scholarly journals Truck stability on different types of horizontal curves combined with vertical alignments

2021 ◽  
Author(s):  
Essam Mohamed S. A. E. A. Dabbour
Keyword(s):  
Three Dimensional ◽  
Computer Software ◽  
Design Guidelines ◽  
Vehicle Stability ◽  
Horizontal Curves ◽  
Different Types ◽  
Current Design ◽  
Single Compound ◽  
Margin Of Safety ◽  
Design Speed

The combination of horizontal curves with vertical alignments is commonly used in different classifications of highways; either on highway mainstream or on highway interchange ramps. The horizontal curves, combined with vertical alignments, may be single, compound or reverse horizontal curves. The current design guidelines do not adequately investigate vehicle stability on such three-dimensional (3D) alignments. Computer software that simulates vehicle behaviour on different geometrical alignments was employed to investigate vehicle stability on such 3D alignments. It was found that vehicle safety is questionable, especially for larger vehicles on reverse curves associated with vertical alignments. The critical speed, where the vehicle starts to rollover or skid, was found to be close to design speed for those 3D alignments. Design aids were then developed to address the recommended solutions to maintain the margin of safety required.

scholarly journals Truck stability on different types of horizontal curves combined with vertical alignments

2021 ◽  
Author(s):  
Essam Mohamed S. A. E. A. Dabbour
Keyword(s):  
Three Dimensional ◽  
Computer Software ◽  
Design Guidelines ◽  
Vehicle Stability ◽  
Horizontal Curves ◽  
Different Types ◽  
Current Design ◽  
Single Compound ◽  
Margin Of Safety ◽  
Design Speed

The combination of horizontal curves with vertical alignments is commonly used in different classifications of highways; either on highway mainstream or on highway interchange ramps. The horizontal curves, combined with vertical alignments, may be single, compound or reverse horizontal curves. The current design guidelines do not adequately investigate vehicle stability on such three-dimensional (3D) alignments. Computer software that simulates vehicle behaviour on different geometrical alignments was employed to investigate vehicle stability on such 3D alignments. It was found that vehicle safety is questionable, especially for larger vehicles on reverse curves associated with vertical alignments. The critical speed, where the vehicle starts to rollover or skid, was found to be close to design speed for those 3D alignments. Design aids were then developed to address the recommended solutions to maintain the margin of safety required.

Design radius requirements for simple horizontal curves on three-dimensional alignments

2003 ◽  
Vol 30 (6) ◽  
pp. 1022-1033 ◽  
Author(s):  
Said M Easa ◽  
Essam Dabbour
Keyword(s):  
Three Dimensional ◽  
Design Guidelines ◽  
Comfort Level ◽  
Vertical Alignment ◽  
Passenger Cars ◽  
Minimum Radius ◽  
Horizontal Curves ◽  
Design Speed ◽  
Side Friction ◽  
Mathematical Relationships

Current North American design guides have established mathematical relationships to calculate the minimum radius required for horizontal curves as a function of design speed, maximum superelevation, and maximum side friction. For three-dimensional (3-D) alignments, the design guides consider the alignment as two separate horizontal and vertical alignments and consequently ignore the effect of vertical alignment. This paper evaluates the effect of vertical alignment on minimum radius requirements using computer simulation, with a focus on trucks. For 3-D alignments, the results showed that existing design guidelines for minimum radius need to be increased by as much as 20% to achieve the same comfort limit on flat horizontal curves. It is interesting to note that in some cases truck rollover occurred before the side-friction comfort level is reached. This indicates the need for developing a different design control for trucks on 3-D alignments than the comfort criterion used for passenger cars on flat horizontal curves. Based on the simulation results, mathematical models for design radius requirements for passenger cars and trucks were developed.Key words: geometric design, horizontal curve radius, three-dimensional alignments, vehicle stability.

Establishing design guidelines for compound horizontal curves on three-dimensional alignments

2005 ◽  
Vol 32 (4) ◽  
pp. 615-626 ◽  
Author(s):  
Said Easa ◽  
Essam Dabbour
Keyword(s):  
Three Dimensional ◽  
Design Guidelines ◽  
Simulation Software ◽  
Lateral Acceleration ◽  
Vertical Alignment ◽  
Vehicle Simulation ◽  
Minimum Radius ◽  
Horizontal Curves ◽  
Flat Terrain ◽  
Current Design

In current design guides, the minimum radii of compound horizontal curves are based on the design requirements of simple horizontal curves for each arc on flat terrain. Such a design ignores the effects of compound curvature and vertical alignment. This paper uses computer simulation software to establish the minimum radius requirements for compound curves, considering these effects. The actual lateral acceleration experienced by a vehicle negotiating a two-dimensional (2-D) simple curve is recorded as a base scenario to facilitate the analysis of a compound curve on a flat terrain or combined with vertical alignment (three-dimensional (3-D) compound curves). The vertical alignments examined include upgrades, downgrades, crest curves, and sag curves. Mathematical models for minimum radius requirements were developed for flat and 3-D compound curves. Three types of design vehicles were used. The results show that an increase in the minimum radius ranging from 5% to 26% is required to compensate for the effects of both compound curvature and vertical alignment.Key words: highway geometric design, compound horizontal alignments, side friction, vehicle simulation, 3-D alignments.

scholarly journals A Review on Studies Based on Vehicle Stability and Safety on Rural Horizontal Curves

2021 ◽  
Author(s):  
Y K Remya ◽  
Anitha Jacob ◽  
E A Subaida
Keyword(s):  
Computer Simulations ◽  
Field Studies ◽  
Design Guidelines ◽  
Influential Factors ◽  
Vehicle Stability ◽  
Vehicle Occupant ◽  
Horizontal Curves ◽  
Curve Design ◽  
The World ◽  
Current Design

All over the world India bangs the top most position in crash deaths. Nearly 1.2 lakh people die every year on Indian roads. Crashes involving rolloverand lateral skidding are now responsible for almost 1/3 of all highway vehicle occupant fatalities. So, rollovers and skidding are more serious than other types of crashes. One of the major reasons for such incidents is vehicle instability at curves due to its inconsistent geometric design. This necessitates a review on current design guidelines followed in India. Many researchers have pointed out drawbacks of current design approach and a few have identified various influential factors which are significant in curve design to reduce rollover and lateral skidding. When some researchers conducted field studies to measure vehicle stability at selected curves, some carried out computer simulations. There are efforts to incorporate vehicular characteristics in curve design which is much appreciable. This paper aims to project efforts made by researchers to reduce vehicle instability at horizontal curves. Moreover, gaps in these research works and scope for further research are highlighted.

Social Factors and Interface Design Guidelines

2006 ◽  
pp. 523-532
Author(s):  
Zhe Xu ◽  
David John ◽  
Anthony C. Boucouvalas
Keyword(s):  
Social Presence ◽  
Interface Design ◽  
Three Dimensional ◽  
Design Guidelines ◽  
Chat Room ◽  
Two Dimensional ◽  
Contributing Factors ◽  
Business Systems ◽  
Different Types ◽  
Video And Audio

Designing an attractive user interface for Internet communication is the objective of every software developer. However, it is not an easy task as the interface will be accessed by an uncertain number of users with various purposes. To interact with users, text, sounds, images, and animations can be provided according to different situations. Originally, text was the only medium available for a user to communicate over the Internet. With technology development, multimedia channels (e.g., video and audio) emerged into the online context. Individuals’ sociability may influence human behaviour. Some people prefer a quiet environment and others enjoy more liveliness. On the other hand, the activity purpose influences the environment preference as well. Following usability principles and task analysis (Badre, 2002; Cato, 2001; Dix, Finlay, Abowd, & Beale, 1998; McCraken & Wolfe, 2004; Neilsen, 2000; Nielsen & Tahir, 2002; Preece, Rogers, & Sharp, 2002), we can predict that business-oriented systems and informal systems will require different types of interfaces: Business systems are concerned with the efficiency of performing tasks, while the effectiveness of informal systems depend more on the user’s satisfaction with the experience of interacting with the system. Suppose you are an Internet application designer; should you provide a vivid and multichannel interface or a concise and clear appearance? When individuals’ sociability and the activity purpose contradict, should the interface design follow the sociability requirement, the purpose of the activity, or even neither of them? To answer these questions, the characteristics of communication interfaces should be examined. For face-to-face communications, sounds, voices, various facial expressions, and physical movements are the most important contributing factors. These features are named physical and social presence (Loomis, Golledge, & Klatzky, 1998). In the virtual world, real physical presence does not exist anymore; however, emotional feelings, group feelings, and other social feelings are existent but vary in quantity. The essential differences of interfaces are the quantity of the presented social feelings. For example, a three-dimensional (3-D) interface may provide more geographical and social feelings than a two-dimensional (2-D) chat room may present. To assess the different feelings that may emerge from different interfaces, a two-dimensional chat room and a three-dimensional chatting environment were developed. The identification of social feelings present in the different interface styles is presented first. Then an experiment that was carried out to measure the influence the activity styles and the individuals’ sociability have on the interface preferences is discussed. The questions raised in this article are “What are the social feelings that may differ between the two interfaces (2-D vs. 3-D)?” and “Will users prefer different interfaces for different types of activities?”

First-Order Reliability Analysis of Vehicle Safety in Highway Horizontal Curves

2013 ◽  
Author(s):  
Jaekwan Shin ◽  
Ikjin Lee
Keyword(s):  
Reliability Analysis ◽  
Failure Modes ◽  
Design Method ◽  
First Order ◽  
Horizontal Curves ◽  
State Highway ◽  
Reliability Method ◽  
Current Design ◽  
Margin Of Safety ◽  
Analytic Models

This study presents a reliability analysis of vehicle sideslip and rollover in highway horizontal curves, mainly focusing on exit ramps and interchanges. To accurately describe failure modes of a ground vehicle, analytic models for sideslip and rollover are derived considering nonlinear characteristics of vehicle behavior using the commercial software, TruckSim®, with high fidelity. Then, the probability of accident is evaluated using the First-Order Reliability Method (FORM). Furthermore, sensitivity functions of each failure mode are analytically derived to apply FORM. Numerical studies are conducted using a single-unit truck model. The results show that a truck is more likely to rollover than to slip at dry load. To propose practical application of the study, the reliability analysis for the minimum radius recommended by American Association of State Highway and Transportation Officials (AASHTO) at various speeds and bank angles is conducted. The reliability analysis of current design method shows that the method cannot provide the sufficient margin of safety against both of rollover and sideslip when there are deviations from assumed conditions, especially at low speed of vehicles.

Assessment of horizontal curves of an existing road using reliability concepts

2005 ◽  
Vol 32 (6) ◽  
pp. 1030-1038 ◽  
Author(s):  
Tomás Echaveguren ◽  
Marcelo Bustos ◽  
Hernán de Solminihac
Keyword(s):  
High Impact ◽  
Point Of View ◽  
Maximum Speed ◽  
Operating Speed ◽  
Skid Resistance ◽  
Operational Conditions ◽  
Horizontal Curves ◽  
Margin Of Safety ◽  
Design Speed ◽  
Curve Radius

Horizontal curves on road are commonly analyzed under design speed point of view, where it is assumed that the maximum speed of a vehicle in a curve is the design speed. The empirical evidence has demonstrated that when the design speed is low, the operating speed tends to be higher. This happens because of an available remaining lateral (or transverse) friction for speeds over design speed. This condition is determined by a speed limit, obtained from the demand and supply equilibrium of friction of a pavement. The difference between operating and design speeds is usually considered as the margin of safety of a horizontal curve on a road. In this study, a methodology to determine the margin of safety of an existing curve is proposed. The methodology is based on the reliability theory by which reliability of operational conditions can be analyzed by using a reliability index as a margin of safety. A case study for light vehicles is evaluated to determine high impact variables over reliability, such as, macrotexture, skid resistance, curve radius, and superelevation. The results obtained in this study demonstrated that curve radius, skid resistance, and macrotexture are variables with high impact over failure probability. In constrast, superelevation has little effect on the failure probability.Key words: reliability, horizontal curves, operating speed, skid resistance, pavement texture.

Highway Alignment: Three-Dimensional Problem and Three-Dimensional Solution

1998 ◽  
Vol 1612 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Yasser Hassan ◽  
Said M. Easa ◽  
A. O. Abd El Halim
Keyword(s):  
Three Dimensional ◽  
Computer Software ◽  
Geometric Design ◽  
Analytical Models ◽  
Dimensional Solution ◽  
Distance Analysis ◽  
Sight Distance ◽  
The Status ◽  
Current Design ◽  
Highway Alignment

Highway geometric design has usually been considered in separate two-dimensional (2-D) projections of horizontal and vertical alignments. Such a practice was followed mainly because three-dimensional (3-D) analysis of combined highway alignments was expected to be difficult. As a result, the effect of ignoring the 3-D nature of the highway alignment could not be quantified. With the long-term objective of developing 3-D design practice, a framework for 3-D highway geometric design was developed and 3-D sight distance was extensively studied as the first design basis. The status of sight distance in current design policies and previous research is summarized, and mainly 2-D analysis was considered. The five main tasks performed to cover the 3-D highway sight distance are presented. ( a) As a preliminary step, the 2-D sight distance on complex separate horizontal and vertical alignments was modeled, and the finite element method was used for the first time in the highway geometric design. ( b) The 2-D models were then expanded to cover the daytime and nighttime sight distances on 3-D combined alignments. ( c) The analytical models were coded into computer software that can determine the available sight distance on actual highway segments. ( d) The models were applied in 3-D design of combined horizontal and vertical curves in cut-and-fill sections, and preliminary design aids were derived. ( e) Finally, a new concept of red zones was suggested to mark the locations on alignments designed according to current practices where the available sight distance will drop below that required. A comprehensive work on 3-D sight distance analysis has been compiled that should be of great importance for highway researchers and professionals.

Ultrastructural Investigations of the Contractile Filaments of Amoebae

1974 ◽  
Vol 32 ◽  
pp. 188-189
Author(s):  
P.L. Moore
Keyword(s):  
Cytoplasmic Streaming ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Amoeboid Movement ◽  
Different Types ◽  
Chemical Conditions ◽  
Complete Interpretation

Previous freeze fracture results on the intact giant, amoeba Chaos carolinensis indicated the presence of a fibrillar arrangement of filaments within the cytoplasm. A complete interpretation of the three dimensional ultrastructure of these structures, and their possible role in amoeboid movement was not possible, since comparable results could not be obtained with conventional fixation of intact amoebae. Progress in interpreting the freeze fracture images of amoebae required a more thorough understanding of the different types of filaments present in amoebae, and of the ways in which they could be organized while remaining functional.The recent development of a calcium sensitive, demembranated, amoeboid model of Chaos carolinensis has made it possible to achieve a better understanding of such functional arrangements of amoeboid filaments. In these models the motility of demembranated cytoplasm can be controlled in vitro, and the chemical conditions necessary for contractility, and cytoplasmic streaming can be investigated. It is clear from these studies that “fibrils” exist in amoeboid models, and that they are capable of contracting along their length under conditions similar to those which cause contraction in vertebrate muscles.

A Study on Utilization of Three-Dimensional Sensor Lip Image for Developing a Pronunciation Recognition System

2019 ◽  
Vol 63 (5) ◽  
pp. 50402-1-50402-9 ◽  
Author(s):  
Ing-Jr Ding ◽  
Chong-Min Ruan
Keyword(s):  
Principal Component Analysis ◽  
Automatic Speech Recognition ◽  
Feature Fusion ◽  
Three Dimensional ◽  
Principal Component ◽  
Recognition System ◽  
Geometrical Characteristics ◽  
3D Geometry ◽  
Different Types ◽  
The Disabled

Abstract The acoustic-based automatic speech recognition (ASR) technique has been a matured technique and widely seen to be used in numerous applications. However, acoustic-based ASR will not maintain a standard performance for the disabled group with an abnormal face, that is atypical eye or mouth geometrical characteristics. For governing this problem, this article develops a three-dimensional (3D) sensor lip image based pronunciation recognition system where the 3D sensor is efficiently used to acquire the action variations of the lip shapes of the pronunciation action from a speaker. In this work, two different types of 3D lip features for pronunciation recognition are presented, 3D-(x, y, z) coordinate lip feature and 3D geometry lip feature parameters. For the 3D-(x, y, z) coordinate lip feature design, 18 location points, each of which has 3D-sized coordinates, around the outer and inner lips are properly defined. In the design of 3D geometry lip features, eight types of features considering the geometrical space characteristics of the inner lip are developed. In addition, feature fusion to combine both 3D-(x, y, z) coordinate and 3D geometry lip features is further considered. The presented 3D sensor lip image based feature evaluated the performance and effectiveness using the principal component analysis based classification calculation approach. Experimental results on pronunciation recognition of two different datasets, Mandarin syllables and Mandarin phrases, demonstrate the competitive performance of the presented 3D sensor lip image based pronunciation recognition system.

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