Pub Date : 2024-07-31DOI: 10.1177/03611981241244798
Tisura D. Gamage, Alan T. Jenn, Gil Tal
A network of reliable corridor charging stations is essential to building driver confidence in long-distance battery electric vehicle trips. Here, we propose a detailed methodology to measure station reliability based on charging infrastructure data. By assigning charging events to unique charging visits, our methodology can capture a holistic overview of the driver’s charging experience. We use real world charging data collected between 2019 and 2022 from 54 Direct Current Fast Chargers (DCFCs) in 36 corridor charging stations across California to demonstrate that our overarching reliability framework is close to the experience of users. Our analysis of two different charging networks shows that users of these networks have an average chance of 83% and 77% generally successful outcomes, respectively, after one or more tries at a charging station location. We also find significant variation in station performance within the same network (i.e., 79%–87% and 13%–95%, respectively). Furthermore, we observe that at least 3% of users are facing unexpected charging interruptions. In addition, we demonstrate a practical application of our framework for deep diagnostics of the charging eco-system using error codes to identify common issues such as vehicle/charger communication issues, safety issues, payment issues, and cable/connector issues. We compare how error codes alone are not a good proxy to diagnose charging failures. As more data from DCFCs becomes available, our methodology can become a mainstream tool for evaluating station reliability.
{"title":"Novel Methodology to Measure the Reliability of Public DC Fast Charging Stations","authors":"Tisura D. Gamage, Alan T. Jenn, Gil Tal","doi":"10.1177/03611981241244798","DOIUrl":"https://doi.org/10.1177/03611981241244798","url":null,"abstract":"A network of reliable corridor charging stations is essential to building driver confidence in long-distance battery electric vehicle trips. Here, we propose a detailed methodology to measure station reliability based on charging infrastructure data. By assigning charging events to unique charging visits, our methodology can capture a holistic overview of the driver’s charging experience. We use real world charging data collected between 2019 and 2022 from 54 Direct Current Fast Chargers (DCFCs) in 36 corridor charging stations across California to demonstrate that our overarching reliability framework is close to the experience of users. Our analysis of two different charging networks shows that users of these networks have an average chance of 83% and 77% generally successful outcomes, respectively, after one or more tries at a charging station location. We also find significant variation in station performance within the same network (i.e., 79%–87% and 13%–95%, respectively). Furthermore, we observe that at least 3% of users are facing unexpected charging interruptions. In addition, we demonstrate a practical application of our framework for deep diagnostics of the charging eco-system using error codes to identify common issues such as vehicle/charger communication issues, safety issues, payment issues, and cable/connector issues. We compare how error codes alone are not a good proxy to diagnose charging failures. As more data from DCFCs becomes available, our methodology can become a mainstream tool for evaluating station reliability.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"96 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141867500","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}
This study aims to investigate the different behaviors with respect to safety measures related to the interaction of e-scooters and bikes with cars in mixed traffic. E-scooters are relatively new vulnerable road users, and their behavior is still not fully understood. For this purpose, an observational study was carried out at an unsignalized at-grade intersection in the city of Catania, Italy. A total of 128 interactions between cars and e-scooters and 89 interactions between cars and bikes were detected. Specifically, two surrogate measures of safety were used, the time to collision (TTC) and post encroachment time (PET), which relate to the “crossing” and the “following” interactions between cars and bikes/e-scooters. The results show that 50% of the “crossings” involving bikes were close interactions with low TTCs representing high risk (TTC < 1.5); meanwhile, for the “crossing” interactions between cars and e-scooters, the same threshold of TTC relates to percentiles of more than 80%. In addition, more than 60% of interactions between cars and e-scooters were characterized by PET values representing a potentially high risk (PET < 1.0 s). The results provide a useful starting point for the elaboration and adaptation of new regulations for mixed traffic conditions including e-scooters that are currently being introduced in several countries with different rules. It should be noted that e-scooters are an intrinsically different transport mode from a bicycle, mainly because their interactions in mixed traffic show that they are prone to a higher risk of closer interactions.
{"title":"Comparison of E-Scooter and Bike Users’ Behavior in Mixed Traffic","authors":"Natalia Distefano, Salvatore Leonardi, Mariusz Kieć, Carmelo D’Agostino","doi":"10.1177/03611981241263339","DOIUrl":"https://doi.org/10.1177/03611981241263339","url":null,"abstract":"This study aims to investigate the different behaviors with respect to safety measures related to the interaction of e-scooters and bikes with cars in mixed traffic. E-scooters are relatively new vulnerable road users, and their behavior is still not fully understood. For this purpose, an observational study was carried out at an unsignalized at-grade intersection in the city of Catania, Italy. A total of 128 interactions between cars and e-scooters and 89 interactions between cars and bikes were detected. Specifically, two surrogate measures of safety were used, the time to collision (TTC) and post encroachment time (PET), which relate to the “crossing” and the “following” interactions between cars and bikes/e-scooters. The results show that 50% of the “crossings” involving bikes were close interactions with low TTCs representing high risk (TTC < 1.5); meanwhile, for the “crossing” interactions between cars and e-scooters, the same threshold of TTC relates to percentiles of more than 80%. In addition, more than 60% of interactions between cars and e-scooters were characterized by PET values representing a potentially high risk (PET < 1.0 s). The results provide a useful starting point for the elaboration and adaptation of new regulations for mixed traffic conditions including e-scooters that are currently being introduced in several countries with different rules. It should be noted that e-scooters are an intrinsically different transport mode from a bicycle, mainly because their interactions in mixed traffic show that they are prone to a higher risk of closer interactions.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"1148 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141867504","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 : 2024-07-30DOI: 10.1177/03611981241262299
Serena Alexander, Bo Yang, Owen Hussey
Highway capacity expansion has wide impacts on land use and land cover (LULC). Cost–benefit analyses and environmental review processes for roadway capacity expansion and maintenance decisions do not comprehensively consider the LULC impacts. This study examined land cover changes directly associated with highway expansion in California, and the relationship between land use and the vegetation impacts of highway projects using satellite remote sensing data. The methodology involves a geospatial analysis of normalized difference vegetation index (NDVI) data in 18 sites across California before and after highway expansion project completion. We accounted for seasonality and included a set of control sites. Findings indicate that the impacts of highway expansion on changes in NDVI are diverse, stressing the importance of the environmental context around each individual project site. Sites that are located near less-developed areas with more extensive natural vegetation (e.g., sprawled areas or exurbs), show a significant decline in NDVI values. Virtually all sites with insignificant changes in NDVI after highway expansion are located in areas that already exhibit heavy urban development (e.g., Los Angeles, San José) or are otherwise located near large expanses of bare, non-vegetated earth. Also, project sites that experienced multiple types of construction (i.e., adding more lanes, widening sections, bridge renovation, etc.) were more likely to exhibit decreasing NDVI values compared with project sites that only experienced one type of construction. Decisions about highway construction and capacity expansion should consider the context and the full environmental impacts, including land use and land cover changes over time.
{"title":"Examining the Land Use and Land Cover Impacts of Highway Capacity Expansions in California Using Remote Sensing Technology","authors":"Serena Alexander, Bo Yang, Owen Hussey","doi":"10.1177/03611981241262299","DOIUrl":"https://doi.org/10.1177/03611981241262299","url":null,"abstract":"Highway capacity expansion has wide impacts on land use and land cover (LULC). Cost–benefit analyses and environmental review processes for roadway capacity expansion and maintenance decisions do not comprehensively consider the LULC impacts. This study examined land cover changes directly associated with highway expansion in California, and the relationship between land use and the vegetation impacts of highway projects using satellite remote sensing data. The methodology involves a geospatial analysis of normalized difference vegetation index (NDVI) data in 18 sites across California before and after highway expansion project completion. We accounted for seasonality and included a set of control sites. Findings indicate that the impacts of highway expansion on changes in NDVI are diverse, stressing the importance of the environmental context around each individual project site. Sites that are located near less-developed areas with more extensive natural vegetation (e.g., sprawled areas or exurbs), show a significant decline in NDVI values. Virtually all sites with insignificant changes in NDVI after highway expansion are located in areas that already exhibit heavy urban development (e.g., Los Angeles, San José) or are otherwise located near large expanses of bare, non-vegetated earth. Also, project sites that experienced multiple types of construction (i.e., adding more lanes, widening sections, bridge renovation, etc.) were more likely to exhibit decreasing NDVI values compared with project sites that only experienced one type of construction. Decisions about highway construction and capacity expansion should consider the context and the full environmental impacts, including land use and land cover changes over time.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141867506","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 : 2024-07-30DOI: 10.1177/03611981241263571
Gabriel Arce, Mary Sharifi
Deterioration of corrugated steel culverts (CSCs) is a significant problem for the Virginia Department of Transportation and other U.S. transportation agencies. Spray-on lining using shotcrete engineered cementitious composites (ECCs) is a promising structural repair strategy for deteriorated CSCs. This study evaluates the feasibility of practical sprayable ECCs using natural silica sand and low fiber content, while forgoing the use of commonly utilized calcium sulfoaluminate cement to allow for delivery of the materials via ready-mixed concrete trucks. Aspects of the compositional space evaluated include the effect of a hybrid polyvinyl alcohol/polyethylene fiber system, silica fume (SF), shrinkage reducing admixture (SRA), and air-entraining admixture (AEA) on the properties of the composites. Experimental results suggested that the development of the proposed materials is feasible, because flow characteristics associated with shotcrete ECCs and ECC-like tensile ductility were achieved in the fresh and hardened state, respectively. Notwithstanding, further mixture optimization may be required for satisfactory field performance, which should be assessed through field testing. Generally, the use of the hybrid fiber system tended to improve the strength and ductility of the composites, especially when coupled with the use of SF. Furthermore, SF was effective at mitigating the strength loss associated with the incorporation of AEA and SRA, and meaningfully improved surface resistivity. SF also tended to reduce the mixture’s flow, whereas the contrary occurred with the use of SRA and AEA. SRA contributed to the reduction in drying shrinkage at early ages. However, the effect of SRA in reducing shrinkage was negligible at later ages.
{"title":"Feasibility of Sprayable Engineered Cementitious Composites Using Natural Sand and Low Fiber Content: Effect of Hybrid Fiber System, Silica Fume, and Air-Entraining and Shrinkage-Reducing Admixtures","authors":"Gabriel Arce, Mary Sharifi","doi":"10.1177/03611981241263571","DOIUrl":"https://doi.org/10.1177/03611981241263571","url":null,"abstract":"Deterioration of corrugated steel culverts (CSCs) is a significant problem for the Virginia Department of Transportation and other U.S. transportation agencies. Spray-on lining using shotcrete engineered cementitious composites (ECCs) is a promising structural repair strategy for deteriorated CSCs. This study evaluates the feasibility of practical sprayable ECCs using natural silica sand and low fiber content, while forgoing the use of commonly utilized calcium sulfoaluminate cement to allow for delivery of the materials via ready-mixed concrete trucks. Aspects of the compositional space evaluated include the effect of a hybrid polyvinyl alcohol/polyethylene fiber system, silica fume (SF), shrinkage reducing admixture (SRA), and air-entraining admixture (AEA) on the properties of the composites. Experimental results suggested that the development of the proposed materials is feasible, because flow characteristics associated with shotcrete ECCs and ECC-like tensile ductility were achieved in the fresh and hardened state, respectively. Notwithstanding, further mixture optimization may be required for satisfactory field performance, which should be assessed through field testing. Generally, the use of the hybrid fiber system tended to improve the strength and ductility of the composites, especially when coupled with the use of SF. Furthermore, SF was effective at mitigating the strength loss associated with the incorporation of AEA and SRA, and meaningfully improved surface resistivity. SF also tended to reduce the mixture’s flow, whereas the contrary occurred with the use of SRA and AEA. SRA contributed to the reduction in drying shrinkage at early ages. However, the effect of SRA in reducing shrinkage was negligible at later ages.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141867497","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 : 2024-07-30DOI: 10.1177/03611981241263570
Ge Shi, Yu Song, Carol Atkinson-Palombo, Norman Garrick
Vision Zero has been increasingly embraced by jurisdictions across the United States. Existing research primarily focuses on the theoretical principles and effectiveness of specific engineering measures. However, there is limited understanding of the holistic effects of Vision Zero treatments, in the context of street type and urban environment. We developed a street typology framework to categorize street segments using four design and operational features: street width, traffic direction (one- versus two-way), number of travel lanes, and presence of on-street parking. We applied a sample-based partitioning around medoids algorithm to classify 90,327 street segments in New York City. This process results in six distinctive types of street segment. To integrate neighborhood-level factors (e.g., land use variables and sociodemographics), we aggregated street segments of a given street type for each neighborhood. Negative binomial regression models were developed for pedestrian and car occupant crash injuries and fatalities separately for three periods: 2014 to 2016, 2017 to 2019, and 2020 to 2022. Our findings showed that street-segment groups with narrower, two-way sections and greater tree canopy coverage were significantly associated with a lower risk of casualties for both pedestrians and motorized users. Street-segment groups located in neighborhoods with a larger percentage of African American and Hispanic American residents experienced a significantly greater risk of casualties. Vision Zero treatments had mixed effects on safety outcomes. Streets treated with leading pedestrian intervals showed a lower risk of casualties. Neighborhood- and arterial slow zones were associated with a lower risk of car occupant casualties.
{"title":"Pedestrian and Car Occupant Crash Casualties Over a 9-Year Span of Vision Zero in New York City","authors":"Ge Shi, Yu Song, Carol Atkinson-Palombo, Norman Garrick","doi":"10.1177/03611981241263570","DOIUrl":"https://doi.org/10.1177/03611981241263570","url":null,"abstract":"Vision Zero has been increasingly embraced by jurisdictions across the United States. Existing research primarily focuses on the theoretical principles and effectiveness of specific engineering measures. However, there is limited understanding of the holistic effects of Vision Zero treatments, in the context of street type and urban environment. We developed a street typology framework to categorize street segments using four design and operational features: street width, traffic direction (one- versus two-way), number of travel lanes, and presence of on-street parking. We applied a sample-based partitioning around medoids algorithm to classify 90,327 street segments in New York City. This process results in six distinctive types of street segment. To integrate neighborhood-level factors (e.g., land use variables and sociodemographics), we aggregated street segments of a given street type for each neighborhood. Negative binomial regression models were developed for pedestrian and car occupant crash injuries and fatalities separately for three periods: 2014 to 2016, 2017 to 2019, and 2020 to 2022. Our findings showed that street-segment groups with narrower, two-way sections and greater tree canopy coverage were significantly associated with a lower risk of casualties for both pedestrians and motorized users. Street-segment groups located in neighborhoods with a larger percentage of African American and Hispanic American residents experienced a significantly greater risk of casualties. Vision Zero treatments had mixed effects on safety outcomes. Streets treated with leading pedestrian intervals showed a lower risk of casualties. Neighborhood- and arterial slow zones were associated with a lower risk of car occupant casualties.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"149 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141867508","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}
This study develops safety performance functions (SPFs) for severe (“KA” or “fatal and suspected serious injury”) distraction-related crashes along Kentucky’s rural and urban two-lane undivided roadway segments using recent four-year (2018–2021) crash records. Additional efforts were made to meticulously scrutinize crash narratives categorized as non-distracted and correct those cases. To account for crash under-dispersion, the Conway–Maxwell–Poisson, heterogeneous Conway–Maxwell–Poisson, zero-inflated Conway–Maxwell–Poisson, and zero-inflated heterogeneous Conway–Maxwell–Poisson (ZI-HTCMP) models were fitted and compared. The ZI-HTCMP model outperformed the other models with respect to several goodness-of-fit measures (e.g., mean absolute deviance and mean square prediction error). From the developed SPFs for rural and urban two-lane roads, wider lanes and higher speed limits (55 mph) were associated with increased severe distraction-related crash frequencies. Furthermore, some variables were found to be significant in rural areas, but insignificant in urban areas, and vice versa. For example, major collector roads, minor collector/local roads, the presence of roadside guardrails, wider right-hand shoulders, the presence of horizontal curves, and the presence of vertical grades were associated with increased crash frequencies along rural two-lane roads. In addition, the proportion of heavy vehicles (>5%) and the existence of paved shoulders were associated with increased crashes along urban two-lane roads. The empirical Bayes method was then used to rank the top 10 distraction-related high crash locations (HCLs) for both rural and urban two-lane segments. In-depth investigation of HCLs highlighted single-vehicle distraction-related crashes as the most common collision type. Countermeasures were proposed to help reduce severe distraction-related crashes, for example, installing chevron signs along rural two-lane roads.
{"title":"Developing Safety Performance Functions for Severe Distraction-Related Crashes along Kentucky’s Rural and Urban Two-Lane Roadways","authors":"Arunabha Banerjee, Bharat Kumar Pathivada, Kirolos Haleem, Dylan Justice, Evan Brittenham, Joshua Oliver","doi":"10.1177/03611981241263568","DOIUrl":"https://doi.org/10.1177/03611981241263568","url":null,"abstract":"This study develops safety performance functions (SPFs) for severe (“KA” or “fatal and suspected serious injury”) distraction-related crashes along Kentucky’s rural and urban two-lane undivided roadway segments using recent four-year (2018–2021) crash records. Additional efforts were made to meticulously scrutinize crash narratives categorized as non-distracted and correct those cases. To account for crash under-dispersion, the Conway–Maxwell–Poisson, heterogeneous Conway–Maxwell–Poisson, zero-inflated Conway–Maxwell–Poisson, and zero-inflated heterogeneous Conway–Maxwell–Poisson (ZI-HTCMP) models were fitted and compared. The ZI-HTCMP model outperformed the other models with respect to several goodness-of-fit measures (e.g., mean absolute deviance and mean square prediction error). From the developed SPFs for rural and urban two-lane roads, wider lanes and higher speed limits (55 mph) were associated with increased severe distraction-related crash frequencies. Furthermore, some variables were found to be significant in rural areas, but insignificant in urban areas, and vice versa. For example, major collector roads, minor collector/local roads, the presence of roadside guardrails, wider right-hand shoulders, the presence of horizontal curves, and the presence of vertical grades were associated with increased crash frequencies along rural two-lane roads. In addition, the proportion of heavy vehicles (>5%) and the existence of paved shoulders were associated with increased crashes along urban two-lane roads. The empirical Bayes method was then used to rank the top 10 distraction-related high crash locations (HCLs) for both rural and urban two-lane segments. In-depth investigation of HCLs highlighted single-vehicle distraction-related crashes as the most common collision type. Countermeasures were proposed to help reduce severe distraction-related crashes, for example, installing chevron signs along rural two-lane roads.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141867509","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 : 2024-07-30DOI: 10.1177/03611981241263561
Chengshuai Liu, Hui He, Peng Chen
The outbreak of COVID-19 in 2019 caused a huge impact on people’s lives. Uncovering the variation of public traffic daily patterns during the pre-pandemic and pandemic periods would help interpret the impact of the pandemic on people’s routine activity and promote the sustainable development of public transport systems. By collecting subway traffic data during the pre-pandemic and pandemic periods in Beijing, China, this paper analyzes the spatial and temporal variation of subway ridership and seeks to find out what sort of environment variables related to the variation of subway ridership during the two periods. The results show that the ridership of Beijing subway during the pandemic period decreased by 91.69% compared with the pre-pandemic period. On working days and non-working days during the pandemic period, the subway stations experiencing huge ridership reductions were mainly distributed within the core urban areas, while in the morning peak hours, the stations experiencing huge ridership reduction were located within suburban areas. The origin-destination stations with a large decrease in ridership were mainly distributed along the central to northern directions of Beijing but, on non-working days, they were mainly distributed along the central to northwestern directions of Beijing. The results of the regression analysis indicated that, during the pandemic period, the industrial parks were significantly positively correlated with subway ridership, while the pedestrian road network density was significantly negatively correlated with subway ridership.
{"title":"Spatial and Temporal Variation of Subway Ridership before and during the COVID-19 Period in Beijing","authors":"Chengshuai Liu, Hui He, Peng Chen","doi":"10.1177/03611981241263561","DOIUrl":"https://doi.org/10.1177/03611981241263561","url":null,"abstract":"The outbreak of COVID-19 in 2019 caused a huge impact on people’s lives. Uncovering the variation of public traffic daily patterns during the pre-pandemic and pandemic periods would help interpret the impact of the pandemic on people’s routine activity and promote the sustainable development of public transport systems. By collecting subway traffic data during the pre-pandemic and pandemic periods in Beijing, China, this paper analyzes the spatial and temporal variation of subway ridership and seeks to find out what sort of environment variables related to the variation of subway ridership during the two periods. The results show that the ridership of Beijing subway during the pandemic period decreased by 91.69% compared with the pre-pandemic period. On working days and non-working days during the pandemic period, the subway stations experiencing huge ridership reductions were mainly distributed within the core urban areas, while in the morning peak hours, the stations experiencing huge ridership reduction were located within suburban areas. The origin-destination stations with a large decrease in ridership were mainly distributed along the central to northern directions of Beijing but, on non-working days, they were mainly distributed along the central to northwestern directions of Beijing. The results of the regression analysis indicated that, during the pandemic period, the industrial parks were significantly positively correlated with subway ridership, while the pedestrian road network density was significantly negatively correlated with subway ridership.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141867503","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 : 2024-07-30DOI: 10.1177/03611981241260704
Qingfu Li, Hailong Wang, Huijun Xue
The early strength, microstructure, and structure of cement mortar under low-temperature curing conditions were investigated through compressive strength tests, scanning electron microscopy, x-ray diffraction, synchronous thermal analysis (thermogravimetric analysis coupled with differential scanning calorimetry), and nuclear magnetic resonance tests. The study focused on the impact of the single addition of nano-activated CaCO3 (NAC) and the simultaneous addition of metakaolin (MK) on cement mortar. The results indicate that the addition of NAC accelerated the early hydration of cement. At a 1% dosage, the compressive strength increased by 6.84%, 14.77%, and 18.58% at 1 day, 3 days, and 7 days, respectively. When 5% MK was co-added, the compressive strength increased by 15.16%, 27.85%, and 21.66% at 1 day, 3 days, and 7 days, respectively. The combination of NAC and MK accelerated the hydration of cement, refined the products, reduced the porosity, improved the microstructure, and enhanced the early compressive strength of cement-based materials.
{"title":"Influence of Nano-Activated CaCO3-Metakaolin on Early Strength and Microstructure of Cement","authors":"Qingfu Li, Hailong Wang, Huijun Xue","doi":"10.1177/03611981241260704","DOIUrl":"https://doi.org/10.1177/03611981241260704","url":null,"abstract":"The early strength, microstructure, and structure of cement mortar under low-temperature curing conditions were investigated through compressive strength tests, scanning electron microscopy, x-ray diffraction, synchronous thermal analysis (thermogravimetric analysis coupled with differential scanning calorimetry), and nuclear magnetic resonance tests. The study focused on the impact of the single addition of nano-activated CaCO<jats:sub>3</jats:sub> (NAC) and the simultaneous addition of metakaolin (MK) on cement mortar. The results indicate that the addition of NAC accelerated the early hydration of cement. At a 1% dosage, the compressive strength increased by 6.84%, 14.77%, and 18.58% at 1 day, 3 days, and 7 days, respectively. When 5% MK was co-added, the compressive strength increased by 15.16%, 27.85%, and 21.66% at 1 day, 3 days, and 7 days, respectively. The combination of NAC and MK accelerated the hydration of cement, refined the products, reduced the porosity, improved the microstructure, and enhanced the early compressive strength of cement-based materials.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141867432","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 : 2024-07-30DOI: 10.1177/03611981241263564
Yunsheng Zhu, Ruiyang Hua, Liming Song, Kaifeng Wang, Yue Li
With the widespread utilization of composite pavements in highway tunnel projects, the flammability issue of asphalt layers has garnered increasing attention. Previous research has demonstrated that the addition of flame retardants effectively reduces the occurrence of pavement fires. However, there are few studies combining asphalt flame retardant technology with tunnel composite pavement structures. Therefore, this paper, considering the context of actual engineering projects, uses ABAQUS software to analyze and calculate the mechanical response of the tunnel composite pavement, considering the thickness of various asphalt layers under the ablation depth. Key design indexes such as shear stress and lower tensile strain of the asphalt layer, the bottom tensile stress of the cement concrete subgrade, and interlayer shear stress between the asphalt layer and cement concrete subgrade of composite pavements are analyzed using the nonlinear finite element analysis method. The findings enable the determination of the optimal thickness of the composite pavement asphalt layer combination after ablation, thus contributing to enhancing the safety of tunnel pavements.
{"title":"Study on Mechanical Properties of Tunnel Flame Retardant Asphalt Pavement Considering the Ablative Effect","authors":"Yunsheng Zhu, Ruiyang Hua, Liming Song, Kaifeng Wang, Yue Li","doi":"10.1177/03611981241263564","DOIUrl":"https://doi.org/10.1177/03611981241263564","url":null,"abstract":"With the widespread utilization of composite pavements in highway tunnel projects, the flammability issue of asphalt layers has garnered increasing attention. Previous research has demonstrated that the addition of flame retardants effectively reduces the occurrence of pavement fires. However, there are few studies combining asphalt flame retardant technology with tunnel composite pavement structures. Therefore, this paper, considering the context of actual engineering projects, uses ABAQUS software to analyze and calculate the mechanical response of the tunnel composite pavement, considering the thickness of various asphalt layers under the ablation depth. Key design indexes such as shear stress and lower tensile strain of the asphalt layer, the bottom tensile stress of the cement concrete subgrade, and interlayer shear stress between the asphalt layer and cement concrete subgrade of composite pavements are analyzed using the nonlinear finite element analysis method. The findings enable the determination of the optimal thickness of the composite pavement asphalt layer combination after ablation, thus contributing to enhancing the safety of tunnel pavements.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"74 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141867512","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 : 2024-07-30DOI: 10.1177/03611981241262297
John S. Miller, Nishara Vavitta Parambil
Nationally, some regional planning agencies (RPAs) devote less attention to planning for truck freight than for passengers. To increase future regional truck freight planning, this paper reports the survey results from 22 Virginia RPA freight planning practices. Some RPAs were interested in practices not yet undertaken: provision of parking during emergencies (of interest to half the respondents), incorporation of parking needs as part of zoning ordinances (one-third), and provision of locally funded parking areas (a quarter). RPAs were heterogeneous: none of the 50 practices interested all RPAs and, on average, a given practice interested just 23% of respondents. Practices rarely undertaken but of high interest included identifying critical gaps in the truck freight network, identifying load-restricted bridges affecting business deliveries, and incorporation of parking needs into zoning ordinances. Accordingly, one such practice was piloted with one RPA, demonstrating that having adequate off-site locations to situate trucks for unloading is a pressing problem. The survey and pilot revealed that truck freight planning can be encouraged by tailoring practices to tightly defined regional interests. One pilot question concerned how future land use might stimulate off-site parking demand near pickup or delivery points. The ability to give a rough answer quickly led to a resulting action item proposed by the locality: explicit consideration of truck parking within the county comprehensive plan. The results showed that although additional data can yield a more exact answer, sketch-level planning information was sufficient to initiate a collaborative effort between a state and a willing regional participant.
{"title":"Assessing Regional Agency Interest in Truck Freight Planning Practices: Insights from Virginia","authors":"John S. Miller, Nishara Vavitta Parambil","doi":"10.1177/03611981241262297","DOIUrl":"https://doi.org/10.1177/03611981241262297","url":null,"abstract":"Nationally, some regional planning agencies (RPAs) devote less attention to planning for truck freight than for passengers. To increase future regional truck freight planning, this paper reports the survey results from 22 Virginia RPA freight planning practices. Some RPAs were interested in practices not yet undertaken: provision of parking during emergencies (of interest to half the respondents), incorporation of parking needs as part of zoning ordinances (one-third), and provision of locally funded parking areas (a quarter). RPAs were heterogeneous: none of the 50 practices interested all RPAs and, on average, a given practice interested just 23% of respondents. Practices rarely undertaken but of high interest included identifying critical gaps in the truck freight network, identifying load-restricted bridges affecting business deliveries, and incorporation of parking needs into zoning ordinances. Accordingly, one such practice was piloted with one RPA, demonstrating that having adequate off-site locations to situate trucks for unloading is a pressing problem. The survey and pilot revealed that truck freight planning can be encouraged by tailoring practices to tightly defined regional interests. One pilot question concerned how future land use might stimulate off-site parking demand near pickup or delivery points. The ability to give a rough answer quickly led to a resulting action item proposed by the locality: explicit consideration of truck parking within the county comprehensive plan. The results showed that although additional data can yield a more exact answer, sketch-level planning information was sufficient to initiate a collaborative effort between a state and a willing regional participant.","PeriodicalId":517391,"journal":{"name":"Transportation Research Record: Journal of the Transportation Research Board","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141867435","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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