Pub Date : 2024-08-06DOI: 10.1177/03611981241265844
Saed N. A. Aker, Hasan Ozer
Cold recycling technology has recently achieved significant success in highway maintenance and construction applications. In this study, the potential of incorporating emulsion-based cold recycled layers into airfield pavement design is explored. The permanent deformation resistance of cold recycled (CR) mixtures was characterized under various stress states and loading conditions to provide a realistic representation of the loads induced by aircraft tires on typical airfield pavement structures. Finite element modeling simulations of several airfield structures incorporating a CR layer were leveraged to derive the triaxial stress states induced by the moving load of various aircraft tires on the CR layer. A mix design was developed using a common approach. The simulated stress states were then projected and applied to the developed mix design in triaxial compression repeated load permanent deformation experiments. The influence of time and temperature dependence of the material on permanent deformation was also studied. The experiment highlighted the sensitivity of the mixture to tire pressure, surface layer thickness, vehicle speed, and temperature. The results indicate that the selection of cold recycling applications for airfield pavement should account for the unique site-specific conditions and the structural composition of the pavement where the CR layer will be incorporated. The evident viscoplastic characteristics in CR mixtures in the triaxial repeated load experiments highlighted the importance of considering them in the structural design of the CR layer.
{"title":"Cold Recycling Technology for Airfield Pavement Rehabilitation Practices","authors":"Saed N. A. Aker, Hasan Ozer","doi":"10.1177/03611981241265844","DOIUrl":"https://doi.org/10.1177/03611981241265844","url":null,"abstract":"Cold recycling technology has recently achieved significant success in highway maintenance and construction applications. In this study, the potential of incorporating emulsion-based cold recycled layers into airfield pavement design is explored. The permanent deformation resistance of cold recycled (CR) mixtures was characterized under various stress states and loading conditions to provide a realistic representation of the loads induced by aircraft tires on typical airfield pavement structures. Finite element modeling simulations of several airfield structures incorporating a CR layer were leveraged to derive the triaxial stress states induced by the moving load of various aircraft tires on the CR layer. A mix design was developed using a common approach. The simulated stress states were then projected and applied to the developed mix design in triaxial compression repeated load permanent deformation experiments. The influence of time and temperature dependence of the material on permanent deformation was also studied. The experiment highlighted the sensitivity of the mixture to tire pressure, surface layer thickness, vehicle speed, and temperature. The results indicate that the selection of cold recycling applications for airfield pavement should account for the unique site-specific conditions and the structural composition of the pavement where the CR layer will be incorporated. The evident viscoplastic characteristics in CR mixtures in the triaxial repeated load experiments highlighted the importance of considering them in the structural design of the CR layer.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"193 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933692","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 : 2024-08-06DOI: 10.1177/03611981241265845
Ayenew Yihune Demeke, Moein Younesi Heravi, Israt Sharmin Dola, Youjin Jang, Chau Le, Inbae Jeong, Zhibin Lin, Danling Wang
Highway work zones are critical areas where accidents frequently occur, often because of the proximity of workers to heavy machinery and ongoing traffic. With technological advancements in sensor technologies and the Internet of Things, promising solutions are emerging to address these safety concerns. This paper provides a systematic review of existing studies on the application of sensor technologies in enhancing highway work zone safety, particularly in preventing intrusion and proximity hazards. Following the PRISMA (preferred reporting items for systematic reviews and meta-analyses) protocol, the review examines a broad spectrum of publications on various sensor technologies, including GPS (global positioning system), radar, laser, infrared, radio-frequency identification, Bluetooth, ultrasonic, and infrared sensors, detailing their application in reducing intrusion and proximity incidents. The review also assesses these technologies in relation to their accuracy, range, power consumption, cost, and user-friendliness, with a specific emphasis on their suitability for highway work zones. The findings highlighted the potential of sensor technologies to significantly enhance work zone safety. As there are a wide range of sensor technologies to choose from, the review also revealed that the selection of sensors for a particular application needs careful consideration of pertinent factors. Finally, although sensor technologies offer promising solutions for enhancing highway work zone safety, their effective implementation requires comprehensive consideration of various factors beyond their technological capabilities, including developing integrated, cost-effective, user-friendly, and secure systems, and creating regulatory frameworks to support the rapid development of these technologies.
{"title":"Advancing Highway Work Zone Safety: A Comprehensive Review of Sensor Technologies for Intrusion and Proximity Hazards","authors":"Ayenew Yihune Demeke, Moein Younesi Heravi, Israt Sharmin Dola, Youjin Jang, Chau Le, Inbae Jeong, Zhibin Lin, Danling Wang","doi":"10.1177/03611981241265845","DOIUrl":"https://doi.org/10.1177/03611981241265845","url":null,"abstract":"Highway work zones are critical areas where accidents frequently occur, often because of the proximity of workers to heavy machinery and ongoing traffic. With technological advancements in sensor technologies and the Internet of Things, promising solutions are emerging to address these safety concerns. This paper provides a systematic review of existing studies on the application of sensor technologies in enhancing highway work zone safety, particularly in preventing intrusion and proximity hazards. Following the PRISMA (preferred reporting items for systematic reviews and meta-analyses) protocol, the review examines a broad spectrum of publications on various sensor technologies, including GPS (global positioning system), radar, laser, infrared, radio-frequency identification, Bluetooth, ultrasonic, and infrared sensors, detailing their application in reducing intrusion and proximity incidents. The review also assesses these technologies in relation to their accuracy, range, power consumption, cost, and user-friendliness, with a specific emphasis on their suitability for highway work zones. The findings highlighted the potential of sensor technologies to significantly enhance work zone safety. As there are a wide range of sensor technologies to choose from, the review also revealed that the selection of sensors for a particular application needs careful consideration of pertinent factors. Finally, although sensor technologies offer promising solutions for enhancing highway work zone safety, their effective implementation requires comprehensive consideration of various factors beyond their technological capabilities, including developing integrated, cost-effective, user-friendly, and secure systems, and creating regulatory frameworks to support the rapid development of these technologies.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933646","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 : 2024-08-05DOI: 10.1177/03611981241263809
Mitsuyoshi Fukushi, Felipe Delgado, Sebastián Raveau
Airport development is a critical factor for regional growth, improving connectivity, and stimulating economic growth. Considering the complexity of planning and policy making in this area, multiple models and frameworks have been introduced to support decision-making processes. Among these, Discrete Choice Models (DCM) stand out for their capacity to project market flows, assess the validity and benefits of implementing airport modifications, tailor policies, improve the operations’ service level, and boost revenues. Given their extensive use and importance, a thorough review of DCM applications within the context of air transportation is both timely and necessary. This review organizes and evaluates the use of DCMs in air transport research. Both descriptive and predictive applications of DCMs are analyzed, focusing on choices related to airports and related levels, such as access mode and airline decisions. Each reviewed study is classified based on the type of model used, application context, data characteristics, employed variables, and methodological contributions. Through this analysis, six prevailing gaps are identified in the current state of DCM application in air transportation: improve data quality, enhance models with detailed trip and passenger information, explore advanced modeling techniques, incorporate general correlation and substitution structures, consider non-compensatory decision-making processes, and extend applications to new geographic and temporal contexts.
{"title":"Discrete Choice Model Applications for Air Passenger Airport Choices: A Literature Review","authors":"Mitsuyoshi Fukushi, Felipe Delgado, Sebastián Raveau","doi":"10.1177/03611981241263809","DOIUrl":"https://doi.org/10.1177/03611981241263809","url":null,"abstract":"Airport development is a critical factor for regional growth, improving connectivity, and stimulating economic growth. Considering the complexity of planning and policy making in this area, multiple models and frameworks have been introduced to support decision-making processes. Among these, Discrete Choice Models (DCM) stand out for their capacity to project market flows, assess the validity and benefits of implementing airport modifications, tailor policies, improve the operations’ service level, and boost revenues. Given their extensive use and importance, a thorough review of DCM applications within the context of air transportation is both timely and necessary. This review organizes and evaluates the use of DCMs in air transport research. Both descriptive and predictive applications of DCMs are analyzed, focusing on choices related to airports and related levels, such as access mode and airline decisions. Each reviewed study is classified based on the type of model used, application context, data characteristics, employed variables, and methodological contributions. Through this analysis, six prevailing gaps are identified in the current state of DCM application in air transportation: improve data quality, enhance models with detailed trip and passenger information, explore advanced modeling techniques, incorporate general correlation and substitution structures, consider non-compensatory decision-making processes, and extend applications to new geographic and temporal contexts.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"307 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933634","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 : 2024-08-05DOI: 10.1177/03611981241265851
Daniel Niruban Subramaniam, Arulanantham Anburuvel
Pervious concrete (PC) is a structural element with environmental benefits. The industrial application is highly limited by restrictions in predicting performance owing to high uncertainties and issues in mass-producing with uniform characteristics. Primary performance indicators of PC are compressive strength, porosity, and permeability, where the porosity distribution and pore characteristics are crucial in its mechanical properties. Although compaction can improve uniformity in the properties of concrete, it is properly employed in PCs to ensure connectivity between pores and thereby enhance permeability. The compactability of fresh concrete predominantly depends on binder thickness dictated by aggregate-to-binder (A/B) ratio, water-to-binder (W/B) ratio, aggregate size, shape distribution of aggregates, and interfacial transition zone. In addition, the method of compaction, the compaction energy, and the distribution of compaction energy in the concrete matrix affect the above. The concrete compaction methods and their effectiveness vary between laboratory studies and field-scale installations. This state-of-the-art critical review of literature reviews the performance parameters of PC, compaction types and methods, compactability of PC, and models currently employed to optimize the mix design. It also highlights the potential trends for future studies to assist optimization of compaction in PC. The authors believe that this comprehensive review would assist professionals in developing a standard code of practice for using PC concrete.
透水混凝土（PC）是一种具有环境效益的结构元素。由于性能预测存在很大的不确定性，而且在大规模生产具有统一特性的产品时也存在问题，因此其工业应用受到很大限制。PC 的主要性能指标是抗压强度、孔隙率和渗透性，其中孔隙率分布和孔隙特征对其机械性能至关重要。虽然压实可以提高混凝土性能的均匀性，但在 PC 中适当使用压实可以确保孔隙之间的连通性，从而提高渗透性。新拌混凝土的压实度主要取决于粘结剂厚度，而粘结剂厚度又取决于骨料与粘结剂（A/B）比、水与粘结剂（W/B）比、骨料粒度、骨料形状分布和界面过渡区。此外，压实方法、压实能量以及压实能量在混凝土基体中的分布也会影响上述因素。无论是实验室研究还是现场安装，混凝土压实方法及其效果都不尽相同。这篇最新的文献评论回顾了 PC 的性能参数、压实类型和方法、PC 的密实性以及目前用于优化混合设计的模型。它还强调了未来研究的潜在趋势，以帮助优化 PC 的压实效果。作者认为，这篇全面的综述将有助于专业人士制定使用 PC 混凝土的标准操作规范。
{"title":"Performance Analysis Relevant to Primary Design Parameters of Pervious Concrete: A Critical Review","authors":"Daniel Niruban Subramaniam, Arulanantham Anburuvel","doi":"10.1177/03611981241265851","DOIUrl":"https://doi.org/10.1177/03611981241265851","url":null,"abstract":"Pervious concrete (PC) is a structural element with environmental benefits. The industrial application is highly limited by restrictions in predicting performance owing to high uncertainties and issues in mass-producing with uniform characteristics. Primary performance indicators of PC are compressive strength, porosity, and permeability, where the porosity distribution and pore characteristics are crucial in its mechanical properties. Although compaction can improve uniformity in the properties of concrete, it is properly employed in PCs to ensure connectivity between pores and thereby enhance permeability. The compactability of fresh concrete predominantly depends on binder thickness dictated by aggregate-to-binder (A/B) ratio, water-to-binder (W/B) ratio, aggregate size, shape distribution of aggregates, and interfacial transition zone. In addition, the method of compaction, the compaction energy, and the distribution of compaction energy in the concrete matrix affect the above. The concrete compaction methods and their effectiveness vary between laboratory studies and field-scale installations. This state-of-the-art critical review of literature reviews the performance parameters of PC, compaction types and methods, compactability of PC, and models currently employed to optimize the mix design. It also highlights the potential trends for future studies to assist optimization of compaction in PC. The authors believe that this comprehensive review would assist professionals in developing a standard code of practice for using PC concrete.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"130 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933635","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 : 2024-08-03DOI: 10.1177/03611981241266839
Shiguo Xiao, Tianyi Dai, Shaohong Li
A simplified analytical method is provided for the overall seismic and static stability of embankments supported with concrete piles in soft soil according to the pseudo-static approach. Mobilized shear forces on the piles intersected by the slip surface are involved in the proposed method. This method was originally established on four aspects: the circular slip surface assumption, pile bending–tension failure mechanism, simplified Bishop’s assumption, and elastic-beam-on-foundation model. The proposed method innovatively obtained the overall safety factor and critical slip surface of the piled-embankment system as well as the bending moment and shear force profiles of the piles. Moreover, it reproduced the progressive failure process of the system with the piles fracturing gradually. This method was verified by centrifugal tests and numerical simulations, and their safety factor relative errors were within 5%. Examples showed the safety factor decreased nonlinearly by 33% as the horizontal seismic coefficient increased from 0 to 0.2. The piles fractured progressively toward the interior of the system after the first one failed at the embankment toe. As the pile spacing in the two directions respectively increased from 3 to 5 times the pile diameter, the shear force of the critical pile at the slip surface increased slightly. Reinforcements in the embankment cushion may deepen the pile failure positions. This work provides a significant design reference for piled embankments under seismic conditions, including aspects such as overall stability, internal forces, and the progressive fracture of piles.
{"title":"Simplified Analysis Method of Seismic and Static Stability for Embankments Supported with Concrete Piles in Soft Ground","authors":"Shiguo Xiao, Tianyi Dai, Shaohong Li","doi":"10.1177/03611981241266839","DOIUrl":"https://doi.org/10.1177/03611981241266839","url":null,"abstract":"A simplified analytical method is provided for the overall seismic and static stability of embankments supported with concrete piles in soft soil according to the pseudo-static approach. Mobilized shear forces on the piles intersected by the slip surface are involved in the proposed method. This method was originally established on four aspects: the circular slip surface assumption, pile bending–tension failure mechanism, simplified Bishop’s assumption, and elastic-beam-on-foundation model. The proposed method innovatively obtained the overall safety factor and critical slip surface of the piled-embankment system as well as the bending moment and shear force profiles of the piles. Moreover, it reproduced the progressive failure process of the system with the piles fracturing gradually. This method was verified by centrifugal tests and numerical simulations, and their safety factor relative errors were within 5%. Examples showed the safety factor decreased nonlinearly by 33% as the horizontal seismic coefficient increased from 0 to 0.2. The piles fractured progressively toward the interior of the system after the first one failed at the embankment toe. As the pile spacing in the two directions respectively increased from 3 to 5 times the pile diameter, the shear force of the critical pile at the slip surface increased slightly. Reinforcements in the embankment cushion may deepen the pile failure positions. This work provides a significant design reference for piled embankments under seismic conditions, including aspects such as overall stability, internal forces, and the progressive fracture of piles.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933638","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 : 2024-08-03DOI: 10.1177/03611981241265690
Patrick Lou, Chan Yang, Hani Nassif
Truck load spectra based on weigh-in-motion (WIM) measurements have been utilized in developing site-specific live load models to predict the maximum load effects on bridges. Conventional load extrapolation has been utilized to develop the AASHTO load-and-resistance factor design (LRFD) Bridge Design Specifications, while few studies have evaluated the accuracy of the load extrapolation techniques with actual data. The current AASHTO Manual for Bridge Evaluation (MBE) utilizes the top 5% of the load effects to extrapolate the 5-year maximum load effects for load rating. However, in the cases of high truck volume, the predicted 5-year maximum load effects using AASHTO MBE are significantly lower than the observed value because of the selection of the upper tail. Therefore, the choice of the upper tail size needs further validation. This paper proposes a modification to the conventional live load extrapolation method. Firstly, more accurate maximum load values for different return periods are determined through simulation and validated using 7 years of continuous data. Then, the values from conventional live load extrapolations using different upper tail sizes are obtained and compared with the simulation values. The optimal upper tail size is determined when the minimum error is yielded. The findings suggest that using a specific number of trucks for the upper tail yields greater accuracy compared to a percentage-based approach. Specifically, the recommended range is between 3,000 to 5,000 trucks, with an optimal number of 3,600. This paper concludes with recommendations to the AASHTO MBE to enhance the accuracy of live load extrapolation.
{"title":"Prediction of Maximum Live-Load Effects for Bridges Based on Weigh-in-Motion Data","authors":"Patrick Lou, Chan Yang, Hani Nassif","doi":"10.1177/03611981241265690","DOIUrl":"https://doi.org/10.1177/03611981241265690","url":null,"abstract":"Truck load spectra based on weigh-in-motion (WIM) measurements have been utilized in developing site-specific live load models to predict the maximum load effects on bridges. Conventional load extrapolation has been utilized to develop the AASHTO load-and-resistance factor design (LRFD) Bridge Design Specifications, while few studies have evaluated the accuracy of the load extrapolation techniques with actual data. The current AASHTO Manual for Bridge Evaluation (MBE) utilizes the top 5% of the load effects to extrapolate the 5-year maximum load effects for load rating. However, in the cases of high truck volume, the predicted 5-year maximum load effects using AASHTO MBE are significantly lower than the observed value because of the selection of the upper tail. Therefore, the choice of the upper tail size needs further validation. This paper proposes a modification to the conventional live load extrapolation method. Firstly, more accurate maximum load values for different return periods are determined through simulation and validated using 7 years of continuous data. Then, the values from conventional live load extrapolations using different upper tail sizes are obtained and compared with the simulation values. The optimal upper tail size is determined when the minimum error is yielded. The findings suggest that using a specific number of trucks for the upper tail yields greater accuracy compared to a percentage-based approach. Specifically, the recommended range is between 3,000 to 5,000 trucks, with an optimal number of 3,600. This paper concludes with recommendations to the AASHTO MBE to enhance the accuracy of live load extrapolation.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"106 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933639","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 : 2024-08-03DOI: 10.1177/03611981241266840
Anton Galich, Carina Kehrt
Online shopping has gained popularity in many countries over the past two decades. As a result, the question of whether it reduces the overall transportation volume from fewer personal shopping trips or increases it because of more freight transportation, especially in the courier, express, and parcel segment, is a hot topic in transportation research. Yet few studies have applied a holistic approach to distinguishing online-shopping behavior with regard to different product categories, the distances traveled to purchase different products on physical shopping trips, the means of transportation used on these trips, and the freight transportation caused by online shopping. In addition, the outbreak of the COVID-19 pandemic in spring 2020 led to a dramatic increase in online shopping in many countries, with people trying to avoid physical shopping trips for health reasons. Against this background, this article attempts to clarify the net effects of online shopping on transportation volume both before and during the pandemic. For this purpose, two online surveys were conducted to capture online-shopping behavior and its effects on transportation before (2018) and during the pandemic (2021). The investigation area was Germany. The analysis showed that the pandemic generated more online shopping and more personal shopping trips. However, the overall mileage resulting from personal shopping trips, freight transportation, and pick-up and drop-off trips caused by online shopping remained relatively constant, as people traveled shorter distances during the pandemic.
{"title":"Assessing the Impacts of COVID-19 on Online-Shopping Behavior, the Resulting Delivery and Shipping Behavior of Private Households, and Freight Transportation: An Empirical Study of Germany","authors":"Anton Galich, Carina Kehrt","doi":"10.1177/03611981241266840","DOIUrl":"https://doi.org/10.1177/03611981241266840","url":null,"abstract":"Online shopping has gained popularity in many countries over the past two decades. As a result, the question of whether it reduces the overall transportation volume from fewer personal shopping trips or increases it because of more freight transportation, especially in the courier, express, and parcel segment, is a hot topic in transportation research. Yet few studies have applied a holistic approach to distinguishing online-shopping behavior with regard to different product categories, the distances traveled to purchase different products on physical shopping trips, the means of transportation used on these trips, and the freight transportation caused by online shopping. In addition, the outbreak of the COVID-19 pandemic in spring 2020 led to a dramatic increase in online shopping in many countries, with people trying to avoid physical shopping trips for health reasons. Against this background, this article attempts to clarify the net effects of online shopping on transportation volume both before and during the pandemic. For this purpose, two online surveys were conducted to capture online-shopping behavior and its effects on transportation before (2018) and during the pandemic (2021). The investigation area was Germany. The analysis showed that the pandemic generated more online shopping and more personal shopping trips. However, the overall mileage resulting from personal shopping trips, freight transportation, and pick-up and drop-off trips caused by online shopping remained relatively constant, as people traveled shorter distances during the pandemic.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"74 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141968787","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 : 2024-08-03DOI: 10.1177/03611981241260701
Emmanuel A. Marfo, Mubbashar A. Khan, Tau Wu, Tara L. Cavalline, Ali Karimoddini
It is critically important to plan properly for integrating and deploying unmanned aerial vehicles (UAVs) in the bridge inspection process, there is a need for tools to support implementation and decision-making regarding the use of UAVs at specific structures. In this study, a resource estimation tool that can be used to estimate the resources required for UAV-assisted bridge inspections is developed. The tool can aid inspectors in determining the estimated flight time and resources required for using a specific UAV and operator during the inspection of a specific bridge. The tool supports the development of optimal flight paths based on the structural geometry and positioning of structural elements of a bridge, establishes a range of recommended flight speeds for conducting reliable UAV-assisted bridge inspections based on the skill level(s) of the pilot(s) who were involved in conducting inspections. The developed tool also establishes a recommended range of wind speed and the corresponding standoff clearance information for safely conducting UAV-assisted bridge inspections. The tool also provides an estimated number of batteries required to allow the estimated required flight time. In this paper, the development of the tool is described, and the advantages of the tool are illustrated by its application in a case study involving a 10-span steel continuous multi-beam bridge with a reinforced concrete deck. The tool is developed as a spreadsheet and is publicly available through a GitHub page, accessible at https://github.com/ACCESSLab/Resource-Assessment-Tool-for-Effective-UAV-Assisted-Bridge-Inspection .
{"title":"Resource Assessment Tool for Effective Unmanned-Aerial-Vehicle-Assisted Bridge Inspections","authors":"Emmanuel A. Marfo, Mubbashar A. Khan, Tau Wu, Tara L. Cavalline, Ali Karimoddini","doi":"10.1177/03611981241260701","DOIUrl":"https://doi.org/10.1177/03611981241260701","url":null,"abstract":"It is critically important to plan properly for integrating and deploying unmanned aerial vehicles (UAVs) in the bridge inspection process, there is a need for tools to support implementation and decision-making regarding the use of UAVs at specific structures. In this study, a resource estimation tool that can be used to estimate the resources required for UAV-assisted bridge inspections is developed. The tool can aid inspectors in determining the estimated flight time and resources required for using a specific UAV and operator during the inspection of a specific bridge. The tool supports the development of optimal flight paths based on the structural geometry and positioning of structural elements of a bridge, establishes a range of recommended flight speeds for conducting reliable UAV-assisted bridge inspections based on the skill level(s) of the pilot(s) who were involved in conducting inspections. The developed tool also establishes a recommended range of wind speed and the corresponding standoff clearance information for safely conducting UAV-assisted bridge inspections. The tool also provides an estimated number of batteries required to allow the estimated required flight time. In this paper, the development of the tool is described, and the advantages of the tool are illustrated by its application in a case study involving a 10-span steel continuous multi-beam bridge with a reinforced concrete deck. The tool is developed as a spreadsheet and is publicly available through a GitHub page, accessible at https://github.com/ACCESSLab/Resource-Assessment-Tool-for-Effective-UAV-Assisted-Bridge-Inspection .","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933637","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}
Although several approaches exist for data imputation, these approaches are not commonly applied in transportation. The current paper is geared toward assisting transportation researchers and practitioners in developing models using datasets with missing data. The study begins with a data simulation exercise evaluating different solutions implemented for missing data. The dimensions considered in our analysis include: the nature of independent variables, different types of missing variables, different shares of missing values, multiple data sample sizes, and evaluation of single imputation (SI), multiple imputation (MI) and complete case data (CCD) approach. The comparison is conducted by adopting the appropriate inference process for the MI approach with multiple realizations. From the simulation exercise, we find that the MI approach consistently performs better than the SI approach. Among various realizations, the MI approach with five realizations is selected based on our results. The MI approach with five realizations is compared with the CCD approach under different conditions using model fit measures and parameter marginal effects. In the presence of a small share of missing data, for larger datasets, the results suggest that it might be beneficial to develop a CCD model by dropping observations with missing values as opposed to developing imputation models. However, when the share of missing data warrants variable exclusion, it is important and even necessary that the MI approach be employed for model development. In the second part of the paper, based on our findings, we implemented the MI approach for real empirical datasets with missing values for four discrete outcome variables.
虽然有几种数据估算方法，但这些方法在交通领域的应用并不普遍。本文旨在帮助交通研究人员和从业人员使用缺失数据集开发模型。研究从数据模拟练习开始，评估了针对缺失数据实施的不同解决方案。我们在分析中考虑的维度包括：自变量的性质、不同类型的缺失变量、不同份额的缺失值、多种数据样本大小，以及对单一估算 (SI)、多重估算 (MI) 和完整案例数据 (CCD) 方法的评估。通过采用适当的推理过程，对多重实现的 MI 方法进行比较。通过模拟练习，我们发现 MI 方法的性能始终优于 SI 方法。根据我们的结果，在各种实现方式中，我们选择了五种实现方式的 MI 方法。在不同条件下，我们使用模型拟合度量和参数边际效应对五次变现的 MI 方法和 CCD 方法进行了比较。结果表明，在缺失数据比例较小的情况下，对于较大的数据集，通过放弃缺失值观测值来建立 CCD 模型可能比建立估算模型更有利。然而，当缺失数据的比例需要排除变量时，采用 MI 方法来建立模型是重要的，甚至是必要的。在本文的第二部分，根据我们的研究结果，我们对四个离散结果变量缺失值的真实经验数据集实施了 MI 方法。
{"title":"Comparing the Performance of Different Missing Data Imputation Approaches in Discrete Outcome Modeling","authors":"Md Istiak Jahan, Tanmoy Bhowmik, Lauren Hoover, Naveen Eluru","doi":"10.1177/03611981241264278","DOIUrl":"https://doi.org/10.1177/03611981241264278","url":null,"abstract":"Although several approaches exist for data imputation, these approaches are not commonly applied in transportation. The current paper is geared toward assisting transportation researchers and practitioners in developing models using datasets with missing data. The study begins with a data simulation exercise evaluating different solutions implemented for missing data. The dimensions considered in our analysis include: the nature of independent variables, different types of missing variables, different shares of missing values, multiple data sample sizes, and evaluation of single imputation (SI), multiple imputation (MI) and complete case data (CCD) approach. The comparison is conducted by adopting the appropriate inference process for the MI approach with multiple realizations. From the simulation exercise, we find that the MI approach consistently performs better than the SI approach. Among various realizations, the MI approach with five realizations is selected based on our results. The MI approach with five realizations is compared with the CCD approach under different conditions using model fit measures and parameter marginal effects. In the presence of a small share of missing data, for larger datasets, the results suggest that it might be beneficial to develop a CCD model by dropping observations with missing values as opposed to developing imputation models. However, when the share of missing data warrants variable exclusion, it is important and even necessary that the MI approach be employed for model development. In the second part of the paper, based on our findings, we implemented the MI approach for real empirical datasets with missing values for four discrete outcome variables.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933641","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 : 2024-08-03DOI: 10.1177/03611981241265850
Xiao Chen, Hao Wang
Sea level rise (SLR) caused by climate change has posed great challenges to coastal infrastructure. It is important for airport agencies to take SLR impact into account for resilient pavement design and maintenance. This study aims to develop a methodological framework to evaluate the impact of SLR on airfield pavement considering three different SLR-induced hazards, namely extreme precipitation, flooding, and groundwater rise. For each hazard, moisture variations in unbound materials of the airfield pavement were first analyzed using hydraulic models. The floodwater can flow to the area beneath the aircraft loading position via both the unpaved zone and surface cracks. Based on the moisture-dependent modulus, critical pavement responses under aircraft loading were then calculated using mechanical models. Finally, cumulative damage factors caused by each hazard were calculated using existing airfield pavement failure models to quantify the damage caused by SLR. The results show that extreme precipitation causes little damage to the structural life of airfield pavement, while groundwater level rise can cause 29% damage to pavement subgrade when the subbase was immersed. The impact of flooding on subgrade is much more remarkable than that on the asphalt layer, with the damage changing from 25% to 50% depending on the recovery process.
{"title":"Impact of Sea Level Rise-Induced Hazards on Airfield Pavement Performance: A Simulation Study","authors":"Xiao Chen, Hao Wang","doi":"10.1177/03611981241265850","DOIUrl":"https://doi.org/10.1177/03611981241265850","url":null,"abstract":"Sea level rise (SLR) caused by climate change has posed great challenges to coastal infrastructure. It is important for airport agencies to take SLR impact into account for resilient pavement design and maintenance. This study aims to develop a methodological framework to evaluate the impact of SLR on airfield pavement considering three different SLR-induced hazards, namely extreme precipitation, flooding, and groundwater rise. For each hazard, moisture variations in unbound materials of the airfield pavement were first analyzed using hydraulic models. The floodwater can flow to the area beneath the aircraft loading position via both the unpaved zone and surface cracks. Based on the moisture-dependent modulus, critical pavement responses under aircraft loading were then calculated using mechanical models. Finally, cumulative damage factors caused by each hazard were calculated using existing airfield pavement failure models to quantify the damage caused by SLR. The results show that extreme precipitation causes little damage to the structural life of airfield pavement, while groundwater level rise can cause 29% damage to pavement subgrade when the subbase was immersed. The impact of flooding on subgrade is much more remarkable than that on the asphalt layer, with the damage changing from 25% to 50% depending on the recovery process.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"57 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933642","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}
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