The Experts below are selected from a list of 7362 Experts worldwide ranked by ideXlab platform
P. Vedagiri - One of the best experts on this subject based on the ideXlab platform.
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Proactive pedestrian safety evaluation at unprotected mid-block Crosswalk locations under mixed traffic conditions
Safety Science, 2016Co-Authors: Br Kadali, P. VedagiriAbstract:The pedestrian safety can be evaluated by proactive methods (conflict techniques). Proactive method is a cost-effective technique as compared to the historic crash data analysis. Pedestrian safety studies at mid-block Crosswalks based on proactive methods are required due to the growing number of pedestrian crossing facilities in developing countries. Hence, the present study evaluated the pedestrian safety at unprotected mid-block Crosswalks by considering the proactive safety measure as a pedestrian safety margin (PSM). PSM is the time difference between accepted vehicular time gap with reference to the pedestrian crossing path and pedestrian actual crossing time (based on the field conditions). To fulfill this objective eight unprotected mid-block Crosswalks were selected which have different roadway characteristics. Video graphic survey has been conducted for data collection at these locations. PSM values were extracted corresponding to the pedestrian behavioural, vehicular and traffic characteristics at all the eight Crosswalks. Further, stepwise regression and binary logit models (the probability of pedestrian-vehicle non-conflict) have been developed in order to find out the factors contributing to the PSM values as well as predicting the probability of avoiding conflict with an approaching vehicle at unprotected mid-block Crosswalks. From the study, it is observed that pedestrian behavioural characteristics such as rolling behaviour and speed change conditions significantly reduce the PSM values, and it influences the probability of avoiding conflict with an approaching vehicle at unprotected mid-block Crosswalks. These findings may be useful for evaluation of the existing unprotected mid-block Crosswalk locations and for increasing the pedestrian safety at these Crosswalks by considering suitable control measurements on pedestrian behaviour under mixed traffic conditions. Language: en
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evaluation of pedestrian Crosswalk level of service los in perspective of type of land use
Transportation Research Part A-policy and Practice, 2015Co-Authors: Raghuram B Kadali, P. VedagiriAbstract:In India pedestrians usually cross the road at mid-block Crosswalks due to ease of access to their destination or the development of adjacent land use types such as shopping, business areas, school and residential areas. The behaviour of pedestrian will change with respect to different land use type and this change in behaviour of pedestrian further reflects change in perceived level of service (LOS). So, it is important to evaluate the quality of service of such crossing facilities with respect to different land-use type under mixed traffic conditions. In this framework, pedestrian perceived LOS were collected with respect to different land-use type such as shopping, residential and business areas. The ordered probit (OP) model was developed by using NLOGIT software package, with number of vehicles encountered, road crossing difficulty as well as safety considered as primary factors along with pedestrian individual factors (gender and age), land-use type and roadway geometry. From the model results, it has been concluded that perceived safety, crossing difficulty, land-use condition, number of vehicles encountered, median width and number of lanes have significant effect on pedestrian perceived LOS at unprotected (un-signalized) mid-block Crosswalks in mixed traffic scenario. The inferences of these results highlights the importance of land use planning in designing a new set of pedestrian access facilities for unprotected mid-block Crosswalks under mixed traffic conditions. Also the study results would be useful for evaluating pedestrian accessibility taking into account different land-use type and planning required degree of segregation with vehicular movement at unprotected mid-block Crosswalk locations.
Wael K.m. Alhajyaseen - One of the best experts on this subject based on the ideXlab platform.
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Empirical Study on Pedestrian Signal Design and Compliance in the State of Qatar
International Journal of Civil Engineering, 2019Co-Authors: Deepti Muley, Wael K.m. Alhajyaseen, Mohamed Kharbeche, Mohammed Al-salemAbstract:To ensure safe crossing manoeuvres at signalized Crosswalks, the pedestrian delays and allocation of sufficient pedestrian green and flashing green times should be considered at design stage. The pedestrian signal settings in the State of Qatar were analyzed through empirical observations of eight Crosswalks. Video recording technique was used to record the pedestrian movements and signal settings at selected Crosswalks. The results indicated that excessive delays resulted in low compliance rates at all Crosswalks and the signal phasing affected compliance rate. Moreover, the analysis of crossing speed indicated that the speed (1.2 m/s) currently specified by the Qatar Traffic Control Manual, 2015 for determining clearance time is sufficient for safe crossing. In addition, the results of speed analysis indicated that the gender, type of pedestrian signal display, and Crosswalk length affect the crossing speed of pedestrians. A comparison of crossing times with the provided signal timings indicated that a lower pedestrian flashing green is provided at all sites, and excessively large buffer intervals are available. These results demonstrate the urgent need to modify signal settings to enable more opportunities for walking and legal crossings. It is recommended that pedestrian signals should be always activated based on the applied phasing plan without the need for pressing the push buttons. These push buttons can be used to recall early pedestrian green to reduce their waiting time. Furthermore, at major crossings, countdown timers showing time remaining for PG should be installed to improve compliance rates.
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ANT/SEIT - Pedestrians’ Speed Analysis at Signalized Crosswalks
Procedia Computer Science, 2018Co-Authors: Deepti Muley, Wael K.m. Alhajyaseen, Mohamed Kharbeche, Mohammed Al-salemAbstract:Abstract Pedestrian speed is essential for designing signal timings as well as for understanding pedestrian safety issues. This paper presents analysis of three types of pedestrian speeds (entry speed, crossing speed, and exit speed) at three signalized Crosswalks in the State of Qatar. Pedestrian movements were tracked using TrafficAnalyzer software and data were analyzed to determine the effect of signal indications, Crosswalk length, and crossing direction on pedestrian speeds. The results of this analysis showed that only 23.69% pedestrians crossed legally, during pedestrian green or pedestrian flashing green interval. Moreover, the pedestrian entry speeds were significantly affected by the pedestrian signal indications. Furthermore, the crossing speeds were positively correlated with Crosswalk length for pedestrians crossing on green and red indications while pedestrian exit speeds were independent of Crosswalk length but significantly affected by crossing direction.
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Quality of pedestrian flow and Crosswalk width at signalized intersections
Iatss Research, 2010Co-Authors: Wael K.m. Alhajyaseen, Hideki NakamuraAbstract:Among various pedestrian facilities, signalized Crosswalks are the most complex and critical ones. Their geometry and configuration including width, position and angle directly affect the safety, cycle length and resulting delays for all users. Existing manuals do not provide clear and rational specifications for the required Crosswalk width under different pedestrian demand combinations and properties. Furthermore, they do not consider the bi-directional flow effects on crossing speed and time when addressing pedestrian flow at signalized Crosswalks. However, quantifying the effects of such interactions on the behavior of pedestrian flow is a prerequisite for improving the geometric design and configuration of signalized Crosswalks. The objective of this paper is to develop a methodology for estimating the required Crosswalk width at different pedestrian demand combinations and a pre-defined LOS. The developed methodology is based on theoretical modeling for total pedestrian platoon crossing time, which consists of discharge and crossing times. The developed models are utilized to generate the fundamental diagrams of pedestrian flow at signalized Crosswalks. A comprehensive discussion about the effects of bi-directional flow and various pedestrian age groups on the characteristics of pedestrian flow and the capacity of signalized Crosswalks is presented. It is found that the maximum reduction in the capacity of signalized Crosswalks occurs at roughly equal pedestrian flows from both sides of the Crosswalk. By utilizing existing LOS thresholds for pedestrian flow at signalized Crosswalks, the required Crosswalk widths for various pedestrian demand combinations are proposed for implementation.
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Design Criteria for Crosswalk Width and Position at Signalized Intersections
International symposium on Highway Geometric Design, 2010Co-Authors: Wael K.m. Alhajyaseen, Hideki NakamuraAbstract:Existing optimization methodologies for intersection operations assumes a fixed geometric design; however to produce the best performance, the geometry and operational system should be optimized simultaneously. Crosswalks at signalized intersections are complex and critical pedestrian facilities. Their geometry and configuration directly affect the safety, cycle length and resulting delays for all users. As Crosswalks become wider or they are placed further upstream, the cycle length will increase due to the all-red time requirement, which deteriorates the overall mobility levels of signalized intersections. In contrast, when Crosswalk width decreases, the required minimum pedestrian crossing time increases due to the bi-directional pedestrian flow effects, which leads to longer cycle length. Furthermore, existing manuals and guidelines do not offer any specification for the required Crosswalk width under various pedestrian demand conditions. This study aims to develop new criteria for designing Crosswalk width at signalized intersections, which can optimize the performance of signalized intersections from the viewpoint of vehicular traffic and pedestrians. The proposed methodology considers pedestrian demand and its characteristics, vehicle demand and the geometric characteristics of the intersection. The concept of optimized Crosswalk width is proposed and demonstrated through a case study. Moreover, a comprehensive discussion regarding the existing strategies on positioning Crosswalks is presented. The merits and drawbacks of each pattern are discussed. A previously developed methodology for modeling pedestrian flow at signalized Crosswalks is utilized to estimate crossing time requirements and the reduction in crossing speed due to the bi-directional flow effects. It was found that at signalized intersections, which are characterized by low pedestrian and high vehicle demands, Crosswalk width of 2 meters is appropriate to minimize cycle length and resulting delays for all users including pedestrians.
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Methodology for Modeling Pedestrian Platoon Discharge and Crossing Times at Signalized Crosswalks
Transportation Research Board, 2009Co-Authors: Wael K.m. Alhajyaseen, Hideki NakamuraAbstract:Optimizing Crosswalk configurations including width, position and angle is an important concern to improve the overall performance of signalized intersections. Quantifying the effects of bi-directional flow and Crosswalk width on pedestrian walking speed and crossing time is a prerequisite for improving the geometric design and configuration of signalized Crosswalks. The time used by a pedestrian platoon to cross a signalized Crosswalk is divided into discharge time and crossing time. Discharge time is a function of pedestrian demand and Crosswalk width while pedestrian crossing time is basically a function of Crosswalk length and walking speed. However when pedestrian demand increases at both sides of the Crosswalk, crossing time increases due to interactions between conflicting pedestrian flows. A variety of methods have been developed for determining appropriate pedestrian crossing times. Although many of these methods have useful applications, most of them have shortcomings when considering the effects of bi-directional flow on crossing time. No consideration is given to deceleration or reduction in walking speed that results from the interaction between conflicting flows. Furthermore existing models tend to underestimate the discharge time necessary for a pedestrian platoon waiting at the edge of the Crosswalk. This study proposes a new methodology for modeling pedestrian discharge and crossing times. Discharge time is modeled by using shockwave theory while crossing time is modeled by applying aerodynamic drag theory. The developed methodology provides a rational quantification for the effects of bi-directional pedestrian flow and Crosswalk geometry on walking speed and crossing time.
Hideki Nakamura - One of the best experts on this subject based on the ideXlab platform.
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Quality of pedestrian flow and Crosswalk width at signalized intersections
Iatss Research, 2010Co-Authors: Wael K.m. Alhajyaseen, Hideki NakamuraAbstract:Among various pedestrian facilities, signalized Crosswalks are the most complex and critical ones. Their geometry and configuration including width, position and angle directly affect the safety, cycle length and resulting delays for all users. Existing manuals do not provide clear and rational specifications for the required Crosswalk width under different pedestrian demand combinations and properties. Furthermore, they do not consider the bi-directional flow effects on crossing speed and time when addressing pedestrian flow at signalized Crosswalks. However, quantifying the effects of such interactions on the behavior of pedestrian flow is a prerequisite for improving the geometric design and configuration of signalized Crosswalks. The objective of this paper is to develop a methodology for estimating the required Crosswalk width at different pedestrian demand combinations and a pre-defined LOS. The developed methodology is based on theoretical modeling for total pedestrian platoon crossing time, which consists of discharge and crossing times. The developed models are utilized to generate the fundamental diagrams of pedestrian flow at signalized Crosswalks. A comprehensive discussion about the effects of bi-directional flow and various pedestrian age groups on the characteristics of pedestrian flow and the capacity of signalized Crosswalks is presented. It is found that the maximum reduction in the capacity of signalized Crosswalks occurs at roughly equal pedestrian flows from both sides of the Crosswalk. By utilizing existing LOS thresholds for pedestrian flow at signalized Crosswalks, the required Crosswalk widths for various pedestrian demand combinations are proposed for implementation.
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Design Criteria for Crosswalk Width and Position at Signalized Intersections
International symposium on Highway Geometric Design, 2010Co-Authors: Wael K.m. Alhajyaseen, Hideki NakamuraAbstract:Existing optimization methodologies for intersection operations assumes a fixed geometric design; however to produce the best performance, the geometry and operational system should be optimized simultaneously. Crosswalks at signalized intersections are complex and critical pedestrian facilities. Their geometry and configuration directly affect the safety, cycle length and resulting delays for all users. As Crosswalks become wider or they are placed further upstream, the cycle length will increase due to the all-red time requirement, which deteriorates the overall mobility levels of signalized intersections. In contrast, when Crosswalk width decreases, the required minimum pedestrian crossing time increases due to the bi-directional pedestrian flow effects, which leads to longer cycle length. Furthermore, existing manuals and guidelines do not offer any specification for the required Crosswalk width under various pedestrian demand conditions. This study aims to develop new criteria for designing Crosswalk width at signalized intersections, which can optimize the performance of signalized intersections from the viewpoint of vehicular traffic and pedestrians. The proposed methodology considers pedestrian demand and its characteristics, vehicle demand and the geometric characteristics of the intersection. The concept of optimized Crosswalk width is proposed and demonstrated through a case study. Moreover, a comprehensive discussion regarding the existing strategies on positioning Crosswalks is presented. The merits and drawbacks of each pattern are discussed. A previously developed methodology for modeling pedestrian flow at signalized Crosswalks is utilized to estimate crossing time requirements and the reduction in crossing speed due to the bi-directional flow effects. It was found that at signalized intersections, which are characterized by low pedestrian and high vehicle demands, Crosswalk width of 2 meters is appropriate to minimize cycle length and resulting delays for all users including pedestrians.
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Methodology for Modeling Pedestrian Platoon Discharge and Crossing Times at Signalized Crosswalks
Transportation Research Board, 2009Co-Authors: Wael K.m. Alhajyaseen, Hideki NakamuraAbstract:Optimizing Crosswalk configurations including width, position and angle is an important concern to improve the overall performance of signalized intersections. Quantifying the effects of bi-directional flow and Crosswalk width on pedestrian walking speed and crossing time is a prerequisite for improving the geometric design and configuration of signalized Crosswalks. The time used by a pedestrian platoon to cross a signalized Crosswalk is divided into discharge time and crossing time. Discharge time is a function of pedestrian demand and Crosswalk width while pedestrian crossing time is basically a function of Crosswalk length and walking speed. However when pedestrian demand increases at both sides of the Crosswalk, crossing time increases due to interactions between conflicting pedestrian flows. A variety of methods have been developed for determining appropriate pedestrian crossing times. Although many of these methods have useful applications, most of them have shortcomings when considering the effects of bi-directional flow on crossing time. No consideration is given to deceleration or reduction in walking speed that results from the interaction between conflicting flows. Furthermore existing models tend to underestimate the discharge time necessary for a pedestrian platoon waiting at the edge of the Crosswalk. This study proposes a new methodology for modeling pedestrian discharge and crossing times. Discharge time is modeled by using shockwave theory while crossing time is modeled by applying aerodynamic drag theory. The developed methodology provides a rational quantification for the effects of bi-directional pedestrian flow and Crosswalk geometry on walking speed and crossing time.
Ching Yao D Chan - One of the best experts on this subject based on the ideXlab platform.
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application of sfca pedestrian simulation model to the signalized Crosswalk width design
Transportation Research Part A-policy and Practice, 2015Co-Authors: Gang B Ren, Wei C Wang, Ching Yao D ChanAbstract:This study presents a new approach for specifying the design of the signalized Crosswalk width. Based on the analysis of the characteristics of bi-direction pedestrian flows at the subject signalized Crosswalk, a crossing time (CT) estimation model is proposed and developed by taking the time lag of pedestrian platoons as well as bi-direction effects into consideration. Subsequently, two important indicators (proportion of delay in the crossing time, i.e. PDC, and local density level, i.e. LDL) are introduced into the evaluation of pedestrian crossing efficiency and comfort level respectively. It is shown in our work that CT, PDC, and LDL can be successfully obtained with the implementation of cellular automaton into the pedestrian simulation model by incorporating social forces (SFCA). Moreover, the relationships among CT, PDC, and LDL as well as the Crosswalk width and pedestrian demand are modeled and illustrated. By synthesizing all indicators, a method is introduced to determine the recommended maximum and minimum widths for signalized Crosswalks under different pedestrian demand volumes. Our methodologies demonstrate that they may help traffic engineers and specialists make a sensible choice of the Crosswalk width. The outcome of our work will further give traffic engineers and practitioners new insights for the design and planning of signalized pedestrian Crosswalks and constitute an important contribution to the understanding and evaluation of pedestrian movements in this aspect.
James M. Coughlan - One of the best experts on this subject based on the ideXlab platform.
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ICME Workshops - Smartphone-based Crosswalk detection and localization for visually impaired pedestrians
... IEEE International Conference on Multimedia and Expo workshops. IEEE International Conference on Multimedia and Expo, 2013Co-Authors: Vidya Nariyambut Murali, James M. CoughlanAbstract:This paper describes recent work on the “Crosswatch” project, which is a computer vision-based smartphone system developed for providing guidance to blind and visually impaired travelers at traffic intersections. A key function of Crosswatch is self-localization - the estimation of the user's location relative to the Crosswalks in the current traffic intersection. Such information may be vital to users with low or no vision to ensure that they know which Crosswalk they are about to enter, and are properly aligned and positioned relative to the Crosswalk. However, while computer vision-based methods have been used for finding Crosswalks and helping blind travelers align themselves to them, these methods assume that the entire Crosswalk pattern can be imaged in a single frame of video, which poses a significant challenge for a user who lacks enough vision to know where to point the camera so as to properly frame the Crosswalk. In this paper we describe work in progress that tackles the problem of Crosswalk detection and self-localization, building on recent work describing techniques enabling blind and visually impaired users to acquire 360° image panoramas while turning in place on a sidewalk. The image panorama is converted to an aerial (overhead) view of the nearby intersection, centered on the location that the user is standing at, so as to facilitate matching with a template of the intersection obtained from Google Maps satellite imagery. The matching process allows Crosswalk features to be detected and permits the estimation of the user's precise location relative to the Crosswalk of interest. We demonstrate our approach on intersection imagery acquired by blind users, thereby establishing the feasibility of the approach.
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smartphone based Crosswalk detection and localization for visually impaired pedestrians
International Conference on Multimedia and Expo, 2013Co-Authors: Vidya Nariyambut Murali, James M. CoughlanAbstract:This paper describes recent work on the “Crosswatch” project, which is a computer vision-based smartphone system developed for providing guidance to blind and visually impaired travelers at traffic intersections. A key function of Crosswatch is self-localization - the estimation of the user's location relative to the Crosswalks in the current traffic intersection. Such information may be vital to users with low or no vision to ensure that they know which Crosswalk they are about to enter, and are properly aligned and positioned relative to the Crosswalk. However, while computer vision-based methods have been used for finding Crosswalks and helping blind travelers align themselves to them, these methods assume that the entire Crosswalk pattern can be imaged in a single frame of video, which poses a significant challenge for a user who lacks enough vision to know where to point the camera so as to properly frame the Crosswalk. In this paper we describe work in progress that tackles the problem of Crosswalk detection and self-localization, building on recent work describing techniques enabling blind and visually impaired users to acquire 360° image panoramas while turning in place on a sidewalk. The image panorama is converted to an aerial (overhead) view of the nearby intersection, centered on the location that the user is standing at, so as to facilitate matching with a template of the intersection obtained from Google Maps satellite imagery. The matching process allows Crosswalk features to be detected and permits the estimation of the user's precise location relative to the Crosswalk of interest. We demonstrate our approach on intersection imagery acquired by blind users, thereby establishing the feasibility of the approach.