In observing driver courtesy towards pedestrians at unsignalized crosswalks, a behavioral model was adopted in a simulation based on the GM Car-Following Model. The SIMI Motion Software was used to extract the vehicle...In observing driver courtesy towards pedestrians at unsignalized crosswalks, a behavioral model was adopted in a simulation based on the GM Car-Following Model. The SIMI Motion Software was used to extract the vehicle operation data from Wenyi South Road and Hanyuan Road in Xi'an City. The parameters of the GM Car-Following Model were calibrated by genetic algorithm. The road simulation environment based on the Car-Following Model was constructed by MATLAB. In the case of no stopping, uniform deceleration avoidance with advance notice, emergency brake avoidance without advance notice, changes such as the displacement of the Car-Following queue, headway, speed, acceleration, and deceleration were analyzed by numerical simulation. The results show that when there is advance notice before the crosswalk, the minimum headway distances of Car1-Car2, Car2-Car3, Car3-Car4 and Car4-Car5 are 7.09 m, 7.38 m, 7.65 m, 7.91 m, and the average rates of change of the headway during deceleration are 0.78 m/s, 0.74 m/s, 0.71 m/s, 0.68 m/s respectively;in the absence of advance notice before the crosswalk, the minimum headway distances of Car1-Car2, Car2-Car3, Car3-Car4 and Car4-Car5 are 7.28 m, 7.75 m, 8.19 m, 8.59 m, and the average rates of change of the headway during deceleration are 1.57 m/s, 1.25 m/s, 1.04 m/s, 0.96 m/s, respectively. Therefore, in order to effectively prevent the occurrence of vehicle rear-end events, it's necessary to set traffic signs and markings on the preceding section of the intersection or road exhibiting behavioral comity.展开更多
When arranging the pedestrian infrastructure,one of the most important components that make a tangible contribution to the safety of pedestrians is to organize the safe road crossing.In cities,pedestrians often cross ...When arranging the pedestrian infrastructure,one of the most important components that make a tangible contribution to the safety of pedestrians is to organize the safe road crossing.In cities,pedestrians often cross a road in the wrong place due to established routes or inadequate location of crosswalks.Accidents with the participation of pedestrians who crossed the road neglecting the traffic rules,make up a significant part of the total amount of road accidents.In this paper,we propose a method that allows us,on the basis of the results of a computer simulation of pedestrian traffic,to obtain predicted routes for road crossing and to indicate optimal locations for crosswalks that take into account established pedestrian routes and increase their safety.The work describes an extension for the existing AntRoadPlanner simulation algorithm,which searches for and clusters points where pedestrians cross the roadway and suggests locations for new crosswalks.This method was tested on the basis of a comparative simulation of several territories before and after its application,as well as on the basis of a field study of the territories.The developed algorithm can also be used to search for other potentially dangerous places for pedestrians on plans of districts,for example,crossings in places with limited visibility.展开更多
The phenomenon that pedestrians do not walk in the crosswalk during pedestrian green is defined as overflow violation, which is illegal but common. Broadly varying crossing positions at far-side cross-section may resu...The phenomenon that pedestrians do not walk in the crosswalk during pedestrian green is defined as overflow violation, which is illegal but common. Broadly varying crossing positions at far-side cross-section may result in widely distributed conflict points with left-turning and right-turning vehicles, which may cause the occurrence of severe conflicts. This paper proposes a model to estimate the overflow pedestrians' crossing positions at the far-side cross-section of signalized crosswalk, which enables us to better understand pedestrian overflow violation behavior and finally facilitate their safety. After analysis, the intersection geometry and destination are determined as the critical factors causing pedestrians to overflow. And then, Weibull distribution is employed to describe the stochastic characteristics of overflow pedestrians' crossing position distribution at the far-side cross-section. A crossing position distribution model which takes the crosswalk length, width and distance between crosswalk and destination into account is developed. The established model is validated by comparing the observed pedestrian crossing positions with the estimated crossing positions. The validation results suggest that the established model is capable of being adopted to estimate the overflow pedestrians' crossing positions at far-side cross-section. Based on the model, countermeasure for overflow violation can be put forward to prevent pedestrians from walking outside the crosswalk.展开更多
Existing optimization methodologies for intersection operations assumes a fixed geometric design, however the geometry and operational system should be simultaneously optimized to produce the best performance. Signali...Existing optimization methodologies for intersection operations assumes a fixed geometric design, however the geometry and operational system should be simultaneously optimized to produce the best performance. Signalized crosswalks 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 propose new criteria for designing crosswalk width at signalized intersections, which can optimize the performance from the viewpoint of vehicular traffic and pedestrians. The proposed methodology considers pedestrian demand and its characteristics （such as bi-directional flow effects）, 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 merits and drawbacks of existing strategies on positioning crosswalks is presented. 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.展开更多
The effects of the interactions between bi-directional pedestrians on the crossing time and the crosswalk width are studied. Firstly,the crossing process of bi-directional pedestrians is analyzed.The total crosswalk t...The effects of the interactions between bi-directional pedestrians on the crossing time and the crosswalk width are studied. Firstly,the crossing process of bi-directional pedestrians is analyzed.The total crosswalk time is divided into a discharge time and a crossing time. The interactions between bi-directional pedestrians are quantified with the drag force theory. Then,a model is developed to study the crossing time based on the kinetic energy theory and momentum theory. Subsequently,the related parameters of the proposed model are calibrated with observed information. The relationships among crosswalk width,signal time,pedestrian volume and level of service are simulated with the proposed model. The results are verified and compared with other models. The proposed model has an absolute value of relative error of 9. 38%,which is smaller than that of the Alhajyaseen model（ 15. 26%） and Highway Capacity Manual（ HCM） model（ 12. 42%）. Finally,suggested crosswalk widths at different conditions are successfully estimated with the proposed crossing time model.展开更多
Crosswalk presence data are crucial for pedestrian safety and urban planning.However,obtaining such data at a large scale is often challenging due to the high cost associated with traditional collection methods.While ...Crosswalk presence data are crucial for pedestrian safety and urban planning.However,obtaining such data at a large scale is often challenging due to the high cost associated with traditional collection methods.While automated methods based on computer vision have been explored to detect crosswalks from aerial images,a major obstacle to their application is the handling of candidate crosswalks occluded by objects or shadows in the aerial ima-gery.To address this challenge,this study explores different deep learning-based solutions,including the aerial-view method(AVM)and street-view method(SVM),which are com-monly used,and a combination of them,i.e.,the dual-perspective method(DPM).Deep learning models based on convolutional neural networks(CNNs)with the VGG16 architec-ture were trained using 16815 images to automatically detect crosswalks from both aerial and street view images.To compare the performance of these methods in handling occlu-sions,1378 images from a heavily occluded area were processed separately by the three methods.The results showed that the AVM suffered the most when dealing with images from a heavily occluded area,resulting in the lowest accuracy,precision,recall,and F1 score among the three methods.On the other hand,the SVM outperformed the AVM sig-nificantly.The DPM demonstrated the highest accuracy and precision values,indicating its superiority in accurately predicting the location of a crosswalk.However,the SVM exhibited the highest recall value,highlighting its superior ability to recover an occluded crosswalk among all methods.展开更多
External human–machine interfaces(eHMIs)of highly automated vehicles(HAVs)have been developed to communicate vehicle intentions to pedestrians and other road users.This study conducted an online experiment with 33 pa...External human–machine interfaces(eHMIs)of highly automated vehicles(HAVs)have been developed to communicate vehicle intentions to pedestrians and other road users.This study conducted an online experiment with 33 participants to investigate the impact of a novel HAV’s eHMI of augmented reality(AR)crosswalks on pedestrian crossings using virtual simulation scenario videos and questionnaires.To verify the effectiveness of the AR crosswalk,comparative analyses were performed on eHMIs across 5 modalities:baseline,pedestrian silhouette,virtual eyes,AR headlight,and AR crosswalk,in conjunction with 2 vehicle physical modes(yielding and non-yielding).Metrics used in the study included crossing percentages before the HAV passed,crossing decision time,comprehensibility,and perceived safety.The results indicated that for yielding vehicles,the AR crosswalk resulted in the shortest crossing decision time,the highest comprehensibility,and the highest perceived safety scores.This study provides guidelines for the design of eHMIs and demonstrates that AR eHMIs based on an intelligent vehicle infrastructure cooperative system,can effectively address the one-to-many interaction problem.展开更多
This work presents a simulation model for unsignalized crosswalks which takes into account collisions between vehicles and pedestrians,thus allowing to assess the estimated yearly pedestrian fatality.In particular,we ...This work presents a simulation model for unsignalized crosswalks which takes into account collisions between vehicles and pedestrians,thus allowing to assess the estimated yearly pedestrian fatality.In particular,we focus on a method to calibrate such a model combining measurable crosswalk characteristics,such as maximum speed limit or drivers’compliance,with statistical data for past accidents obtained from local municipality.In order to perform simulations under realistic conditions,we constructed a one-week scenario where pedestrian and vehicle traffic vary using specific patterns each hour of the week.The constructed traffic profile is based on openly available data and the suitability for the scenario considered(a crosswalk in Milan,Italy)is investigated showing that cultural/lifestyle elements determine the variation of weekly traffic.Simulations using the constructed one-week scenario were used to obtain the only non-measurable parameter which account for pedestrians’and drivers’distraction.In addition,we also focused on the presence of elderly pedestrians which have different physiological characteristics compared to adults or children and are becoming an important part of the population in several countries around the globe.The simulation model presented here and the method suggested for calibration may be employed in different contexts,thus allowing to build an important tool to be used not only for transportation efficiency/optimization but also for safety analysis.展开更多
The drivers’yielding distance to pedestrians at midblock crosswalks affects pedestrians’perceived safety.This distance can be influenced by either crosswalk-related or noncrosswalk.In most cases,crosswalk-related fe...The drivers’yielding distance to pedestrians at midblock crosswalks affects pedestrians’perceived safety.This distance can be influenced by either crosswalk-related or noncrosswalk.In most cases,crosswalk-related features are readily available or easy to collect compared to non-crosswalk features.However,the extent to which crosswalk-related features affect the spatial yielding compliance is not clear.This study evaluated the role of combined crosswalk-related features on drivers’spatial yielding compliance at signalized midblock crosswalks.The study used observational survey data collected from fifteen flash-based signalized midblock crosswalks located in Las Vegas,Nevada.Three logistic regression models,with crosswalk-related features only,non-crosswalk features only,and combined features,were developed and compared.It was revealed that the performance difference between the model with crosswalk-related features only and combined features was insignificant.This study found that the presence of state’s law signs,“PED XING”signs,and placement of rectangular rapid flashing beacons(RRFBs)on the advanced pedestrians crossing signs(APCSs),are significant factors for high spatial yielding compliance.On the contrary,the yield line’s presence at a distance greater than 40 ft from the crosswalk,presence of one stage crossing,and high Annual Average Daily Traffic(AADT)negatively affects the spatial yielding compliance.Moreover,the findings suggest that researchers should be careful about excluding the non-crosswalk features from the analysis.To improve spatial yielding compliance,several recommendations that the city planners and engineers can adopt are provided.展开更多
The increased number of data repositories has greatly increased the availability of open data.To enable broad discovery and access to research dataset,some data repositories have begun leveraging the web architecture ...The increased number of data repositories has greatly increased the availability of open data.To enable broad discovery and access to research dataset,some data repositories have begun leveraging the web architecture by embedding structured metadata markup in dataset web landing pages using vocabularies from Schema.org and extensions.This paper aims to examine metadata interoperability for supporting global data discovery.Specifically,the paper reports a survey on which metadata schema has been adopted by participating data repositories,and presents an analysis of crosswalks from fourteen research data schemas to Schema.org.The analysis indicates most descriptive metadata are interoperable among the schemas,the most inconsistent mapping is the rights metadata,and a large gap exists in the structural metadata and controlled vocabularies to specify various property values.The analysis and collated crosswalks can serve as a reference for data repositories when they develop crosswalks from their own schemas to Schema.org,and provide the research data community a benchmark of structured metadata implementation.展开更多
Delays of both pedestrians,who are classified according to whether complying with traffic law,and vehicles at a signalized crosswalk are analyzed in this paper.The truncated Adams' model is applied to generate the...Delays of both pedestrians,who are classified according to whether complying with traffic law,and vehicles at a signalized crosswalk are analyzed in this paper.The truncated Adams' model is applied to generate the probability and mean of delay of pedestrians non-complying with traffic law.Using the section-based traffic queuing-theory and the stochastic decomposition property of M/G/1vacation system with exhaustive service,the mean delay of vehicles is formulated.A multi-objective optimization model simultaneously minimizing the delays of pedestrians and vehicles during a signal period is proposed.The effects,which several model parameters have on the delays and the optimal solution of the model,are illustrated by numerical examples.展开更多
Like roadway information is to motor vehicle safety,pedestrian facility information(e.g.,sidewalk presence)is crucial towards improving the safety of these vulnerable road users.Yet unlike widely accessible roadway da...Like roadway information is to motor vehicle safety,pedestrian facility information(e.g.,sidewalk presence)is crucial towards improving the safety of these vulnerable road users.Yet unlike widely accessible roadway data,pedestrian facility data is unavailable for most state agencies.Without this information,data-driven problem identification,countermeasure analysis,project evaluation,and performance management will be heavily impeded.Thus,urgent need for this data was recognized by state departments of transportation(DOTs).To address this need,we developed an automated approach for the automated detection of crosswalks in satellite images.The most advanced deep learning methodology,transfer learning with a convolutional neural network(CNN)was used to handle realworld images.During the prediction process,a satellite image of a roadway pavement was analyzed by the satellite view model to predict the presence of a crosswalk.Then,the street view image of the same target was detected by the integrated street view model as a ground truth check.A total of 18361 images from Bing maps in satellite view and street view were used to train and test the deep learning model.As a result,the satellite view model itself achieved 98.43%accuracy using testing data from the same region.When dealing with data from another region,using the satellite view detection with ground truth checking increased the accuracy by 49%.It is obvious that by integrating the ground truth checking model into the satellite view crosswalk detection,we can obtain a more robust model which can handle highly occluded,low quality satellite images.展开更多
基金Supported by the National Natural Science Foundation of China(51678132)the Key Research and Development Project of Science and Technology Department in Jiangxi Province(20161BBG70044)the Fundamental Research Funds for the Central Universities of China(300102218521)
文摘In observing driver courtesy towards pedestrians at unsignalized crosswalks, a behavioral model was adopted in a simulation based on the GM Car-Following Model. The SIMI Motion Software was used to extract the vehicle operation data from Wenyi South Road and Hanyuan Road in Xi'an City. The parameters of the GM Car-Following Model were calibrated by genetic algorithm. The road simulation environment based on the Car-Following Model was constructed by MATLAB. In the case of no stopping, uniform deceleration avoidance with advance notice, emergency brake avoidance without advance notice, changes such as the displacement of the Car-Following queue, headway, speed, acceleration, and deceleration were analyzed by numerical simulation. The results show that when there is advance notice before the crosswalk, the minimum headway distances of Car1-Car2, Car2-Car3, Car3-Car4 and Car4-Car5 are 7.09 m, 7.38 m, 7.65 m, 7.91 m, and the average rates of change of the headway during deceleration are 0.78 m/s, 0.74 m/s, 0.71 m/s, 0.68 m/s respectively;in the absence of advance notice before the crosswalk, the minimum headway distances of Car1-Car2, Car2-Car3, Car3-Car4 and Car4-Car5 are 7.28 m, 7.75 m, 8.19 m, 8.59 m, and the average rates of change of the headway during deceleration are 1.57 m/s, 1.25 m/s, 1.04 m/s, 0.96 m/s, respectively. Therefore, in order to effectively prevent the occurrence of vehicle rear-end events, it's necessary to set traffic signs and markings on the preceding section of the intersection or road exhibiting behavioral comity.
基金This work was financially supported by Russian Science Foundation with co-financing of Bank Saint Petersburg[Agreement#17-71-30029].
文摘When arranging the pedestrian infrastructure,one of the most important components that make a tangible contribution to the safety of pedestrians is to organize the safe road crossing.In cities,pedestrians often cross a road in the wrong place due to established routes or inadequate location of crosswalks.Accidents with the participation of pedestrians who crossed the road neglecting the traffic rules,make up a significant part of the total amount of road accidents.In this paper,we propose a method that allows us,on the basis of the results of a computer simulation of pedestrian traffic,to obtain predicted routes for road crossing and to indicate optimal locations for crosswalks that take into account established pedestrian routes and increase their safety.The work describes an extension for the existing AntRoadPlanner simulation algorithm,which searches for and clusters points where pedestrians cross the roadway and suggests locations for new crosswalks.This method was tested on the basis of a comparative simulation of several territories before and after its application,as well as on the basis of a field study of the territories.The developed algorithm can also be used to search for other potentially dangerous places for pedestrians on plans of districts,for example,crossings in places with limited visibility.
基金the National Natural Science Foundation of China(Nos.51278520 and 51278220)
文摘The phenomenon that pedestrians do not walk in the crosswalk during pedestrian green is defined as overflow violation, which is illegal but common. Broadly varying crossing positions at far-side cross-section may result in widely distributed conflict points with left-turning and right-turning vehicles, which may cause the occurrence of severe conflicts. This paper proposes a model to estimate the overflow pedestrians' crossing positions at the far-side cross-section of signalized crosswalk, which enables us to better understand pedestrian overflow violation behavior and finally facilitate their safety. After analysis, the intersection geometry and destination are determined as the critical factors causing pedestrians to overflow. And then, Weibull distribution is employed to describe the stochastic characteristics of overflow pedestrians' crossing position distribution at the far-side cross-section. A crossing position distribution model which takes the crosswalk length, width and distance between crosswalk and destination into account is developed. The established model is validated by comparing the observed pedestrian crossing positions with the estimated crossing positions. The validation results suggest that the established model is capable of being adopted to estimate the overflow pedestrians' crossing positions at far-side cross-section. Based on the model, countermeasure for overflow violation can be put forward to prevent pedestrians from walking outside the crosswalk.
文摘Existing optimization methodologies for intersection operations assumes a fixed geometric design, however the geometry and operational system should be simultaneously optimized to produce the best performance. Signalized crosswalks 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 propose new criteria for designing crosswalk width at signalized intersections, which can optimize the performance from the viewpoint of vehicular traffic and pedestrians. The proposed methodology considers pedestrian demand and its characteristics （such as bi-directional flow effects）, 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 merits and drawbacks of existing strategies on positioning crosswalks is presented. 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.
基金Supported by the National Natural Science Foundation of China(51278220)
文摘The effects of the interactions between bi-directional pedestrians on the crossing time and the crosswalk width are studied. Firstly,the crossing process of bi-directional pedestrians is analyzed.The total crosswalk time is divided into a discharge time and a crossing time. The interactions between bi-directional pedestrians are quantified with the drag force theory. Then,a model is developed to study the crossing time based on the kinetic energy theory and momentum theory. Subsequently,the related parameters of the proposed model are calibrated with observed information. The relationships among crosswalk width,signal time,pedestrian volume and level of service are simulated with the proposed model. The results are verified and compared with other models. The proposed model has an absolute value of relative error of 9. 38%,which is smaller than that of the Alhajyaseen model（ 15. 26%） and Highway Capacity Manual（ HCM） model（ 12. 42%）. Finally,suggested crosswalk widths at different conditions are successfully estimated with the proposed crossing time model.
基金supported by the National Science Foundation under the Major Research Instrumentation(MRI)program(No.ACI 1626217).
文摘Crosswalk presence data are crucial for pedestrian safety and urban planning.However,obtaining such data at a large scale is often challenging due to the high cost associated with traditional collection methods.While automated methods based on computer vision have been explored to detect crosswalks from aerial images,a major obstacle to their application is the handling of candidate crosswalks occluded by objects or shadows in the aerial ima-gery.To address this challenge,this study explores different deep learning-based solutions,including the aerial-view method(AVM)and street-view method(SVM),which are com-monly used,and a combination of them,i.e.,the dual-perspective method(DPM).Deep learning models based on convolutional neural networks(CNNs)with the VGG16 architec-ture were trained using 16815 images to automatically detect crosswalks from both aerial and street view images.To compare the performance of these methods in handling occlu-sions,1378 images from a heavily occluded area were processed separately by the three methods.The results showed that the AVM suffered the most when dealing with images from a heavily occluded area,resulting in the lowest accuracy,precision,recall,and F1 score among the three methods.On the other hand,the SVM outperformed the AVM sig-nificantly.The DPM demonstrated the highest accuracy and precision values,indicating its superiority in accurately predicting the location of a crosswalk.However,the SVM exhibited the highest recall value,highlighting its superior ability to recover an occluded crosswalk among all methods.
基金supported in part by the Natural Science Foundation of China under Grant 52272417in part by the Science and Technology Development Project of Jilin Province under Grant 20230301008ZD.
文摘External human–machine interfaces(eHMIs)of highly automated vehicles(HAVs)have been developed to communicate vehicle intentions to pedestrians and other road users.This study conducted an online experiment with 33 participants to investigate the impact of a novel HAV’s eHMI of augmented reality(AR)crosswalks on pedestrian crossings using virtual simulation scenario videos and questionnaires.To verify the effectiveness of the AR crosswalk,comparative analyses were performed on eHMIs across 5 modalities:baseline,pedestrian silhouette,virtual eyes,AR headlight,and AR crosswalk,in conjunction with 2 vehicle physical modes(yielding and non-yielding).Metrics used in the study included crossing percentages before the HAV passed,crossing decision time,comprehensibility,and perceived safety.The results indicated that for yielding vehicles,the AR crosswalk resulted in the shortest crossing decision time,the highest comprehensibility,and the highest perceived safety scores.This study provides guidelines for the design of eHMIs and demonstrates that AR eHMIs based on an intelligent vehicle infrastructure cooperative system,can effectively address the one-to-many interaction problem.
基金financially supported by the JST-Mirai Program Grant Number JPMJMI17D4.
文摘This work presents a simulation model for unsignalized crosswalks which takes into account collisions between vehicles and pedestrians,thus allowing to assess the estimated yearly pedestrian fatality.In particular,we focus on a method to calibrate such a model combining measurable crosswalk characteristics,such as maximum speed limit or drivers’compliance,with statistical data for past accidents obtained from local municipality.In order to perform simulations under realistic conditions,we constructed a one-week scenario where pedestrian and vehicle traffic vary using specific patterns each hour of the week.The constructed traffic profile is based on openly available data and the suitability for the scenario considered(a crosswalk in Milan,Italy)is investigated showing that cultural/lifestyle elements determine the variation of weekly traffic.Simulations using the constructed one-week scenario were used to obtain the only non-measurable parameter which account for pedestrians’and drivers’distraction.In addition,we also focused on the presence of elderly pedestrians which have different physiological characteristics compared to adults or children and are becoming an important part of the population in several countries around the globe.The simulation model presented here and the method suggested for calibration may be employed in different contexts,thus allowing to build an important tool to be used not only for transportation efficiency/optimization but also for safety analysis.
基金the Department of Civil and Environmental Engineering and Construction at the University of Nevada,Las Vegas,for the financial and material support
文摘The drivers’yielding distance to pedestrians at midblock crosswalks affects pedestrians’perceived safety.This distance can be influenced by either crosswalk-related or noncrosswalk.In most cases,crosswalk-related features are readily available or easy to collect compared to non-crosswalk features.However,the extent to which crosswalk-related features affect the spatial yielding compliance is not clear.This study evaluated the role of combined crosswalk-related features on drivers’spatial yielding compliance at signalized midblock crosswalks.The study used observational survey data collected from fifteen flash-based signalized midblock crosswalks located in Las Vegas,Nevada.Three logistic regression models,with crosswalk-related features only,non-crosswalk features only,and combined features,were developed and compared.It was revealed that the performance difference between the model with crosswalk-related features only and combined features was insignificant.This study found that the presence of state’s law signs,“PED XING”signs,and placement of rectangular rapid flashing beacons(RRFBs)on the advanced pedestrians crossing signs(APCSs),are significant factors for high spatial yielding compliance.On the contrary,the yield line’s presence at a distance greater than 40 ft from the crosswalk,presence of one stage crossing,and high Annual Average Daily Traffic(AADT)negatively affects the spatial yielding compliance.Moreover,the findings suggest that researchers should be careful about excluding the non-crosswalk features from the analysis.To improve spatial yielding compliance,several recommendations that the city planners and engineers can adopt are provided.
文摘The increased number of data repositories has greatly increased the availability of open data.To enable broad discovery and access to research dataset,some data repositories have begun leveraging the web architecture by embedding structured metadata markup in dataset web landing pages using vocabularies from Schema.org and extensions.This paper aims to examine metadata interoperability for supporting global data discovery.Specifically,the paper reports a survey on which metadata schema has been adopted by participating data repositories,and presents an analysis of crosswalks from fourteen research data schemas to Schema.org.The analysis indicates most descriptive metadata are interoperable among the schemas,the most inconsistent mapping is the rights metadata,and a large gap exists in the structural metadata and controlled vocabularies to specify various property values.The analysis and collated crosswalks can serve as a reference for data repositories when they develop crosswalks from their own schemas to Schema.org,and provide the research data community a benchmark of structured metadata implementation.
基金supported by the National Natural Science Foundation of China under Grant Nos.71261016and 71401050the Program for New Century Excellent Talents in University under Grant No.NCET-12-1016+1 种基金the Natural Science Foundation of Inner Mongolia of China under Grant No.2014JQ03the Fundamental Research Funds for the Central Universities under Grant No.2013HGBZ0174
文摘Delays of both pedestrians,who are classified according to whether complying with traffic law,and vehicles at a signalized crosswalk are analyzed in this paper.The truncated Adams' model is applied to generate the probability and mean of delay of pedestrians non-complying with traffic law.Using the section-based traffic queuing-theory and the stochastic decomposition property of M/G/1vacation system with exhaustive service,the mean delay of vehicles is formulated.A multi-objective optimization model simultaneously minimizing the delays of pedestrians and vehicles during a signal period is proposed.The effects,which several model parameters have on the delays and the optimal solution of the model,are illustrated by numerical examples.
基金support for this study from Grant No.NCHRP-IDEA 209 under the Innovations Deserving Exploratory Analysis(IDEA)Program of the Transportation Research Board’s National Cooperative Highway Research Program.
文摘Like roadway information is to motor vehicle safety,pedestrian facility information(e.g.,sidewalk presence)is crucial towards improving the safety of these vulnerable road users.Yet unlike widely accessible roadway data,pedestrian facility data is unavailable for most state agencies.Without this information,data-driven problem identification,countermeasure analysis,project evaluation,and performance management will be heavily impeded.Thus,urgent need for this data was recognized by state departments of transportation(DOTs).To address this need,we developed an automated approach for the automated detection of crosswalks in satellite images.The most advanced deep learning methodology,transfer learning with a convolutional neural network(CNN)was used to handle realworld images.During the prediction process,a satellite image of a roadway pavement was analyzed by the satellite view model to predict the presence of a crosswalk.Then,the street view image of the same target was detected by the integrated street view model as a ground truth check.A total of 18361 images from Bing maps in satellite view and street view were used to train and test the deep learning model.As a result,the satellite view model itself achieved 98.43%accuracy using testing data from the same region.When dealing with data from another region,using the satellite view detection with ground truth checking increased the accuracy by 49%.It is obvious that by integrating the ground truth checking model into the satellite view crosswalk detection,we can obtain a more robust model which can handle highly occluded,low quality satellite images.
