bluuebunny/crossref_metadata_2025 huggingface dataset:
Microbiological transformations of phosphorus and sulphur compounds in acid soils
Authors: Stamenov Dragana , Jarak Mirjana , Djuric Simonida , Jafari Hajnal , Bjelic Dragana
Published: January 2013

The dynamics of phosphorus and sulphur in soil is closely related to the
dynamics of the biological cycle in which microorganisms play a central role.
There is not much microbiological activity in acid soils because aerobes are
scarce, rhizosphere is restricted to the shallow surface layer, and the
biomass of microorganisms decreases with higher acidity. The aim of the
research was to investigate the number of microorganisms, which decompose
organic and inorganic phosphorus compounds and organic sulphur compounds in
calcocambisol, luvisol, and pseudogley. The following parameters were
determined in the soil samples: pH in H2O and in 1MKCl; the content of CaCO3
(%); humus content (%), nitrogen content (%); the content of physiologically
active phosphorus and potassium (mg P2O5/100g of soil; mg K2O/100g of soil).
The number of microorganisms was determined by the method of agar plates on
appropriate nutrient media: the number of microorganisms solubilizing
phosphates on a medium by Muramcov; the number of microorganisms that
decompose organic phosphorus compounds on a medium with lecithin; and the
number of microorganisms that transform organic sulphur compounds on a medium
by Baar. All three types of soil are acid non-carbonate soils with a low
level of available phosphorus and a more favorable amount of potassium,
nitrogen, and humus. The largest number of bacteria, which transform organic
phosphorus compounds, was found in calcocambisol. The largest number of
phosphate solubilizing bacteria was recorded in pseudogley, whereas the
largest number of phosphate solubilizing fungi was recorded in calcocambisol.
The largest number of bacteria, which transform organic sulphur compounds,
was recorded in pseudogley.
Preliminary checklist of Myxomycota and Ascomycota from Fruska Gora mountain
Authors: Karaman Maja , Novakovic Milana , Savic Dragisa , Matavulj Milan
Published: January 2013

Fruska Gora mountain represents very important source of natural and
semi-natural forest ecosystems in the northern part of the Republic of Serbia
and therefore it is important source of habitats for different groups of
fungi. As opposed to coordinated inventory and monitoring projects of fungi
established around Europe long ago, mycological researches in Serbia are
still sporadic and insufficiently coordinated by authorities and experts. In
accordance with that, available data concerning the state of fungi in Serbia
are scarce. The aim of this work was to collect all relevant unpublished data
considering fungi in Fruska Gora and to present checklist of two fungal
phyla: Myxomycota and Ascomycota. In the presented checklist, 23 recorded
species of Myxomycota (known as fungal analogues) were distributed in 2
classes, 5 orders, and 7 families. The first class (Protosteliomycetes)
contained only one species - Ceratiomyxa fruticulosa (fam. Ceratiomyxaceae).
The largest order was Trichiales (9 species), while the dominant families
were Stemonitidaceae and Trichiaceae, each with 6 species recorded. The most
abundant species was Lycogala epidendrum (fam. Reticulariaceae), with 13
records. Phylum Ascomycota was represented with 95 species belonging to 6
classes, 12 orders and 29 families. The most highly represented classes were
Leotiomycetes (32 species) and Pezizomycetes (31 species). The most abundant
species were: Xylaria polymorpha (17 records), Xylaria hypoxylon (14
records), and Sarcoscypha coccinea (14 records).
Fungi in the legislation of the Republic of Serbia
Authors: Ivancevic Boris , Matavulj Milan , Vukojevic Jelena , Karaman Maja
Published: January 2013

Conservation and protection of fungi have lately been considered as extremely
important elements of the environmental conservation, and numerous
environmental, scientific, medical, economic, cultural, ethical, and other
reasons for such attitude exist today. This paper presents an overview of
official regulations on the protection of fungi in the Republic of Serbia
from the Act of Protection of 1991 until today. The paper lists and analyses
the good and bad provisions of individual legal regulations. It registers the
effects of the adopted regulations on the actual efficiency of protection of
endangered species of fungi (macrofungi, mushrooms), and considers the impact
of chronological development of legislation on the population of fungi in
nature, and presents general measures to improve protection of mushrooms in
the future. These measures primarily include reliable information and study
of fungi as a basis for their effective protection based on scientific
knowledge.
In vivo effects of two acidic soft drinks on shear bond strength of metal orthodontic brackets with and without resin infiltration treatment
Authors: Hammad Shaza M. , Enan Enas T.
Published: January 2013

Objectives:

To evaluate the in vivo effects of two acidic soft drinks (Coca-Cola and Sprite) on the shear bond strength of metal orthodontic brackets with and without resin infiltration treatment. In addition, the enamel surface was evaluated, after debonding, using a scanning electron microscope.

Materials and Methods:

Sixty noncarious maxillary premolars, scheduled for extraction in 30 orthodontic patients, were used. Patients were randomly divided into two groups according to the soft drink tested (Coca-Cola or Sprite). In each group, application of resin infiltration (Icon. DMG, Hamburg, Germany) was done on one side only before bonding of brackets. Patients were told to rinse their mouth with their respective soft drink at room temperature for 5minutes, three times a day for 3months. Shear bond strength was tested with a universal testing machine. After shearing test, a scanning electron microscope was used to evaluate enamel erosion. Statistical analysis was performed by twoway analysis of variance followed by the least significant difference test.

Results:

The Coca-Cola group without resin infiltration showed the lowest resistance to shearing forces. Scanning electron micrographs of both groups after resin application showed a significant improvement compared with results without resin use, as the enamel appeared smoother and less erosive.

Conclusion:

Pretreatment with the infiltrating resin has proved to result in a significant improvement in shear bond strength, regardless of the type of soft drink consumed.
Effect of premolar extraction on mandibular third molar impaction in young adults
Authors: Türköz Çağrı , Ulusoy Çağrı
Published: January 2013

Objective:

To test the null hypothesis that orthodontic therapy with or without premolar extraction does not result in any difference in third molar impaction.

Materials and Methods:

Two groups were formed: 22 patients in one group with first premolar extractions and 22 patients in the other group without extractions. All patients were nongrowing subjects who had normal gonial angles and were skeletal Class I at the beginning of treatment. The available space for third molars, inclination of second and third molars, and angle between the second and third molars were evaluated. Also, the correlation of measured parameters and type of orthodontic therapy with the eruption of third molars was evaluated.

Results:

Of the third molars, 81.8% were impacted in the nonextraction group and 63.6% were impacted in the extraction group. Impaction of mandibular third molars was significantly correlated to the pretreatment and posttreatment inclination of third molars and the angle between the second and third molars. In the extraction therapy group, the retromolar distance increased significantly with a mean of 1.30 ± 1.25 mm.

Conclusions:

When the inclination of the third molar is inconvenient, the tooth may remain impacted even if there is enough retromolar space.
Factors Expressed by Murine Embryonic Pancreatic Mesenchyme Enhance Generation of Insulin-Producing Cells From hESCs
Authors: Guo Tingxia , Landsman Limor , Li Na , Hebrok Matthias
Published: January 2013

Islet transplantation has proven to be a successful strategy to restore normoglycemia in patients with type 1 diabetes (T1D). However, the dearth of cadaveric islets available for transplantation hampers the widespread application of this treatment option. Although human embryonic stem cells and induced pluripotent stem cells are capable of generating insulin-producing cells in vitro when provided with the appropriate inductive cues, the insulin-expressing cells that develop behave more like immature β-cells with minimal sensitivity to glucose stimulation. Here, we identify a set of signaling factors expressed in mouse embryonic mesenchyme during the time when foregut and pancreatic progenitors are specified and test their activities during in vitro differentiation of human embryonic stem cells. Several of the identified factors work in concert to expand the pancreatic progenitor pool. Interestingly, transforming growth factor (TGF)-β ligands, most potent in inducing pancreatic progenitors, display strong inhibitory effects on subsequent endocrine cell differentiation. Treatment with TGF-β ligands, followed by the addition of a TGF-β receptor antagonist, dramatically increased the number of insulin-producing cells in vitro, demonstrating the need for dynamic temporal regulation of TGF-β signaling during in vitro differentiation. These studies illustrate the need to precisely mimic the in vivo conditions to fully recapitulate pancreatic lineage specification in vitro.
Fibroblast Growth Factor 21 Mediates Specific Glucagon Actions
Authors: Habegger Kirk M. , Stemmer Kerstin , Cheng Christine , Müller Timo D. , Heppner Kristy M. , Ottaway Nickki , Holland Jenna , Hembree Jazzminn L. , Smiley David , Gelfanov Vasily , Krishna Radha , Arafat Ayman M. , Konkar Anish , Belli Sara , Kapps Martin , Woods Stephen C. , Hofmann Susanna M. , D’Alessio David , Pfluger Paul T. , Perez-Tilve Diego , Seeley Randy J. , Konishi Morichika , Itoh Nobuyujki , Kharitonenkov Alexei , Spranger Joachim , DiMarchi Richard D. , Tschöp Matthias H.
Published: January 2013

Glucagon, an essential regulator of glucose homeostasis, also modulates lipid metabolism and promotes weight loss, as reflected by the wasting observed in glucagonoma patients. Recently, coagonist peptides that include glucagon agonism have emerged as promising therapeutic candidates for the treatment of obesity and diabetes. We developed a novel stable and soluble glucagon receptor (GcgR) agonist, which allowed for in vivo dissection of glucagon action. As expected, chronic GcgR agonism in mice resulted in hyperglycemia and lower body fat and plasma cholesterol. Notably, GcgR activation also raised hepatic expression and circulating levels of fibroblast growth factor 21 (FGF21). This effect was retained in isolated primary hepatocytes from wild-type (WT) mice, but not GcgR knockout mice. We confirmed this link in healthy human volunteers, where injection of natural glucagon increased plasma FGF21 within hours. Functional relevance was evidenced in mice with genetic deletion of FGF21, where GcgR activation failed to induce the body weight loss and lipid metabolism changes observed in WT mice. Taken together, these data reveal for the first time that glucagon controls glucose, energy, and lipid metabolism at least in part via FGF21-dependent pathways.
An approximation to the cross sections of Z
l boson production at CLIC by using neural networks
Authors: Akkoyun Serkan , Kara Seyit
Published: January 2013

In this work, the possible dynamics associated with leptophilic Z
l boson at CLIC (Compact Linear Collider) have been investigated by using artificial neural networks (ANNs). These hypotetic massive boson Z
l have been shown through the process e
+
e
−→µ+µ−. Furthermore, the invariant mass distributions for final muons have been consistently predicted by using ANN. For these highly non-linear data, we have constructed consistent empirical physical formulas (EPFs) by appropriate feed-forward ANN. These ANNEPFs can be used to derive further physical functions which could be relevant to studying Z
l.
World Transit Research
Authors: Currie Graham , Delbosc Alexa , Forbes Pauline
Published: January 2013

Transit research is explored with the aim of understanding areas covered, research trends, research uses, and how research provision matches needs. The method involves an empirical analysis of the content, use, and users of the World Transit Research Clearinghouse website ( http://www.worldtransitresearch.info ). Results indicate that the Transportation Research Record is the academic journal that publishes the most transit research, but only 14% of its papers are on transit. Transport Policy is the second-largest source, but papers on transit make up 58% of its publications. Most research papers on transit concern bus, rail, or mass transit. In the past decade, the most significant change in publications by transit mode is that the segment on bus rapid transit research has grown, although it still accounts for a small share of overall content. Consumption of research content by mode is highest for bus rapid transit, followed by light rail or tram, then by bicycle or pedestrian. A comparison of research supply and research consumption suggests that research papers concerning (in order) sustainability, urban density, and ridership growth have the highest readership but represent a small share of research content in the field. User surveys had a low response rate but the responses received suggest that professionals including government policy makers, consultants, and academics are the major research users. The most common use of transit research is to be kept informed; however, research also is cited as evidence, notably by academics. A modest but significant share of professionals use transit research for transit policy, service development, or both. Opportunities for future research are identified.
Optimal Length of Transit Network with Traffic Performance Microsimulation
Authors: Estrada Miquel , Robusté Francesc , Amat Jordi , Badia Hugo , Barceló Jaume
Published: January 2013

This paper examines the design of high-performance transit networks that minimize transit agency costs, the time of transit users in the system, and the travel time of car users. Surface transit services need segregated lanes to achieve a target cruising speed so that the transit network length has a significant effect on traffic performance. This effect is modeled with the macroscopic fundamental diagram (MFD). The optimization proceeds in two steps. First, an analytic model defines the optimal layout of surface transit networks according to the time headway, stop spacing, line spacing, and network size variables. Then, the average travel time of the traffic network is evaluated with the MFD curve corresponding to the former transit network length. The full methodology has been implemented in the city of Barcelona, Spain. MFD was calibrated in the city's central district by means of traffic microsimulation runs. The social optimum for the number of corridors is 15, somewhat smaller than the optimization that does not consider traffic (23 corridors).
Development of Location Method for Urban Public Transit Networks Based on Hub-and-Spoke Network Structure
Authors: Wang Zhenbao , Chen Yanyan
Published: January 2013

A location method is presented for an urban public transit (PT) network based on the hub-and-spoke network structure model. The proposed method integrates the PT lines with transfer hubs. PT lines fall into four major service levels: subway, bus rapid transport, bus, and feeder bus. The transfer hubs fall into three major categories: intermodal terminals, transfer centers, and transfer stations. Every level of PT line is located by connecting the different classes of transfer hubs. The optimization objectives, constraints, and procedures for PT line locations are present, and they vary by level of PT service. The design and implementation of the proposed method are illustrated by a case study for the city of Fuzhou, China. The proposed allocation method offers a new approach for increasing the PT level of service of a high-density city. The procedure for allocating PT lines is practical and maneuverable.
Multiobjective Approach to Creating Bus Timetables with Multiple Vehicle Types
Authors: Hassold Stephan , Ceder Avishai (Avi)
Published: January 2013

In times of climate change and scarce resources, it is essential to reduce emissions and to use fuel as economically as possible. The transportation sector alone accounts for 44% of the energy use in New Zealand, with only about one-quarter of that amount being used by the transportation industry for transporting goods. Therefore, an attractive public transport service and prudent use of its vehicles can help make travel more economical, thus saving resources and reducing carbon dioxide emissions. How to make public bus services more attractive is demonstrated with two simultaneous objectives: minimizing the expected passenger waiting time and minimizing the discrepancy from a desired occupancy level on the vehicles. The first objective is intended to improve the service and attract more users, and the second objective is intended to ensure economical operation. A network-based procedure is used to create timetables with multiple vehicle types to solve this multiobjective problem. The method is applied to a case study in Auckland, New Zealand, and results in a savings of more than 43% of passenger waiting time while attaining an acceptable passenger load on all vehicles.
Residential Property Values and New Jersey Transit Village Program
Authors: Noland Robert B. , DiPetrillo Stephanie , Lahr Michael L.
Published: January 2013

Since 1999, 23 New Jersey transit villages have been designated in New Jersey municipalities, with the intention of intensifying development around rail stations and bus hubs. As one test of the effectiveness of this state effort, the appreciation in residential property values is investigated and compared with that in other municipalities in the state. Some limited positive evidence is found to support the New Jersey transit village designation. Econometric analysis of the change in average residential sales price over 9 years finds an association but cannot establish a causal effect. Case study analysis of selected New Jersey transit villages suggests that the forethought, commitment, and political will required to apply for transit village status may be what sparks municipal development rather than the designation itself.
Winners or Losers
Authors: Fan Yingling , Guthrie Andrew
Published: January 2013

Existing research rarely goes beyond individual dimensions of neighborhood change to explore the broader neighborhood impacts of transit investments as perceived by neighborhood residents. To fill gaps in this knowledge, the residents of selected neighborhoods along four transit corridors in the Twin Cities area of Minnesota were surveyed. Survey results show that residents of the study neighborhoods had generally positive perceptions of transit-induced neighborhood change. However, significant differences existed between urban and suburban areas and between individual neighborhoods. In addition, African-Americans, immigrants, frequent transit users, carless residents, and new residents in general had more positive perceptions of transit-induced neighborhood change than did whites, nonimmigrants, infrequent or nontransit users, residents with access to a motor vehicle, and longtime residents. Asian urbanites had more negative perceptions. Implications of these findings are discussed.
Station Parking and Transit-Oriented Design
Authors: Martin Peter C. , Hurrell William E.
Published: January 2013

A simple analysis framework is presented to assist transit agencies and station-area communities in making informed planning decisions regarding the highest and best use of parking areas at suburban transit stations. The framework provides the flexibility to tailor values to local settings. The success of high-capacity transit systems depends on well-located and -designed stations. Outside regional commercial business districts, the most favored means of access to transit stations often is a park-and-ride facility. Many suburban station locations have reached full use of limited parking resources, and parking capacity has begun to limit opportunities to increase rail transit ridership. Thus, these major cost transit investments are not fulfilling their full potential as a result of constrained access capacity. Also, many station communities increasingly have been pressuring transit agencies to convert some station patron parking to transit-oriented development (TOD) uses, and some nearby private parking lots have been lost to TOD. Thus, station parking is not only limited but also under pressure for reduction. Little information exists to help transit agencies and local communities understand the highest and best use of limited station site resources. A simple spreadsheet analysis framework is presented to help transit agencies and local communities make informed decisions regarding parking and TOD. This suggested analysis framework focuses on the rail transit ridership implications of parking versus TOD and on the cost of station parking.
Spatially Aware Model for Optimal Site Selection
Authors: Efthymiou Dimitrios , Antoniou Constantinos , Tyrinopoulos Yannis
Published: January 2013

People's perceptions about the appropriate location of mobility centers are modeled. A case study for the Municipality of Kalamaria in Thes-saloniki, Greece, is presented. The results of a stated preference survey, which revealed residents' perceptions about the optimal locations for these centers, as well as the spatial and other characteristics of the region, were used as inputs. Models were then developed and estimated: a linear regression model, a spatial simultaneous autoregressive (SAR) model, and a geographically weighted regression (GWR) model. The exploratory analysis used the respondents' perception of optimal location as the response variable, and the explanatory variables are information about the population; points of interest; bus routes; average income; road network (i.e., length, number of lanes, and average speeds); and distances from stadium, pedestrian shopping zone, and paid parking facility. Results indicated that the selection of the appropriate location for a mobility center was influenced primarily by number of residents, number of points of interest, number of bus routes, average vehicle speed, and length of the road network. The GWR model seemed to fit the data best, whereas Moran's I-test showed that the model solved the autocorrelation of the residuals, something that the other models [ordinary least squares (OLS) and SARmix] fail to accomplish. The model's predicted values were localized (unlike OLS) and made the decision easier. The proposed method is generic (not system dependent) and can be applied to different optimal location selection schemes, especially those with similar demand characteristics (e.g., for automobile- or bike-sharing stations).
Substitution or Complementarity
Authors: Tang Lei , Ross Hilary , Han Xiaoli
Published: January 2013

The effects of a real-time bus information system, Chicago Transit Authority (CTA) Bus Tracker, on the ridership of the CTA transit rail system in Chicago, Illinois, are examined with panel data on monthly average weekday ridership at each transit train station in the entire CTA system from January 2005 through December 2010. Other factors that might contribute to changes in CTA rail ridership (e.g., socioeconomic situation, transit service, and weather) are controlled. Results of a mixed linear model indicate that Bus Tracker service increases CTA train ridership. This increase might be attributable to the increased intermodal transfer efficiency between CTA buses and trains that results from the real-time bus information provided. Findings suggest that the complementarity effect of providing real-time bus information outweighs its substitution effect on the ridership of a connected transit rail system. Together with the findings from an earlier study (which show that Bus Tracker service helps to increase bus ridership), study results provide empirical evidence in support of the hypothesis that implementation of a real-time transit information system leads to gains in transit ridership.
Mapping Oversized and Overweight Truck Routes with Procedure Based on Geographic Information Systems
Authors: Li Yingfeng , Le Jerry T. , Middleton Danny R. , Quiroga Cesar A.
Published: January 2013

Effective and sufficient support for the transportation of oversized and overweight (OS-OW) loads on the nation's transportation system is important to a vibrant economy. The availability of advanced tools and technologies based on geographic information systems (GIS) has increased considerably the ability of transportation policy makers to analyze vehicle routing data better. The Texas Department of Transportation recently initiated a research effort to analyze the routes of historically permitted OS-OW loads. The primary objectives of this research included the development of criteria for assigning current and projected OS-OW groups to an improved road network, the identification of strategic infrastructure improvements to accommodate such loads, and the development of optimal and alternative routes for priority load groups between the most common origins and destinations. As part of the project, the research team developed a highly efficient GIS-mapping approach and converted a massive data set of OS-OW permit routes into a GIS format. The mapping approach enabled batch processing and directly queried, retrieved, and stored data from and to an Oracle database. This paper presents part of the findings of this research, with a focus on the GIS mapping process of the historical OS-OW permit routes. The GIS approach will be particularly valuable for those states that are, or will be, automating their process for OS-OW permitting through GIS-based tools. In addition, the research provides valuable lessons for other states that are looking for a workable solution to analyze effectively mass historical OS-OW routing data.
Monitoring Travel Time Reliability from the Cloud
Authors: Lei Hao , Xing Tao , Taylor Jeffrey D. , Zhou Xuesong
Published: January 2013

Under the existing loosely distributed sensor environment with heterogeneous data sources, transportation planning and management agencies have found a critical need for the efficient storage, processing, and extraction of network-level information. The emerging practice of cloud computing provides a revolutionary solution for network-level information needs. This paper introduces MapReduce, a distributed computing framework for the design of data-intensive software systems that can manage and manipulate a large volume of data. With a focus on a traffic-oriented, data-intensive application, the researchers designed and implemented a system for the provision of traveler information based on travel time reliability. The system leverages the unified data storage and computing platform provided by the cloud computing architecture.
Design of Open Source Framework for Traffic and Travel Simulation
Authors: Tamminga Guus , Miska Marc , Santos Edgar , Van Lint Hans , Nakasone Arturo , Prendinger Helmut , Hoogendoorn Serge
Published: January 2013

For the evaluation, design, and planning of traffic facilities and measures, traffic simulation packages are the de facto tools for consultants, policy makers, and researchers. However, the available commercial simulation packages do not always offer the desired work flow and flexibility for academic research. In many cases, researchers resort to designing and building their own dedicated models, without an intrinsic incentive (or the practical means) to make the results available in the public domain. To make matters worse, a substantial part of these efforts pertains to rebuilding basic functionality and, in many respects, reinventing the wheel. This problem not only affects the research community but adversely affects the entire traffic simulation community and frustrates the development of traffic simulation in general. For this problem to be addressed, this paper describes an open source approach, OpenTraffic, which is being developed as a collaborative effort between the Queensland University of Technology, Australia; the National Institute of Informatics, Tokyo; and the Technical University of Delft, the Netherlands. The OpenTraffic simulation framework enables academics from geographic areas and disciplines within the traffic domain to work together and contribute to a specific topic of interest, ranging from travel choice behavior to car following, and from response to intelligent transportation systems to activity planning. The modular approach enables users of the software to focus on their area of interest, whereas other functional modules can be regarded as black boxes. Specific attention is paid to a standardization of data inputs and outputs for traffic simulations. Such standardization will allow the sharing of data with many existing commercial simulation packages.
Modeling Annual Average Daily Traffic with Integrated Spatial Data from Multiple Network Buffer Bandwidths
Authors: Pulugurtha Srinivas S. , Kusam Prasanna R.
Published: January 2013

This paper presents a geospatial method to develop models to estimate annual average daily traffic (AADT) along a link with integrated spatial data from multiple network buffer bandwidths. The method incorporated spatial data that captured principles and statistical techniques to estimate directly AADT, and thereby bypassed the sequential four-step method. Spatial data (off-network characteristics, such as demographic, socioeconomic, and land use) captured from multiple network buffer bandwidths around a link were integrated with spatial weights that decreased as the distance from the link increased. Off-network and on-network characteristics were used as independent variables. The AADT calculated from field observations was used as the dependent variable. The applicability of Poisson and negative binomial distributions to the development of the models in a generalized framework for estimating equations was examined. A chi-square statistic test was conducted to validate the developed models and assess their applicability. The results indicated that the models based on the negative binomial distribution were more suitable than the models based on the Poisson distribution to integrate spatially varying data and estimate AADT. The maximum distance necessary to capture and to integrate spatial data varied by road functional class.
Inferring Road Maps from Global Positioning System Traces
Authors: Biagioni James , Eriksson Jakob
Published: January 2013

As a result of the availability of Global Positioning System (GPS) sensors in a variety of everyday devices, GPS trace data are becoming increasingly abundant. One potential use of this wealth of data is to infer and update the geometry and connectivity of road maps through the use of what are known as map generation or map inference algorithms. These algorithms offer a tremendous advantage when no existing road map data are present. Instead of the expense of a complete road survey, GPS trace data can be used to generate entirely new sections of the road map at a fraction of the cost. In cases of existing maps, road map inference may not only help to increase the accuracy of available road maps but may also help to detect new road construction and to make dynamic adaptions to road closures—useful features for in-car navigation with digital road maps. In past research, proposed algorithms had been evaluated qualitatively with little or no comparison with prior work. This lack of quantitative and comparative evaluation is addressed in this paper with the following contributions: (a) a comprehensive survey of the current literature on map generation; (b) a description of the first method for the automatic evaluation of generated maps; (c) a qualitative, quantitative, and comparative evaluation of three reference algorithms; and (d) an open source implementation of each of the three algorithms, with a 118-h trace data set and ground truth map for unrestricted use by the automatic map generation community.
Engaging New Partners in Transportation Research
Authors: Newton Mark P. , Bullock Darcy M. , Watkinson Charles , Bracke Paul J. , Horton Deborah K.
Published: January 2013

Over the past several decades a variety of federal and state programs have invested in transportation research. The U.S. Department of Transportation annually invests approximately $180 million in State Planning and Research (SPR) and university transportation centers (UTCs). This investment generates an extensive portfolio of gray literature (i.e., patents, governmental or scientific research group technical reports, white papers, or preprints) that is not yet uniformly cataloged or accessible, despite the best efforts of the National Technical Information Service, TRB, and the National Transportation Library. This paper reports on a review of the publishing and archiving practices for transportation research technical reports, summarizes best practices, and recommends that UTC and SPR research programs seek and strengthen partnerships with libraries to facilitate the improved production, stewardship, and dissemination of research reports. This paper describes an open access program in Indiana that has digitally archived approximately 1,500 SPR reports dating from 1956, implemented consistent name authority, and created digital object identifiers for reports and data sets to systematically integrate technical reports into scholarly literature. Through new partnerships between the researchers and the home institution, researchers have developed processes to leverage technical report production with the university press to ensure an agile adaptation to emerging digital publishing and open access trends. The adoption of the techniques and the partnerships described in this paper are believed to result in a more efficient investment of state and national transportation research funds by reducing research duplication and demonstrating an improved stewardship of research dollars.
Probabilistic Model for Design of Freeway Acceleration Speed-Change Lanes
Authors: Hassan Yasser , Sarhan Mohamed , Salehi Mohsen
Published: January 2013

A speed-change lane (SCL) is an auxiliary lane added to the traveled way for the acceleration and deceleration of vehicles entering or leaving a roadway. When the length of an acceleration SCL is adequate, drivers are able to accelerate comfortably from the speed at entrance to a speed appropriate to the road, find a gap in the traffic flow, and merge in a safe and secure manner. The length of an SCL is currently determined in terms of the ramp design speed, the freeway design speed, and the acceleration rate. Embedded in these values are assumptions for the operating speed at the entrance and merging points. This study examined a probabilistic approach instead of such a deterministic approach. The main benefit of a probabilistic approach is that traffic flow characteristics are assumed to be stochastic; therefore, the outcome of a probabilistic methodology is a distribution of drivers’ acceleration distance on the SCL. The reliability-based analysis enables designers to select a specific percentile value of this distribution as a design length that better matches a certain situation and avoids unnecessary extra construction costs. This paper presents analytical and simulation models for the application of the reliability approach, with all parameters based on recently collected field data. Even though the presented model should be superior to the deterministic model adopted in current design guides, additional enhancements are recommended for a full reliability-based, safety-explicit design model.
Geometric Design, Speed, and Safety
Authors: Porter Richard J. , Donnell Eric T. , Mason John M.
Published: January 2013

A performance-based approach to the interaction of geometric design, speed, and safety is considered given the availability of two key documents: the Highway Safety Manual and Modeling Operating Speed: Synthesis Report. A historical look at the concept of design speed shows that although the definition of design speed has changed on more than one occasion, the same basic philosophy that related design speed to a safe speed is still reflected in current policy in supplemental guidance related to the selection of design speed. A conservative approach to establishing design criteria, used to address the range of driver, vehicle, and roadway conditions and capabilities that a designer must consider, is demonstrated. Operating speeds are shown to be higher than design speeds for design speeds of approximately 55 mph or less. This outcome may be considered undesirable, but that categorization seems to be based more on subjective judgments of what is desirable than on actual safety findings. Finally, the idea of speed management through the use of roadway geometrics (i.e., geometric designs that influence driver selection of operating speed)—one component of self-enforcing, self-explaining roadway design—is explored. Findings uncover possible challenges to implementing this idea. Five related questions are addressed: (a) What is known about the relationships between road geometry and operating speeds? (b) To what degree does road geometry influence operating speeds? (c) How are safety and security influenced by road geometry? (d) What are the potential impacts on large vehicles? and (e) What is the nature of the speed–safety trade-off?
Design Guidance for Freeway Main-Line Ramp Terminals
Authors: Torbic Darren J. , Hutton Jessica M. , Bokenkroger Courtney D. , Brewer Marcus A.
Published: January 2013

This paper presents the results of a study to develop improved design guidance for freeway main-line ramp terminals on the basis of modern driver behavior and vehicle performance capabilities. The primary steps included a crash analysis, an observational field study, and a driver behavioral study. This research reached several key conclusions, as follows. Vehicle merging speeds tend to be closer to freeway speeds at tapered acceleration lanes than at parallel acceleration lanes. The recommended minimum lengths for acceleration lanes presented in the 2004 edition of AASHTO's A Policy on Geometric Design of Highways and Streets (Green Book) are conservative and, under certain conditions, could be reduced by 15%. In a situation in which a significant volume of trucks uses an entrance ramp, an acceleration lane length that will better accommodate trucks can be derived by using speed–distance curves developed for a range of weight-to-power ratios. The recommended minimum lengths for deceleration lanes presented in the 2004 Green Book are conservative and do not account for deceleration in the freeway. Providing deceleration lanes longer than the minimum values given in the Green Book may promote casual deceleration by exiting drivers. Several potential changes for consideration in the next edition of the Green Book are recommended on the basis of the findings and conclusions of this research.
Structural and Safety Investigation of Statewide Performance of Weathered Steel Beam Guardrail in North Carolina
Authors: Findley Daniel J. , Cunningham Christopher M. , Schroeder Bastian J. , Vaughan Christopher L. , Fowler Tyler J.
Published: January 2013

This paper evaluates the structural integrity and safety performance of weathered steel beam guardrail (WSBG) in North Carolina. WSBG is a popular alternative to galvanized steel guardrail (GSG) in that it is an aesthetic solution that blends in with the surrounding natural environment. A New Hampshire study, however, found that WSBG deteriorates more quickly. That study prompted an FHWA recommendation discouraging the use of WSBG across the country. This paper describes a comprehensive study of all WSBG installations in North Carolina, where weather conditions and deicing practices are generally much less severe than in New Hampshire. The research results did not show any trends of deteriorating thickness as a function of guardrail age (the oldest installation was almost 30 years old), elevation (the tallest installation was 4,200 ft), and annual average daily traffic (the highest traffic volume was 27,000 vehicles per day). The WSBG at all 25 test sites was shown to be above AASHTO minimum thickness specifications of 0.096 in. at a 95% confidence level. From a safety perspective, the research results suggested a lower percentage of injury collisions at WSBG installations relative to GSG installations at comparison sites, although low crash sample sizes made a more robust comparison difficult. Overall, this research suggests there are no structural concerns about using WSBG in North Carolina. The findings of this study may have broader policy implications for other states.
Field Application and Assessment of the Safety Edge
Authors: Hallmark Shauna L. , McDonald Thomas , Sperry Robert , Knapp Keith
Published: January 2013

Pavement edge drop-off can be a serious safety concern when a vehicle leaves the paved roadway surface and encounters a significant difference in vertical elevation between the paved roadway and the adjacent unpaved shoulder. Edge drop-offs are potential safety hazards because scrubbing between the pavement edge and tire can result in loss of control. FHWA developed the Safety Edge on the basis of research results that indicated a sloped pavement edge surface could be more easily traversed by a vehicle leaving its lane and attempting to remount the pavement edge. The Safety Edge is a design feature that creates an approximate 30° fillet along the outside edge of the paved section of a roadway. Although a number of benefits have been attributed to the Safety Edge, agencies in Iowa were slow to adopt it. To accelerate use of the Safety Edge, the research team marketed and monitored it in Iowa during the 2010 construction season. This project provided the opportunity to evaluate the Safety Edge as well as summarize lessons learned from agencies and contractors. Evaluation of the Safety Edge included assessment of the consistency of slope application, identification of common problems during construction, measurement of the density of the Safety Edge, and computation of the approximate additional material needed to construct the Safety Edge. The team also measured drop-off formation along previously constructed Safety Edge sites and compared this with control sites to assess any difference in occurrence.
Development and Implementation of the Simplified Midwest Guardrail System Stiffness Transition
Authors: Lechtenberg Karla A. , Rosenbaugh Scott K. , Bielenberg Robert W. , Mongiardini Mario , Faller Ronald K. , de Albuquerque Francisco Daniel Benicio
Published: January 2013

The varied lateral stiffness between bridge rails and approach guardrail systems may cause vehicle pocketing or wheel snagging to occur near rigid bridge rail ends. To mitigate this potential hazard, an approach guardrail transition (AGT) is used to provide a gradual increase in the lateral stiffness of the barrier between the W-beam guardrail system and the bridge railing. However, these transitions can also cause a propensity for vehicle pocketing or wheel snagging if the change in lateral stiffness occurs too rapidly. Recently, a stiffness transition based on NCHRP Report 350 was developed for use with the Midwest Guardrail System (MGS) and a stiff Thrie beam AGT, and successful testing was performed close to the upstream end of the AGT. The transition was designed with three sizes of steel posts, one of which was nonstandard for state departments of transportation. Thus, a simplified version of the original MGS stiffness transition that used two common sizes of steel posts was developed and was subjected to full-scale crash testing according to Test Level 3 as set forth in the Manual for Assessing Safety Hardware. Subsequently, dynamic post properties obtained from bogie testing and numerical simulations were used to develop an equivalent wood post version of the simplified MGS stiffness transition. Recommendations are made regarding the attachment of the stiffness transitions to FHWA-accepted Thrie beam bridge rail AGTs.
Low-Cost Median Barrier Gate
Authors: Bligh Roger P. , Arrington Dusty R. , Sheikh Nauman M. , Meza Rory , Silvestri Chiara
Published: January 2013

Median barriers are commonly used to separate opposing lanes of traffic on divided highways and to separate managed lanes from general purpose lanes. Concrete median barriers (CMBs) are often preferred on urban freeways with narrow medians because of their minimal deflection and low maintenance. However, long, continuous runs of CMBs limit access of emergency and maintenance vehicles to the other side of a roadway or a managed lane. Implementation of crashworthy median barrier gates at these locations can maintain the desired level of median protection for motorists while offering improved cross-median access for emergency and maintenance vehicles. A new median barrier gate was developed and crash tested. The gate spans a 30-ft opening in a CMB and consists of two vertically stacked 12- x 12- x ¼-in. steel tubes connected to steel end brackets with 2¼-in. diameter steel pins. The gate is economical to fabricate and install. It can be manually operated by a single person and is designed to accommodate reversible traffic flow on both sides of the median and be operable in both directions on each end. The median barrier gate satisfies the criteria for impact performance of Test Level 3 of the Manual for Assessing Safety Hardware and is considered suitable for implementation on divided highways at locations where cross-median access is desired.
Comparison of Crash Test and Simulation Results for Impact of Silverado Pickup into New Jersey Barrier under Manual for assessing Safety Hardware
Authors: Marzougui Dhafer , Kan Cing-Dao (Steve) , Opiela Kenneth S.
Published: January 2013

The National Crash Analysis Center (NCAC) at the George Washington University simulated the crash of a 2,270-kg Chevrolet Silverado pickup truck into a standard 32-in. New Jersey shape concrete barrier under the requirements of Test 3–11 of the Manual for Assessing Safety Hardware (MASH). The new, detailed finite element (FE) model for the Chevrolet Silverado was used as the surrogate for the MASH 2270P test vehicle. An FE model of the New Jersey barrier was drawn from the array of NCAC hardware models. The primary objective of this analysis was to simulate the crash test conducted to evaluate how this commonly used, NCHRP 350–approved device would perform under the more rigorous MASH crashworthiness criteria. A secondary objective was to use newly developed verification and validation (V&V) procedures to compare the results of the detailed simulation with the results of crash tests undertaken as part of another project. The crash simulation was successfully executed with the detailed Silverado FE model and NCAC models of the New Jersey concrete barrier. Traditional comparisons of the simulation results and the data derived from the crash test suggested that the modeling provided viable results. Further comparisons employing the V&V procedures provided a structured assessment across multiple factors reflected in the phenomena importance ranking table. Statistical measures of the accuracy of the test in comparison with simulation results provided a more robust validation than previous approaches. These comparisons further confirmed that the model was able to replicate impacts with a 2270P vehicle, as required by MASH.