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

Wood, Jonathan; Donnell, Eric T.

doi:10.3141/2638-01

Cited by 27 publications

(24 citation statements)

References 24 publications

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“…Compared to the current AASHTO model, the latter model shows lower SSD values on low-volume roads and higher values on rural and urban freeways. In 2017, Wood and Donnell [32] revised the SSD model in a different context to improve accuracy and safety. Their goal was to improve the reliability of the SSD model by accounting for lighted versus unlighted-nighttime conditions.…”

Section: Development Of Highway Geometric Design Elementsmentioning

confidence: 99%

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

Khoury

Amine

Saad

2019

Journal of Advanced Transportation

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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.

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Section: Development Of Highway Geometric Design Elementsmentioning

confidence: 99%

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

Khoury

Amine

Saad

2019

Journal of Advanced Transportation

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“…The stochastic nature of the design parameters is accounted for by expressing input parameters with regards to their probability distribution. In this paper, a reliability analysis is used to compare the difference in the probability of noncompliance (P nc ) obtained using SSD MWL values and the 3D ASD obtained from LiDAR data, and SSD recommended by Wood et al (8).…”

Section: Reliability Analysis and Road Geometric Designmentioning

confidence: 99%

“…In this paper, different horizontal curves were studied by calculating different SSD MWL values for each curve depending on the degree of curvature (D ) and delta (D ) from the MWL perspective. Then, a reliability analysis was performed to compare the difference in the probability of non-compliance (P nc ) obtained using SSD MWL values, the 3D available sight distance, and SSD calculated based on the model proposed by Wood et al (8). In reliability theory, the stochastic nature of the design parameters is taken into account by expressing input parameters with regards to their probability distribution (37,38).…”

Section: Reliability Analysismentioning

confidence: 99%

Calibrating Design Guidelines using Mental Workload and Reliability Analysis

Habib

Gouda

El-Basyouny

2020

Transportation Research Record: Journal of the Transportation R

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The generic nature of road design is indiscriminate to age, race, or gender, as it is implicitly assumed that there are few behavioral differences between drivers while traversing various alignment elements (e.g., horizontal curves, tangential segments, etc.). For instance, the perception reaction time required, which is based on an 85th percentile value, on a tangent section is the same as that on a horizontal curve. This suggests that current guidelines do not consider the complexity that some geometric features might induce on drivers, and consequently, there is a need to address the many considerations of diversity. In this respect, human factors should be explicitly included in design guidelines. One aspect of human factors that has received little attention in the literature is related to the mental workload. In this study, a procedure is presented to estimate the mental workload for stopping sight distance. Then, reliability analysis is conducted to compare the change in the probability of non-compliance owing to the available sight distance and based on the mental workload. By analyzing data from 12 horizontal curves in Alberta, Canada, the probability of non-compliance dropped from 9.1% to 0.7%, and a moderate correlation with collisions was found. The results of the analysis showed that incorporating mental workload into the geometric design process can improve safety performance.

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“…Most data were determined from the percentile values of the random variables reported in the literature. For normally distributed random variables, the relationship between the mean and extreme value is given by Hussain and Easa [26] as:…”

Section: Data Preparationmentioning

confidence: 99%

“…The more advanced first-order method (FORM) has been used by several authors, including Osama et al [20], Richl and Sayed [21], De Santos-Berbe et al [22], and Llorca et al [23]. In addition, some researchers have used Monte Carlo (MC) simulation, such as El-Khoury and Hobeika [24] who studied passing sight distance (PSD) on two-lane highways; Sarhan and Hassan [25], who studied sight distance on three-dimensional highway alignments; Wood and Donnell [26], who studied sight distance on horizontal curves; and Andrade-Catano et al [27], who studies headlight sight distance on sag vertical curves. MC simulation has also been used in some studies to verify the assumptions of the analytical reliability methods [17].…”

Section: Introductionmentioning

confidence: 99%

Reliability Analysis of Intersection Sight Distance at Roundabouts

Easa

Liu

et al. 2020

Infrastructures

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This paper presents a reliability-based method for the design of intersection sight distance (ISD) at traffic roundabouts using the linear and nonlinear deceleration profiles of the entry vehicles. The reliability method is based on the first-order second moment method which is simple and relatively accurate compared with advanced methods. The nonlinear deceleration profile includes a shape parameter that produces the linear profile as a special case. Deterministic and reliability-based formulas for the required ISD for an approaching vehicle are developed for the entry vehicle on the left and the vehicle on the circulating roadway. Then, the design values of the ISD legs, applicable to any type of roundabout, are presented for different probabilities of non-compliance (Pnc) and different coefficients of variations. For the special case of single-lane symmetrical roundabouts, which have a well-defined geometry, the lateral clearance needs are established. The sensitivity analysis shows that ISD is very sensitive to both the mean and variance of the critical headway. The results show that the deterministic method results in ISD values that correspond to a very small Pnc, indicating that the method is very conservative. The proposed method, which provides flexibility in selecting ISD for any given Pnc, should be of interest to highway designers and practitioners to promote roundabout safety.

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

Cited by 27 publications

References 24 publications

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

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

Calibrating Design Guidelines using Mental Workload and Reliability Analysis

Reliability Analysis of Intersection Sight Distance at Roundabouts

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