Use of Side Friction in Horizontal Curve Design: A Margin of Safety Assessment

2016 ◽  
Vol 2588 (1) ◽  
pp. 61-70 ◽  
Author(s):  
Eric Donnell ◽  
Jonathan Wood ◽  
Scott Himes ◽  
Darren Torbic
Keyword(s):  
Safety Assessment ◽  
Horizontal Curve ◽  
Curve Design ◽  
Margin Of Safety ◽  
Side Friction

scholarly journals Horizontal Curve Design - Centrifugal Force, Side Friction, and Other Myths

1993 ◽  
Vol 10 (2) ◽  
Author(s):  
Joseph P. Tarris
Keyword(s):  
Centrifugal Force ◽  
Careful Analysis ◽  
Horizontal Curve ◽  
Early Analysis ◽  
Curve Design ◽  
Vital Effect ◽  
Side Friction

Upon first accepting an appointment, the forensic engineer must make a preliminary and thorough determination, analyzing all the known and available facts pertaining to the dispute. Early decisions and the advice given to attorneys can have a vital effect on the direction of the litigation and influence the forensic engineers position in the litigation. The purpose of this early analysis and research is to formulate responsibility and fault. Whether the forensic engineer is engaged before or after filing of the lawsuit is irrelevant, as the same careful analysis of the facts and conditions apply

Development and Adoption of Early AASHO Design Criteria

1998 ◽  
Vol 1612 (1) ◽  
pp. 26-33 ◽  
Author(s):  
Jerome Hall ◽  
Daniel Turner
Keyword(s):  
Design Parameters ◽  
Design Criteria ◽  
Adoption Process ◽  
Horizontal Curve ◽  
Highway Design ◽  
Initial Development ◽  
Design Processes ◽  
Blue Book ◽  
Curve Design ◽  
Independent Design

The conception, development, and adoption of early AASHO highway design criteria are documented. Examining the early efforts states used to select a design vehicle and develop horizontal curve design criteria illustrates why AASHO’s leadership was necessary. AASHO’s slow and somewhat haphazard criteria development, and the disparity from state to state, demonstrated the need for a national consensus in highway design parameters. AASHO’s role in providing these criteria is outlined through its initial development of policy booklets, followed by its 1954 publication of the landmark Blue Book. The processes by which nine states adopted the AASHO guidance are briefly reviewed. In several cases, the AASHO policy was embraced immediately, and in others it was accepted slowly as states clung to their independent design processes and only gradually updated their design criteria. A few simple conclusions are drawn about the development and adoption process, particularly as it may relate to tomorrow’s highway design criteria.

Modeling Safety Effects of Horizontal Curve Design on Injury Severity of Single-Motorcycle Crashes with Mixed-Effects Logistic Model

2017 ◽  
Vol 2637 (1) ◽  
pp. 38-46 ◽  
Author(s):  
Chunfu Xin ◽  
Zhenyu Wang ◽  
Chanyoung Lee ◽  
Pei-Sung Lin
Keyword(s):  
Logistic Model ◽  
Injury Severity ◽  
Unobserved Heterogeneity ◽  
Mixed Effects ◽  
Severe Injury ◽  
Horizontal Curve ◽  
Random Parameters ◽  
Horizontal Curves ◽  
Curve Design ◽  
Motorcycle Crashes

Horizontal curves have been of great interest to transportation researchers because of expected safety hazards for motorcyclists. The impacts of horizontal curve design on motorcycle crash injuries are not well documented in previous studies. The current study aimed to investigate and to quantify the effects of horizontal curve design and associated factors on the injury severity of single-motorcycle crashes with consideration of the issue of unobserved heterogeneity. A mixed-effects logistic model was developed on the basis of 2,168 single-motorcycle crashes, which were collected on 8,597 horizontal curves in Florida for a period of 11 years (2005 to 2015). Four normally distributed random parameters (moderate curves, reverse curves, older riders, and male riders) were identified. The modeling results showed that sharp curves (radius <1,500 ft) compared with flat curves (radius ≥4,000 ft) tended to increase significantly the probability of severe injury (fatal or incapacitating injury) by 7.7%. In total, 63.8% of single-motorcycle crashes occurring on reverse curves are more likely to result in severe injury, and the remaining 26.2% are less likely to result in severe injury. Motorcyclist safety compensation behaviors (psychologically feeling safe, and then riding aggressively, or vice versa) may result in counterintuitive effects (e.g., vegetation and paved medians, full-access-controlled roads, and pavement conditions) or random parameters (e.g., moderate curve and reverse curve). Other significant factors include lighting conditions (darkness and darkness with lights), weekends, speed or speeding, collision type, alcohol or drug impairment, rider age, and helmet use.

scholarly journals Safety Assessment and Biological Effects of a New Cold Processed SilEmulsion for Dermatological Purpose

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Sara Raposo ◽  
Ana Salgado ◽  
Lídia Gonçalves ◽  
Pedro C. Pinto ◽  
Manuela Urbano ◽  
...  
Keyword(s):  
Safety Assessment ◽  
Biological Effects ◽  
Response Assessment ◽  
Skin Surface ◽  
Patch Tests ◽  
Hazard Exposure ◽  
Margin Of Safety ◽  
Skin Surface Lipids

It is of crucial importance to evaluate the safety profile of the ingredients used in dermatological emulsions. A suitable equilibrium between safety and efficacy is a pivotal concern before the marketing of a dermatological product. The aim was to assess the safety and biological effects of a new cold processed silicone-based emulsion (SilEmulsion). The hazard, exposure, and dose-response assessment were used to characterize the risk for each ingredient. EpiSkin assay and human repeat insult patch tests were performed to compare the theoretical safety assessment toin vitroandin vivodata. The efficacy of the SilEmulsion was studied using biophysical measurements in human volunteers during 21 days. According to the safety assessment of the ingredients, 1,5-pentanediol was an ingredient of special concern since its margin of safety was below the threshold of 100 (36.53). EpiSkin assay showed that the tissue viability after the application of the SilEmulsion was 92 ± 6% and, thus considered nonirritant to the skin. The human studies confirmed that the SilEmulsion was not a skin irritant and did not induce any sensitization on the volunteers, being safe for human use. Moreover, biological effects demonstrated that the SilEmulsion increased both the skin hydration and skin surface lipids.

scholarly journals Determination of Applicable Adjacent Horizontal Curve Radii Using Operating Speed

2019 ◽  
Vol 31 (4) ◽  
pp. 443-452
Author(s):  
Dražen Cvitanić ◽  
Biljana Maljković
Keyword(s):  
Dynamic Consistency ◽  
Operating Speed ◽  
Demand Side ◽  
Horizontal Curve ◽  
Driving Dynamic ◽  
The Road ◽  
Design Speed ◽  
Side Friction ◽  
Limiting Values

Design of curves and their adjacent elements presents the greatest safety problem on rural two-lane roads. The use of the existing alignment consistency safety criteria (design, operating speed, and driving dynamic consistency) could have some shortcomings, especially in countries where the project or design speed is in use instead of (higher) operating speed. The consequence is that the designer should use smaller cross fall on curves than needed, while the calculated side friction is lower than in reality. Further, the existing graphs of adjacent curve radii do not take into account that there is a maximum operating speed achieved for a certain radius or long tangent above which it does not increase. This paper presents a methodology for determination of adjacent horizontal curve radii, with and without tangent between, based on the operating speed models which include dependence of operating speeds on tangents and curves on speed of adjacent alignment elements as well as maximum tangent and curve speed. The developed graphs of adjacent radii at the same time include the limiting values of driving dynamic consistency criteria, so the road designer does not need to calculate permissible and demand side friction for every combination of adjacent alignment elements.

scholarly journals Investigating Automobile Passengers’ Comfort and Safety on Scenic Road Using Sideway Force Coefficient

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Ronghua Wang ◽  
Xingliang Liu ◽  
Feijie Han
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
Lateral Acceleration ◽  
Driving Safety ◽  
Horizontal Curve ◽  
Force Coefficient ◽  
Safe Driving ◽  
Minimum Radius ◽  
Curve Design ◽  
Naturalistic Driving

To satisfy passengers’ experiential demand in scenic roads, a study on passengers’ comfort in the aspect of horizontal curve design is stated in this study. A new indicator sideway force coefficient (SFC) describing passengers’ comfort is introduced, which differs from lateral acceleration. The mechanism of SFC is provided depending on the dynamic balance condition of the vehicle on horizontal curve and S F C c representing passengers’ comfort tolerance limitation is investigated. A large scale naturalistic driving experiments along a park road are conducted, and the S F C c value from naturalistic driving experiments is verified through numerical simulation of 15 horizontal curves from 5 scenic roads from the perspectives of both passengers’ comfort and driving safety. The statistical analysis on data collected in field tests indicates that age and gender have no effect on S F C c , and the value of S F C c is determined as 0.291. The corresponding minimum radius limits under 20–60 km/h and superelevation 6%, 8%, and 10% are proposed. The numerical simulation denotes, when satisfying the comfort demand of passengers (SFC less than 0.291), the lateral distance path is in a safe range, which could also satisfy the safe driving requirements. Thus, S F C c and minimum radius limits proposed in this study are proved to be credible and appropriate for the curve design of horizontal alignment in scenic roads.

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