was in Ida County, Iowa, where five cotton-wood glued-laminated deck bridges, supported by either steel beams or glued-laminated beams, were designed, fabricated, and installed in 1999. The third project was in West Virginia, where nine timber decks with steel-beam bridges were constructed on “orphan roads” in 1999.
Lessons-Learned System for Highway Constructibility
Authors: Khwaja Nabeel A. , O’Connor James T.
Published: April 2007

A 14.5-km (9-mi) stretch of the North Central Expressway in Dallas, Texas, was reconstructed to increase capacity and improve the geometric design of the freeway. The decade-long reconstruction project is considered by many industry experts to be one of the most complex ever undertaken by the Texas Department of Transportation. Much was learned concerning constructibility of urban freeway reconstruction projects, presenting the opportunity to document lessons and store them in an electronic format. A relational database using Microsoft Access was created to classify and store the lessons for easy retrieval and distribution.
Allocation of Risks Under Build-Operate-Transfer Delivery Approach for Transport Infrastructure Projects
Authors: Abdul-Malak Mohamed-Asem U. , Kaysi Isam A. , Schoucair Marwan S.
Published: April 2007

The need for the build-operate-transfer (BOT) approach in the development of infrastructure projects has risen in recent years, due to budgetary and financial constraints faced by the public sector in both developing and developed countries, tightened by the necessity to repair, maintain, and modernize the existing infrastructure facilities. Risk factors that influence the parties of a prospective BOT contract during the various phases of the contract are presented. In particular, the factors pertaining to the precontract stage and to the political, construction, commercial, and financial categories of possible risks are addressed. Integrated schemes assimilating the risks involved and the corresponding alleviation measures are offered.
Environmental and Economic Effects of E-Commerce: A Case Study of Book Publishing and Retail Logistics
Authors: Scott Matthews H. , Hendrickson Chris T. , Soh Denise L.
Published: April 2007

The advent of the Internet and e-commerce has brought a new way of marketing and selling many products, including books. The systemwide effects of this retailing shift on costs and the environment are still unclear. Although reductions in inventories and returns provide significant environmental savings, some major concerns of the new e-commerce business models are the energy and packaging materials used by the logistics networks for product fulfillment and delivery. This study analyzes the different logistics networks and assesses the environmental and cost effects of different delivery systems. The definition of analysis system boundaries determines the overall assessment of economic and environmental effects of e-commerce for book retailing. With a return (remainder) rate of 35 percent for best-selling books, e-commerce logistics costs less and has fewer environmental effects, especially if private automobile travel for shopping is included. Excluding the need to return books, costs and environmental effects are comparable for the two delivery methods.
Traffic Simulation at International Ports of Entry: El Paso-Mexico Case Study
Authors: Ashur Suleiman , Weissmann José , Perez Sonia , Weissmann Angela J.
Published: April 2007

Since the implementation of the North American Free Trade Agreement (NAFTA) in 1993, international commercial traffic has grown significantly. Texas has been the largest port of entry for trade at the U.S.-Mexico border since 1994, accounting for approximately 75 percent of the trade. Under NAFTA, FHWA predicts that trade through Texas could increase up to 120 percent in the coming years. Texas has 18 border sectors with Mexico, many of which have congestion primarily caused by ineffective interaction among inspection procedures and traffic management or lack of adequate transportation planning. A simulation model, developed using a general-purpose industrial engineering simulation package, can help determine the best alternative for preventing congestion at the ports of entry and the associated traffic operation effects on the road network adjoining the international bridges, while yet maintaining an adequate inspection of commercial trucks. A case study of the Ysleta-Zaragoza Bridge in El Paso, Texas, is presented. The simulation shows that the traffic flow at the Ysleta-Zaragoza Bridge is efficient with the current infrastructure and traffic operations. However, the expected future increase in traffic volume will generate a spill-back into major freeways close to the bridge. A proposed solution to this problem is presented.
Freight Trucking in a Sustainable Transportation System: Framework for Analysis
Authors: Richardson Barbara C.
Published: April 2007

A framework is presented for analysis of the long-term sustainability of freight trucking in the context of the intermodal freight transportation system. The role of the trucking industry among other transportation modes is described, including an explanation of transportation system sustainability. Topics include the present view of issues surrounding the trucking industry in a sustainable transportation system; views of students, academia, and industry on freight trucking in a sustainable transportation system; and a framework to use in analyzing the role of government and industry in moving toward sustainability. This framework brings into perspective the conditions of transportation system sustainability and freight trucking factors affecting it. The findings are based on data collected through a literature search, a set of focused discussions, and a survey of freight trucking company executives.
Effect of Increased Truck Traffic from Chickamauga Lock Closure
Authors: Chatterjee Arun , Wegmann Frederick J. , Mike Jackson N. , Everett Jerry D. , Bray Larry G.
Published: April 2007

The lock at Chickamauga Dam on the Tennessee River may have to close for various periods for major repair work. Such scheduled or unscheduled closures will disrupt the barge traffic serving many industries located upstream of the dam. Some of the commodities moving on barges will be diverted to trucks, depending on the nature of the closures, and the new truck traffic may result in a variety of effects, or externalities. A method is presented to estimate the effects of increased truck traffic. Delays from traffic congestion and incidents, pavement damage, truck-related accidents, and air pollution are examined. The study was performed for the Tennessee Valley Authority.
Innovative Application for Dynamic Navigational Support and Transport Management on Inland Waterways: Experience from a Research Project on the Danube River
Authors: Pfliegl Reinhard
Published: April 2007

The widespread use of inland waterways as a common transport mode is a main objective of European traffic policy, specifically in view of the expected dramatic increase in transport along the Trans-European Network, a main economic lifeline in Europe. Transport operators’ limited acceptance of the inland waterway reflects unreliable calculations of estimated time of arrival, shifting water levels or other environmental events, unexpected delays in passing locks and borders, and insufficient transport monitoring capability. Implementing a telematics-based river information service will help to alleviate waterway transportation problems on the Danube River early in the day and improve the safety and productivity of transportation by integrating river-based transport information services with the intermodal transport chain. The proposed system meets the requirements of the Supreme Shipping Authority of Austria to generate a tactical and strategic traffic image on the Danube in Austria to fulfill its legal commitments to ensure safe and secure transport operations on the Danube. Communications interfaces will link the Austrian network connecting other users downstream as well (e.g., Hungary, Slovakia). Traffic information services will be provided to ship operators, ship owners, and transport operators carrying people and goods. The system consists of a transponder-based network using radio links embedded in a wire-based communications network on shore controlled by central management facilities providing tactical traffic information on a geographic-information-system-based application. A separate system and network management unit will ensure safe operations with a low failure rate, depending on the level of redundancy implemented. The overall system concept uses the results and provisional standards defined in the European Union project Inland Navigation Demonstrator for River Information Services. The basic functionality of the system was demonstrated in a field trial near Hinesburg, Austria, in mid-April 1999, and in Grain, Austria, in November 1999. The main system will be developed in a test center in Vienna during 2001 and 2002.
Which Method Is Better for Developing Freight Planning Models at Seaports—Neural Networks or Multiple Regression?
Authors: Al-Deek Haitham M.
Published: April 2007

Ports are the primary generators of freight traffic in the United States. Seaport operations will require operational and infrastructure changes to maintain the growth of international cargo operations. Truck and rail trip generation and modal split models will provide transportation planners and public agencies with valuable information for prioritizing funds for roadway upgrade projects and port infrastructure modifications. Two methods are presented for developing freight trip generation models—regression analysis and back-propagation neural networks. These models are applied in predicting the levels of cargo truck traffic moving inbound and outbound at seaports. For the Port of Miami, the back-propagation neural network model was more accurate than the regression analysis model. However, the neural network model requires a sizable database. A second application of the back-propagation neural networks approach developed a truck trip generation model and a truck-rail modal split model for the Port of Jacksonville. The primary factors affecting truck and rail volume were found to be the amount and direction of cargo vessel freight, commodity type (bulk, break bulk, or liquid bulk), and weekday of operation. In summary, the neural network model results were found significantly accurate for both Florida ports.
Freight Ferries in New York–New Jersey Harbor: How to Make Them Happen
Authors: Weisbrod Roberta E.
Published: April 2007

The potential for freight ferries in New York–New Jersey harbor is examined. Freight ferries are defined as fast ferries transporting high-value, time-sensitive cargo, particularly air cargo, but also courier packages and even premium passengers. The proposal by a private entity for freight ferries is consistent with the trends toward increased use of fast ferries nationally, and the incipient use of these ferries at several worldwide locations. In the greater New York–New Jersey metropolitan area, freight ferries offer several opportunities. These ferries help to remedy the ongoing problem of congestion in the New York–New Jersey metropolitan area, particularly on roads and at crossings associated with air cargo surface delivery. Air cargo brings high economic value to the region, but the congestion problem must be resolved to maintain that contribution. Freight ferries create synergies with other freight and passenger delivery services. These ferries can also spur redevelopment of waterfront communities, particularly those waterfront locations isolated from the rest of the metropolitan area. However, implementing freight ferries has its obstacles. The major hurdle is finding appropriate landing sites, which is difficult because of competing uses, failure to plan for landing sites, and labor considerations. Safety and air quality issues also need to be addressed. Elements of a bold plan to make freight ferries happen in the New York–New Jersey metropolitan region are suggested.
Threat Assessment of Hazardous Materials Transportation in Aircraft Cargo Compartments
Authors: LaFrance-Linden Dawn , Watson Spencer , Haines Marsha J.
Published: April 2007

The Volpe National Transportation Systems Center of the U.S. Department of Transportation’s (DOT) Research and Special Programs Administration (RSPA) has conducted a quantitative threat assessment for RSPA’s Office of Hazardous Materials Safety (OHMS) to determine the probability of a life-threatening incident occurring as the result of transporting hazardous materials in aircraft cargo compartments. The study team developed a threat assessment model using an event tree method and threat scenarios that were refined with the assistance of a panel of experts, which contributed potential countermeasures, suggested experimental tests, and provided input data for the model. Additional input was developed from data collected by OHMS, the Volpe study team, and support contractors. The threat scenarios were developed using three possible cases: (a) packages that comply with DOT regulations for shipment on passenger flights; (b) packages that comply with DOT regulations for shipment on cargo-only flights; and (c) packages that do not comply with DOT regulations for air transport. Materials chosen for each hazardous material class and division represented the worst-case situation for air shipments (materials that are among the more dangerous in their class or division, commercially available, and likely to be transported by air). The specific chemical, physical, and toxicological properties of these materials were used as input. The model calculated the likelihood of life-threatening incidents on the basis of a package containing the selected material being on board, specific cargo compartment type, and the package’s state of compliance.
Procedure for Use of Falling Weight Deflectometer to Determine AASHTO Layer Coefficients
Authors: Pologruto Michael
Published: April 2007

The AASHTO pavement design model is one of the most widely used empirical design models for flexible pavement design. A factor complicating its utility is the use of an abstract quality, the structural number (SN), to quantify the strength of the total pavement structure. A consequence of the use of SN is the need for structural layer coefficients to characterize the component materials of the pavement structure. These layer coefficients are difficult to assess directly. However, a method for determination of layer coefficients with a falling weight deflectometer (FWD) that are representative of the in situ behavior of the pavement materials is presented. This method is based on a model provided in the 1993 edition of the AASHTO Guide for Design of Pavement Structures for assessment of the effective SN. The Vermont Agency of Transportation (VTrans) has established a procedure that uses FWD data and the AASHTO effective SN model to characterize layer coefficients for Vermont pavement materials. VTrans found that the layer coefficients determined for unbound subbases were reasonable, whereas layer coefficients estimated for asphalt cement concrete materials were generally 25 to 35 percent higher than AASHTO’s implied maximum of 0.44. However, a statistical analysis indicates considerable support for the predictive qualities of FWD-derived layer coefficients to approximate the in situ layer coefficients estimated by an elastic layer simulation.
DIPLODEF: A Unified Backcalculation System for Asphalt and Concrete Pavements
Authors: Kothandram Sathyanarayanan , Ioannides Anastasios M.
Published: April 2007

The absence of a single backcalculation program that can incorporate all combinations of the four widely used pavement models (elastic layer, plate, elastic solid, and dense liquid) deprives the pavement community of the ability to perform comparative studies. The program DIPLODEF was developed to analyze both asphalt concrete and portland cement concrete pavement systems. The new code was assembled from an existing backcalculation program called WESDEF by replacement of its engine, WESLEA, with DIPLOMAT. In addition to the elastic layer and elastic solid models, DIPLOMAT can accommodate the plate and dense liquid idealizations and can analyze multilayer asphalt and concrete pavement systems with user-defined inputs. DIPLODEF has been thoroughly debugged and tested for consistency and reasonableness. Analyses involving various combinations of elastic layers, plates, and springs were performed. Finally, a rating scheme was devised to standardize the assessment of the precision of backcalculated values and permit consistency in comparisons of results.