New Stopping Sight Distance Model for Use in Highway Geometric Design

2000 ◽  
Vol 1701 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Daniel B. Fambro ◽  
Kay Fitzpatrick ◽  
Rodger J. Koppa
Keyword(s):  
Geometric Design ◽  
Safe Driving ◽  
New Model ◽  
Basic Model ◽  
Sight Distance ◽  
Distance Model ◽  
Minimum Requirements ◽  
Design Values ◽  
Current Minimum ◽  
Stopping Sight Distance

Stopping sight distance is an important design parameter in that it defines the minimum sight distance that must be provided at all points along the highway. Thus, it influences geometric design values, construction costs, and highway safety. Stopping sight distance is defined as the sum of two components—brake reaction distance and braking distance. The basic model for calculating stopping sight distances was formalized in 1940, and the model’s parameters have been altered to compensate for changes in eye height, object height, and driver behavior over the past 50 years. Recent studies, however, question whether the model’s parameters and assumptions represent real-world conditions. A new model for determining stopping sight distance requirements for geometric design of highways is presented. This model is based on parameters describing driver and vehicle capabilities that can be validated with field data and defended as safe driving behavior. More than 50 drivers, 3,000 braking maneuvers, 1,000 driver eye heights, and 1,000 accident narratives were used to develop the recommended parameter values for the new model. The recommended values are attainable by most drivers, vehicles, and roadways. This model results in stopping sight distances, sag vertical curve lengths, and lateral clearances that are between the current minimum and desirable requirements and crest vertical curve lengths that are shorter than current minimum requirements.

scholarly journals An Initial Investigation of the Effects of a Fully Automated Vehicle Fleet on Geometric Design

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
John Khoury ◽  
Kamar Amine ◽  
Rima Abi Saad
Keyword(s):  
Autonomous Vehicles ◽  
Autonomous Vehicle ◽  
Real Life ◽  
Geometric Design ◽  
Design Elements ◽  
Sight Distance ◽  
Human Driver ◽  
Projected Change ◽  
Vehicle Fleet ◽  
Stopping Sight Distance

This paper investigates the potential changes in the geometric design elements in response to a fully autonomous vehicle fleet. When autonomous vehicles completely replace conventional vehicles, the human driver will no longer be a concern. Currently, and for safety reasons, the human driver plays an inherent role in designing highway elements, which depend on the driver’s perception-reaction time, driver’s eye height, and other driver related parameters. This study focuses on the geometric design elements that will directly be affected by the replacement of the human driver with fully autonomous vehicles. Stopping sight distance, decision sight distance, and length of sag and crest vertical curves are geometric design elements directly affected by the projected change. Revised values for these design elements are presented and their effects are quantified using a real-life scenario. An existing roadway designed using current AASHTO standards has been redesigned with the revised values. Compared with the existing design, the proposed design shows significant economic and environmental improvements, given the elimination of the human driver.

scholarly journals 3D Sight Distance Calculation and Estimation of its Effect on Road Accidents in GIS Environment

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Ali Sahaf ◽  
Mostafa Mohammadi ◽  
Ali Abdoli
Keyword(s):  
Flow Speed ◽  
Geometric Design ◽  
Road Accidents ◽  
Factors Affecting ◽  
Sight Distance ◽  
Performance Error ◽  
Stopping Sight Distance ◽  
Gis Environment ◽  
Gis Software ◽  
Human Death

Nowadays, one of the main causes of human death is driving accidents. Across the world 1.2 million people die and several million people get injured annually as a result of road accidents. One of the main solutions that is important in resolving the problem of accidents is identifying the factors and their role and impact and the contribution of each in the accident. The stopping sight distance in the route is one of the initial factors in the driver’s performance error as well as the occurrence of an accident, financial losses, and deaths. The geometric design of roads is generally designed according to two-dimensional rules and regulations. Hence, today, given the remarkable advances in computer science and programming, there are many possibilities for 3D modeling of the route. Therefore, the calculation of the stopping sight distance should be based on existing facts and new scientific achievements. On the contrary, the stopping sight distance is one of the factors affecting driving crashes; therefore, this paper tries to investigate the accident occurrence probability in other spots of the existing route by calculating 3D stopping sight distance and using drivers’ free flow speed, as well as using the GIS software. In this way, the results of this study can pave the way for improving the geometric design of existing roads as well as prioritizing the correction of the accidental points of existing routes.

Sight distance evaluation on complex highway vertical alignments

1996 ◽  
Vol 23 (3) ◽  
pp. 577-586 ◽  
Author(s):  
Said M. Easa ◽  
Yasser Hassan ◽  
A. O. Abd El Halim
Keyword(s):  
Key Words ◽  
Geometric Design ◽  
Vertical Alignment ◽  
Common Tangent ◽  
Current Field ◽  
Analytical Methodology ◽  
Sight Distance ◽  
Stopping Sight Distance

Sight distance (stopping, passing, and decision) is a key element in highway geometric design. Existing models for evaluating sight distance on vertical alignments are applicable only to simple, isolated elements such as a crest vertical curve, a sag vertical curve, and a reverse vertical curve (a sag curve following a crest curve, or vice versa). This paper presents an analytical methodology for evaluating sight distance on complex vertical alignments that involve any combination of vertical alignment elements. The methodology can be used for evaluating passing sight distance on two-lane highways, and stopping sight distance and decision sight distance on all highways. Sight distance controlled by the headlight beam can also be evaluated. The locations of sight-hidden dips, which may develop when a sag vertical curve follows a crest vertical curve with or without a common tangent, can be determined. Also, sight distances obstructed by overpasses are evaluated. A profile of the available sight distance can be established and used to evaluate sight distance deficiency and the effect of alignment improvements. A software was developed and can be used for determining the available sight distance accurately. The software may replace the current field and graphical practice for establishing the no-passing zones and evaluating stopping and decision sight distances on complex vertical alignments. Key words: sight distance, vertical alignment, highway, passing zones.

Stopping Sight Distance and Available Sight Distance: New Model and Reliability Analysis Comparison

2017 ◽  
Vol 2638 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Jonathan S. Wood ◽  
Eric T. Donnell
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Design Criterion ◽  
Geometric Design ◽  
Design Criteria ◽  
Sight Distance ◽  
Stopping Sight Distance ◽  
Future Work ◽  
Important Design ◽  
Design Guidance

Stopping sight distance (SSD) is an important design criterion used in the geometry of highways and streets. Design guidance implies that SSD is used to ensure safety along the roadway. This paper reviews SSD design criteria and develops an updated model to improve consistency between available sight distance and SSD criteria found in geometric design policy. A new variable, the distance from the front of the car to the driver’s eye ( Lfront-eye), is used in the updated model. Distributional values for Lfront-eye are determined. A method accounting for lighted (daytime and lighted nighttime) versus unlighted nighttime conditions is also discussed. A probabilistic analysis of vertical curve SSD uses Monte Carlo simulation. The results of this analysis are compared with the SSD model found in current geometric design policy. Possible values for Lfront-eye that can be used in design guidance are proposed. Potential issues that should be investigated in future work are discussed.

Driver Eye and Vehicle Heights for Use in Geometric Design

1998 ◽  
Vol 1612 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Kay Fitzpatrick ◽  
Torsten Lienau ◽  
Daniel B. Fambro
Keyword(s):  
Geometric Design ◽  
Design Criteria ◽  
Passenger Cars ◽  
Passenger Car ◽  
Sight Distance ◽  
Total Vehicle ◽  
Vehicle Fleet ◽  
Stopping Sight Distance

Driver eye, headlight, taillight, and vehicle heights are important elements for determining passing and intersection sight distances and horizontal and vertical curve lengths to provide required stopping sight distance. Driver eye and object heights have varied significantly since their inception in the 1920s, when their values were suggested as 1676 mm. The objective of this study was to determine appropriate driver eye, headlight, taillight, and vehicle heights for use in developing geometric design criteria. The results of this research were used to recommend a driver eye height of 1080 mm for design purposes. This value represents 90 percent of the passenger car driver eye height values and an even higher percentage of the total vehicle fleet, because passenger cars have the lowest driver eye height values and represent fewer than two-thirds of the total vehicle fleet. Headlight and taillight heights of 600 mm are recommended for design. These values represent over 90 and 95 percent of the passenger cars observed in this study, respectively. The vehicle height recommendation for sight distance was 1315 mm, which represents the 10th percentile passenger car height values measured in the research.

scholarly journals An Intelligent and Autonomous Sight Distance Evaluation Framework for Sustainable Transportation

2021 ◽  
Vol 13 (16) ◽  
pp. 8885
Author(s):  
Vivek Singhal ◽  
Divya Anand ◽  
Hani Moaiteq Aljahdali ◽  
Nitin Goyal ◽  
Aman Singh ◽  
...  
Keyword(s):  
Sustainable Transportation ◽  
Evaluation Framework ◽  
Supervised Machine Learning ◽  
Level Crossings ◽  
Road Vehicle ◽  
Accident Prediction ◽  
Rail Track ◽  
Sight Distance ◽  
Distance Model ◽  
Stopping Sight Distance

Railways are facing a serious problem of road vehicle–train collisions at unmanned railway level crossings. The purpose of the study is the development of a safe stopping sight distance and sight distance from road to rail track model with appropriate computation and analysis. The scope of the study lies in avoiding road vehicle–train collisions at unmanned railway level crossings. An intelligent and autonomous framework is being developed using supervised machine learning regression algorithms. Further, a sight distance from road to rail track model is being developed for road vehicles of 0.5 to 10 m length using the observed geometric characteristics of the route. The model prediction accuracy obtained better results in the development of a stopping sight distance model in comparison to other intelligent algorithms. The developed model suggested an increment of approximately 23% in the current safe stopping sight distance on all unmanned railway level crossings. Further, the feature analysis indicates the ‘approach road gradient’ to be the major contributing parameter for safe stopping sight distance determination. The accident prediction study finally indicates that, as the safe stopping sight distance is increased by following the developed model, it is predicted to decrease road vehicle–train collisions.

New Algorithm for Modeling of Bronchial Trees

2012 ◽  
Vol 17 (4) ◽  
pp. 179-190
Author(s):  
Kacper Pluta ◽  
Marcin Janaszewski ◽  
Michał Postolski
Keyword(s):  
Quantitative Analysis ◽  
3D Model ◽  
Ct Images ◽  
Basic Algorithm ◽  
New Model ◽  
Comparison Of Results ◽  
Basic Model ◽  
New Models ◽  
Bronchial Tubes

Abstract The article presents new conception of 3D model of human bronchial tubes, which represents bronchial tubes extracted from CT images of the chest. The new algorithm which generates new model is an extension of the algorithm (basic algorithm) proposed by Hiroko Kitaoka, Ryuji Takaki and Bela Suki. The basic model has been extended by geometric deformations of branches and noise which occur in bronchial trees extracted from CT images. The article presents comparison of results obtained with the use of the new algorithm and the basic one. Moreover, the discussion of usefulness of generated new models for testing of algorithms for quantitative analysis of bronchial tubes based on CT images is also included.

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