bluuebunny/crossref_metadata_2025 huggingface dataset:
Ventricular Fibrillation and the Use of Automated External Defibrillators on Children
Authors:   Committee on Pediatric Emergency Medicine and Section on Cardiology and Cardiac Surgery
Published: October 2007

The use of automated external defibrillators (AEDs) has been advocated in recent years as one part of the chain of survival to improve outcomes for adult cardiac arrest victims. When AEDs first entered the market, they had not been tested for pediatric usage and rhythm interpretation. In addition, the presumption was that children do not experience ventricular fibrillation, so they would not benefit from the use of AEDs. Recent literature has shown that children do experience ventricular fibrillation, which has a better outcome than do other cardiac arrest rhythms. At the same time, the arrhythmia software on AEDs has become more extensive and validated for children, and attenuation devices have become available to downregulate the energy delivered by AEDs to allow their use on children. Pediatricians are now being asked whether AED programs should be implemented, and where they are being implemented, pediatricians are being asked to provide guidance on the use of them on children. As AED programs expand, pediatricians must advocate on behalf of children so that their needs are accounted for. For pediatricians to be able to provide guidance and ensure that children are included in AED programs, it is important for pediatricians to know how AEDs work, be up-to-date on the literature regarding pediatric fibrillation and energy delivery, and understand the role of AEDs as life-saving interventions for children.
Mortality and Exploitation Rate Estimates for the Recreational Bay Scallop Fishery off the Gulf Coast of Florida, USA
Authors: Greenawalt-Boswell Jaime , Frazer Thomas K. , Jacoby Charles A. , Arnold William S.
Published: October 2007

Historically, the bay scallop Argopecten irradians supported recreational and commercial fisheries along Florida's Gulf Coast. Declines in density led to a ban on commercial fishing and tighter regulation of recreational fishing. In support of sustainable management, we derived estimates of mortality and exploitation from a multiyear series of preharvest and postharvest surveys of bay scallop density at five locations; catch curves from two locations during 3 years; and an aerial survey of recreational effort. Surveys at locations not subject to harvest yielded natural mortality estimates from which we derived estimates of fishing mortality and exploitation. Based solely on preharvest and postharvest surveys, we estimated the seasonal exploitation rate (u) as 0.0684. Based on all relevant surveys of bay scallop density, we calculated means and 95% confidence intervals for actual seasonal mortality (A = 0.6365 ± 0.06833), daily instantaneous total mortality (Z = 0.0153 ± 0.00293), daily instantaneous natural mortality (M = 0.0145 ± 0.00314), and daily instantaneous fishing mortality (F = 0.0013 ± 0.0055; 0.0000 replaced the negative lower confidence limit in further calculations). We used the means and confidence limits for M and F to calculate a mean and range for u (mean = 0.0575, range = 0.0000–0.2335). Effort on weekends and holidays was significantly greater than effort on weekdays. Data on effort and harvest generated u-values of 0.1244 at Homosassa and 0.1667 at Steinhatchee. Overall, our results confirm that natural mortality is substantially higher than fishing mortality for bay scallops. Simulations indicated that current levels of harvest, current bag limits, and potential variations in catches are unlikely to extirpate bay scallops if initial densities are at least 25 scallops/600 m2 and if u stays within the calculated range. Our data did not indicate significant compensatory or depensatory mortality.
The Effects of Boat Propeller Scarring on Nekton Growth in Subtropical Seagrass Meadows
Authors: Burfeind Dana D. , Stunz Gregory W.
Published: October 2007

An increasing boating population has led to extensive propeller scarring in many shallow seagrass meadows, and research has focused on relating scarring to nekton abundance; however, little information exists on the impacts on habitat functionality. In this study we moved beyond simple measures of faunal density as an indicator of habitat quality by comparing the growth rates of common estuarine nekton in different levels of propeller scarring in Redfish Bay, Texas. Growth rates of selected fauna were examined by using field enclosures and otolith microstructure analysis. Otolith microstructure analysis on pinfish Lagodon rhomboides indicated no difference in growth rates at various scarring intensities. We conducted field growth enclosure experiments on a common decapod crustacean, the white shrimp Litopenaeus setiferus. White shrimp showed significantly lower growth in highly scarred areas than in reference sites. These results suggest that regions of low‐level propeller scarring (less than 15%) may have little effect on small‐scale habitat quality. However, higher levels of propeller scarring may affect habitat quality; therefore, more information is needed to characterize the large‐scale effects of propellers at higher scarring intensities.
Determinants of salivary cotinine level: a population-based study in Brazil
Authors: Figueiredo Valeska Carvalho , Szklo Moyses , Szklo André Salem , Benowitz Neal , Lozana José Azevedo , Casado Leticia , Masson Elaine , Samet Jonathan
Published: October 2007

OBJECTIVE: A cross-sectional population-based study was conducted to assess, in active smokers, the relationship of number of cigarettes smoked and other characteristics to salivary cotinine concentrations. METHODS: A random sample of active smokers aged 15 years or older was selected using a stepwise cluster sample strategy, in the year 2000 in Rio de Janeiro, Brazil. The study included 401 subjects. Salivary cotinine concentration was determined using gas chromatography with nitrogen-phosphorus detection. A standard questionnaire was used to collect demographic and smoking behavioral data. The relation between the number of cigarettes smoked in the last 24h and cotinine level was examined by means of a nonparametric fitting technique of robust locally weighted regression. RESULTS: Significantly (p<0.05) higher adjusted mean cotinine levels were found in subjects smoking their first cigarette within five minutes after waking up, and in those smoking 1-20 cigarettes in the last 24h who reported inhaling more than ½ the time. In those smoking 1-20 cigarettes, the slope was significantly higher for those subjects waiting for more than five minutes before smoking their first cigarette after waking up, and those smoking "light" cigarettes when compared with their counterparts. These heterogeneities became negligible and non-significant when subjects with cotinine >40 ng/mL per cigarette were excluded. CONCLUSIONS: There was found a positive association between self-reporting smoking five minutes after waking up, and inhaling more than ½ the time are consistent and higher cotinine levels. These can be markers of dependence and higher nicotine intake. Salivary cotinine proved to be a useful biomarker of recent smoking and can be used in epidemiological studies and smoking cessation programs.
Twenty-five years of the AIDS epidemic in Brazil: principal epidemiological findings, 1980-2005
Authors: Fonseca Maria Goretti P. , Bastos Francisco I.
Published: October 2007

The Brazilian AIDS epidemic is undergoing important changes in its third decade. The present article reviews some central findings: the proportional reduction in cases related to injection drug use; the stability, in recent years, of new cases in the male homosexual/bisexual population; and the relative and absolute increment in heterosexual transmission, even though the estimates of incident rates still point to the first two categories mentioned as those most affected by the epidemic. Still should be detached the persistent increase in incidence rates among women and its stability in the younger age groups, probably the result of behavior changes (such as the consistent use among youth of condoms in sexual relations with casual partners and a reduction in cases related to injection drug use). It is well-know that HIV prevalence in the general population has stabilized at less than 1%, which characterizes Brazil as one of the countries with a concentrated epidemic. The article also emphasizes the growth of AIDS morbidity-mortality in the less favored socioeconomic strata and in women, and the stability of the mortality rate among men.
Control of mother-to-child transmission of infectious diseases in Brazil: progress in HIV/AIDS and failure in congenital syphilis
Authors: Ramos Jr. Alberto Novaes , Matida Luiza Harunari , Saraceni Valéria , Veras Maria Amélia de S. M. , Pontes Ricardo José Soares
Published: October 2007

In Brazil, syphilis and HIV infection are considered serious public health problems. However, in practice, epidemiological surveillance, prevention measures, and prenatal care seem to be more effective in the control of mother-to-child transmission of the HIV than in the control of transmission of the Treponema pallidum. Here we discuss the differences in surveillance, prenatal care, and care of the newborn. Important differences were identified. It is concluded that there is an urgent need to establish prevention of mother-to-child transmission of syphilis as a public health priority, using an integrated approach including women's health, children's health, primary health care, and STD/AIDS programs on all governmental levels. These issues also need to be discussed with all stakeholders involved. Important aspects related to the problem are the training of public health professionals, as well as the participation of the community. The elimination of congenital syphilis does not require expensive drugs, and diagnostic tools, but a long-term sustainable approach.
Mother-to-child transmission of HIV in Brazil during the years 2000 and 2001: results of a multi-centric study
Authors: Succi Regina Célia de Menezes
Published: October 2007

The objective of this study was to assess mother-to-child transmission rates of HIV in Brazil during the years 2000 and 2001, and to identify the maternal and neonatal variables that were associated with this transmission. It was a cross-sectional, observational study with retrospective data obtained from patient medical records. The children were followed at 63 medical sites situated in five geographical macro-regions of the country (20 States and the Federal Capital). Children enrolled were those that were born of HIV-infected mothers and it was necessary for the mothers to present documented proof of HIV-infection before or during pregnancy, at time of delivery or in the first three months after delivery. There were 2,924 children enrolled and mother-to-child transmission rates of HIV were 8.6% (95%CI: 7.2-10.2) for the year 2000 and 7.1% (95%CI: 5.8-8.6) for the year 2001. The following variables were associated with lower mother-to-child transmission rates of HIV: elective cesarean section, diagnosis of mother's infection before or during pregnancy, access to HIV viral load and T CD4+ lymphocyte count during prenatal care, greater birth weight and avoidance of breastfeeding.
Our (not so) polyglot pollies
Authors: Lo Bianco Joseph
Published: October 2007

The present article reports on research conducted during late 2004 on the language abilities of Australia’s parliamentarians and a parliamentary debate in 2005 on languages in Australia. A small questionnaire was administered to all members of the nine legislative structures of Australia comprising six states, two territories and the one Federal parliament. This is the first such survey in Australia. While the response rate was uneven, from good to poor, the survey does shed light on the range and number of languages other than English spoken by Australia’s parliamentary representatives, where their language capabilities were gained, how proficient they estimate themselves to be, and in what settings their language skills are used. The paper includes a comparison between these Australian data and equivalent, though slightly less sketchy, data from the UK. The article concludes with the text and debate of a recent private members’ bill on languages and makes comments on the responses in light of the language abilities of the parliamentarians.
Dynamics of Photoinduced Interfacial Electron Transfer and Charge Transport in Dye-Sensitized Mesoscopic Semiconductors
Authors: Thorsmølle Verner K. , Wenger Bernard , Teuscher Joël , Bauer Christophe , Moser Jacques-E.
Published: October 2007

Molecular systems designed for the conversion of solar energy offer ideal models in the study of the kinetics of light-induced electron transfer at surfaces. Due to their high porosity, nanocrystalline oxide semiconductor films allow investigations of interfacial and lateral charge
transfer processes that are barely detectable on flat surfaces. Although it has proven to be very promising, the redox photochemistry of the metal oxide | molecular monolayer | electrolyte interface is still a largely unexplored scientific domain, offering huge potential for investigation
and exploitation of physical and chemical processes. Carrier trapping and charge transport are also key to the efficiency of molecular photonic devices. Carrier dynamics and transport in unconventional media are studied utilizing THz time domain spectroscopy. We summarize here some aspects
of the work currently carried out in these fields as part of our continued effort in the fundamental study of the dynamics of photoinduced electron transfer processes.
Photochemistry of Reactive Intermediates
Authors: Bally Thomas
Published: October 2007

This paper illustrates the research on the photochemistry of reactive intermediates that was (and still is) carried out in the author's research group on three typical examples: the photochemistry of arylcarbenes, arylnitrenes, and organic radical cations.
Photolatent Tertiary Amines – A New Technology Platform for Radiation Curing
Authors: Dietliker Kurt , Jung Tunja , Studer Katia , Benkhoff Johannes
Published: October 2007

The lack of efficient photolatent amine catalysts has so far prevented the use of base-catalyzed formulations in radiation curing. The development of two new photocatalysts which release 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) or tertiary amines upon irradiation opens new opportunities
for this technology. Photolatent DBN is used for crosslinking processes where strong bases are required as catalyst, such as coatings crosslinked via the Michael addition reaction, while a tertiary amine efficiently catalyzes reactions involving more acidic compounds. A UV-A curable
car refinish clear lacquer has been developed as a first example of a commercial formulation using a photolatent amine as catalyst.
Applied Photochemistry – Light Controlled Perfume Release
Authors: Derrer Samuel , Flachsmann Felix , Plessis Caroline , Stang Melanie
Published: October 2007

Ambient light is one of the most suitable available trigger conditions for the release of covalently bound volatile odorants in home- and laundry-care applications. We report on three complementary classes of light-cleavable fragrance precursors, covering the controlled release of odorants
with a wide range of functional groups. o-Hydroxy cinnamates 1 undergo a UV-induced double bond isomerization followed by transesterification to release coumarin and a fragrance alcohol of choice. ?-Alkoxyacetophenones 10 and ?,?-dialkoxyacetophenones
12 undergo Norrish type II fragmentations upon UV-irradiation, thereby releasing one or two equivalents of fragrant aldehydes, respectively. Finally, photoexcited Xanthenoic esters 22 undergo fragmentation to release reactive acyl radicals, which further cyclize onto internal
olefins to form perfumery lactones of various ring sizes.
Continuous Process Engineering with Microreactors: A Complementary Method in Fribourg
Authors: Naef Olivier
Published: October 2007

Microreactors are discussed as a complementary tool for chemical development. Two reactions were studied: the formation of an ionic liquid, the 3-butyl-1-methylimidazolium bromide is presented, and the synthesis of cinnamaldehyde.
Effects of forest certification towards sustainable community forestry in Nepal
Authors: Kandel Pem N
Published: October 2007

In early 2005, 10,045 ha Community Forests (CFs) were certified in Bajhang and Dolakha districts of Nepal by using the Forest Stewardship Council (FSC) certification scheme. After two years of forest certification, subsequent questions are being asked such as: What benefits have certification brought for the Forest Users Groups (FUGs)? What tangible differences are there in forest management system because of forest certification? and What lessons have been learnt from the certified forests? In an attempt to answer these questions, a study was carried out in April 2007 in Dolakha district where 11 (2,182 ha) community managed forests were certified in 2005. On the basis of field study from two certified forests (Vitteripakha and Suspa) of the district, this paper analyzes the effects of forest certification and its implications for enhancing Sustainable Community Forestry (SCF) in Nepal.

Key words: Sustainable forest management, forest certification, community forestry

Banko Janakari: A journal of forestry information for Nepal Vol.17(1) 2007 pp.11-16
Evaluating collaborative management of forest from Rangapur CFM, Rautahat
Authors: Poudel Mohan
Published: October 2007

Collaborative Forest Management (CFM) is the youngest forestry program implemented so far in Nepal focusing on sustainable management of the Nepal’s productive Terai forest. It has been defined as working partnership between the key stakeholders in the management of the given forest. CFM aims to manage the Terai forest through involvement of the local people in decision making, implementation, benefit sharing and monitoring along with local government bodies (DDC, VDC) and national forest authority (DFO). Rangapur is one of the three pilot CFM sites comprising 1472 ha forest with 22 VDCs and a Municipality as command-area in Rautahat district of Nepal. Despite several promising impacts, some weaknesses and threats of CFM have also been realized within its two years of implementation in Rangapur. This paper assesses and evaluates major achievements, strengths, weaknesses, threats and opportunities of CFM hoping useful towards sustainability.

Key words: Sustainability, partnership, stakeholders, Rangapur, pilot

Banko Janakari: A journal of forestry information for Nepal Vol.17(1) 2007 pp.32-38
Experimentation with Gray Theory for Pavement Smoothness Prediction
Authors: Wang Kelvin C. P. , Li Qiang , Hall Kevin D. , Elliott Robert P.
Published: October 2007

Riding quality is a dominant characteristic of pavement performance. In the proposed mechanistic–empirical pavement design guide (MEPDG), the functional performance indicator is pavement smoothness as indicated by the international roughness index (IRI). The MEPDG IRI prediction models were developed on the basis of a general hypothesis in which changes in smoothness are caused in part by various distresses, which can be predicted. With pavement distress data from the Long-Term Pavement Performance (LTPP) database, traditional regression analysis was used statistically to establish the MEPDG prediction equations. The gray system theory was devised in the 1980s for modeling uncertain systems with the characteristics of partially known information. A pavement performance prediction system can fit the domain of the gray system. The gray theory–based prediction method was used to develop IRI prediction equations. With the data exported from the LTPP database, it was found that certain specific distresses significantly affect the accuracy of the predictions. Combined with the results of gray relational analysis and the gray prediction methodology, gray model–based smoothness predictions are established by using influencing factors similar to those used in MEPDG. From comparisons of results from the two prediction methodologies with actual LTPP data, it is shown that the gray model–based method provides promising results and is useful for modeling pavement performance.
Changes in Key Flexible Pavement Condition Measurements for Typical Warranty Periods
Authors: Stroup-Gardiner Mary , Zech Wesley C. , Rathod Jignesh
Published: October 2007

The Long-Term Pavement Performance (LTPP) DataPave database was used to extract pavement condition and limited structural information along with traffic data for 191 randomly selected new asphalt pavement sections from across the country. Pavement performance data were limited to the collection of longitudinal cracking in the wheelpaths, fatigue cracking, and transverse cracking. Rather than models for the type and extent of pavement distresses with age, a simplified process that coded the database for the first occurrence of a given distress in each of the 191 new test sections was developed. This approach was used to determine the percentage of pavements exhibiting a given type of distress at 3, 5, 7, 10, 15, and 20 years. The results indicate the following: at 3 years, no longitudinal, fatigue, or transverse cracking is present; at 5 years, less than 2% of the sections experienced longitudinal (wheelpath), fatigue, or transverse cracking; at 7 years, between 3% and 6% of the sections exhibited longitudinal, fatigue, or thermal cracking; at 15 years, approximately 50% of sections showed signs of cracking distresses; at 20 years, between 60% and 70% of the sections contained excessive cracking.
Dynamic Probabilistic Approach for Long-Term Pavement Restoration Program with Added User Cost
Authors: Abaza Khaled A. , Murad Maher M.
Published: October 2007

A dynamic probabilistic-based approach has been developed for generating a long-term pavement restoration program for a given pavement system. The probabilistic approach applies the basic principles of stochastic processes to predict pavement conditions. Initial state probabilities and transition probabilities are the two main parameters required to develop the future state probability functions used in formulating an effective optimum decision policy. The future state probabilities are only functions of the restoration variables representing potential restoration actions. An optimum decision policy is deployed to yield a pavement restoration program comprising ( n) restoration plans corresponding to ( n) transitions. The derived pavement restoration program takes into consideration the long-term transitional performance and budget requirements. The applied decision policy is based on either maximizing the expected system condition ratings subjected to budget constraints or minimizing the net system costs subjected to desired expected system condition ratings. The net system cost may include restoration cost, deteriorated pavement added user cost, and work-zone added user cost. The two decision policy options are subjected to other constraints placing limits on the state probability functions and restoration variables. The restoration variables as applied to state probability functions result in optimum models that are sequentially solved to maintain their linearity. Sample results from a case study have indicated the usefulness of the developed dynamic probabilistic approach in yielding potential long-term pavement restoration programs.
Methodology of Applying Heavy Weight Deflectometer for Calculation of Runway Pavement Classification Number
Authors: Chou Chia-Pei , Wang Shih-Ying , Tsai Chen-Yu
Published: October 2007

The International Civil Aviation Organization requires every airport that serves commercial airline operations to publish its pavement classification number (PCN) in its own aeronautical information publication. This number is defined as a number expressing the bearing strength of a pavement for unrestricted operations. Likewise, each airline must provide the aircraft classification number (ACN) that corresponds to each type of aircraft it operates. Only when the aircraft's ACN is less than the airport's PCN is the aircraft allowed to land with its maximum landing weight. Otherwise, the aircraft is restricted to a certain weight limit. There are two ways to determine the PCN: the using aircraft method and the technical method. Many airports chose to determine the PCN by the using aircraft method because of its simplicity. However, the technical method, which can specify the pavement structural bearing capacity more accurately, can give a more precise PCN than the using aircraft method. An in-depth description of the establishment of a technical methodology for determining PCNs by applying the heavy weight deflectometer field data is presented. A practical case study of a runway with two kinds of slab thickness mixed with two types of subgrade strengths is introduced for calculating the PCN through the established methodology.
Performance-Specified Maintenance Contracts
Authors: Manion Mike , Tighe Susan L.
Published: October 2007

In Australia and New Zealand, there has been a movement toward the private-sector delivery of road maintenance and management by using the performance-specified contract (PSMC) model. These are long-term contracts tendered competitively with a lump sum price. Initially the contracts concentrated on the physical attributes of the network that had to be maintained for the contract period. However, as these contracts matured, a reduction in the crash rates was observed. It was considered that the successful operation of a PSMC contributed to this reduction. By using data and calculation methods developed by Land Transport New Zealand and applying social costs for crashes normally used for justifying capital projects, it can be seen that the social cost of crashes is being reduced at a significantly greater rate on the PSMC 001 network than on the remainder of the state highway network. The value of savings ahead of the national trend has been more than NZ$31 million for a 3-year period. The contractor's performance is measured on the social cost of crashes that occur on the network, regardless of crash causation. To keep the contractor motivated, the contract includes provisions to adjust the contract payments as based on the safety performance. This approach requires a fundamental shift in the attitude of the contractor, moving from a reactive position to a new position of prevention with particular attention on improved safety. Performance data from a 7-year contract and a 3-year contract from New Zealand are presented. Improved safety performance has become a hallmark in these contracts, and safety performance continues to improve through innovations and commitment.
Expected Service Life of Hot-Mix Asphalt Pavements in Long-Term Pavement Performance Program
Authors: Von Quintus Harold L. , Mallela Jagannath , Jiang Jane , Buncher Mark
Published: October 2007

One of the objectives for the Long-Term Pavement Performance (LTPP) program is to develop improved design methodologies for pavements. To achieve that objective, hundreds of hot-mix asphalt (HMA) test sections have been established and are being monitored to determine the performance characteristics of HMA pavements. The data from this program can be used to validate improved design methodologies and to establish the service life of HMA pavements. Specific findings are summarized from a study sponsored by the Asphalt Pavement Alliance to determine the expected service life of HMA or flexible pavements included in LTPP by using survivability analyses.
Network-Level Falling Weight Deflectometer Testing
Authors: Alam Javed , Galal Khaled A. , Diefenderfer Brian K.
Published: October 2007

A project was initiated to collect network-level falling weight deflectometer (FWD) data along Virginia's Interstate system. The FWD data collection aims to build a comprehensive database of deflection data and associated structural analysis to be used for future implementation of the Mechanistic–Empirical Pavement Design Guide. Virginia's current network-level evaluation protocol requires that pavements be tested every tenth of a mile at four drop levels, with three deflection basins (repetitions) collected at each drop level. To test the more than 2,000 lane miles of Interstate system, it was necessary to determine if the number of test points per mile and the number of load levels used could be reduced to increase the testing production rate and reduce the high cost of testing and traffic control. FWD testing was initiated on the entire length of I-77 and on portions of I-64 and I-81 by using the current testing protocol with only two deflection basins collected at each drop level. A comprehensive statistical analysis was performed on subgrade moduli, effective structural number, and layer moduli calculated by using the AASHTO and the ELMOD methods, respectively. The results of this study document that network-level testing at 10 points per mile can be reduced to three points per mile, and the four FWD drop levels can be reduced to only one drop level, with two deflection basins collected at this load level, without statistically compromising the quality of the data collected. However, the recommendation was made to collect data at multiple load levels for future in situ characterization of material stress sensitivity.
Comparison of Automated Pavement Distress Data Collection Procedures for Local Agencies in San Francisco Bay Area, California
Authors: Albitres Carlos M. Chang , Smith Roger E. , Pendleton Olga J.
Published: October 2007

Many local agencies in the San Francisco Bay Area in California use manual surveys to collect pavement distress data to calculate pavement condition index (PCI) values for use in pavement management. Many of these agencies then use pavement performance curves and trigger values in their decision trees or matrices based on these resulting PCI values and derived parameters as major components of the agencies’ pavement management decision support systems. Automated pavement distress data collection procedures are available, but all available procedures and equipment do not necessarily reproduce the PCI from manual surveys. These differences in the PCI calculated from different distress data collection methods can lead to substantially different pavement treatment recommendations and fund needs. A 2-year project was conducted for the Metropolitan Transportation Commission of the San Francisco Bay Area to evaluate the effect of the use of different methods to determine the PCI. The study included statistical analyses and comparison of seven pavement distress types for asphalt pavements and the resulting PCI. The methodology, interpretation, and findings from the study are described. Emphasis is given to differences observed in the results and analysis of their causes. Practical recommendations for future use of automated pavement distress data collection procedures for local agencies are given.
Evaluating Nonlinear Elastic Models for Unbound Granular Materials in Accelerated Testing Facility
Authors: González Alvaro , Saleh Mofreh , Ali Adnan
Published: October 2007

The characterization of unbound granular materials is particularly important in thin-surfaced pavements where most of the bearing capacity is provided by the granular layers. For an accurate modeling of the elastic response of these materials, several important models described in the literature have been considered in a study. Three of the most-used nonlinear elastic models for unbound granular materials used by researchers and practitioners in the pavement engineering field are evaluated. The nonlinear elastic models of the materials were especially implemented in ABAQUS, a general purpose, three-dimensional finite element code (3D-FEM) that uses user-defined material subroutines. The 3D-FEM solutions were validated through a set of data collected in the full-scale Canterbury Accelerated Pavement Testing Indoor Facility (CAPTIF). Vertical, transverse, and longitudinal strains were measured at CAPTIF through an array of strain gauges buried at different depths in the pavement sections. The vertical stresses were measured by load pressure cells at different locations in the pavement sections. In general, the results obtained from the nonlinear models are considered good for the materials and structures studied in the research. Little difference in the accuracy of the nonlinear models was found.
Mechanistic Analyses of FHWA's Accelerated Loading Facility Pavements
Authors: Al-Khateeb Ghazi , Gibson Nelson , Qi Xicheng
Published: October 2007

In-depth details are provided for mechanistic analyses conducted for the asphalt pavements of the FHWA accelerated loading facility (ALF) by using available programs, including KENPAVE, WINLEA, EVERSTRS, EVERFLEX, and VESYS 5W. These pavements were constructed by using highly modified and unmodified asphalt binders. The described analyses focused on primary response under the ALF pavements. This study included multilayer elastic theory (MLET) solutions, finite element analysis, and analysis using the VESYS 5W program. Predictions of the primary response for the fatigue mode included the horizontal tensile stress and strain at the bottom of the hot-mix asphalt (HMA) layer and for the rutting mode included the vertical compressive stress and strain on top of each pavement layer. The impact of loading frequency and stress sensitivity (nonlinearity) on fatigue primary response, rutting primary response, and principal stresses was investigated. The frequency did affect the fatigue tensile stress and strain, primarily at the bottom of the HMA layer. It also affected the major and minor principal stresses, particularly at the bottom of the HMA layer. The frequency effect on the rutting compressive stress was insignificant, whereas it was considerable for the compressive strain within the HMA layer. The MLET solutions that used a linear elastic base provided reasonable predictions for the measured tensile strains for highly modified and unmodified asphalt pavements with an absolute percentage error in the range of 0% to 15% percent in most cases. The solutions of the MLET and VESYS 5W programs were capable of providing good predictions of the vertical deformation within the HMA layer that correlated well with the measured permanent deformation values.
Estimation of Representative Capital and Maintenance Costs for Canadian Roads
Authors: Swan D. J. , Hajek Jerry J. , Hein David K. , Jacques Bruno
Published: October 2007

Procedures are described for estimating annualized life-cycle costs of road infrastructure for road classes and geographical regions of Canada. Estimated costs are total annualized costs required for constructing and maintaining road infrastructure. Total costs include initial construction costs for pavements, bridges, and other road infrastructure components; subsequent maintenance rehabilitation costs; and costs of routine and winter maintenance. The work is part of the Full Cost Investigation Project currently under way by Transport Canada. This project assesses total transportation costs for transportation modes in Canada. Total annualized road costs were estimated for 1-km-long, one-lane road segments selected to represent the entire Canadian provincial and municipal road network. Estimates were completed for 196 representative road segments covering 14 road functional classes in 14 geographical regions. Cost estimates were expressed as equivalent uniform annual costs and were carried out with an Excel-based computational model, which uses quantities and unit costs of dozens of road infrastructure components. Quantities and unit costs were established through surveys of Canadian federal, provincial, territorial, and municipal agencies; documentation review; and engineering judgment. Annualized costs for building and maintaining road infrastructure estimated by the model were compared with actual annual capital and maintenance expenditures reported by Canadian transportation agencies. Results indicate a basic correspondence between annualized costs estimated by the model and annual expenditures reported by transportation agencies, particularly for annual operating costs.
Evaluating Management Decisions to Reduce Environmental Risk of Roadside-Applied Herbicides
Authors: Giudice Ben D. , Massoudieh Arash , Young Thomas M.
Published: October 2007

Management decisions concerning the spraying of herbicides on highway roadsides are evaluated on the basis of their impact on resulting environmental risk. A mathematical transport model was previously applied to the State of California with a Monte Carlo technique, and in this study the results are manipulated to evaluate the risk reduction that results from restricting herbicide application on the basis of site characteristics or changing other application practices. Results show that eliminating herbicide applications where the slope of the grass adjacent to the highway is greater than 30° has little or no effect on risk. Eliminating application where the width of the grass adjacent to the highway is less than 2 m or where soil organic carbon content is less than 0.5% can lead to significant reductions in environmental risk for certain herbicides. Additionally, limiting the width of the spray zone and applying the minimum manufacturer-suggested application rate reduce the risk to aquatic ecosystems. Applying at the minimum rate has the greatest potential to decrease risk. Results of this study show that management decisions can have a significant effect on limiting herbicide runoff risks to aquatic ecosystems. Decision makers would have to weigh costs of alternatives to herbicide spraying for controlling roadside vegetation against the environmental risk reductions.
Best Practices for Rehabilitation and Moving of Historic Metal Truss Bridges
Authors: McKeel Wallace T. , Miller Ann B. , Clark Katherine S.
Published: October 2007

The Virginia Department of Transportation (DOT) is responsible for the management of about 30 historic truss bridges. Too often, these structures do not meet today's traffic demands or safety standards. Their general deterioration necessitates that they be disassembled and relocated, rehabilitated and re-erected, or stored. The technology and materials used to build them are no longer in use, and many people with practical experience are no longer working. Little information is readily available on effectively identifying and safely performing necessary operations. Virginia DOT's Knowledge Management Division and the Virginia Transportation Research Council interviewed active and retired engineers, consultants, field personnel, environmental specialists, and architectural historians to collect best practices related to pin-connected and riveted truss bridges. Discussion of the issues faced by those moving and rehabilitating historic metal truss bridges is framed by using the process followed for the recent rehabilitation of a historic truss bridge in Goshen, Virginia. Best practices identified through the examination of this and other projects are also presented.
Preservation Effects on Performance of Bituminous over Aggregate Base Pavements in Minnesota
Authors: Lukanen Erland O.
Published: October 2007

Use of the Minnesota Department of Transportation pavement management data to evaluate the effect of pavement preservation activities on pavement performance is described. Evaluation focuses on bituminous over aggregate base pavements constructed between 1985 and 2005. Pavement data were initially divided into subsets of data: one for pavements with no preservation and the other for pavements that received preservation. The subset that included preservation activities was further subdivided for comparison into those that received thin mill and overlay or thin overlays and those that did not. Data analysis showed that preservation improved pavement performance and that thin overlays and thin mill and overlays were the preservation treatments that provided the greatest performance improvements but were used for the poorest performing pavements.
Evaluation of Current State of Flexible Overlay Design for Rigid and Composite Pavements in the United States
Authors: Bennert Thomas , Maher Ali
Published: October 2007

Current composite pavement practices and key hot-mix asphalt (HMA) overlay design features, mainly to mitigate reflective cracking in the HMA overlay, used by state highway agencies in the United States are summarized. This information was obtained from a comprehensive survey conducted from January to May 2006 under a research effort for the New Jersey Department of Transportation to help minimize or retard the onset of reflective cracking in HMA overlays on portland cement concrete (PCC)/composite pavements. Information is provided on reflective cracking mitigation methods (successes and failures), current in-place composite/PCC pavement designs, treatments to prepare PCC pavement before HMA overlay and typical time until reflective cracking appears in the HMA overlay. Parameters that state agencies use to characterize pavement site conditions, including nondestructive testing, traffic conditions, and laboratory testing are also given. Further analysis is conducted by comparing the low temperature climatic conditions of the state to the low temperature performance grade of the asphalt binder commonly used in the HMA overlay. This examination and summary of survey findings on current pavement design practices and design features on the use of flexible overlays for rigid pavements in the United States will be of interest to state agencies, practitioners, and pavement researchers.
Low-Temperature Characterization of Hot-Poured Crack Sealant by Crack Sealant Direct Tensile Tester
Authors: Al-Qadi I. L. , Yang S.-H. , Dessouky S. , Masson J.-F.
Published: October 2007

The current specifications for selecting crack sealants correlate poorly with actual field performance. To address this issue and assist in predicting the low-temperature properties of hot-poured bituminous crack sealants, a modified direct tensile tester method has been developed. Sample geometry is modified to accommodate testing sealants. A sensitivity analysis considering various loading rates, sample lengths, and cross-section areas was conducted to define both optimized specimen geometry and testing protocol. Two types of sealants, having a wide range of rheological behaviors (one polymer-modified and one having crumb rubber), were tested at low temperature. Results showed that the rich polymer–modified sealant has a high resistance to failure compared with the sealant with crumb rubber–modified. Each sealant was tested at the lowest corresponding expected service temperature. A performance parameter, strain energy density, was proposed to differentiate crack sealant material in the laboratory.
Early Thermodegradation of Bituminous Sealants Resulting from Improper Installation
Authors: Masson J.-F. , Collins P. , Bundalo-Perc S. , Woods J. R. , Al-Qadi I. L.
Published: October 2007

Bituminous sealants used in roadway maintenance often have a short effective service life, in great part as a result of improper installation and heating, in particular. To determine the effect of thermal history on sealant characteristics, sealant samples were collected during an operation that started with reheating of a full kettle of bituminous sealant. Results of Fourier transform infrared spectroscopy, thermogravimetry, gel permeation chromatography, and dynamic shear rheometry showed that the sealant had degraded and that the extent of degradation was greatest early in the operation. Application of degraded sealant throughout installation showed the need for improved material and construction specifications, along with improved field control measures.
Using Real Options for Revenue Risk Mitigation in Transportation Project Financing
Authors: Chiara Nicola , Garvin Michael J.
Published: October 2007

Effective risk management is essential for success in transportation project financing arrangements such as build–operate–transfer (BOT). Both sponsors and lenders consider the revenue risk an extremely important factor when they assess a BOT project's feasibility. One potential strategy for mitigating the revenue risk is a revenue guarantee, in which a guarantor secures a minimum amount of revenue for a project; such guarantees take the form of a put option. However, the inclusion of such guarantees in BOT arrangements is hampered by the lack of methods to determine the value, or the fair price, of these types of options. Current valuation techniques lack the flexibility to structure the options in a manner that is affordable to the government and attractive to the private sector. This significant shortcoming opens a research opportunity to explore the development of methods for valuing more flexible and affordable guarantee structures. This paper presents two new valuation methods, the multi–least squares Monte Carlo method and the multi-exercise boundary method, which model the revenue guarantee as a multiple-exercise real option. The two valuation methods successfully combine Monte Carlo simulation and dynamic programming techniques to price multiple-exercise real options. A hypothetical case study illustrates the application and the potential of the two methods to serve as tools for risk mitigation in BOT projects.
Analysis of Traffic Sign Asset Management Scenarios
Authors: Harris Elizabeth Allison , Rasdorf William , Hummer Joseph E. , Yeom Chunho
Published: October 2007

Minimum traffic sign retroreflectivity standards proposed for the Manual on Uniform Traffic Control Devices by the FHWA will present numerous management challenges to state and local departments of transportation (DOTs) responsible for traffic sign assets. These DOTs are looking at how to comply with the standard while minimizing sign maintenance costs. This paper presents an analysis of several traffic sign retroreflectivity maintenance methods using a sign asset management simulation based on inspection and sign data gathered in the field. The simulation evaluated 30 sign asset management scenarios in terms of annual maintenance cost per sign and percentage of traffic signs not compliant with the proposed FHWA standard. The simulation results found that, generally, higher costs for sign maintenance resulted in a lower percentage of noncompliant signs. However, for some scenarios using the visual nighttime inspection method, lower percentages of noncompliant signs were found even with relatively low maintenance costs per sign. Increasing the maintenance cost per sign by 10% resulted in an approximately 10% or more reduction in the number of noncompliant signs. It is recommended that DOTs implement a 100% Type III sign replacement policy because Type I signs have a greater life-cycle cost than do Type III signs. DOTs need to allocate an adequate annual budget for sign replacement and should establish their own minimum retroreflectivity standards. The sign asset management simulation developed as part of this study could be modified so that its use could be extended to other DOTs.
Estimating Highway Investment Requirements with Uncertain Demands
Authors: Yin Yafeng , Lawphongpanich Siriphong
Published: October 2007

This paper proposes a systems approach for estimating investment requirements for a highway network with uncertain demands. The problem is formulated as a mathematical program with equilibrium constraints, assuming that travel demands belong to an ellipsoidal likelihood region and that traffic flows on the underlying network are in user equilibrium. The proposed algorithm obtains a solution by solving a sequence of problems. Numerical results from the nine-node and Sioux Falls networks demonstrate that the proposed approach is able to produce a solution that guarantees the future system performance without requiring an excessive amount of investment.