Pub Date : 2023-11-01DOI: 10.1061/jtepbs.teeng-7875
Pinlong Cai, Guangquan Lu
{"title":"Trajectory Guidance for Connected Human-Driving Vehicles through the Interactions between Drivers and Roadside Units","authors":"Pinlong Cai, Guangquan Lu","doi":"10.1061/jtepbs.teeng-7875","DOIUrl":"https://doi.org/10.1061/jtepbs.teeng-7875","url":null,"abstract":"","PeriodicalId":49972,"journal":{"name":"Journal of Transportation Engineering","volume":"12 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134956804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.1061/jtepbs.teeng-7903
Yuyan “Annie” Pan, Han Zheng, Jifu Guo, Yanyan Chen
Traffic congestion occurs when there is a mismatch between the demand for road use and the available capacity. The volume-delay function (VDF) can quantify the relationship between travel time and the volume of traffic on a particular link, and also provide insight into the state of a traffic system, such as whether it is congested or uncongested. In this paper, we present a VDF model that is based on the fundamental diagram and has two main components: (1) an improved VDF with fewer parameters that can handle both congested and uncongested traffic conditions, based on a fundamental diagram, and (2) a model-based VDF practical calibration framework for practical traffic applications that can determine key parameters for a link in a corridor. Our experiments using corridors in Los Angeles and Beijing demonstrate that our proposed analytical methods effectively calculate road impedance under congested conditions. The results indicate that the proposed model is superior to other existing models in terms of the root mean squared error (RMSE) and mean absolute error (MAE). In addition, our calibrated results indicate that the travel time index (TTI) in Los Angeles is 2.12, in Beijing is 1.74. The model proposed in this paper provides a useful calibration tool for enhancing model performance and improving the accuracy of travel time and speed estimates in traffic assignment.
{"title":"Modified Volume-Delay Function Based on Traffic Fundamental Diagram: A Practical Calibration Framework for Estimating Congested and Uncongested Conditions","authors":"Yuyan “Annie” Pan, Han Zheng, Jifu Guo, Yanyan Chen","doi":"10.1061/jtepbs.teeng-7903","DOIUrl":"https://doi.org/10.1061/jtepbs.teeng-7903","url":null,"abstract":"Traffic congestion occurs when there is a mismatch between the demand for road use and the available capacity. The volume-delay function (VDF) can quantify the relationship between travel time and the volume of traffic on a particular link, and also provide insight into the state of a traffic system, such as whether it is congested or uncongested. In this paper, we present a VDF model that is based on the fundamental diagram and has two main components: (1) an improved VDF with fewer parameters that can handle both congested and uncongested traffic conditions, based on a fundamental diagram, and (2) a model-based VDF practical calibration framework for practical traffic applications that can determine key parameters for a link in a corridor. Our experiments using corridors in Los Angeles and Beijing demonstrate that our proposed analytical methods effectively calculate road impedance under congested conditions. The results indicate that the proposed model is superior to other existing models in terms of the root mean squared error (RMSE) and mean absolute error (MAE). In addition, our calibrated results indicate that the travel time index (TTI) in Los Angeles is 2.12, in Beijing is 1.74. The model proposed in this paper provides a useful calibration tool for enhancing model performance and improving the accuracy of travel time and speed estimates in traffic assignment.","PeriodicalId":49972,"journal":{"name":"Journal of Transportation Engineering","volume":"105 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136102566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The information exchange among vehicles and road infrastructure with wide sensing range can be accomplished by roadside units (RSUs). Communication delays occur and are influenced by different approaches of deployment of RSUs, which increases the complexity of vehicle automatic control in a mixed traffic flow. Therefore, a speed control strategy was proposed for mixed traffic flow considering RSU deployment distance, interaction radius, and communication delay, aimed at enhancing traffic safety and efficiency. The characteristics of RSU deployment were modeled as functions, where an adaptive efficiency function was proposed to evaluate different RSU deployment plans. An improved speed control model was then developed based on the characteristics of the RSU in the mixed traffic flow. In addition, numerical analysis and simulation were carried out to evaluate vehicle stability and traffic throughput based on the improved speed control model. The analysis results show that the proposed model is stable under different updating frequencies, with the best stability achieved when the velocity update frequency is 500 and the velocity update time interval is 0.01 s. Moreover, it was found that the spatial occupancy rate increases with the increment of penetration rate of autonomous vehicles, which improves the rate by at least 20% compared to the no-control scenario. Additionally, the average speed is also increased by 30% while under the influence of communication delays. This paper investigated the relationship between characteristics of RSUs and traffic performances, which is essential for DOTs to develop an effective RSU plan to adapt to the mixed traffic flow.
{"title":"Improved Speed Control Strategy for Mixed Traffic Flow Considering Roadside Unit","authors":"Wei Hao, Donglei Rong, Zhaolei Zhang, Young-Ji Byon, Daxin Tian","doi":"10.1061/jtepbs.teeng-7428","DOIUrl":"https://doi.org/10.1061/jtepbs.teeng-7428","url":null,"abstract":"The information exchange among vehicles and road infrastructure with wide sensing range can be accomplished by roadside units (RSUs). Communication delays occur and are influenced by different approaches of deployment of RSUs, which increases the complexity of vehicle automatic control in a mixed traffic flow. Therefore, a speed control strategy was proposed for mixed traffic flow considering RSU deployment distance, interaction radius, and communication delay, aimed at enhancing traffic safety and efficiency. The characteristics of RSU deployment were modeled as functions, where an adaptive efficiency function was proposed to evaluate different RSU deployment plans. An improved speed control model was then developed based on the characteristics of the RSU in the mixed traffic flow. In addition, numerical analysis and simulation were carried out to evaluate vehicle stability and traffic throughput based on the improved speed control model. The analysis results show that the proposed model is stable under different updating frequencies, with the best stability achieved when the velocity update frequency is 500 and the velocity update time interval is 0.01 s. Moreover, it was found that the spatial occupancy rate increases with the increment of penetration rate of autonomous vehicles, which improves the rate by at least 20% compared to the no-control scenario. Additionally, the average speed is also increased by 30% while under the influence of communication delays. This paper investigated the relationship between characteristics of RSUs and traffic performances, which is essential for DOTs to develop an effective RSU plan to adapt to the mixed traffic flow.","PeriodicalId":49972,"journal":{"name":"Journal of Transportation Engineering","volume":"297 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134957089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.1061/jtepbs.teeng-8017
Jinqu Chen, Xiaowei Liu, Bo Du, Wenxin Li, Yong Yin, Xinyue Xu
In daily operation, urban rail transit (URT) systems often experience disturbances that result in a partial reduction in transport capacity [partial disturbances (PDs)] rather than disturbances leading to a complete reduction in transport capacity. However, research that assesses the resilience of URT networks under PDs remains limited. This paper addresses this gap by proposing a passenger-oriented resilience assessment model for URT networks under PDs, considering the travel behaviors of passengers and different relations (i.e., linear, concave, and convex) between the velocity coefficient and failure severity. A simulation-based assessment approach was developed to solve the resilience assessment model. A numerical experiment was conducted on the Chengdu subway network in China. The results demonstrate that the performance indicator employed herein reflects the impact of passenger travel time distribution on network performance. Deliberate PDs cause more significant performance losses than random PDs. Moreover, the network is the least resilient under PDs considering the convex relation between the velocity coefficient and failure severity. The resilience-based critical link of each line is not fixed and varies with the failure severity and disturbance occurrence time. Increasing the failure severity of PDs results in more severe performance losses than increasing the number of PDs. Additionally, the passenger-oriented resilience of a URT network can be enhanced by improving the passengers’ tolerable delay time and disturbance duration.
{"title":"Passenger-Oriented Resilience Assessment of an Urban Rail Transit Network under Partial Disturbances","authors":"Jinqu Chen, Xiaowei Liu, Bo Du, Wenxin Li, Yong Yin, Xinyue Xu","doi":"10.1061/jtepbs.teeng-8017","DOIUrl":"https://doi.org/10.1061/jtepbs.teeng-8017","url":null,"abstract":"In daily operation, urban rail transit (URT) systems often experience disturbances that result in a partial reduction in transport capacity [partial disturbances (PDs)] rather than disturbances leading to a complete reduction in transport capacity. However, research that assesses the resilience of URT networks under PDs remains limited. This paper addresses this gap by proposing a passenger-oriented resilience assessment model for URT networks under PDs, considering the travel behaviors of passengers and different relations (i.e., linear, concave, and convex) between the velocity coefficient and failure severity. A simulation-based assessment approach was developed to solve the resilience assessment model. A numerical experiment was conducted on the Chengdu subway network in China. The results demonstrate that the performance indicator employed herein reflects the impact of passenger travel time distribution on network performance. Deliberate PDs cause more significant performance losses than random PDs. Moreover, the network is the least resilient under PDs considering the convex relation between the velocity coefficient and failure severity. The resilience-based critical link of each line is not fixed and varies with the failure severity and disturbance occurrence time. Increasing the failure severity of PDs results in more severe performance losses than increasing the number of PDs. Additionally, the passenger-oriented resilience of a URT network can be enhanced by improving the passengers’ tolerable delay time and disturbance duration.","PeriodicalId":49972,"journal":{"name":"Journal of Transportation Engineering","volume":"80 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134957399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.1061/jtepbs.teeng-7870
Yu Sun, Erik Jenelius, Wilco Burghout, Binglei Xie
The introduction of automated vehicles (AVs) is commonly expected to improve different aspects of transportation. A long transition period in which AVs will coexist with human-driven vehicles (HVs) is expected until AVs become prevalent. Dedicated lane strategy is considered an effective way to improve road capacity and promote AV use. However, there is a lack of comprehensive research on when and how to implement lane management strategies, and further verification is needed to determine to what extent lane management strategies will affect traffic flow. The dedicated lane strategy will first be applied in highway scenarios, and the merging area is an important zone prone to congestion on highways. There are many impacts of AV on the merging area of highways, but research on the issue that the traffic flow is continually affected after the completion of merging is still lacking. Therefore, this study establishes a lane control strategies framework to investigate the effect on road capacity on the multilane freeway after the merging area. This paper explores the traffic performance of three different lane control strategies with mixed AV/HV traffic flow and investigate when the tested strategies make sense and how sensitive they are to varying AV rates and demands. Specifically, using the open-source microscopic traffic simulation tool SUMO, this study investigates the impacts on traffic performance in terms of throughput, travel time and space mean speed on two-lane motorways at increasing penetration rates of AVs. Moreover, three different lane control strategies (two mixed lanes, one reserved AV lane, and one reserved HV lane) are compared under various demand and AV rates. The simulation results demonstrate that road capacity increases convexly with AV rates. In addition, the results show that the capacity on a one-way two-lane motorway road can be improved with appropriate lane control strategies, especially under high demand and at low to medium AV rates.Practical ApplicationsThe simulation experiments are described in this study, in which a SUMO-based study is designed to evaluate the different capacities for pure HV or AV traffic, and different lane control strategies under different AV rates and traffic demands, together with the results and the traffic performance in terms of changes in capacity, by measuring throughput. We first evaluate the traffic performance of three different lane control strategies with mixed AV/HV traffic flow and investigate when the tested strategies make sense and how sensitive they are to varying AV rates and demands. According to the results, lane strategy can improve traffic capacity. Based on the giving quantized extent of the capacity improvement, the authorities can make decisions on when and how to deploy to dedicated lanes systematically. Lane strategies can significantly improve traffic performance; it should be deployed first on highways, as there is less interference, especially in merging areas, wh
{"title":"Evaluation of Motorway Lane Control Strategies for Mixed Flow of Autonomous and Human-Driven Vehicles","authors":"Yu Sun, Erik Jenelius, Wilco Burghout, Binglei Xie","doi":"10.1061/jtepbs.teeng-7870","DOIUrl":"https://doi.org/10.1061/jtepbs.teeng-7870","url":null,"abstract":"The introduction of automated vehicles (AVs) is commonly expected to improve different aspects of transportation. A long transition period in which AVs will coexist with human-driven vehicles (HVs) is expected until AVs become prevalent. Dedicated lane strategy is considered an effective way to improve road capacity and promote AV use. However, there is a lack of comprehensive research on when and how to implement lane management strategies, and further verification is needed to determine to what extent lane management strategies will affect traffic flow. The dedicated lane strategy will first be applied in highway scenarios, and the merging area is an important zone prone to congestion on highways. There are many impacts of AV on the merging area of highways, but research on the issue that the traffic flow is continually affected after the completion of merging is still lacking. Therefore, this study establishes a lane control strategies framework to investigate the effect on road capacity on the multilane freeway after the merging area. This paper explores the traffic performance of three different lane control strategies with mixed AV/HV traffic flow and investigate when the tested strategies make sense and how sensitive they are to varying AV rates and demands. Specifically, using the open-source microscopic traffic simulation tool SUMO, this study investigates the impacts on traffic performance in terms of throughput, travel time and space mean speed on two-lane motorways at increasing penetration rates of AVs. Moreover, three different lane control strategies (two mixed lanes, one reserved AV lane, and one reserved HV lane) are compared under various demand and AV rates. The simulation results demonstrate that road capacity increases convexly with AV rates. In addition, the results show that the capacity on a one-way two-lane motorway road can be improved with appropriate lane control strategies, especially under high demand and at low to medium AV rates.Practical ApplicationsThe simulation experiments are described in this study, in which a SUMO-based study is designed to evaluate the different capacities for pure HV or AV traffic, and different lane control strategies under different AV rates and traffic demands, together with the results and the traffic performance in terms of changes in capacity, by measuring throughput. We first evaluate the traffic performance of three different lane control strategies with mixed AV/HV traffic flow and investigate when the tested strategies make sense and how sensitive they are to varying AV rates and demands. According to the results, lane strategy can improve traffic capacity. Based on the giving quantized extent of the capacity improvement, the authorities can make decisions on when and how to deploy to dedicated lanes systematically. Lane strategies can significantly improve traffic performance; it should be deployed first on highways, as there is less interference, especially in merging areas, wh","PeriodicalId":49972,"journal":{"name":"Journal of Transportation Engineering","volume":"281 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134903018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.1061/jtepbs.teeng-7838
Yiqi Hou, Min Yang, Lichao Wang, Mingye Zhang, Da Lei
Demand-responsive feeder transit (DRFT) is an emerging urban public transport mode with the advantage of offering flexible door-to-door services in the high-speed railway hub area. However, the existing bus scheduling schemes can hardly meet personalized and diversified passenger transfer demands in the station-city integrated high-speed railway hub, reducing the attractiveness of DRFT. This paper studies the DRFT scheduling problem considering static and dynamic travel demands under the background of mobility as a service (MaaS). An information-based DRFT system framework is proposed, where the K-means clustering algorithm is implemented to select target bus stops from regional road networks for passengers to get on and off. A two-stage mixed integer programming model is first formulated to generate operational routes and optimize the static and dynamic scheduling before and after departure. The objective functions reflect the operating benefits of public transport enterprises and the travel costs of passengers, and the demand characteristics in different driving directions are taken into account in the model. Then, an improved genetic algorithm is developed to solve the model, which is called the genetic algorithm-exact algorithm (GA-EA) in this paper. Finally, the proposed model and algorithm are evaluated using the case study of the Nanjingnan Railway Station area. The experiment results show that the optimal scheme can provide a 100% demand-response rate, reasonable service time, and valid driving routes. In addition, compared with GA, the average search time of GA-EA is shortened by 43.5% and the total objective function value is increased by 2.16%. The findings in this paper can provide practical guidance on DRFT scheduling and improve the efficiency of bus feeder service.
{"title":"Static and Dynamic Scheduling Method of Demand-Responsive Feeder Transit for High-Speed Railway Hub Area","authors":"Yiqi Hou, Min Yang, Lichao Wang, Mingye Zhang, Da Lei","doi":"10.1061/jtepbs.teeng-7838","DOIUrl":"https://doi.org/10.1061/jtepbs.teeng-7838","url":null,"abstract":"Demand-responsive feeder transit (DRFT) is an emerging urban public transport mode with the advantage of offering flexible door-to-door services in the high-speed railway hub area. However, the existing bus scheduling schemes can hardly meet personalized and diversified passenger transfer demands in the station-city integrated high-speed railway hub, reducing the attractiveness of DRFT. This paper studies the DRFT scheduling problem considering static and dynamic travel demands under the background of mobility as a service (MaaS). An information-based DRFT system framework is proposed, where the K-means clustering algorithm is implemented to select target bus stops from regional road networks for passengers to get on and off. A two-stage mixed integer programming model is first formulated to generate operational routes and optimize the static and dynamic scheduling before and after departure. The objective functions reflect the operating benefits of public transport enterprises and the travel costs of passengers, and the demand characteristics in different driving directions are taken into account in the model. Then, an improved genetic algorithm is developed to solve the model, which is called the genetic algorithm-exact algorithm (GA-EA) in this paper. Finally, the proposed model and algorithm are evaluated using the case study of the Nanjingnan Railway Station area. The experiment results show that the optimal scheme can provide a 100% demand-response rate, reasonable service time, and valid driving routes. In addition, compared with GA, the average search time of GA-EA is shortened by 43.5% and the total objective function value is increased by 2.16%. The findings in this paper can provide practical guidance on DRFT scheduling and improve the efficiency of bus feeder service.","PeriodicalId":49972,"journal":{"name":"Journal of Transportation Engineering","volume":"187 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134957119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1061/jpeodx.pveng-1291
Pranav R. T. Peddinti, Harish Puppala, Byungmin Kim
Pavement monitoring involves periodic damage detection and condition assessment of pavements for efficient pavement management. Unmanned aerial vehicle (UAV)-based pavement monitoring requires multidisciplinary knowledge of pavement distress, drone type, payload, flight parameters, drone deployment, and image processing. Owing to the availability of various UAVs, data sensing devices, operating ecosystems, and post-processing tools, selecting an appropriate combination of these systems is crucial. Therefore, the primary objective of this study is to provide essential knowledge on the prevalent challenges of existing monitoring techniques and discuss the potential advantages of UAVs over conventional pavement monitoring practice. A state-of-the-art review emphasizing UAV technicalities in the context of image-based pavement monitoring is presented. A detailed workflow and checklist for drone deployment is drafted for novice users to ensure safe and high-quality data acquisition. Finally, the present challenges and future scope of UAV-based pavement monitoring is discussed. Overall, this study aims to provide inclusive and comprehensive information on UAV-based pavement monitoring to beginner researchers.
{"title":"Pavement Monitoring Using Unmanned Aerial Vehicles: An Overview","authors":"Pranav R. T. Peddinti, Harish Puppala, Byungmin Kim","doi":"10.1061/jpeodx.pveng-1291","DOIUrl":"https://doi.org/10.1061/jpeodx.pveng-1291","url":null,"abstract":"Pavement monitoring involves periodic damage detection and condition assessment of pavements for efficient pavement management. Unmanned aerial vehicle (UAV)-based pavement monitoring requires multidisciplinary knowledge of pavement distress, drone type, payload, flight parameters, drone deployment, and image processing. Owing to the availability of various UAVs, data sensing devices, operating ecosystems, and post-processing tools, selecting an appropriate combination of these systems is crucial. Therefore, the primary objective of this study is to provide essential knowledge on the prevalent challenges of existing monitoring techniques and discuss the potential advantages of UAVs over conventional pavement monitoring practice. A state-of-the-art review emphasizing UAV technicalities in the context of image-based pavement monitoring is presented. A detailed workflow and checklist for drone deployment is drafted for novice users to ensure safe and high-quality data acquisition. Finally, the present challenges and future scope of UAV-based pavement monitoring is discussed. Overall, this study aims to provide inclusive and comprehensive information on UAV-based pavement monitoring to beginner researchers.","PeriodicalId":49972,"journal":{"name":"Journal of Transportation Engineering","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136033768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1061/jtepbs.teeng-7803
Henry P. Sawaki, John H. Kodi, Angela E. Kitali, Emmanuel Kidando, Geophrey Mbatta
Pedestrian safety is a critical societal concern, especially in low-income countries, as pedestrian crashes increase worldwide. Among other road users, pedestrians are most vulnerable to severe injury and mortality in traffic crashes. Several studies have examined factors associated with the severity of pedestrian crashes in developed countries. However, there are limited comprehensive studies on pedestrian safety in low-income countries. Therefore, this study explored factors influencing the severity of pedestrian crashes in Dar es Salaam, Tanzania, using a Bayesian logit model. The analysis involved 1,711 pedestrian crashes collected manually from the police logbook from 2015 through 2021. The results showed that young pedestrians (35 years and younger) are likely to sustain fatal injuries when involved in a crash. A higher fatality risk was also observed for pedestrian–vehicle crashes that occurred during winter and on streets. Crashes occurring at locations with wider medians and involving older pedestrians (55+) had a lower probability of a fatality. Identifying these risk factors for pedestrians provides valuable inputs that will assist with developing a comprehensive pedestrian safety action plan.
{"title":"Analyzing Pedestrian Fatality Risk in a Developing Country: Empirical Assessment with Insights from Dar es Salaam, Tanzania","authors":"Henry P. Sawaki, John H. Kodi, Angela E. Kitali, Emmanuel Kidando, Geophrey Mbatta","doi":"10.1061/jtepbs.teeng-7803","DOIUrl":"https://doi.org/10.1061/jtepbs.teeng-7803","url":null,"abstract":"Pedestrian safety is a critical societal concern, especially in low-income countries, as pedestrian crashes increase worldwide. Among other road users, pedestrians are most vulnerable to severe injury and mortality in traffic crashes. Several studies have examined factors associated with the severity of pedestrian crashes in developed countries. However, there are limited comprehensive studies on pedestrian safety in low-income countries. Therefore, this study explored factors influencing the severity of pedestrian crashes in Dar es Salaam, Tanzania, using a Bayesian logit model. The analysis involved 1,711 pedestrian crashes collected manually from the police logbook from 2015 through 2021. The results showed that young pedestrians (35 years and younger) are likely to sustain fatal injuries when involved in a crash. A higher fatality risk was also observed for pedestrian–vehicle crashes that occurred during winter and on streets. Crashes occurring at locations with wider medians and involving older pedestrians (55+) had a lower probability of a fatality. Identifying these risk factors for pedestrians provides valuable inputs that will assist with developing a comprehensive pedestrian safety action plan.","PeriodicalId":49972,"journal":{"name":"Journal of Transportation Engineering","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136117158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-01DOI: 10.1061/jtepbs.teeng-7776
Md Mintu Miah, Stephen P. Mattingly, Kate Kyung Hyun
The quality of the bicycle network determines ridership, safety, connectivity, equity, and livability. Very few former research studies investigated network connectivity for individual user types and identify network needs and barriers based on these rider types. This study measures the network connectivity for different rider types using level of traffic stress (LTS) and graph theory concepts. As a symbolic representation of a road network and its connectivity, a graph represents the structural properties of networks and compares one measure over another by taking into account spatial features. In addition, this study defines a bicycle network for different types of riders using LTS metrics based on traffic speed, road geometry, and traffic volume. This study evaluates the OpenStreetMap (OSM) bicycle network for Portland, Oregon, as a case study. Three transit stations in the downtown, riverside, and residential area were considered to assess the connectivity and barriers with a home at block level for last and first-mile coverage. The analysis shows that 29% of links in Portland need to be improved with more bicycle facilities to provide access to basic adult riders, and 33% of links require improvement for children. The networks are well connected for “strong and fearless” and “confident and enthused” users but not well connected for basic adults and children in many neighborhoods with low alpha and grid tree pattern (GTP) indices. The results indicate that planners and designers need to improve their network connectivity for all types of users to ensure equal active transportation opportunities beyond a particular portion of the network.Practical ApplicationsIn general, a well-connected network is important to provide the shortest route from origin to destination and safe traveling paths for all ages of people. It is critical for cities or government agencies to understand how their network is connected to different users because this knowledge will provide a fundamental basis for resource prioritizations on bicycle network improvement. This study developed a strategy using traffic stress and geometric properties of the network to assess their network connectivity. Practitioners can apply these techniques on a small scale (e.g., around transit stations) as well as large scale (e.g., entire city network) to identify the network connectivity. This study extends the applications to evaluate transportation equity in bicycle networks using served/ unserved populations where disparities in network connectivity exist to favor higher-income people.
{"title":"Evaluation of Bicycle Network Connectivity Using Graph Theory and Level of Traffic Stress","authors":"Md Mintu Miah, Stephen P. Mattingly, Kate Kyung Hyun","doi":"10.1061/jtepbs.teeng-7776","DOIUrl":"https://doi.org/10.1061/jtepbs.teeng-7776","url":null,"abstract":"The quality of the bicycle network determines ridership, safety, connectivity, equity, and livability. Very few former research studies investigated network connectivity for individual user types and identify network needs and barriers based on these rider types. This study measures the network connectivity for different rider types using level of traffic stress (LTS) and graph theory concepts. As a symbolic representation of a road network and its connectivity, a graph represents the structural properties of networks and compares one measure over another by taking into account spatial features. In addition, this study defines a bicycle network for different types of riders using LTS metrics based on traffic speed, road geometry, and traffic volume. This study evaluates the OpenStreetMap (OSM) bicycle network for Portland, Oregon, as a case study. Three transit stations in the downtown, riverside, and residential area were considered to assess the connectivity and barriers with a home at block level for last and first-mile coverage. The analysis shows that 29% of links in Portland need to be improved with more bicycle facilities to provide access to basic adult riders, and 33% of links require improvement for children. The networks are well connected for “strong and fearless” and “confident and enthused” users but not well connected for basic adults and children in many neighborhoods with low alpha and grid tree pattern (GTP) indices. The results indicate that planners and designers need to improve their network connectivity for all types of users to ensure equal active transportation opportunities beyond a particular portion of the network.Practical ApplicationsIn general, a well-connected network is important to provide the shortest route from origin to destination and safe traveling paths for all ages of people. It is critical for cities or government agencies to understand how their network is connected to different users because this knowledge will provide a fundamental basis for resource prioritizations on bicycle network improvement. This study developed a strategy using traffic stress and geometric properties of the network to assess their network connectivity. Practitioners can apply these techniques on a small scale (e.g., around transit stations) as well as large scale (e.g., entire city network) to identify the network connectivity. This study extends the applications to evaluate transportation equity in bicycle networks using served/ unserved populations where disparities in network connectivity exist to favor higher-income people.","PeriodicalId":49972,"journal":{"name":"Journal of Transportation Engineering","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136117157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-01DOI: 10.1061/jpeodx.pveng-1153
Albert M. Hung, Mingxia Li, Guoxiong Wu, Elham H. Fini
This paper studies the merits of applying liquified polyethylene (PE) as a modifier for bitumen. Chemical recycling of PE is often incomplete and generates some amount of waste “PE oil”. The viscoelasticity and chemical characteristics of bitumen modified with PE oil were examined using dynamic shear rheometry, infrared spectroscopy, and adhesion measurements in comparison and in conjunction with bitumen modified with wax, which is one of the most common additives in warm-mix bitumen. The study found that PE oil softens bitumen without severely increasing the creep compliance or viscoelastic damping properties. Wax-modified bitumen showed enrichment of crystallized alkanes at the free bitumen surface that negatively impacted adhesion and interface healing. The introduction of PE oil to wax-modified bitumen did not appreciably decrease the fraction of crystallized wax. Thus, PE oil may not be effective as an additive for warm-mix wax-modified bitumen. However, the PE oil showed potential in protecting bitumen against ultraviolet (UV) aging, and it is worth further exploration as an anti-aging agent, or as a rejuvenator for reclaimed asphalt pavement. The outcomes of this study promote plastic recycling by presenting the merits of applications of liquefied waste PE in the design and engineering of bituminous composites.
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