As the era of autonomous vehicles (AVs) approaches, understanding how passengers’ time use during a trip may change from a traditional vehicle (non-AV) to an AV is important to the adoption and use of AVs. In this study, a latent class analysis (LCA) as well as a latent transition analysis (LTA) are adopted to investigate the choice of travel activities of individuals as passengers in a traditional vehicle, such as a car or transit, and the anticipated shift in these activities in an AV. Since individuals may perform different activities during different trip purposes, activity choices and non-AV to AV transition dynamics are explored from two different perspectives: commute trips (e.g., to work or school) and non-commute trips (e.g., leisure, errands, or medical). Findings from the LCA models show three distinct groups of individuals with varying activity preferences in a traditional vehicle and four distinct groups that could emerge in an AV. AV users exhibited a higher preference for activities such as texting/browsing social media, relaxing, and working, suggesting that AVs may offer passengers a more productive use of their travel time. Furthermore, the LTA model shows that there is a good portion of individuals who were performing one or two activities in a traditional vehicle now becoming variety seekers that could perform at least four different activities in an AV, further corroborating the findings that AVs could provide a more productive and efficient use of travel time.
随着自动驾驶汽车（AVs）时代的到来，了解乘客在出行过程中的时间使用如何从传统车辆（非自动驾驶汽车）向自动驾驶汽车转变，对于自动驾驶汽车的采用和使用非常重要。本研究采用潜类分析法（LCA）和潜转移分析法（LTA），研究作为传统车辆（如汽车或公交车）乘客的个人出行活动选择，以及这些活动在自动驾驶汽车中的预期转变。由于个人在不同的出行目的下可能进行不同的活动，因此从通勤出行（如上班或上学）和非通勤出行（如休闲、跑腿或就医）这两个不同的角度探讨了活动选择和非自动驾驶汽车向自动驾驶汽车过渡的动态。生命周期评估模型的研究结果表明，在传统汽车中，有三类不同的人具有不同的活动偏好，而在 AV 中，可能会出现四类不同的人。自动驾驶汽车用户表现出对发短信/浏览社交媒体、放松和工作等活动的更高偏好，这表明自动驾驶汽车可以让乘客更有效地利用旅行时间。此外，LTA 模型显示，有相当一部分人原来在传统车辆中从事一两项活动，现在变成了追求多样化的人，他们可以在自动驾驶汽车中从事至少四项不同的活动，这进一步证实了自动驾驶汽车可以更有效地利用旅行时间这一结论。
{"title":"Passenger Time Use Comparison Between Traditional and Autonomous Vehicles: A Latent Class and Transition Analysis","authors":"Nadim Hamad, Divyakant Tahlyan, Hoseb Abkarian, Hani Mahmassani","doi":"10.1177/03611981241263824","DOIUrl":"https://doi.org/10.1177/03611981241263824","url":null,"abstract":"As the era of autonomous vehicles (AVs) approaches, understanding how passengers’ time use during a trip may change from a traditional vehicle (non-AV) to an AV is important to the adoption and use of AVs. In this study, a latent class analysis (LCA) as well as a latent transition analysis (LTA) are adopted to investigate the choice of travel activities of individuals as passengers in a traditional vehicle, such as a car or transit, and the anticipated shift in these activities in an AV. Since individuals may perform different activities during different trip purposes, activity choices and non-AV to AV transition dynamics are explored from two different perspectives: commute trips (e.g., to work or school) and non-commute trips (e.g., leisure, errands, or medical). Findings from the LCA models show three distinct groups of individuals with varying activity preferences in a traditional vehicle and four distinct groups that could emerge in an AV. AV users exhibited a higher preference for activities such as texting/browsing social media, relaxing, and working, suggesting that AVs may offer passengers a more productive use of their travel time. Furthermore, the LTA model shows that there is a good portion of individuals who were performing one or two activities in a traditional vehicle now becoming variety seekers that could perform at least four different activities in an AV, further corroborating the findings that AVs could provide a more productive and efficient use of travel time.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933688","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 : 2024-08-07DOI: 10.1177/03611981241265847
Dachina Gunasekaran, Bassem Andrawes
Transverse cracks in precast prestressed concrete (PPC) bridge deck girders cause a notable increase in strand stresses and adversely affect the cracked girder’s capacity and durability. This numerical study analyzes the impact of transverse cracks on the behavior of PPC bridge deck girders by relating the crack width to the residual capacity, stresses, and load rating of the cracked girders. A non-linear finite element (FE) model is developed to understand the behavior and predict the stresses in an in-service PPC bridge deck girder damaged by a transverse crack. The residual capacity and built-up stresses obtained from the FE model are used in the load rating analysis of the cracked PPC bridge deck girder. A parametric study is conducted to understand the effect of the influencing parameters, such as the girder geometry and material properties, on the damaged girder’s behavior. For an 838 mm × 914 mm PPC deck girder, the statistically significant parameters are found to be the span length ( L), strand diameter ( db), and skew angle ([Formula: see text]). From the numerical analysis of the in-service PPC bridge deck girder, the load rating is predicted to be governed by the capacity for the existing 0.25 mm crack. In the parametric study of the 838 mm × 914 mm PPC deck girder, the inventory rating factor of the prestressing strands in tension is predicted to decrease linearly for crack width up to 0.64 mm, while the capacity inventory rating factor is predicted to decrease by up to 73.8% for the crack width of 0.64 mm.
预制预应力混凝土（PPC）桥面梁中的横向裂缝会导致钢绞线应力显著增加，并对开裂梁的承载能力和耐久性产生不利影响。本数值研究分析了横向裂缝对 PPC 桥面梁行为的影响，将裂缝宽度与裂缝梁的剩余承载力、应力和额定荷载联系起来。开发了一个非线性有限元 (FE) 模型，以了解横向裂缝损坏的在役 PPC 桥面梁的行为并预测其应力。在对开裂的 PPC 桥面梁进行荷载等级分析时，将使用从 FE 模型中获得的残余承载力和累积应力。为了解影响参数（如梁的几何形状和材料属性）对受损梁行为的影响，进行了参数研究。对于 838 mm × 914 mm 的 PPC 桥面梁，发现具有统计意义的参数是跨度长度（L）、钢绞线直径（db）和倾斜角（[公式：见正文]）。通过对使用中的 PPC 桥面梁进行数值分析，预测其额定荷载受现有 0.25 毫米裂缝的承载能力制约。在 838 mm × 914 mm PPC 桥面梁的参数研究中，预测张拉中预应力钢绞线的库存额定系数在裂缝宽度达到 0.64 mm 时呈线性下降，而在裂缝宽度达到 0.64 mm 时，预测承载力库存额定系数下降达 73.8%。
{"title":"Parametric Study on Transversely Cracked Precast Prestressed Concrete Bridge Deck Girders with Rectangular Voids","authors":"Dachina Gunasekaran, Bassem Andrawes","doi":"10.1177/03611981241265847","DOIUrl":"https://doi.org/10.1177/03611981241265847","url":null,"abstract":"Transverse cracks in precast prestressed concrete (PPC) bridge deck girders cause a notable increase in strand stresses and adversely affect the cracked girder’s capacity and durability. This numerical study analyzes the impact of transverse cracks on the behavior of PPC bridge deck girders by relating the crack width to the residual capacity, stresses, and load rating of the cracked girders. A non-linear finite element (FE) model is developed to understand the behavior and predict the stresses in an in-service PPC bridge deck girder damaged by a transverse crack. The residual capacity and built-up stresses obtained from the FE model are used in the load rating analysis of the cracked PPC bridge deck girder. A parametric study is conducted to understand the effect of the influencing parameters, such as the girder geometry and material properties, on the damaged girder’s behavior. For an 838 mm × 914 mm PPC deck girder, the statistically significant parameters are found to be the span length ( L), strand diameter ( d<jats:sub>b</jats:sub>), and skew angle ([Formula: see text]). From the numerical analysis of the in-service PPC bridge deck girder, the load rating is predicted to be governed by the capacity for the existing 0.25 mm crack. In the parametric study of the 838 mm × 914 mm PPC deck girder, the inventory rating factor of the prestressing strands in tension is predicted to decrease linearly for crack width up to 0.64 mm, while the capacity inventory rating factor is predicted to decrease by up to 73.8% for the crack width of 0.64 mm.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933686","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 : 2024-08-07DOI: 10.1177/03611981241265843
Jonas Kapitza
Trip chaining and the use of travel time by commuters have long been the foci of considerable research interest. However, despite this attention, few studies have investigated the differences in behavior associated with daytime and nighttime travel. To fill this gap in the literature, the present study investigated the influence of time of day on trip chaining and travel time use. The analysis was based on a data set of residents of the Karlsruhe area who regularly commute both during the day and at night. The data set was analyzed both descriptively and through the application of a series of logistic regression models. The results indicated that nighttime had a significant influence on the formation of trip chains and the use of time during the commute. For example, both the number of trip chains formed and the number of activities performed during the commute are reduced at night. The reasons for forming trip chains also varied according to the time of day. Whereas most trip chains were formed for errands during the day, at night, the majority were formed to pursue leisure activities. In addition, activities such as working, telephoning, looking at the landscape, or reading were significantly reduced at night. The findings of this study contribute to a more in-depth understanding of commuter behavior, on the basis of which, innovative and efficient mobility strategies can be further developed.
{"title":"Time Matters: Analyzing the Impact of Nighttime on Commuter Trip Chaining Behavior and Travel Time Use in Karlsruhe, Germany","authors":"Jonas Kapitza","doi":"10.1177/03611981241265843","DOIUrl":"https://doi.org/10.1177/03611981241265843","url":null,"abstract":"Trip chaining and the use of travel time by commuters have long been the foci of considerable research interest. However, despite this attention, few studies have investigated the differences in behavior associated with daytime and nighttime travel. To fill this gap in the literature, the present study investigated the influence of time of day on trip chaining and travel time use. The analysis was based on a data set of residents of the Karlsruhe area who regularly commute both during the day and at night. The data set was analyzed both descriptively and through the application of a series of logistic regression models. The results indicated that nighttime had a significant influence on the formation of trip chains and the use of time during the commute. For example, both the number of trip chains formed and the number of activities performed during the commute are reduced at night. The reasons for forming trip chains also varied according to the time of day. Whereas most trip chains were formed for errands during the day, at night, the majority were formed to pursue leisure activities. In addition, activities such as working, telephoning, looking at the landscape, or reading were significantly reduced at night. The findings of this study contribute to a more in-depth understanding of commuter behavior, on the basis of which, innovative and efficient mobility strategies can be further developed.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"86 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933685","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 : 2024-08-07DOI: 10.1177/03611981241262313
Ziang He, Yu Han, Weihong Guo, Yanjie Ji, Pan Liu
This paper proposes a macroscopic fundamental diagram (MFD)-based perimeter control approach for coordinated ramp metering, aiming to minimize the total time spent (TTS) of a freeway network (stretch) with multiple bottlenecks. To address problems incurred from limited queue storage space and minimum green time at on-ramps, the proposed method extends previous approaches in two aspects. Firstly, a coordinated ramp control approach is proposed to ensure that the total metered on-ramp flow remains below the value determined by the MFD-based perimeter regulator, thereby preventing network over-saturation. Secondly, a novel queue management approach is developed to prevent on-ramp queue saturation and its associated side effects, for example, spillback or insufficient control actions. This approach determines the quasi-optimal flow of the next upstream (slave) on-ramp, based on the predicted queue of each (master) on-ramp suffering from excessive queues. The proposed perimeter controller was tested using SUMO, a microscopic simulator, on a realistic freeway network, and compared with other existing strategies, including HERO and perimeter controllers with other metered on-ramp flow distribution approaches. The simulation results suggest that the proposed strategy can ( i) effectively mitigate congestion and maintain capacity within the freeway network, resulting in reduced overall TTS, and ( ii) appropriately delay or prevent queue saturation at on-ramps.
{"title":"Perimeter Control-Based Coordinated Ramp Metering with Linked Queue Management for Freeway Networks","authors":"Ziang He, Yu Han, Weihong Guo, Yanjie Ji, Pan Liu","doi":"10.1177/03611981241262313","DOIUrl":"https://doi.org/10.1177/03611981241262313","url":null,"abstract":"This paper proposes a macroscopic fundamental diagram (MFD)-based perimeter control approach for coordinated ramp metering, aiming to minimize the total time spent (TTS) of a freeway network (stretch) with multiple bottlenecks. To address problems incurred from limited queue storage space and minimum green time at on-ramps, the proposed method extends previous approaches in two aspects. Firstly, a coordinated ramp control approach is proposed to ensure that the total metered on-ramp flow remains below the value determined by the MFD-based perimeter regulator, thereby preventing network over-saturation. Secondly, a novel queue management approach is developed to prevent on-ramp queue saturation and its associated side effects, for example, spillback or insufficient control actions. This approach determines the quasi-optimal flow of the next upstream (slave) on-ramp, based on the predicted queue of each (master) on-ramp suffering from excessive queues. The proposed perimeter controller was tested using SUMO, a microscopic simulator, on a realistic freeway network, and compared with other existing strategies, including HERO and perimeter controllers with other metered on-ramp flow distribution approaches. The simulation results suggest that the proposed strategy can ( i) effectively mitigate congestion and maintain capacity within the freeway network, resulting in reduced overall TTS, and ( ii) appropriately delay or prevent queue saturation at on-ramps.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933691","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 : 2024-08-07DOI: 10.1177/03611981241265852
Navaratnarajah Sathiparan, Daniel Niruban Subramaniam
Pervious concrete is a unique type of concrete with high porosity that allows water to pass through. This characteristic makes it beneficial for various applications, such as stormwater management, groundwater recharge, and reduced heat island effect. However, pervious concrete typically requires more cement than conventional concrete because of its mix design. This increased cement content can be partially replaced with supplementary cementitious materials, such as silica fume. This review article investigates the influence of silica fume on the properties of pervious concrete, including the mechanical properties (compressive strength, splitting tensile strength, and flexural strength), durability (resistance to freeze–thaw cycles and abrasion), and environmental aspects. The article highlights that silica fume can improve the mechanical properties and durability of pervious concrete up to an optimal replacement level. The optimum replacement level of cement with silica fume was found to be 10%–15%. Beyond this level, the performance of pervious concrete decreases. The pervious concrete containing silica fume showed superior abrasion resistance and improved freeze–thaw resistance compared to conventional pervious concrete. In addition, incorporating silica fume in pervious concrete reduces cement usage, leading to a lower environmental impact and more sustainable construction practices. The article also analyzes the limitations of using silica fume, such as the potential for reduced workability because of its fine particle size. Overall, the review suggests that silica fume is a promising supplementary cementitious material for enhancing the performance and sustainability of pervious concrete.
{"title":"Sustainable Pervious Concrete with Silica Fume as Cement Replacement: A Review","authors":"Navaratnarajah Sathiparan, Daniel Niruban Subramaniam","doi":"10.1177/03611981241265852","DOIUrl":"https://doi.org/10.1177/03611981241265852","url":null,"abstract":"Pervious concrete is a unique type of concrete with high porosity that allows water to pass through. This characteristic makes it beneficial for various applications, such as stormwater management, groundwater recharge, and reduced heat island effect. However, pervious concrete typically requires more cement than conventional concrete because of its mix design. This increased cement content can be partially replaced with supplementary cementitious materials, such as silica fume. This review article investigates the influence of silica fume on the properties of pervious concrete, including the mechanical properties (compressive strength, splitting tensile strength, and flexural strength), durability (resistance to freeze–thaw cycles and abrasion), and environmental aspects. The article highlights that silica fume can improve the mechanical properties and durability of pervious concrete up to an optimal replacement level. The optimum replacement level of cement with silica fume was found to be 10%–15%. Beyond this level, the performance of pervious concrete decreases. The pervious concrete containing silica fume showed superior abrasion resistance and improved freeze–thaw resistance compared to conventional pervious concrete. In addition, incorporating silica fume in pervious concrete reduces cement usage, leading to a lower environmental impact and more sustainable construction practices. The article also analyzes the limitations of using silica fume, such as the potential for reduced workability because of its fine particle size. Overall, the review suggests that silica fume is a promising supplementary cementitious material for enhancing the performance and sustainability of pervious concrete.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933687","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: 10.1177/03611981241265848
Abhitesh Sachdeva, G.D. Ransinchung R.N, Praveen Kumar, Meraj Alam Khan
The fundamental concern of the full-depth reclamation (FDR) technique using Portland cement (FDR-PC) lies in its detrimental effect on the environment. Therefore, researchers are exploring alternative binders that are comparatively greener but compatible with FDR. This study evaluates both the strength and durability aspects of FDR incorporating geopolymer binder (FDR-GP) as an alternative to conventional FDR-PC. Various blends of fly ash (FA) and ground granulated blast furnace slag (GGBS) have been experimented with as geopolymer pre-cursors, ensuring that the additive content does not exceed 20% by weight of the total mix. Sodium hydroxide (NaOH) was utilized for the alkalinization in varying molarities to enhance the performance of the mixes. The experimental design was formulated to achieve a target 7-day unconfined compressive strength (UCS) strength of 4.95 MPa. This was obtained at a lower molarity (M) of 2 M and a 70% FA, 30% GGBS binder content. The mixes performed satisfactorily in both compression and flexure, along with excellent durability properties analyzed through wetting and drying tests. Furthermore, the long-term performance of FDR-GP mixes was investigated with regard to both UCS and flexural strength after 56, 161, and 238 days of curing. Thereafter, a comprehensive microstructural analysis was conducted to understand the fundamental changes in the matrix that influence mix performance. The outcome of this research confirms the potential of using FA/GGBS-based geopolymer as an alternative binder in FDR projects of flexible pavement, the mechanical and durability properties of which adequately satisfy the requirements as stipulated in various design standards.
{"title":"Can Geopolymer Be a Replacement for Portland Cement in Full-Depth Reclamation Projects? Short- and Long-Term Performance Analysis","authors":"Abhitesh Sachdeva, G.D. Ransinchung R.N, Praveen Kumar, Meraj Alam Khan","doi":"10.1177/03611981241265848","DOIUrl":"https://doi.org/10.1177/03611981241265848","url":null,"abstract":"The fundamental concern of the full-depth reclamation (FDR) technique using Portland cement (FDR-PC) lies in its detrimental effect on the environment. Therefore, researchers are exploring alternative binders that are comparatively greener but compatible with FDR. This study evaluates both the strength and durability aspects of FDR incorporating geopolymer binder (FDR-GP) as an alternative to conventional FDR-PC. Various blends of fly ash (FA) and ground granulated blast furnace slag (GGBS) have been experimented with as geopolymer pre-cursors, ensuring that the additive content does not exceed 20% by weight of the total mix. Sodium hydroxide (NaOH) was utilized for the alkalinization in varying molarities to enhance the performance of the mixes. The experimental design was formulated to achieve a target 7-day unconfined compressive strength (UCS) strength of 4.95 MPa. This was obtained at a lower molarity (M) of 2 M and a 70% FA, 30% GGBS binder content. The mixes performed satisfactorily in both compression and flexure, along with excellent durability properties analyzed through wetting and drying tests. Furthermore, the long-term performance of FDR-GP mixes was investigated with regard to both UCS and flexural strength after 56, 161, and 238 days of curing. Thereafter, a comprehensive microstructural analysis was conducted to understand the fundamental changes in the matrix that influence mix performance. The outcome of this research confirms the potential of using FA/GGBS-based geopolymer as an alternative binder in FDR projects of flexible pavement, the mechanical and durability properties of which adequately satisfy the requirements as stipulated in various design standards.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141968786","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: 10.1177/03611981241265842
Jing Wang, Tingting Gao, Jingzhe Zhang, Chuang Tu
To address the route planning issues under the community group purchase model for joint delivery, this study thoroughly considers electric logistics vehicles with different recharging methods. The objective is to minimize the sum of operating costs, recharging costs, time window penalty costs, and carbon emission costs. Separate multi-objective optimization models for route planning are constructed for both charging and battery-swapping logistics vehicles. An improved seagull optimization algorithm, guided by the golden sine strategy of the Lévy flight guidance mechanism, is employed to avoid local optima and enhance the solution efficiency. The feasibility of the models and the algorithm is verified through simulation examples. Experimental results show that, at the current stage, battery-swapping logistics vehicles display significant advantages over charging electric logistics vehicles. Although battery-swapping logistics vehicles extend delivery time, they can reduce the total delivery costs to a certain extent. Therefore, the future development prospects of battery-swapping logistics vehicles will be even broader.
{"title":"Research on Joint Distribution Path Planning of Electric Logistics Vehicles with Different Recharge Modes","authors":"Jing Wang, Tingting Gao, Jingzhe Zhang, Chuang Tu","doi":"10.1177/03611981241265842","DOIUrl":"https://doi.org/10.1177/03611981241265842","url":null,"abstract":"To address the route planning issues under the community group purchase model for joint delivery, this study thoroughly considers electric logistics vehicles with different recharging methods. The objective is to minimize the sum of operating costs, recharging costs, time window penalty costs, and carbon emission costs. Separate multi-objective optimization models for route planning are constructed for both charging and battery-swapping logistics vehicles. An improved seagull optimization algorithm, guided by the golden sine strategy of the Lévy flight guidance mechanism, is employed to avoid local optima and enhance the solution efficiency. The feasibility of the models and the algorithm is verified through simulation examples. Experimental results show that, at the current stage, battery-swapping logistics vehicles display significant advantages over charging electric logistics vehicles. Although battery-swapping logistics vehicles extend delivery time, they can reduce the total delivery costs to a certain extent. Therefore, the future development prospects of battery-swapping logistics vehicles will be even broader.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933633","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: 10.1177/03611981241266837
Donggyu Min, Hyunsoo Yun, Seung Woo Ham, Dong-Kyu Kim
The digital twin, a real-time replica of physical systems, has garnered attention as a promising tool to strategize and evaluate solutions for complex real-world issues. However, developing digital twins in the field of transportation faces significant challenges related to the real-time estimation of dynamic origin–destination (OD) matrices constrained by computation time. To bridge this gap, microscopic traffic simulations with real-time synchronization are being researched. Nonetheless, the computational issue persists, emphasizing the need for more efficient OD estimation methods. In this regard, our objective is to reduce computation time in simulation-based methods by developing a data-driven metamodel using a deep neural network. The proposed model serves to map the correlation between the OD matrix and detector data. This model simplifies the computational process using hidden layers, rather than calculating complex interactions between vehicles in the traffic simulation. Compared to conventional methods, we evaluate the capability to estimate a reasonable OD matrix within a restricted time and validate our approach using detector data from Daejeon City, South Korea. The findings indicate that by combining our data-driven metamodel with the simultaneous perturbation stochastic approximation, it becomes feasible to estimate a reasonable OD matrix within a stipulated time frame, compared to the conventional method. Given a 1-min time frame, the proposed method outperforms the conventional simulation-based method by improving the calibration performance of traffic flow by 44.5 percentage points. This paper proposes a practical and versatile approach for real-time OD estimation, laying the foundation for extending microscopic traffic simulation into the digital twin.
数字孪生是物理系统的实时复制品，作为一种有前途的工具，它在为复杂的现实世界问题制定战略和评估解决方案方面备受关注。然而，在交通领域开发数字孪生系统面临着重大挑战，即受计算时间限制，无法实时估算动态原点-目的地（OD）矩阵。为了弥补这一差距，人们正在研究实时同步的微观交通模拟。尽管如此，计算问题依然存在，因此需要更高效的起点-终点估计方法。在这方面，我们的目标是利用深度神经网络开发一种数据驱动的元模型，从而减少基于模拟的方法的计算时间。所提出的模型用于映射 OD 矩阵与探测器数据之间的相关性。该模型利用隐藏层简化了计算过程，而不是在交通模拟中计算车辆之间复杂的相互作用。与传统方法相比，我们评估了在限定时间内估算合理的 OD 矩阵的能力，并使用韩国大田市的检测器数据验证了我们的方法。研究结果表明，与传统方法相比，通过将我们的数据驱动元模型与同步扰动随机近似相结合，在规定时间内估算出合理的 OD 矩阵是可行的。在 1 分钟的时间框架内，所提出的方法优于传统的基于模拟的方法，将交通流量的校准性能提高了 44.5 个百分点。本文提出了一种实用且通用的实时 OD 估算方法，为将微观交通仿真扩展到数字孪生奠定了基础。
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Pub Date : 2024-08-06DOI: 10.1177/03611981241257508
Adrian Ricardo Archilla, Phillip S.K. Ooi, Saroj Pathak
The resilient modulus ( Mr) is typically interpreted as the average of the last five secant slopes of the cyclic stress-axial resilient strain curve from repeated loading triaxial tests. It is not uncommon to then fit mathematical models to the secant Mr to derive model parameters ( Ki, more commonly known as K1, K2, and K3) that are then used in pavement analysis. Some engineers also backcalculate Ki from a falling weight deflectometer test. Many researchers use an incremental loading procedure to analyze pavements. When doing so, it is important to consider the nonlinear load-deformation behavior, which is considered only coarsely in the secant slope approach. Some incremental loading procedures assume the geomaterial to be nonlinear elastic while a dynamic finite element analysis typically assumes the geomaterials to be nonlinear and viscoelastic, that is, having springs and dashpots. With the latter, additional damping parameters to represent the viscoelastic effects are required. This paper compares Ki parameters estimated using linear regression on a log transformation of the Mechanistic–Empirical Pavement Design Guide (MEPDG) Mr model, which is a non-viscoelastic secant Mr approach, with those obtained using nonlinear regression of the time dependent deformations when interpreting the Mr test using incremental loading of a: 1) nonlinear elastic geomaterial; and 2) nonlinear viscoelastic geomaterial with inertial mass. The results show that the estimated Ki parameters governing the geomaterial nonlinearity are substantially affected by the estimation method and that the second alternative approach can model hysteresis well.
回弹模量（Mr）通常被解释为重复加载三轴试验中循环应力-轴向回弹应变曲线最后五个正割斜率的平均值。通常情况下，将数学模型拟合到 secant Mr 上，得出模型参数（Ki，通常称为 K1、K2 和 K3），然后用于路面分析。有些工程师还会通过落重挠度仪测试反算 Ki。许多研究人员使用增量加载程序来分析路面。在进行分析时，必须考虑非线性荷载-变形行为，而这种行为在秒坡法中只得到了粗略的考虑。一些增量加载程序假定土工材料为非线性弹性材料，而动态有限元分析通常假定土工材料为非线性粘弹性材料，即具有弹簧和冲刺点。对于后者，需要额外的阻尼参数来表示粘弹性效应。本文比较了使用对数变换线性回归估算的力学-经验路面设计指南（MEPDG）Mr 模型的 Ki 参数（这是一种非粘弹性的秒速快三精准人工下注计划方法）与使用时间相关变形的非线性回归估算的 Ki 参数，后者是在使用增量加载对以下土质材料进行 Mr 试验时获得的：1）非线性弹性土质材料；2）粘弹性土质材料；3）非线性弹性土质材料；4）非线性弹性土质材料：1) 非线性弹性土工材料；以及 2) 具有惯性质量的非线性粘弹性土工材料。结果表明，估算土工材料非线性的 Ki 参数受估算方法的影响很大，而第二种替代方法可以很好地模拟滞后现象。
{"title":"Nonlinear Interpretation of Resilient Modulus Parameters Considering Incremental Static and Dynamic Loading","authors":"Adrian Ricardo Archilla, Phillip S.K. Ooi, Saroj Pathak","doi":"10.1177/03611981241257508","DOIUrl":"https://doi.org/10.1177/03611981241257508","url":null,"abstract":"The resilient modulus ( M<jats:sub>r</jats:sub>) is typically interpreted as the average of the last five secant slopes of the cyclic stress-axial resilient strain curve from repeated loading triaxial tests. It is not uncommon to then fit mathematical models to the secant M<jats:sub>r</jats:sub> to derive model parameters ( K<jats:sub>i</jats:sub>, more commonly known as K<jats:sub>1</jats:sub>, K<jats:sub>2</jats:sub>, and K<jats:sub>3</jats:sub>) that are then used in pavement analysis. Some engineers also backcalculate K<jats:sub>i</jats:sub> from a falling weight deflectometer test. Many researchers use an incremental loading procedure to analyze pavements. When doing so, it is important to consider the nonlinear load-deformation behavior, which is considered only coarsely in the secant slope approach. Some incremental loading procedures assume the geomaterial to be nonlinear elastic while a dynamic finite element analysis typically assumes the geomaterials to be nonlinear and viscoelastic, that is, having springs and dashpots. With the latter, additional damping parameters to represent the viscoelastic effects are required. This paper compares K<jats:sub>i</jats:sub> parameters estimated using linear regression on a log transformation of the Mechanistic–Empirical Pavement Design Guide (MEPDG) M<jats:sub>r</jats:sub> model, which is a non-viscoelastic secant M<jats:sub>r</jats:sub> approach, with those obtained using nonlinear regression of the time dependent deformations when interpreting the M<jats:sub>r</jats:sub> test using incremental loading of a: 1) nonlinear elastic geomaterial; and 2) nonlinear viscoelastic geomaterial with inertial mass. The results show that the estimated K<jats:sub>i</jats:sub> parameters governing the geomaterial nonlinearity are substantially affected by the estimation method and that the second alternative approach can model hysteresis well.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"86 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933644","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: 10.1177/03611981241265841
Steven S. Harrod
Positive train control (PTC) and the European Rail Traffic Management System (ERTMS) are digital railway signal systems in North America and Europe, respectively. They are frequently described as interchangeable, but they are not. This paper explains the history and motivations for each continent, and the general technical and capability differences between the two signal systems. In general, North America revised their signal systems to respond to safety concerns, and Europe committed to replacing their signals to encourage cross-border train traffic. The ERTMS is significantly more expensive than PTC, and the cost has been justified with expectations of greater capacity. Multiple studies find no basis for large capacity increases after implementation of the ERTMS. In addition, the added cost of the ERTMS threatens an already weak rail freight market in Europe.
{"title":"Railway Signal Digitalization with the European Rail Traffic Management System and Positive Train Control: Industry 4.0 Expectations and Reality","authors":"Steven S. Harrod","doi":"10.1177/03611981241265841","DOIUrl":"https://doi.org/10.1177/03611981241265841","url":null,"abstract":"Positive train control (PTC) and the European Rail Traffic Management System (ERTMS) are digital railway signal systems in North America and Europe, respectively. They are frequently described as interchangeable, but they are not. This paper explains the history and motivations for each continent, and the general technical and capability differences between the two signal systems. In general, North America revised their signal systems to respond to safety concerns, and Europe committed to replacing their signals to encourage cross-border train traffic. The ERTMS is significantly more expensive than PTC, and the cost has been justified with expectations of greater capacity. Multiple studies find no basis for large capacity increases after implementation of the ERTMS. In addition, the added cost of the ERTMS threatens an already weak rail freight market in Europe.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141933689","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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