scholarly journals Reliability analysis of truck escape ramp design

2021 ◽  
Author(s):  
Kaitlyn Ann Greto
Keyword(s):  
Reliability Analysis ◽  
Safety Margin ◽  
Rolling Resistance ◽  
Second Moment ◽  
First Order ◽  
Stopping Distance ◽  
Design Variables ◽  
Reliability Method ◽  
First Order Second Moment ◽  
Design Speed

The truck escape ramp design presented by the Transportation Association of Canada is based on deterministic values of the design variables which include the required stopping distance, design speed, rolling resistance, and grade. Currently, a reliability analysis of the design of truck escape ramps does not exist. This report presents two methods used to analyze the reliability of truck escape ramp design; the first order second moment reliability method and the advanced first order second moment reliability method. These methods do not rely on deterministic values rather the mean and variance (moments) of each random variable’s probability distribution. Each reliability method was used to analyze truck escape ramps with one grade and two grades, for a total of four cases. The results of each case are provided and discussed along with an application to two existing truck escape ramps. The results show that the advanced first order second moment reliability method ensures more accurate results as well as a larger safety margin in comparison to the first order second moment method due to the nature of the methodology itself which considers design points.

scholarly journals Reliability analysis of truck escape ramp design

2021 ◽  
Author(s):  
Kaitlyn Ann Greto
Keyword(s):  
Reliability Analysis ◽  
Safety Margin ◽  
Rolling Resistance ◽  
Second Moment ◽  
First Order ◽  
Stopping Distance ◽  
Design Variables ◽  
Reliability Method ◽  
First Order Second Moment ◽  
Design Speed

The truck escape ramp design presented by the Transportation Association of Canada is based on deterministic values of the design variables which include the required stopping distance, design speed, rolling resistance, and grade. Currently, a reliability analysis of the design of truck escape ramps does not exist. This report presents two methods used to analyze the reliability of truck escape ramp design; the first order second moment reliability method and the advanced first order second moment reliability method. These methods do not rely on deterministic values rather the mean and variance (moments) of each random variable’s probability distribution. Each reliability method was used to analyze truck escape ramps with one grade and two grades, for a total of four cases. The results of each case are provided and discussed along with an application to two existing truck escape ramps. The results show that the advanced first order second moment reliability method ensures more accurate results as well as a larger safety margin in comparison to the first order second moment method due to the nature of the methodology itself which considers design points.

scholarly journals Reliability Analysis Approach For Intersection Sight Distance Of A Symmetrical Single-Lane Roundabout

2021 ◽  
Author(s):  
Paria Sarshar
Keyword(s):  
Reliability Analysis ◽  
Safety Margin ◽  
Random Variables ◽  
Analysis Approach ◽  
Deterministic Models ◽  
Second Moment ◽  
First Order ◽  
Sight Distance ◽  
Design Variables ◽  
First Order Second Moment

The current intersection sight distance values on a roundabout provided by ASSHTO and other worldwide guidelines are based on deterministic methods considering only single variables as the design inputs. However, most of the input design variables such as entering speed and the deceleration rate are random variables which are stochastic in nature. Therefore, this study proposes a reliability analysis approach to add uncertainty to the current deterministic models. Two different reliability approaches; the first order second moment and advanced first order second moment are presented in this paper. These approaches rely on the normal distribution of the random variables using the mean, variance and the covariance of the probability distribution of each variable rather than the single deterministic values. Results show that the AFOSM reliability methodology provides a more conservative outcome which ensures a greater safety margin comparing to FOSM which appears to be a more efficient and robust methodology.

scholarly journals Analysis of passing sight distance using first-order reliability method

2021 ◽  
Author(s):  
Said Easa
Keyword(s):  
Safety Margin ◽  
Field Studies ◽  
Vehicle Speed ◽  
Second Moment ◽  
First Order ◽  
State Highway ◽  
Sight Distance ◽  
Design Variables ◽  
Reliability Method ◽  
First Order Second Moment

Current passing sight distance requirements for two lane highways by the American Association of State Highway and Transportation Officials are based on field studies conducted between 1938 and 1941 which use deterministic values for its design variables such as passing sight distance, speed of the passing vehicle, speed differential between the passed and passing vehicle etc. This report presents three methods to analyze reliability and serves as an extension to the revised model presented by Yasser Hassan, Said Easa and A.O.Abd El Halim whose model sought to improve older models by equally considering both observed passing behaviours of drivers and passing maneuvers that are consistent with two lane highways. Analysis of passing sight distance using first order second moment reliability method, advanced first order second moment and the ellipsoid approach to measure the probability of failure of the passing sight distance design, rely solely on the mean and variance (moments) of each randomly distributed variable in contrast to methods that rely only on deterministic values. Results show the advanced first order second moment and the ellipsoid approach provided more accurate results than first order second moment method which in turn provide a greater safety margin with the later also proving to be a much more robust and efficient method of performing a reliability

scholarly journals Reliability Analysis Approach For Intersection Sight Distance Of A Symmetrical Single-Lane Roundabout

2021 ◽  
Author(s):  
Paria Sarshar
Keyword(s):  
Reliability Analysis ◽  
Safety Margin ◽  
Random Variables ◽  
Analysis Approach ◽  
Deterministic Models ◽  
Second Moment ◽  
First Order ◽  
Sight Distance ◽  
Design Variables ◽  
First Order Second Moment

The current intersection sight distance values on a roundabout provided by ASSHTO and other worldwide guidelines are based on deterministic methods considering only single variables as the design inputs. However, most of the input design variables such as entering speed and the deceleration rate are random variables which are stochastic in nature. Therefore, this study proposes a reliability analysis approach to add uncertainty to the current deterministic models. Two different reliability approaches; the first order second moment and advanced first order second moment are presented in this paper. These approaches rely on the normal distribution of the random variables using the mean, variance and the covariance of the probability distribution of each variable rather than the single deterministic values. Results show that the AFOSM reliability methodology provides a more conservative outcome which ensures a greater safety margin comparing to FOSM which appears to be a more efficient and robust methodology.

scholarly journals Analysis of passing sight distance using first-order reliability method

2021 ◽  
Author(s):  
Said Easa
Keyword(s):  
Safety Margin ◽  
Field Studies ◽  
Vehicle Speed ◽  
Second Moment ◽  
First Order ◽  
State Highway ◽  
Sight Distance ◽  
Design Variables ◽  
Reliability Method ◽  
First Order Second Moment

Current passing sight distance requirements for two lane highways by the American Association of State Highway and Transportation Officials are based on field studies conducted between 1938 and 1941 which use deterministic values for its design variables such as passing sight distance, speed of the passing vehicle, speed differential between the passed and passing vehicle etc. This report presents three methods to analyze reliability and serves as an extension to the revised model presented by Yasser Hassan, Said Easa and A.O.Abd El Halim whose model sought to improve older models by equally considering both observed passing behaviours of drivers and passing maneuvers that are consistent with two lane highways. Analysis of passing sight distance using first order second moment reliability method, advanced first order second moment and the ellipsoid approach to measure the probability of failure of the passing sight distance design, rely solely on the mean and variance (moments) of each randomly distributed variable in contrast to methods that rely only on deterministic values. Results show the advanced first order second moment and the ellipsoid approach provided more accurate results than first order second moment method which in turn provide a greater safety margin with the later also proving to be a much more robust and efficient method of performing a reliability

Reliability analysis of a structural element based on the Advanced First-Order-Second-Moment Method.

1985 ◽  
Vol 51 (472) ◽  
pp. 2811-2816
Author(s):  
Yoshisada MUROTSU ◽  
Masaaki YONEZAWA ◽  
Hiroo OKADA ◽  
Satoshi MATSUZAKI ◽  
Toshiki MATSUMOTO
Keyword(s):  
Reliability Analysis ◽  
Moment Method ◽  
Structural Element ◽  
Second Moment ◽  
First Order ◽  
First Order Second Moment ◽  
Second Moment Method

Reliability-based design of truck escape ramps

2020 ◽  
Vol 47 (4) ◽  
pp. 395-404
Author(s):  
Kaitlyn Greto ◽  
Said M. Easa
Keyword(s):  
United States ◽  
Design Method ◽  
Rolling Resistance ◽  
The United States ◽  
Probability Of Failure ◽  
First Order ◽  
Reliability Based Design ◽  
First Order Second Moment ◽  
Design Speed ◽  
Design Scenario

The design method of truck escape ramps (TERs) presented by the Transportation Association of Canada and other organizations is deterministic and assumes fixed values of the design speed, rolling resistance, and ramp grade. This paper presents a reliability-based method for TER design based on the first-order second-moment (FOSM) method and the advanced FOSM (AFOSM) method. These methods rely on the distribution of the component random variables. Each method was used to analyze a TER with one grade and two grades. The FOSM is simple and can be easily used by practitioners, even with calculators. The AFOSM is more complicated but more accurate as it considers the design points in determining the probability of failure. The AFOSM method was used to establish design graphs for the required length of TERs. Application of the proposed method is illustrated using actual TERs in the United States and considering a hypothetical design scenario.

Reliability Analysis of Wood-Plastic Structural Plates

2011 ◽  
Vol 101-102 ◽  
pp. 1074-1077
Author(s):  
Gui Wen Yu
Keyword(s):  
Structural Material ◽  
Reliability Analysis ◽  
Modulus Of Elasticity ◽  
Moment Method ◽  
Bending Strength ◽  
Second Moment ◽  
First Order ◽  
First Order Second Moment ◽  
Second Moment Method

The wood-plastic structural plates, which were made of polyethylene (PE) and poplar powder, were used in decking as a structural material. It is of great significance to analyze the material reliability for the safety in service. In this paper, the modulus of elasticity and static bending strength of specimens were obtained through test, the first order second moment method (FOSM) was used to analyze the reliability of the wood-plastic structural plates. The result showed that the wood-plastic structural plates have a better reliability, and the reliability of the wood-plastic structural plates was related to the thickness of the specimens.

scholarly journals Reliability of stopping and decision sight distance at roundabouts

2021 ◽  
Author(s):  
Jafar Faizi
Keyword(s):  
Probabilistic Method ◽  
Design Parameters ◽  
Second Moment ◽  
First Order ◽  
State Highway ◽  
Sight Distance ◽  
Design Variables ◽  
First Order Second Moment ◽  
Stopping Sight Distance ◽  
Lateral Clearance

The existing Stopping Sight Distance (SSD) and Decision Sight Distance (DSD) design methods for roundabouts are deterministic. This means that all of the design variables are predetermined, fixed values. This study presents a probabilistic method for the determination of SSD and DSD at roundabouts based on the equation recommended by the American Association of State Highway and Transportation Officials (AASHTO 2011). The reliability-based method considers all design parameters as random variables. Three types of SSD (SSD for approaches, SSD along the circulatory lane, and SSD for exiting vehicles to the pedestrian crosswalk) were considered in this study. DSD was considered for roundabout approaches. The First-Order Second-Moment and Advanced First-Order Second-Moment methods were used to model SSD and DSD. Once the required SSD and DSD were determined, the lateral clearance requirements at every point of the roundabout were calculated.

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