Non-linear impacts of COVID-19 pandemic on human mobility: Lessons from its variations across three pandemic waves

This study sought to understand how the COVID-19 pandemic influenced human mobility patterns in a city, how the influences varied across the pandemic wave phases, and how the influences differed between car and bus trips. Data for the pandemic and individual-level trips were collected from Daejeon Metropolitan City in South Korea. Three indices of trip demand and trip randomness were used to represent mobility patterns and were compared with the number of confirmed COVID-19 cases. The results demonstrated different responses to the pandemic by transportation mode and revealed non-linear impacts of the COVID-19 pandemic on mobility patterns. Car dependency intensified and car trip randomness more sensitively fluctuated as the pandemic spread. The COVID-19 impacts on mobility follow a power-law relationship that revealed the existence of lower bounds of citizens’ travel-related responses to the pandemic, which generally increased over time, but its trend differed according to trip demand and randomness as the pandemic continued. The findings demonstrate variations in mobility patterns due to the long-lasting pandemic, which could not be explained solely by trip demand. This information can assist in the formulation of flexible policies that adapt to changes in travel behaviors

Develop safety surrogate measure for evaluating motor carrier companies and drivers

The risk of accidents of commercial vehicles is higher than that of ordinary vehicles. Traffic fatalities per registered vehicles are 3.8 times higher than in commercial vehicles than ordinary vehicles in 2016. Because of the high severity of accidents, there should be a lot of effort to reduce accidents and manage traffic safety of motor carrier companies. So far, safety assessments for commercial vehicles have been evaluated according to the frequency and the severity of accidents. This approach has several problems. First, the accident can not be preemptively prevented because it is based on the post evaluation of the accident. Second, it is difficult to provide consulting or action guidelines because it is impossible to determine what factors caused traffic accidents. With the recent development of data collection technology, not only traffic accident information, but also the various characteristics of motor carrier companies and drivers such as vehicle driving record, dangerous driving behavior, law violation information are collected. Therefore, this study aims to develop a new safety surrogate measure based on various characteristics of motor carrier companies and drivers

Factors Affecting Crash Involvement of Commercial Vehicle Drivers: Evaluation of Commercial Vehicle Drivers’ Characteristics in South Korea

The aim of this study was to evaluate the effects of driver-related factors on crash involvement of four different types of commercial vehicles—express buses, local buses, taxis, and trucks—and to compare outcomes across types. Previous studies on commercial vehicle crashes have generally been focused on a single type of commercial vehicle; however, the characteristics of drivers as factors affecting crashes vary widely across types of commercial vehicles as well as across study sites. This underscores the need for comparative analysis between different types of commercial vehicles that operate in similar environments. Toward these ends, we analyzed 627,594 commercial vehicle driver records in South Korea using a mixed logit model able to address unobserved heterogeneity in crash-related data. The estimated outcomes showed that driver-related factors have common effects on crash involvement: greater experience had a positive effect (diminished driver crash involvement), while traffic violations, job change, and previous crash involvement had negative effects. However, the magnitude of the effects and heterogeneity varied across different types of commercial vehicles. The findings support the contention that the safety management policy of commercial drivers needs to be set differently according to the vehicle type. Furthermore, the variables in this study can be used as promising predictors to quantify potential crash involvement of commercial vehicles. Using these variables, it is possible to proactively identify groups of accident-prone commercial vehicle drivers and to implement effective measures to reduce their involvement in crashes

DTUMOS, digital twin for large-scale urban mobility operating system

Abstract The advancement of digital twin technology has significantly impacted the utilization of virtual cities in the realm of smart cities and mobility. Digital twins provide a platform for the development and testing of various mobility systems, algorithms, and policies. In this research, we introduce DTUMOS, a digital twin framework for urban mobility operating systems. DTUMOS is a versatile, open-source framework that can be flexibly and adaptably integrated into various urban mobility systems. Its novel architecture, combining an AI-based estimated time of arrival model and vehicle routing algorithm, allows DTUMOS to achieve high-speed performance while maintaining accuracy in the implementation of large-scale mobility systems. DTUMOS exhibits distinct advantages in terms of scalability, simulation speed, and visualization compared to current state-of-the-art mobility digital twins and simulations. The performance and scalability of DTUMOS are validated through the use of real data in large metropolitan cities including Seoul, New York City, and Chicago. DTUMOS’ lightweight and open-source environment present opportunities for the development of various simulation-based algorithms and the quantitative evaluation of policies for future mobility systems

Maritime supply chain risk sentiment and the korea trade volume: A news big-data analysis perspective

This study aims to develop an index for assessing Maritime Supply Chain Risks (MSCRs) capable of preemptively detecting potential crises in the container market and validating the predictive power with Korean container volumes. By employing Lexicon-based text analysis, we scrutinized 174,271 headlines from key maritime and port news from 2004 to 2023 to formulate MSCRs index. Further, the application of a VAR model elucidates the maritime container supply chain market's response to sentiment shocks. Our findings reveal that an integrative sentiment index (MSCRs), considering both maritime and port sectors, possesses higher predictive accuracy than when these sectors are examined individually. Although the shock response of the index is temporary, it exerts a more gradual impact on transshipment throughput.The results of this study underscore the substantial influence of sentiment shocks stemming from maritime transportation news. The constructed MSCRs index emerges as a significant predictive variable for the Korean maritime transportation market. This sentiment index is anticipated to assist government, port authorities, and shipping companies in policy and managerial decision-making, offering enhanced foresight and response mechanisms to navigate and mitigate potential crises

Changes in car and bus usage amid the COVID-19 pandemic: Relationship with land use and land price

This study aimed to explore the impacts of COVID-19 on car and bus usage and their relationships with land use and land price. Large-scale trip data of car and bus usage in Daejeon, South Korea, were tested. We made a trip-chain-level data set to analyze travel behavior based on activity-based travel volumes. Hexagonal cells were used to capture geographical explanatory variables, and a mixed-effect regression model was adopted to determine the impacts of COVID-19. The modeling outcomes demonstrated behavioral differences associated with using cars and buses amid the pandemic. People responded to the pandemic by reducing their trips more intensively during the daytime and weekends. Moreover, they avoided crowded or shared spaces by reducing bus trips and trips toward commercial areas. In terms of social equity, trips of people living in wealthier areas decreased more than those of people living in lower-priced areas, especially trips by buses. The findings contribute to the previous literature by adding a fundamental reference for the different impacts of pandemics on two universal transportation modes

Effects of Urban Sprawl and Vehicle Miles Traveled on Traffic Fatalities

<div><p><b>Objective</b>: Previous research suggests that urban sprawl increases auto-dependency and that excessive auto use increases the risk of traffic fatalities. This indirect effect of urban sprawl on traffic fatalities is compared to non–vehicle miles traveled (VMT)-related direct effect of sprawl on fatalities.</p><p><b>Methods</b>: We conducted a path analysis to examine the causal linkages among urban sprawl, VMT, traffic fatalities, income, and fuel cost. The path diagram includes 2 major linkages: the direct relationship between urban sprawl and traffic fatalities and the indirect effect on fatalities through increased VMT in sprawling urban areas. To measure the relative strength of these causal linkages, path coefficients are estimated using data collected nationally from 147 urbanized areas in the United States.</p><p><b>Results</b>: Through both direct and indirect paths, urban sprawl is associated with greater numbers of traffic fatalities, but the direct effect of sprawl on fatalities is more influential than the indirect effect.</p><p><b>Conclusions</b>: Enhancing traffic safety can be achieved by impeding urban sprawl and encouraging compact development. On the other hand, policy tools reducing VMT may be less effective than anticipated for traffic safety.</p></div

Atomic Layer Deposition Route to Scalable, Electronic-Grade van der Waals Te Thin Films

Scalable production and integration techniques for vander Waals(vdW) layered materials are vital for their implementation in next-generationnanoelectronics. Among available approaches, perhaps the most well-receivedis atomic layer deposition (ALD) due to its self-limiting layer-by-layergrowth mode. However, ALD-grown vdW materials generally require highprocessing temperatures and/or additional postdeposition annealingsteps for crystallization. Also, the collection of ALD-produciblevdW materials is rather limited by the lack of a material-specifictailored process design. Here, we report the annealing-free wafer-scalegrowth of monoelemental vdW tellurium (Te) thin films using a rationallydesigned ALD process at temperatures as low as 50 &amp; DEG;C. They exhibitexceptional homogeneity/crystallinity, precise layer controllability,and 100% step coverage, all of which are enabled by introducing adual-function co-reactant and adopting a so-called repeating dosingtechnique. Electronically, vdW-coupled and mixed-dimensional verticalp-n heterojunctions with MoS2 and n-Si, respectively, aredemonstrated with well-defined current rectification as well as spatialuniformity. Additionally, we showcase an ALD-Te-based threshold switchingselector with fast switching time (&amp; SIM;40 ns), selectivity (&amp; SIM;10(4)), and low V (th) (&amp; SIM;1.3 V).This synthetic strategy allows the low-thermal-budget production ofvdW semiconducting materials in a scalable fashion, thereby providinga promising approach for monolithic integration into arbitrary 3Ddevice architectures