Reliability Approach to Horizontal Curve Design

2014 ◽  
Vol 2436 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Scott C. Himes ◽  
Eric T. Donnell
Keyword(s):  
Horizontal Curve ◽  
Curve Design

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 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.

Framework for Reliability-Based, Safety-Explicit Horizontal Curve Design using Naturalistic Driving Data

2019 ◽  
Vol 2673 (4) ◽  
pp. 605-615
Author(s):  
Bashar Dhahir ◽  
Yasser Hassan
Keyword(s):  
Driver Behavior ◽  
Safety Evaluation ◽  
Safety Performance ◽  
Point Mass ◽  
Horizontal Curve ◽  
Mass Model ◽  
Reliability Indices ◽  
Curve Design ◽  
Naturalistic Driving ◽  
Favorable Weather

The design of horizontal curves is generally based on a deterministic analysis of driver comfort using a point-mass model based on data mostly from the early 1900s and might be outdated. Furthermore, the design lacks quantitative safety evaluation. This paper proposes a new framework for horizontal curve design that provides a quantitative evaluation of safety performance. The framework uses recently collected data from the naturalistic driving study (NDS) to develop models to predict distributions of parameters that reflect contemporary driver behavior, such as speed on curve and comfort threshold in favorable weather and rainy conditions. Statistical models were also developed for more accurate evaluation of vehicle dynamic parameters than the point-mass model. The variability of driver behavior and vehicle dynamics parameters was considered using reliability analysis to develop surrogate safety measures for four design criteria: vehicle stability, comfort threshold, sight distance, and rollover. Safety performance functions were then developed to relate reliability indices to expected safety performance. The results showed that only the driver comfort criterion was not significantly related to expected safety performance. A design example was presented using the proposed framework, which showed the expected change of safety performance of the curve being considered. An optimum radius was then found to minimize the number of expected collisions.

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

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