scholarly journals Automated Assessment of Passing Sight Distance on Rural Highways using Mobile LiDAR Data

2021 ◽  
pp. 036119812110312
Author(s):  
Samaa Agina ◽  
Amr Shalkamy ◽  
Maged Gouda ◽  
Karim El-Basyouny
Keyword(s):  
Lidar Data ◽  
Design Standards ◽  
Rural Highways ◽  
Automated Method ◽  
Lane Marking ◽  
Sight Distance ◽  
Design Requirements ◽  
Stopping Sight Distance ◽  
High Level ◽  
Transportation Agencies

Providing sufficient Available Sight Distance (ASD) that meets the minimum design requirements is crucial for highway safety. Previous work on sight distance assessment focused on Stopping Sight Distance (SSD) with little attention given to Passing Sight Distance (PSD). Insufficient PSD could lead to severe collisions such as head-on and sideswipe crashes. To address this gap, this paper introduces an automated method for PSD assessment on two-lane highways using mobile Light Detection and Ranging (LiDAR) data. The procedure involved extracting centerline lane marking, defining passing-allowed and passing-prohibited regions, computing the ASD, and comparing the existing centerline marking pattern (i.e., passing and no-passing zones) to a proposed lane marking that is based on the ASD for passing maneuvers. Regions that meet the design standards, substandard zones, and non-optimal design regions were all defined. A reallocation of PSD zones was conducted based on the ASD including modifying the existing lane marking pattern, which resulted in increasing the total length of passing zones by up to 20%, providing more, but safer, passing opportunities. A high-level safety assessment of historical collisions showed clusters of crashes along regions where passing is currently allowed at locations where the ASD is less than standard requirements. The proposed framework represents a tool by which transportation agencies could assess PSD, upgrade the design of existing highways, and investigate the consequences of PSD limitations to ensure compliance with standards during highway service life.

Safety Effects of Limited Stopping Sight Distance on Crest Vertical Curves

2000 ◽  
Vol 1701 (1) ◽  
pp. 17-24 ◽  
Author(s):  
Kay Fitzpatrick ◽  
Daniel B. Fambro ◽  
Angela M. Stoddard
Keyword(s):  
Detailed Examination ◽  
Older Drivers ◽  
Rural Highways ◽  
Safety Problem ◽  
Large Sample ◽  
Crash Rates ◽  
Sight Distance ◽  
Stopping Sight Distance ◽  
The Relationship

Previous studies that examined the relationship between stopping sight distance and safety have been inconclusive and inconsistent; however, the fact that a relationship has not been established does not necessarily imply that stopping sight distance is not a contributing factor in some crashes. Instead, it means that existing databases have failed to quantify any relationship that might exist. A promising approach to identifying such a relationship is a detailed examination or case study of crashes from a relatively large sample of limited sight distance roadways. If limited sight distance is a factor that contributes to crashes, it should show up in such a study. The objective of this study was to determine whether stopping sight distance was a contributing factor in crashes on roadway segments with limited sight distance crest vertical curves. This objective was accomplished by reviewing 439 narratives from crashes that occurred on 33 multilane and two-lane roadways with limited sight distance crest vertical curves. The findings suggest that the crash rates on rural two-lane highways with limited stopping sight distance are similar to the crash rates on all two-lane rural highways. They also suggest that the percentage of accidents involving large trucks and older drivers is similar on limited sight distance highways and all two-lane rural highways. Thus, for the range of conditions studied, limited stopping sight distance does not appear to be a safety problem.

scholarly journals Cognitive Load Variability from Road Characteristics Should Influence a Safety Requirement for Vehicle Stopping Sight Distance

2019 ◽  
Vol 63 (1) ◽  
pp. 2129-2133
Author(s):  
Cody A. Pennetti ◽  
Kelsey Hollenback ◽  
Inki Kim ◽  
James H. Lambert
Keyword(s):  
Reaction Time ◽  
Weather Conditions ◽  
Design Standards ◽  
Road Design ◽  
Adverse Weather Conditions ◽  
Sight Distance ◽  
Adverse Weather ◽  
Road Geometry ◽  
Stopping Sight Distance ◽  
Road Characteristics

Current U.S. geometric road design standards are based on a prescribed value for a driver’s perception-reaction time (a constant value of 2.5 seconds), which represents the time necessary for a driver to safely stop the vehicle to avoid a crash (referred to as a stopping sight distance); however, these standards fail to consider how road complexity, driver risk perception, and visual stimuli can influence perception-reaction time. With over a million vehicle fatalities a year (WHO, n.d.), it is necessary to investigate methods of improving driver safety. The influence of road characteristics is considered with some road design policies, but not currently applied to stopping sight distance. This paper introduces theoretical considerations for increasing perception-reaction time (and thereby adjusting speed limits or road geometry) based on roadway complexity (volume of vehicles, road geometry, pedestrian crossings, frequency of adverse weather conditions, or other conditions).

Voxel-Based Methodology for Automated 3D Sight Distance Assessment on Highways using Mobile Light Detection and Ranging Data

2020 ◽  
Vol 2674 (5) ◽  
pp. 587-599 ◽  
Author(s):  
Amr Shalkamy ◽  
Karim El-Basyouny ◽  
Hai Yang Xu
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Light Detection And Ranging ◽  
Lidar Data ◽  
Design Standards ◽  
Light Detection ◽  
Efficient Operation ◽  
Large Scale Assessment ◽  
Sight Distance ◽  
Minimum Requirements

Ensuring that the available sight distance (ASD) on highways meets the minimum requirements of geometric design standards is crucial for safe and efficient operation of highways. Current practices of ASD assessment using design software or through site visits are labor intensive, time consuming, and traffic disruptive. Thus, this paper introduces a fully automated algorithm that allows large-scale assessment of ASD in three-dimensional (3D) space on highways utilizing mobile light detection and ranging (LiDAR) data. The algorithm was tested on LiDAR data of highway segments in Alberta, Canada. The results showed that the algorithm was highly accurate in detecting sight distance limitations at the defined regions and, in all cases, the driver’s vision was restricted by the pavement surface on vertical crest curves. In the case of combined vertical and horizontal curves, the vertical crest curve was found to be the controlling element in sight distance deficiencies. In addition, the assessment of historical collision data revealed clusters along the regions defined with ASD limitations, indicating that restrictions in drivers’ vision could have contributed to the collision occurrence.

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.

scholarly journals Multi-curie production of gallium-68 on a biomedical cyclotron and automated radiolabelling of PSMA-11 and DOTATATE

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Helge Thisgaard ◽  
Joel Kumlin ◽  
Niels Langkjær ◽  
Jansen Chua ◽  
Brian Hook ◽  
...  
Keyword(s):  
Radiochemical Purity ◽  
High Yield ◽  
Clinical Use ◽  
Automated Production ◽  
Automated Method ◽  
Gallium 68 ◽  
High Yields ◽  
High Level ◽  
Mev Protons ◽  
Very High

Abstract Background With increasing clinical demand for gallium-68, commercial germanium-68/gallium-68 ([68Ge]Ge/[68Ga]Ga) generators are incapable of supplying sufficient amounts of the short-lived daughter isotope. In this study, we demonstrate a high-yield, automated method for producing multi-Curie levels of [68Ga]GaCl3 from solid zinc-68 targets and subsequent labelling to produce clinical-grade [68Ga]Ga-PSMA-11 and [68Ga]Ga-DOTATATE. Results Enriched zinc-68 targets were irradiated at up to 80 µA with 13 MeV protons for 120 min; repeatedly producing up to 194 GBq (5.24 Ci) of purified gallium-68 in the form of [68Ga]GaCl3 at the end of purification (EOP) from an expected > 370 GBq (> 10 Ci) at end of bombardment. A fully automated dissolution/separation process was completed in 35 min. Isolated product was analysed according to the Ph. Eur. monograph for accelerator produced [68Ga]GaCl3 and found to comply with all specifications. In every instance, the radiochemical purity exceeded 99.9% and importantly, the radionuclidic purity was sufficient to allow for a shelf-life of up to 7 h based on this metric alone. Fully automated production of up to 72.2 GBq [68Ga]Ga-PSMA-11 was performed, providing a product with high radiochemical purity (> 98.2%) and very high apparent molar activities of up to 722 MBq/nmol. Further, manual radiolabelling of up to 3.2 GBq DOTATATE was performed in high yields (> 95%) and with apparent molar activities (9–25 MBq/nmol) sufficient for clinical use. Conclusions We have developed a high-yielding, automated method for the production of very high amounts of [68Ga]GaCl3, sufficient to supply proximal radiopharmacies. The reported method led to record-high purified gallium-68 activities (194 GBq at end of purification) and subsequent labelling of PSMA-11 and DOTATATE. The process was highly automated from irradiation through to formulation of the product, and as such comprised a high level of radiation protection. The quality control results obtained for both [68Ga]GaCl3 for radiolabelling and [68Ga]Ga-PSMA-11 are promising for clinical use.

Automated method for measuring the extent of selective logging damage with airborne LiDAR data

2018 ◽  
Vol 139 ◽  
pp. 228-240 ◽  
Author(s):  
L. Melendy ◽  
S.C. Hagen ◽  
F.B. Sullivan ◽  
T.R.H. Pearson ◽  
S.M. Walker ◽  
...  
Keyword(s):  
Selective Logging ◽  
Airborne Lidar ◽  
Lidar Data ◽  
Logging Damage ◽  
Automated Method ◽  
Airborne Lidar Data

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.

Visualising Interactions on Mobile Multimodal Sys

2010 ◽  
pp. 430-442 ◽  
Author(s):  
Kristine Deray ◽  
Simeon Simoff
Keyword(s):  
Visual Representations ◽  
Design Guidelines ◽  
Set Design ◽  
Interaction Data ◽  
Human Interactions ◽  
Additional Requirement ◽  
Visual Elements ◽  
Multimodal Systems ◽  
Design Requirements ◽  
High Level

The purpose of this chapter is to set design guidelines on visual representations of interactions for mobile multimodal systems. The chapter looks at the features of interaction as process and how these features are exposed in the data. It presents a three layer framework for designing visual representations for mobile multimodal systems and a method that implements it. The method is based on an operationalisation of the source-target mapping from the contemporary theory of metaphors. Resultant design guidelines are grouped into (i) a set of high-level design requirements for visual representations of interactions on mobile multimodal systems; and (ii) a set of specific design requirements for the visual elements and displays for representing interactions on mobile multimodal systems. The second set then is considered subject to an additional requirement – the preservation of the beauty of the representation across the relevant modalities. The chapter is focused on the modality of the output. Though the chapter considers interaction data from human to human interactions, presented framework and designed guidelines are applicable towards interaction in general.

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