scholarly journals Geometric Design, Speed, and Safety

2012 ◽  
Vol 2309 (1) ◽  
pp. 39-47 ◽  
Author(s):  
Richard J. Porter ◽  
Eric T. Donnell ◽  
John M. Mason
Keyword(s):  
Geometric Design ◽  
Operating Speed ◽  
Highway Safety Manual ◽  
Road Geometry ◽  
Speed Management ◽  
Design Speed ◽  
Synthesis Report ◽  
Definition Of ◽  
Roadway Design ◽  
Selection Of

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?

Formulation and Validation of Operating Speed-Based Design Consistency Models by Bootstrapping

1997 ◽  
Vol 1579 (1) ◽  
pp. 97-103 ◽  
Author(s):  
John McFadden ◽  
Lily Elefteriadou
Keyword(s):  
Additional Data ◽  
Original Data ◽  
Statistical Technique ◽  
Geometric Design ◽  
Operating Speed ◽  
Horizontal Alignment ◽  
Alternative Means ◽  
Design Speed ◽  
Design Consistency ◽  
Consistency Models

Current U.S. policy for designing rural two-lane highways is based on design speed to ensure consistency among consecutive highway segments. The design speed concept, however, does not ensure that a consistent alignment will be achieved. A recent FHWA-sponsored project (Horizontal Alignment Design Consistency for Rural Two-Lane Highways) led to three operating speed-based geometric design consistency models, which have not yet been validated. Traditionally, the validation of such models involves the collection of additional data. The statistical technique known as “bootstrapping” was used to formulate and validate the operating speed-based geometric design consistency models by using the existing FHWA database. Bootstrapping involves random sampling with replacement from the existing database, which becomes the population. One-half of the original data collected are used in formulating the models. The remaining half of the data are subsequently used for validation. The models resulting from bootstrapping were statistically equivalent to the models developed in the FHWA study. In addition, the model validation indicated that the bootstrapping technique used to validate the operating speed models is a viable alternative means of validation. It was concluded that bootstrapping is a very useful tool that can be exploited in many related areas in the transportation field, especially because of the large amounts of data typically required in developing and validating empirical models.

scholarly journals SIGHT DISTANCE ANALYSES IN ROAD DESIGN PROCESS: SERBIAN PRACTICE

Transport ◽  
2016 ◽  
Vol 31 (2) ◽  
pp. 250-259 ◽  
Author(s):  
Dejan Gavran ◽  
Sanja Fric ◽  
Vladan Ilić ◽  
Filip Trpčevski
Keyword(s):  
Cross Sections ◽  
3D Models ◽  
Software Tools ◽  
Design Parameters ◽  
Operating Speed ◽  
The Road ◽  
Road Design ◽  
Sight Distance ◽  
Road Geometry ◽  
Design Speed

New Serbian policies on road design introduce the concept of operating speeds. Decades ago, national policies were based on the constant design speed concept. Among other design parameters, in relation to that constant design speed, minimum radii of horizontal and vertical road geometry were determined. Introduction of the operating speed concept provides for more realistic prediction of speed levels along the road. Unlike the constant design speed, operating speed levels vary along the road, reaching higher levels in curves with larger radii, on straight sections and on reverse curves and dropping down to the design speed level in horizontal curves with the minimum radius. Consequently, besides a constant Stopping Sight Distance (SSD), which is calculated from the constant design speed, the new term, Required Sight Distance (RSD) is introduced. RSD varies along the road, as it is calculated from the operating speed, which also varies along the road. Appropriate RSD analyses are crucial on road rehabilitation projects, since a simple resurfacing that enables higher speed levels, without providing increased RSD, may hamper the safety of a newly resurfaced road. Software tools for predicting operating speed levels and optical analyses of the road are also presented in this paper. Software tools for RSD analyses enable the import of lines of sight into the 3D model of the roadway and their export into the cross sections extracted from the model, thus facilitating the obstacle removal. Also demonstrated are tools for determining Available Sight Distance (ASD), which are based on triangulated 3D models of the roadway as well.

Effect of speed prediction models and perceived radius on design consistency

2005 ◽  
Vol 32 (2) ◽  
pp. 388-399 ◽  
Author(s):  
Laurel Richl ◽  
Tarek Sayed
Keyword(s):  
Prediction Models ◽  
Operating Speed ◽  
The Road ◽  
Speed Prediction ◽  
The Difference ◽  
Design Speed ◽  
Design Consistency ◽  
Side Friction ◽  
Consistency Evaluation ◽  
Selection Of

The most frequently used criteria to evaluate design consistency are the difference between design speed and operating speed, operating speeds on successive elements, and assumed side friction of the road and that demanded by the driver. The operating speed, often obtained using speed prediction models, influences each design consistency criteria. There has been considerable research in developing design consistency measures and evaluation tools, but little research has been done on the influence that different speed prediction models have on design consistency criteria. In addition, there has been little research as to how design factors such as driver perception of combined horizontal and vertical curves influence speed prediction models. This paper investigates how the selection of speed prediction models and driver perception of combined horizontal and vertical curves influence design consistency evaluation. The selection of the speed prediction model has a significant impact on design consistency evaluation. The use of perceived radius, which accounts for driver perception of combined alignments, slightly influenced the outcome of the design consistency evaluation.Key words: design consistency, speed prediction models, driver perception, combined horizontal and vertical curves, perceived radius, geometric design.

Selection and Preparation of Specific Tissue Regions For Tem Using Large Epoxy-Embedded Blocks

1973 ◽  
Vol 31 ◽  
pp. 324-325 ◽  
Author(s):  
P. M. Lowrie ◽  
W. S. Tyler
Keyword(s):  
Electron Microscopy ◽  
Anatomical Structures ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Microscopic Evaluation ◽  
Embedded Blocks ◽  
Specific Tissue ◽  
Definition Of ◽  
Areas Of Interest ◽  
Selection Of

The importance of examining stained 1 to 2μ plastic sections by light microscopy has long been recognized, both for increased definition of many histologic features and for selection of specimen samples to be used in ultrastructural studies. Selection of specimens with specific orien ation relative to anatomical structures becomes of critical importance in ultrastructural investigations of organs such as the lung. The uantity of blocks necessary to locate special areas of interest by random sampling is large, however, and the method is lacking in precision. Several methods have been described for selection of specific areas for electron microscopy using light microscopic evaluation of paraffin, epoxy-infiltrated, or epoxy-embedded large blocks from which thick sections were cut. Selected areas from these thick sections were subsequently removed and re-embedded or attached to blank precasted blocks and resectioned for transmission electron microscopy (TEM).

Safety at Curves and Road Geometry Standards in Some European Countries

1996 ◽  
Vol 1523 (1) ◽  
pp. 99-106 ◽  
Author(s):  
Thierry Brenac
Keyword(s):  
Urban Areas ◽  
National Standards ◽  
European Countries ◽  
Design Standards ◽  
The Road ◽  
Horizontal Curves ◽  
Road Design ◽  
Road Geometry ◽  
Design Speed ◽  
Curve Geometry

This paper deals with safety at horizontal curves on two-lane roads outside urban areas and the way the road design standards of different European countries account for this safety aspect. After a review of some research results, the main aspects of curve geometry and the curve's place in the horizontal alignment are analyzed. The main conclusions are that the traditional design speed approach is insufficient and that formal complementary rules in road design standards, especially to improve compatibility between successive elements of the alignment, must be introduced. If such complementary rules already exist in some national standards, they are neither frequent nor homogeneous throughout the different countries, and it seems that they are not based on sufficiently developed knowledge.

scholarly journals Promotion of Resilience in Migrants: A Systematic Review of Study and Psychosocial Intervention

2021 ◽  
Author(s):  
Maria Ciaramella ◽  
Nadia Monacelli ◽  
Livia Concetta Eugenia Cocimano
Keyword(s):  
Systematic Review ◽  
Psychosocial Intervention ◽  
Life Experiences ◽  
Psychosocial Interventions ◽  
Migrant Population ◽  
Methodological Choices ◽  
Research Questions ◽  
Definition Of ◽  
Selection Of

AbstractThis systematic review aimed to contribute to a better and more focused understanding of the link between the concept of resilience and psychosocial interventions in the migrant population. The research questions concerned the type of population involved, definition of resilience, methodological choices and which intervention programmes were targeted at migrants. In the 90 articles included, an heterogeneity in defining resilience or not well specified definition resulted. Different migratory experiences were not adequately considered in the selection of participants. Few resilience interventions on migrants were resulted. A lack of procedure’s descriptions that keep in account specific migrants’ life-experiences and efficacy’s measures were highlighted.

scholarly journals Getting to Hope: Perspectives from Patients and Caregivers Living with Chronic Childhood Illness

Children ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 525
Author(s):  
Emily von Scheven ◽  
Bhupinder K. Nahal ◽  
Rosa Kelekian ◽  
Christina Frenzel ◽  
Victoria Vanderpoel ◽  
...  
Keyword(s):  
Conceptual Model ◽  
Research Question ◽  
Young Patients ◽  
Future Research ◽  
Childhood Onset ◽  
Virtual Focus Groups ◽  
Definition Of ◽  
Selection Of ◽  
Chronic Childhood ◽  
Research Studies

Promoting hope was identified in our prior work as the top priority research question among patients and caregivers with diverse childhood-onset chronic conditions. Here, we aimed to construct a conceptual model to guide future research studies of interventions to improve hope. We conducted eight monthly virtual focus groups and one virtual workshop with patients, caregivers, and researchers to explore key constructs to inform the model. Discussions were facilitated by Patient Co-Investigators. Participants developed a definition of hope and identified promotors and inhibitors that influence the experience of hope. We utilized qualitative methods to analyze findings and organize the promotors and inhibitors of hope within three strata of the socio-ecologic framework: structural, interpersonal, and intrapersonal. Participants identified three types of interventions to promote hope: resources, navigation, and activities to promote social connection. The hope conceptual model can be used to inform the selection of interventions to assess in future research studies aimed at improving hope and the specification of outcome measures to include in hope research studies. Inclusion of the health care system in the model provides direction for identifying strategies for improving the system and places responsibility on the system to do better to promote hope among young patients with chronic illness and their caregivers.

scholarly journals Examining and Fine-tuning the Selection of Glycan Compositions with GlyConnect Compozitor

2020 ◽  
Vol 19 (10) ◽  
pp. 1602-1618 ◽  
Author(s):  
Thibault Robin ◽  
Julien Mariethoz ◽  
Frédérique Lisacek
Keyword(s):  
Search Engine ◽  
Posttranslational Modifications ◽  
Search Engines ◽  
Web Application ◽  
Contextual Information ◽  
Fine Tuning ◽  
Data Sources ◽  
Web Interface ◽  
Definition Of ◽  
Selection Of

A key point in achieving accurate intact glycopeptide identification is the definition of the glycan composition file that is used to match experimental with theoretical masses by a glycoproteomics search engine. At present, these files are mainly built from searching the literature and/or querying data sources focused on posttranslational modifications. Most glycoproteomics search engines include a default composition file that is readily used when processing MS data. We introduce here a glycan composition visualizing and comparative tool associated with the GlyConnect database and called GlyConnect Compozitor. It offers a web interface through which the database can be queried to bring out contextual information relative to a set of glycan compositions. The tool takes advantage of compositions being related to one another through shared monosaccharide counts and outputs interactive graphs summarizing information searched in the database. These results provide a guide for selecting or deselecting compositions in a file in order to reflect the context of a study as closely as possible. They also confirm the consistency of a set of compositions based on the content of the GlyConnect database. As part of the tool collection of the Glycomics@ExPASy initiative, Compozitor is hosted at https://glyconnect.expasy.org/compozitor/ where it can be run as a web application. It is also directly accessible from the GlyConnect database.

General Schema Theory for Genetic Programming with Subtree-Swapping Crossover: Part II

2003 ◽  
Vol 11 (2) ◽  
pp. 169-206 ◽  
Author(s):  
Riccardo Poli ◽  
Nicholas Freitag McPhee
Keyword(s):  
Genetic Programming ◽  
Schema Theory ◽  
Exact Formulation ◽  
Expected Number ◽  
Size Evolution ◽  
General Schema ◽  
Definition Of ◽  
Effective Fitness ◽  
Selection Of ◽  
Exact Definition

This paper is the second part of a two-part paper which introduces a general schema theory for genetic programming (GP) with subtree-swapping crossover (Part I (Poli and McPhee, 2003)). Like other recent GP schema theory results, the theory gives an exact formulation (rather than a lower bound) for the expected number of instances of a schema at the next generation. The theory is based on a Cartesian node reference system, introduced in Part I, and on the notion of a variable-arity hyperschema, introduced here, which generalises previous definitions of a schema. The theory includes two main theorems describing the propagation of GP schemata: a microscopic and a macroscopic schema theorem. The microscopic version is applicable to crossover operators which replace a subtree in one parent with a subtree from the other parent to produce the offspring. Therefore, this theorem is applicable to Koza's GP crossover with and without uniform selection of the crossover points, as well as one-point crossover, size-fair crossover, strongly-typed GP crossover, context-preserving crossover and many others. The macroscopic version is applicable to crossover operators in which the probability of selecting any two crossover points in the parents depends only on the parents' size and shape. In the paper we provide examples, we show how the theory can be specialised to specific crossover operators and we illustrate how it can be used to derive other general results. These include an exact definition of effective fitness and a size-evolution equation for GP with subtree-swapping crossover.

Military Targeting in the Context of Self-Defence Actions

2015 ◽  
Vol 84 (1) ◽  
pp. 3-28 ◽  
Author(s):  
James A. Green ◽  
Christopher P.M. Waters
Keyword(s):  
Target Selection ◽  
Jus In Bello ◽  
Customary International Law ◽  
Jus Ad Bellum ◽  
Conceptual Clarity ◽  
Starting Point ◽  
Definition Of ◽  
The Relationship ◽  
Self Defence ◽  
Selection Of

For self-defence actions to be lawful, they must be directed at military targets. The absolute prohibition on non-military targeting under the jus in bello is well known, but the jus ad bellum also limits the target selection of states conducting defensive operations. Restrictions on targeting form a key aspect of the customary international law criteria of necessity and proportionality. In most situations, the jus in bello will be the starting point for the definition of a military targeting rule. Yet it has been argued that there may be circumstances when the jus ad bellum and the jus in bello do not temporally or substantively overlap in situations of self-defence. In order to address any possible gaps in civilian protection, and to bring conceptual clarity to one particular dimension of the relationship between the two regimes, this article explores the independent sources of a military targeting rule. The aim is not to displace the jus in bello as the ‘lead’ regime on how targeting decisions must be made, or to undermine the traditional separation between the two ‘war law’ regimes. Rather, conceptual light is shed on a sometimes assumed but generally neglected dimension of the jus ad bellum’s necessity and proportionality criteria that may, in limited circumstances, have significance for our understanding of human protection during war.

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