Pedestrian Crossing Sight Distance: Lateral Clearance Guidelines for Roadways

Easa, Said M.

doi:10.3141/2588-04

“…The sight distance along the major road (curved or straight) or freeway-ramp vehicle is then given by the following equation [3],…”

Section: Fosm Methodsmentioning

confidence: 99%

“…The clearance time is the period between the entry time of the upcoming major-road vehicle to the crosswalk and the time the back of the pedestrian unit clears the crosswalk [3]. From the study of Schoon [2], the value of clearance time was found to be 2 seconds.…”

Section: The Clearance Time Tcmentioning

confidence: 99%

“…The distance over which pedestrians must see approaching traffic to be able to decide a safe gap is called Pedestrian Crossing Distance [1]. Guidelines for pedestrian crossing sight distance (PCSD) have been developed [3]. Basically, pedestrian walking speed and start-up time for signalized intersections were main concerns in earlier studies.…”

Section: Introductionmentioning

confidence: 99%

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Reliability analysis of pedestrian crossing sight distance

Karim¹

2021

Preprint

0

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The main objective of this study was to calculate the required sight distance corresponding to the various probabilities of failure by considering two methods of reliability analysis. This paper presents a probabilistic approach based on such random variables as major road vehicle speed, walking speed, pedestrian observation-reaction time, the length of the crossing unit, pedestrian setback from the nearest curb of the major road. A safety margin is defined as the difference between available and required sight distances. By using the first-order second moment (FOSM) method, relationships for the mean and standard deviation of the safety margin were developed. The advance first-order second-moment (AFOSM) was also used to find the supplied sight distance corresponding to reliability index. Comparison of two methods was done. Obtained results from the two methods were almost similar to a low coefficient of variation. Different design graphs were developed to calculate the required sight distance at a different coefficient of variation corresponding to the probability of failure and different vehicle design. Sensitivity analysis was performed to obtain the most sensitive variable to the pedestrian crossing sight distance. It was found that vehicle speed is more sensitive to required sight distance and perception-reaction time has least effect on supplied (required) sight distance. Application of these methods is presented with two examples. This probabilistic method is valuable in designing pedestrian crossing sight distance for any preferred reliability level.

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“…The pedestrian unit is taken as a point in present design practice. The pedestrian setback is the distance from the place where a pedestrian may stand before crossing the major road to the near curb of the major road [3]. Generally, pedestrians stand 1.8 m back from the face of the curb [14].…”

Section: The Pedestrian Setback Fpmentioning

confidence: 99%

Reliability analysis of pedestrian crossing sight distance

Karim¹

2021

Preprint

0

View full text Add to dashboard Cite

The main objective of this study was to calculate the required sight distance corresponding to the various probabilities of failure by considering two methods of reliability analysis. This paper presents a probabilistic approach based on such random variables as major road vehicle speed, walking speed, pedestrian observation-reaction time, the length of the crossing unit, pedestrian setback from the nearest curb of the major road. A safety margin is defined as the difference between available and required sight distances. By using the first-order second moment (FOSM) method, relationships for the mean and standard deviation of the safety margin were developed. The advance first-order second-moment (AFOSM) was also used to find the supplied sight distance corresponding to reliability index. Comparison of two methods was done. Obtained results from the two methods were almost similar to a low coefficient of variation. Different design graphs were developed to calculate the required sight distance at a different coefficient of variation corresponding to the probability of failure and different vehicle design. Sensitivity analysis was performed to obtain the most sensitive variable to the pedestrian crossing sight distance. It was found that vehicle speed is more sensitive to required sight distance and perception-reaction time has least effect on supplied (required) sight distance. Application of these methods is presented with two examples. This probabilistic method is valuable in designing pedestrian crossing sight distance for any preferred reliability level.

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“…where V e is the design speed of the entering stream, V c is the design speed of the circulating stream, and t c is the critical headway for entering the major road with a value of 5 s for drivers, riders, and cyclists in both equations. Pedestrians do not have standard established formulae to obtain the sight distances they require to perform common maneuvers [30]. Since the crossing maneuver is the one with more fatalities among pedestrians, only their roadway crossing was taken into account.…”

Section: Obtention Of Required Sight Distances (Rsd)mentioning

confidence: 99%

Evaluating Pedestrians’ Safety on Urban Intersections: A Visibility Analysis

González-Gómez

¹

,

Castro

²

2019

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Overall visibility plays a key role in the safety of pedestrians. Despite its importance, verifying the right provisioning of sufficient available sight distances among pedestrians and vulnerable road users (VRUs) is not a prevalent practice. On top of that, the pursuit for more sustainable modes of transportation has promoted the establishment of different shared mobility services which are prone to increase walking and, thus, the number of pedestrians and other VRUs in urban settings. With the intention of verifying how car-centered designs perform for non-motorized users, a 3D procedure that evaluates the visibility of pedestrians and other users is presented and applied to specific cases in Madrid, Spain. The proposed solution employs virtual trajectories of pedestrians with mobility impairments and without them, cyclists, and personal transportation device riders. Their visibility was assessed around the functional area of urban intersections, including zones where possible jaywalking practices might occur. The evaluation was performed three-dimensionally, making use of LiDAR data, GIS tools, and 3D objects. Results show the impact of street furniture location on visibility, the distinctive influence of vegetation on the lines of sight of each observer, and how design parameters that were intended to improve motorized traffic could affect VRU.

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Pedestrian Crossing Sight Distance: Lateral Clearance Guidelines for Roadways

Cited by 11 publications

References 11 publications

Reliability analysis of pedestrian crossing sight distance

Reliability analysis of pedestrian crossing sight distance

Reliability analysis of pedestrian crossing sight distance

Evaluating Pedestrians’ Safety on Urban Intersections: A Visibility Analysis

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