Identification of the Impact of Radius Ratio of Horizontal to Vertical Curves on Highway Safety

CICTP 2020 ◽  
2020 ◽  
Author(s):  
Xiaofei Wang ◽  
Jiangbei Yao ◽  
Zhengkai Li ◽  
Yuntao Liu ◽  
Jin Cai
Keyword(s):  
Highway Safety ◽  
Radius Ratio ◽  
The Impact

Evaluating the Impact of Rumble Strips on Fatal and Injury Freeway Crashes

2018 ◽  
Vol 2672 (30) ◽  
pp. 131-141 ◽  
Author(s):  
Bahar Dadashova ◽  
Lingtao Wu ◽  
Karen Dixon
Keyword(s):  
Alternative Assessment ◽  
Statistical Evaluation ◽  
Cost Effective ◽  
Highway Safety ◽  
Assessment Methods ◽  
Safety Outcomes ◽  
Crash Types ◽  
The Impact ◽  
Rumble Strip ◽  
Study Database

Rumble strips are known to be one of the most cost-effective treatments for preventing roadway departure crashes. However, in recent years some studies have found controversial results indicating that rumble strips may in fact increase the number of more severe crashes. Although these effects are estimated to be very small, highway safety agencies deploy these treatments with an expectation that they will reduce all crash types. In this paper, the authors have conducted a statistical evaluation to determine the impact of rumble strip presence on fatal and injury crashes at freeway locations. For this purpose, the authors acquired an existing database used for one of the aforementioned studies and evaluated the variables using alternative assessment methods. The results of the current study suggest that rumble strips do in fact improve the safety outcomes in rural freeways. These findings are observed to also apply to urban freeways, but the effects are not statistically significant for the study database.

The Impact of Perforation Geometry on Acoustic Damping Attributes of a Perforated Liner With Bias Flow

2012 ◽  
Author(s):  
Alireza Mazdeh ◽  
Reza Kashani
Keyword(s):  
Fluid Dynamic ◽  
Perforated Plate ◽  
Interaction Mechanism ◽  
Industrial Applications ◽  
Radius Ratio ◽  
Damping Properties ◽  
Acoustic Damping ◽  
Spacing Ratio ◽  
Bias Flow ◽  
The Impact

Acoustic damping properties of perforated liners are highly dependent on a number of variables which can be categorized as “flow variables” such as the extent and Mach number of grazing flow as well as bias flow and “geometric variable” such as the shape of the hole which can be rectangular, cylindrical, conical with diverging or converging nozzle, thickness to radius ratio, radius to hole spacing ratio and hole orientation which can be normal to or inclined with respect to the perforated plate. Many of these variables were not incorporated in previous studies. Theoretical and empirical approaches have provided the foundation for understanding the damping properties of liners but they are based on certain simplifying assumptions making them inadequate in addressing the more realistic conditions encountered in industrial applications. These limitations have highlighted the importance of numerical methods for studying damping behavior of liners. Acoustic attributes of perforated plates (mainly in terms of impedance which is a frequency-dependent complex quantity) as a function of non-dimensional variables like Reynolds, Strouhal, Mach, and Helmholtz numbers have been studied by various researchers, including the authors, using a variety of numerical tools starting from the simple 1D network scheme based on linear acoustics and the wall compliance concept introduced by Howe all the way to the computationally intensive Large-Eddy Simulations (LES) and Scaled Adaptive Simulation (SAS) reconstructing the full unsteady turbulent structures. Although the impacts of some geometry variations such as hole inclination angle and diameter, in conjunction with various fluid dynamic parameters, have been investigated using 1D network tools, the focus of LES has been mainly on analysis of a single circular hole with periodic boundary conditions as the representation of multi-perforation (assuming the perforations are spaced far enough from each other so that there is no interaction between neighboring holes). There is certainly a need for thorough investigation of the acoustics impact of these geometric parameters as well as shape of the holes using LES. In an on-going research we are extending the numerical modeling work on characterizing the acoustic damping attributes of a perforation, beyond the current state of the art, by including the geometric variables including hole size, shape, orientation, and radius to thickness ratio, amongst others, in the study. In this paper, following a short review of the research conducted in the recent past for comprehension of the acoustic-vortex interaction mechanism in perforated liners resulting in acoustic absorption, we present the findings on the impact of thickness/radius ratio on the acoustic damping attribute of a perforation. The verification of the CFD results are done by comparing the data with analytical solutions.

Empirical Investigation of Interactive Highway Safety Design Model Accident Prediction Algorithm: Rural Intersections

2003 ◽  
Vol 1840 (1) ◽  
pp. 78-86 ◽  
Author(s):  
Craig Lyon ◽  
Jutaek Oh ◽  
Bhagwant Persaud ◽  
Simon Washington ◽  
Joe Bared
Keyword(s):  
Research Effort ◽  
Methodological Approach ◽  
The United States ◽  
Highway Safety ◽  
Design Model ◽  
Prediction Algorithm ◽  
Parameter Estimates ◽  
Wide Range ◽  
Safety Design ◽  
The Impact

One major gap in transportation system safety management is the ability to assess the safety ramifications of design changes for both new road projects and modifications to existing roads. To fulfill this need, FHWA and its many partners are developing a safety forecasting tool, the Interactive Highway Safety Design Model (IHSDM). The tool will be used by roadway design engineers, safety analysts, and planners throughout the United States. As such, the statistical models embedded in IHSDM will need to be able to forecast safety impacts under a wide range of roadway configurations and environmental conditions for a wide range of driver populations and will need to be able to capture elements of driving risk across states. One of the IHSDM algorithms developed by FHWA and its contractors is for forecasting accidents on rural road segments and rural intersections. The methodological approach is to use predictive models for specific base conditions, with traffic volume information as the sole explanatory variable for crashes, and then to apply regional or state calibration factors and accident modification factors (AMFs) to estimate the impact on accidents of geometric characteristics that differ from the base model conditions. In the majority of past approaches, AMFs are derived from parameter estimates associated with the explanatory variables. A recent study for FHWA used a multistate database to examine in detail the use of the algorithm with the base model-AMF approach and explored alternative base model forms as well as the use of full models that included nontraffic-related variables and other approaches to estimate AMFs. That research effort is reported. The results support the IHSDM methodology.

Understanding the Influence of Climate Elements on Traffic Behavior: The Wind Impact Approach

2021 ◽  
Author(s):  
Ivana Sentić ◽  
Jasmina Đorđević ◽  
Tijana Đorđević ◽  
Mirjana Ljubojević ◽  
Jelena Čukanović
Keyword(s):  
Interpolation Method ◽  
Daily Basis ◽  
Highway Safety ◽  
Highway Design ◽  
Safety Standards ◽  
Planning And Design ◽  
Extreme Wind ◽  
Highway Planning ◽  
Wind Events ◽  
The Impact

Abstract Due to intense highway congestion in Europe, increased percentage of highway accidents, as well as mortality rate, safety is an imperative in highway planning and design. Highway design safety standards have been researched extensively, but not enough attention has been paid to the surrounding environmental impacts, foremost climate elements. Therefore, this research attempts to understand the least researched climate element — the wind, and its impact on highway safety. The highway landscape falls under the category of the wind impacts that can cause significant problems for the drivers throughout the year. The values for wind direction, frequency and intensity were taken from the CARPATCLIM database. The evaluation of homogenized and harmonized set of data on a daily basis for a twenty-year period documented a variety of wind impacts on highway safety. It was found that the wind is constantly present throughout the year, with specific monthly oscillations. By using the ArcGis and the interpolation method, it has been clearly observed at which points the effect of intense winds was present the most. In order to understand the overall image of highway safety, fieldwork was conducted in various meteorological conditions. The checklists photo-documented and qualitatively described the observed extreme wind events (alone or combined with one more climate element). Based on everything described above, the image of the current situation was provided, and the proposal for control of the impact of wind using an adequate vegetation assembly (windbreaks) has been offered.

“Eyes on the Street”: The Impact of Tennessee's Emergency Cellular Telephone Program on Alcohol-Related Fatal Crashes

1999 ◽  
Vol 45 (4) ◽  
pp. 453-466 ◽  
Author(s):  
Stewart J. D'Alessio ◽  
Lisa Stolzenberg ◽  
W. Clinton Terry
Keyword(s):  
Time Series ◽  
Reporting System ◽  
Highway Safety ◽  
Multiple Time ◽  
Multiple Time Series ◽  
Cellular Telephone ◽  
Fatal Crash ◽  
Fatal Crashes ◽  
The Impact ◽  
Percent Decline

Using longitudinal data drawn from Tennessee's Fatality Analysis Reporting System (FARS) and a multiple time-series research design, the authors assessed whether an emergency cellular telephone program, established on April 1, 1995, reduced alcohol-related fatal crashes. Maximum-likelihood results revealed a 2.5 percent decline in the alcohol-related fatal crash rate on roads serviced by the program. No significant change in the monthly percentage of fatal crashes attributed to drunk drivers was observed on roads where the program was not implemented. Emergency cellular telephone programs show promise as an effective and relatively inexpensive means for improving highway safety.

scholarly journals Time-periodic pulse electroosmotic flow of Jeffreys fluids through a microannulus

Open Physics ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 867-876
Author(s):  
Dongsheng Li ◽  
Liang Ma ◽  
Jiayin Dong ◽  
Kun Li
Keyword(s):  
Relaxation Time ◽  
Electroosmotic Flow ◽  
Outer Radius ◽  
Radius Ratio ◽  
Retardation Time ◽  
Static State ◽  
Velocity Amplitude ◽  
Periodic Pulse ◽  
The Impact ◽  
Time Periodic

Abstract In this article, we investigate the time-periodic pulse electroosmotic flow (EOF) of Jeffreys fluids through a microannulus. By using the Laplace transform method, the velocity expression of the pulse EOF is derived. The effect of some variables on the time it takes for the fluid to go from a static state to a flowing state is analyzed. We find that increasing the relaxation time λ ¯ 1 {\bar{\lambda }}_{\text{1}} and decreasing the inner and outer radius ratio α \alpha will result in longer time for the fluid to reach the flowing state, but the retardation time λ ¯ 2 {\bar{\lambda }}_{\text{2}} and the inner and outer zeta potential ratio β \beta have little effect on it. The impact of some related parameters on the pulse EOF velocity for different inner and outer radius ratios ( α \alpha ) is discussed in detail. The results show that for a smaller inner and outer radius ratio α \alpha , the velocity amplitude increases with the relaxation time λ ¯ 1 {\bar{\lambda }}_{\text{1}} and decreases with the retardation time λ ¯ 2 {\bar{\lambda }}_{\text{2}} . As the inner and outer radius ratio α \alpha increases, the effect of relaxation time λ ¯ 1 {\bar{\lambda }}_{\text{1}} on velocity amplitude gradually weakens or even becomes insignificant, and the effect of the retardation time λ ¯ 2 {\bar{\lambda }}_{\text{2}} on the velocity amplitude remains unchanged. Moreover, the velocity amplitude will decrease with the increase in the inner and outer radius ratio α \alpha and its change range will expand from the electric double layer near the annular wall to the entire flow region.

Numerical Modeling of the Acoustic Damping of Perforated Liners With Bias Flow

2013 ◽  
Author(s):  
Alireza Mazdeh ◽  
Ahmad Reza Kashani
Keyword(s):  
Numerical Modeling ◽  
Fluid Dynamic ◽  
Perforated Plate ◽  
Industrial Applications ◽  
Radius Ratio ◽  
Damping Properties ◽  
Acoustic Damping ◽  
Spacing Ratio ◽  
Bias Flow ◽  
The Impact

Acoustic damping properties of perforated liners are highly dependent on a number of variables which can be categorized as “flow variables” such as the extent and Mach number of grazing flow as well as bias flow and “geometric variable” such as the shape of the hole which can be rectangular, cylindrical, conical with diverging or converging nozzle, thickness to radius ratio, radius to hole spacing ratio and hole orientation which can be normal to or inclined with respect to the perforated plate. Theoretical and empirical approaches have provided the foundation for understanding the damping properties of liners but they are based on certain simplifying assumptions making them inadequate in addressing the realistic conditions encountered in industrial applications. These limitations have highlighted the importance of numerical methods for studying damping behavior of liners. Acoustic attributes of perforated plates (mainly in terms of impedance as a function of non-dimensional variables like Reynolds, Strouhal, Mach, and Helmholtz numbers have been studied by various researchers, including the authors, using a variety of numerical tools starting from the simple 1D network scheme based on linear acoustics all the way to the computationally intensive Large-Eddy Simulations (LES) and Scaled Adaptive Simulation (SAS) reconstructing the full unsteady turbulent structures. Although the impacts of some geometry variations such as hole inclination angle and diameter, in conjunction with various fluid dynamic parameters, have been investigated using 1D network tools, the focus of LES has been mainly on analysis of a single circular hole with periodic boundary conditions as the representation of multi-perforation (assuming the perforations are spaced far enough from each other so that there is no interaction between neighboring holes). There is certainly a need for thorough investigation of the acoustic impact of these geometric parameters as well as the shape of the holes using LES. In an on-going research we are extending the numerical modeling work on characterizing the acoustic damping attributes of a perforation, beyond the current state of the art, by including the geometric variables including hole size, shape, orientation, and radius to thickness ratio, amongst others, in the study. In this paper, following a short review of the research conducted in the recent past, we present our findings on the impact of the thickness/radius ratio on the acoustic damping attribute of a perforation.

Simulation Analysis of W-Beam and Highway Bus Based on ADAMS

2012 ◽  
Vol 253-255 ◽  
pp. 2076-2079
Author(s):  
Yang Zhang ◽  
Wen Yong Li ◽  
Yong Cun Zhu
Keyword(s):  
Simulation Analysis ◽  
Highway Safety ◽  
Dynamics Simulation ◽  
Collision Dynamics ◽  
Regulatory Requirements ◽  
Safety Requirements ◽  
Adams Software ◽  
Result Show ◽  
The Impact ◽  
Guiding Effect

In order to meet the highway safety requirements of the bus under different speeds, the model of highway bus and W-beam were established in UG software and the collision dynamics simulation was analyzed in ADAMS software. During a number of simulation experiments, the impact force and the lateral deformation displacements would be done through the W-beam was collided by the bus in different speeds. The result was proven to meet the regulatory requirements of the evaluation specification for highway safety barriers. The result show that: semi-rigid guardrail can be better deformation and guiding effect when the speed of bus was lower than 80 km/h, but when the speed was higher than 80 km/h, the collision avoidance effect of guardrail was poor and the bus was easy to cross the guardrail to case secondary accident.

Obesity and motor vehicle deaths: a panel-data analysis

2020 ◽  
Vol 47 (6) ◽  
pp. 1233-1246
Author(s):  
Mary J. Becker ◽  
Lindsay N. Calkins ◽  
Walter Simmons ◽  
Andrew M. Welki ◽  
Thomas J. Zlatoper
Keyword(s):  
Death Rate ◽  
Motor Vehicle ◽  
Panel Data Analysis ◽  
Seat Belt ◽  
Negative Relationship ◽  
State Level ◽  
Highway Safety ◽  
Significant Positive Association ◽  
Content Type ◽  
The Impact

PurposeThis paper analyzes the impact of obesity on the probability of a motor vehicle fatality (highway death rate) and on its component probabilities: the probability of a fatality, given a crash (vulnerability rate) and the probability of a crash (crash rate).Design/methodology/approachUsing state-level data for 1995–2015, the paper estimates models explaining all three rates. Explanatory factors include obesity and a representative set of potential determinants.FindingsResults indicate that obesity has a statistically significant positive relationship with the highway death rate and the crash rate. Also having a statistically significant positive association with at least one of the three rates are the proportions of young and old drivers, alcohol consumption, the ratio of rural to urban vehicle miles and temperature. Factors with a statistically significant negative relationship with at least one of the rates include primary seat belt laws and precipitation. In 2016, a total of 928 traffic fatalities could have been avoided if obesity rates decreased by one percentage point.Practical implicationsSeat belts and crash dummies should be better designed to fit and represent those with higher BMIs, and education efforts to increase seat belt use should be supplemented with information about the adverse impact of obesity on highway safety.Originality/valueThis paper uses 21 years of state-level information, including socio-economic and regulation data, and contributes to the existing research on the relationship between obesity and highway safety.

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