scholarly journals Determination of minimum horizontal curve radius for safe stopping sight distance of vehicles overpassing truck platoons

2021 ◽  
Author(s):  
Alfredo Garcia ◽  
Daniel Pastor‐Serrano
Keyword(s):  
Horizontal Curve ◽  
Sight Distance ◽  
Stopping Sight Distance ◽  
Curve Radius

scholarly journals Effects of vegetation type and horizontal curve radius on the rate of tree pruning to provide line of sight on main access roads

2014 ◽  
Vol 60 (No. 5) ◽  
pp. 208-211
Author(s):  
M. Nasiri ◽  
M.R. Pourmajidian
Keyword(s):  
Vegetation Type ◽  
Line Of Sight ◽  
Horizontal Curve ◽  
Horizontal Curves ◽  
Sight Distance ◽  
Hardwood Trees ◽  
Significant Difference ◽  
Stopping Sight Distance ◽  
Curve Radius ◽  
Tree Pruning

The present investigation was carried out to assess the influence of vegetation type and horizontal curve radius on the rate of tree pruning to provide the line of sight on horizontal curves in Caspian forests of Iran. For this purpose, the DBH (diameter at breast height) of trees around the curves which must be pruned was measured. Also, the horizontal curves radius was divided into 4 classes and for each class 10 horizontal curves (for each species) were selected and the species which required pruning were measured. The rate of radial pruning was determined to provide a minimum stopping sight distance by means of laser rangefinder along the line of sight. We found an inverse relationship between DBH and the rate of pruning. To provide sight vision, the radial pruning rate decreased regularly with the increasing radius of horizontal curves for coniferous species, while it increased irregularly for broadleaves. There was a significant difference in pruning between different radii of horizontal curves (P < 0.05). According to results, pruning should be done for mixed hardwood trees with widespread crowns and no sharp horizontal curves should be designed at the top or bottom of hills.  

Sight distance red zones on combined horizontal and sag vertical curves

1998 ◽  
Vol 25 (4) ◽  
pp. 621-630 ◽  
Author(s):  
Yasser Hassan ◽  
Said M Easa
Keyword(s):  
Quantitative Analysis ◽  
Three Dimensional ◽  
The Other ◽  
Two Dimensional ◽  
Horizontal Curve ◽  
Sight Distance ◽  
Stopping Sight Distance ◽  
Three Dimensional Models ◽  
Highway Alignment ◽  
Current Standards

Coordination of highway horizontal and vertical alignments is based on subjective guidelines in current standards. This paper presents a quantitative analysis of coordinating horizontal and sag vertical curves that are designed using two-dimensional standards. The locations where a horizontal curve should not be positioned relative to a sag vertical curve (called red zones) are identified. In the red zone, the available sight distance (computed using three-dimensional models) is less than the required sight distance. Two types of red zones, based on stopping sight distance (SSD) and preview sight distance (PVSD), are examined. The SSD red zone corresponds to the locations where an overlap between a horizontal curve and a sag vertical curve should be avoided because the three-dimensional sight distance will be less than the required SSD. The PVSD red zone corresponds to the locations where a horizontal curve should not start because drivers will not be able to perceive it and safely react to it. The SSD red zones exist for practical highway alignment parameters, and therefore designers should check the alignments for potential SSD red zones. The range of SSD red zones was found to depend on the different alignment parameters, especially the superelevation rate. On the other hand, the results showed that the PVSD red zones exist only for large values of the required PVSD, and therefore this type of red zones is not critical. This paper should be of particular interest to the highway designers and professionals concerned with highway safety.Key words: sight distance, red zone, combined alignment.

Three-Dimensional, Probabilistic Highway Design

2008 ◽  
Vol 2060 (1) ◽  
pp. 10-18 ◽  
Author(s):  
Mohamed Sarhan ◽  
Yasser Hassan
Keyword(s):  
Reliability Analysis ◽  
Probabilistic Approach ◽  
Three Dimensional ◽  
Design Parameters ◽  
Horizontal Curve ◽  
Vertical Alignment ◽  
Highway Design ◽  
Side Slope ◽  
Sight Distance ◽  
Stopping Sight Distance

The potential usefulness of reliability analysis has recently been stressed in many engineering applications. Given the variability in the design parameters, a reliability-based probabilistic approach is well suited to replace the current deterministic highway design practice. However, progress in this regard is generally slow. In this study, the reliability analysis was used to estimate the probability of hazard (POH) that might result from insufficiency of sight distances. As an application, the available sight distance was checked against required stopping sight distance on an assumed road segment. Variation of the design parameters was addressed with Monte Carlo simulation using 100,000 sets of design parameters based on distributions available in the literature. A computer program was developed to use these sets of design parameters to calculate the profiles of available and required stopping sight distances in two- and three-dimensional projections as well as the profile of POH. The approach was applied to a horizontal curve overlapping with flat grade, crest curves, and sag curves in a cut section where the side slope would restrict the sightline. The analysis showed that the current deterministic approach yields very conservative estimates of available and required stopping sight distance, resulting in very low POH. The application example also showed the change of POH with the change of vertical alignment parameters.

Reliability Analysis for Roadway Curves with Horizontal Sightline Obstructions

2019 ◽  
Vol 2673 (8) ◽  
pp. 611-622 ◽  
Author(s):  
Daniel J. Cook ◽  
Douglas W. Harwood ◽  
Ingrid B. Potts ◽  
Eric T. Donnell ◽  
Bachir Hamadeh
Keyword(s):  
Reliability Analysis ◽  
Three Dimensions ◽  
Crash Analysis ◽  
Horizontal Curve ◽  
Analysis Model ◽  
Flexible Tool ◽  
Horizontal Curves ◽  
A Value ◽  
Sight Distance ◽  
Stopping Sight Distance

Objects on the inside of a horizontal curve may limit the stopping sight distance (SSD) available to drivers. Crash analysis shows that SSD-related crashes on horizontal curves are limited in number and difficult to quantify. As an alternative, a reliability analysis model was developed to quantify the number of drivers per year who may encounter a stopped vehicle in a sight-restricted area, creating an opportunity where an SSD-related crash might occur on a roadway with a sight obstruction on the inside of a horizontal curve. The model considers roadway alignment in three dimensions. The model formulation is documented and an analysis of the sensitivity of crash opportunities to traffic volume and offset to a sight obstruction is performed. A sensitivity analysis of the reliability analysis model shows that the percentage of vehicles that may encounter a crash-involved vehicle or a queue of stopped vehicles over the course of a year can range from essentially zero to a value approaching 1% of the total yearly flow. The reliability analysis model is a flexible tool that can be used by planners and designers to compare, in a relative sense, the need for sight distance improvements on specific horizontal curves.

The Stopping Sight Distance Test for Freeway Based on the Operating Speed

2011 ◽  
Vol 97-98 ◽  
pp. 180-184
Author(s):  
Yue Zhang
Keyword(s):  
Safety Evaluation ◽  
Operating Speed ◽  
Horizontal Curve ◽  
Passenger Car ◽  
Sight Distance ◽  
Stopping Sight Distance

In this paper, the stopping sight distance of passenger car based on the operating speed was regarded as guideposts, and its corresponding radius of horizontal curve and vertical curve was got according to the calculated results, and available for reference and application in the alignment design and safety evaluation for freeway.

Analysis on the Anti-Glare Plate Setting Distance on Horizontal Curve Sections of Expressway

2014 ◽  
Vol 587-589 ◽  
pp. 2156-2159 ◽  
Author(s):  
Tian Xiao ◽  
Ji Shu Sun ◽  
Can Zhang Jin
Keyword(s):  
Traffic Safety ◽  
Calculation Formula ◽  
Horizontal Curve ◽  
Distance Calculation ◽  
Element Simulation ◽  
Curved Section ◽  
Curve Radius ◽  
The Relationship ◽  
Plate Distance ◽  
Glare Effect

Glare is one of the most important factors threating expressway traffic safety an night. The most commonly way to prevent glaring night is to set anti-glare plate. Different from the straight sections of expressway, the relationship between the front light of vehicles and the distance of anti-glare plate on the horizontal curved section has some-what changed. Through a lot of tests and finite element simulation, the relationship between the distance of anti-glare plate, horizontal curve radius and anti-glare effect were analyzed systematically. Distance calculation formula of anti-glare plate in horizontal curve sections was revised in this paper. The anti-glare plate distance requirement under different expressway alignment design indexes and its calculation formula was proposed. The achievement was beneficial to confirm the anti-glare effect and improve traffic safety. It can provide us with a reference and a supplement of the specification.

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 Three-Dimensional Stopping Sight Distance Calculation Method under High Slope Restraint

2020 ◽  
Vol 10 (20) ◽  
pp. 7118
Author(s):  
Yonghong Yang ◽  
Jiecong Wang ◽  
Yuanbo Xia ◽  
Lan Huang
Keyword(s):  
Calculation Method ◽  
Three Dimensional ◽  
Highway Safety ◽  
Small Radius ◽  
Safety Engineering ◽  
Design Data ◽  
Important Indicator ◽  
High Slope ◽  
Sight Distance ◽  
Stopping Sight Distance

Sight distance is an important indicator to ensure the safety of drivers, and is also an indispensable evaluation basis in highway safety engineering. In mountainous highways, high slopes and small radius often lead to poor visibility and traffic accidents. Through the combined calculation of horizontal and vertical sections, this paper comprehensively considers the specific sizes of roadside clearance, high slope, as well as the position and height of the driver’s view point and other factors, and it analyzes the limited visibility of the driver in the process of driving right turn. An effective and simplified calculation method based on design data for three dimensional (3D) stopping sight distance (S.S.D.) in high fill sections is proposed. Finally, the S.S.D. inspection of the actual highway, based on design speed and operating speed, is carried out, and the sight distance of the calculated point is judged by comparing the value with the normal value and the calculation result of the horizontal sightline offset. The results show that the method proposed in this paper is consistent with the sight distance results obtained by the horizontal sightline offset method, which indicates the calculation method is accurate and provides a technical reference for S.S.D. evaluation in highway safety engineering.

Location-based analysis of car-following behavior during braking using naturalistic driving data

2020 ◽  
Vol 47 (5) ◽  
pp. 498-505 ◽  
Author(s):  
Mostafa H. Tawfeek ◽  
Karim El-Basyouny
Keyword(s):  
Driver Assistance Systems ◽  
Behavioral Measures ◽  
Car Following ◽  
Sight Distance ◽  
Influence Area ◽  
Data Source ◽  
Naturalistic Driving ◽  
Stopping Sight Distance ◽  
Microscopic Modeling ◽  
Rich Data

This study investigates the car-following behavior during braking at intersections and segments. Car-following events were extracted from a naturalistic driving dataset, mapped using ArcGIS, and analyzed to differentiate between the intersection- and segment-related events. The intersection-related events were identified according to an intersection influence area, which was estimated based on the stopping sight distance and the speed limit. Five behavioral measures were quantified based on exploring the probability density functions (PDF) for intersection- and segment-related events. The results showed that there were significant differences between the PDFs of the measures for both cases. Moreover, it was indicated that drivers tend to be more aggressive at intersections compared with segments. Thus, it is crucial to consider the driver’s location when investigating driver behavior. The quantified behavioral measures are a rich data source that can be used for car-following microscopic modeling, surrogate safety analysis, and driver assistance systems development.

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