Tokyo Metropolitan Area Research Articles

Lognormal distribution of daily travel time and a utility model for its emergence

Understanding the nature of human movement is important in many fields, such as transportation management, urban planning, and epidemiology. In this study, we focus on travelers who are grouped by their travel modes in the Tokyo Metropolitan Area. Notably, for each group of travelers, the distribution of daily travel time follows a lognormal distribution. For any travel mode, the distributions of normalized travel time for different years (1968–2008) and distances to the city center converge to a curve, although the average travel time and share of travel modes vary. By employing the concept of utility, we developed a disaggregate model wherein an individual maximizes utility from traveling (=benefit - cost) by modifying daily travel time. This model theoretically explained the observed distributions of travel time. The model was further used to demonstrate travel mode choices. The model parameters were estimated using the distribution of travel time, travel mode share, and manageable assumptions. These results provided interesting interpretations of the perceptual utility of the daily travel time of a population. Moreover, the obtained curves of utility versus time are similar to the shapes of the overall benefits assumed in previous studies. Overall benefit is a concept that has been developed and examined since the 1980s, and our study provides a mathematical foundation for this idea.

How Are Tier 2 Metropolises Affected by Housing Asset Value Deflation in the Depopulation Era? A Comparison between the Tokyo and Kansai Metropolitan Areas

This study analyzes the differences and similarities between Tier 1 (Tokyo) and Tier 2 (Kansai) metropolitan areas due to shrinking city problems. Both metropolitan areas will see a dramatic decrease in the housing asset value (HAV). Kansai is declining at a faster pace than Tokyo: it is projected that HAVs will register a further decrease of around 38% by 2045, and the decline will be quantitatively more important in the northern suburbs of Osaka. These results raised the question of whether Kansai would be more impoverished by HAV deflation. By focusing on the income multiplier of HAV per household, we find that Tokyo has a higher income multiplier of around 4 (against 2 for Osaka), thus causing much greater HAV deflation per household in Tokyo. Greater HAV deflation per household entails more severe problems for elderly households that need to finance their retirement. Considering our findings, despite earlier and faster trends of HAV deflation in the Tier 2 metropolitan area, the Tier 1 metropolitan area could face big socioeconomic challenges in the future. We conclude that HAV deflation leads to problems of different nature depending on metropolitan rank, rather than just knowing which one is losing more through HAV deflation.

Assessing regional variations in hydrogen fuel cell vehicle adoption: An integrative approach using real-world data and analytic hierarchy process in Tokyo

This research delves into the market potential for hydrogen fuel cell vehicles (FCVs) while placing a significant emphasis on evaluating regional distinctions within the Tokyo metropolitan area. We introduce an innovative methodology that seamlessly integrates real-world data and the Analytic Hierarchy Process (AHP) to assess the regional market potential of FCVs. This approach is meticulously designed to capture subtle variations among regions and fine-tune the hierarchy of influencing factors, including vehicle performance, economic costs, social contexts, fuel availability, and policy support. Through an extensive case study conducted in Tokyo, this investigation underscores the impact of regional heterogeneity on consumer choices and substantiates these findings by analyzing real-world FCV sales data. This validation reinforces the reliability of the identified key influencing factors and underscores the critical significance of considering regional differences in comprehending FCV market adoption. The assessment methodology introduced offers a systematic framework for stakeholders in the FCV sector, supporting informed strategic decision-making and policy development.

Climate change adaptation and mitigation potential of EVs in Tokyo metropolitan area

Penetration of low heat-emitting electric vehicles (EVs) in urban areas is expected to have a positive effect on climate change adaptation by improving the thermal environment, and indirect mitigation by reducing building CO2 emissions. To assess these effects, a case study was conducted in Tokyo using an urban canopy model. We quantified the impact and characterize its spatio-temporal structure, through a comparative evaluation with other forms of e-mobility (hybrid electric vehicles and fuel cell vehicles) and established UHI measures (ground greening and cool roofs). EVs showed the largest effect among all e-mobilities, both in absolute temperature reduction (ΔT) and cooling efficiency (ΔT per reduced heat), owing to the positive feedback on atmospheric stability. The ΔT caused by EV is more pronounced in the morning and evening hours, and in urban centers. On the other hand, the ΔT due to UHI measures peaks at midday and is more pronounced in suburban areas. In other words, they complement each other spatially and temporally. The peak ΔT caused by the EVs exceeded that of the UHI measures by approximately 40% of the total area. The contribution of indirect CO2 mitigation is negligible in the life-cycle CO2 emissions of EVs.

Human behavioral response to earthquake early warnings (EEW): Are alerts received on mobile phones inhibiting protective actions?

Earthquake Early Warning (EEW) systems alert residents in locations likely to be shaken by large earthquakes. Despite the short warning period from the reception of an EEW until the arrival of shaking, residents are expected to protect themselves during the available time. Contrary to such expectations, previous research has revealed that most people did not take protective actions after receiving an EEW. Additionally, it was revealed that most people received EEW messages via mobile phones. This study empirically examined the relationship between receiving an EEW on mobile phones and taking protective actions. In the first case, a survey (N = 3000) was conducted to investigate residents’ reactions immediately after receiving an EEW issued for the Tokyo metropolitan area on October 7, 2021, for an earthquake of magnitude 6.0. The results suggested that the most common reaction upon receiving an EEW was to consult mobile phones to better understand the message. Thus, mobile phones receive more attention than the impending danger, resulting in the loss of precious seconds that could be used to take protective actions. In the second case, a survey (N = 1000) was conducted on another EEW issued for an earthquake of magnitude 6.3, which occurred in Ishikawa Prefecture on May 5, 2023. The results were consistent with those of the first survey, suggesting that the findings described above are robust. Finally, this study discusses ways to mitigate the dangers associated with earthquakes based on the findings of these studies.

Value of travel time savings for leisure trip in autonomous vehicles: Case study from the Tokyo Metropolitan Area

This study estimates the value of travel time savings (VTTSs) in autonomous vehicles (AVs) for leisure trip, using data collected from a stated-choice survey in the Tokyo Metropolitan Area, Japan. The survey was implemented through an internet monitoring program from February to March 2020, collecting 1,224 responses to stated-choice questions from 204 respondents. The survey was designed to request that the respondents choose AV or non-AV under six hypothetical conditions of travel time and cost when they are assumed to be using a car rental service to travel alone for a leisure purpose trip. Simple binary logit models are employed with two types of specifications in the utility function. First, the estimation results of the models without heterogeneity in the utility function showed that the VTTS in AVs is lower than that in non-AVs by approximately 7.3 % on average; however, the reduction of VTTS is not statistically significant. Second, the estimation results of the models incorporating observable heterogeneity into the marginal utility with respect to travel time also revealed that the individual’s preference of in-vehicle multitasking, age, and gender do not significantly affect the reduction of VTTS in AVs. Finally, changes in preference of AV-unique multitasking may affect VTTS, which should be monitored for future updating the VTTS guidelines.

Characteristics of Helicobacter pylori Eradication Therapy in Patients 80 Years or Older Living in a Metropolitan Area: A Multicenter Retrospective Study.

The situation of Helicobacter pylori eradication therapy has been changing over time, owing to increases in antimicrobial-resistant strains, lifestyle improvements, and changes in indications for eradication. In Japan, eradication therapy is now available to all H. pylori-positive patients under the medical insurance system, and the potassium-competitive acid blocker vonoprazan has been used for eradication from 2015. Recently, with the aging of society, opportunities to provide eradication to elderly patients are increasing, but the current status and effectiveness of eradication in elderly patients remains unclear. Therefore, we aimed to investigate the trends of H. pylori eradication in a metropolitan area to determine the factors associated with successful H. pylori eradication in elderly patients older than 80 years. Trends in the eradication rates of patients who received first- or second-line eradication at 20 hospitals in the Tokyo metropolitan area from 2013 to 2023 were investigated. The eradication rates in the per-protocol analysis were 82.3% (95% confidence interval [CI]: 81.2%-83.2%) for the first-line treatment (n = 6481), and 87.9% (86.9%-88.9%) for the second-line treatment (n = 4899). Multivariate analysis showed that independent factors for successful eradication in the first-line treatment were an age of older than 80 years (OR: 0.606; 95% CI: 0.448-0.822), peptic ulcers (vs. atrophic gastritis: 3.817; 3.286-4.433), and vonoprazan (vs. proton pump inhibiters (PPIs), 3.817; 3.286-4.433), and an age of older than 80 years (0.503; 0.362-0.699) and vonoprazan (1.386; 1.153-1.667) in the second-line treatment. After 2015, the eradication rate of both first- and second-line therapies were maintained at a higher level than before 2015, owing to the use of vonoprazan. As the H. pylori eradication rate in patients older than 80 years was low, an effective strategy for these patients needs to be developed in the future.

Community gardens and psychological well-being among older people in elderly housing with care services: The role of the social environment

With population aging, increasing numbers of elderly people in Japan are expected to enter aged care facilities (ACFs). Although research has shown that access to community gardens (CGs) is generally beneficial to older people's psychological well-being, the mechanisms by which the usage and quality of CGs influence the well-being of older adults in ACFs remain insufficiently studied. Therefore, this study aims to explore the associations between garden factors (i.e., garden visit frequency and perceived garden quality) and older adults' psychological well-being outcomes (i.e., positive well-being and self-rated health) and to investigate the mediating role of neighborhood social environment factors (i.e., outing frequency, social participation, perceived neighborhood social cohesion, and perceived neighborhood attachment) in these associations. We conducted a questionnaire survey with 322 older adults from twelve elderly housing with care services (EHCSs) in the Tokyo metropolitan area (TMA) of Japan. The multiple regression models showed that both garden factors were positively associated with positive well-being and self-rated health. The parallel mediation models showed that higher garden visit frequency and perceived garden quality were associated with higher outing frequency and perceived neighborhood social cohesion and, in turn, with higher positive well-being. Moreover, higher garden visit frequency and perceived garden quality were associated with greater social participation and thereby with better self-rated health; higher perceived garden quality was also associated with higher perceived neighborhood attachment and thus with better self-rated health. Our findings elucidate the potential mechanisms underlying the beneficial associations between CGs and the psychological well-being of older adults in ACFs, emphasizing the important role of cultivating friendly social environments in CGs in enhancing healthy aging.

Association between subjective well‐being and cognition of neighborhood places: An online questionnaire study conducted in the Tokyo metropolitan area

AbstractImproving individuals' subjective well‐being has become a focus of policymaking globally in recent times. The current study examined the association between cognition of neighborhood places and subjective well‐being, with the aim of informing urban planning and community development efforts to improve the latter. An online questionnaire was distributed among residents in the Tokyo metropolitan area, and 2600 individuals responded. Regression analysis showed that respondents with greater neighborhood awareness and higher levels of education and household income exhibited better subjective well‐being. Moreover, psychological distress, loneliness, and sense of coherence were observed to be associated with amount of cognition of neighborhood places. Another regression analysis revealed that amount of cognition of neighborhood places was associated with education levels and household income independently, suggesting the possibility of amount of cognition of neighborhood places playing a mediatory role in health disparities, a global public health concern. The findings of the current study suggest that urban planning and community development policies should aim to increase individuals' amount of cognition of neighborhood places by improving accessibility and providing information on the history, available facilities, and culture of their neighborhood. These measures should also be conducted in areas with residents from lower socioeconomic strata.

Clinical characteristics in children with maturity-onset diabetes of the young detected by urine glucose screening at schools in the Tokyo Metropolitan Area.

This study aimed to examine the clinical characteristics of young children diagnosed with maturity-onset diabetes (MODY) using urine glucose screening at schools. The study participants were 70 non-obese children who were clinically diagnosed with type 2 diabetes through urine glucose screening at schools in Tokyo between 1974 and 2020. Of these children, 55 underwent genetic testing, and 21 were finally diagnosed with MODY: MODY2 in eight, MODY3 in eight, MODY1 in four and MODY5 in one. A family history of diabetes was found in 76.2% of the patients. Fasting plasma glucose levels did not differ between the different MODY subtypes, while patients with MODY 3, 1, and 5 had significantly higher levels of glycosylated hemoglobin and 2-hour glucose in an oral glucose tolerance test than those with MODY2. In contrast, most patients exhibit mild insulin resistance and sustained β-cell function. In the initial treatment, all patients with MODY2 were well controlled with diet and exercise, whereas the majority of those with MODY3, 1, and 5 required pharmacological treatment within one month of diagnosis. In conclusion, urine glucose screening in schools appears to be one of the best opportunities for early detection of the disease and providing appropriate treatment to patients.

Associations of Working From Home Frequency With Accelerometer-Measured Physical Activity and Sedentary Behavior in Japanese White-Collar Workers: A Cross-Sectional Analysis of the Meiji Yasuda LifeStyle Study.

The association of working from home (WFH) with physical activity (PA) and sedentary behavior (SB) has been explored; however, this association during periods without stringent measures to combat coronavirus disease 2019 is undercharacterized. Particularly, few studies have evaluated the potential effect modification on its associations. Therefore, this study aimed to investigate the associations of WFH frequency with accelerometer-measured PA and SB, along with its effect modifiers, among Japanese white-collar workers during the later pandemic period. A cross-sectional study involving 1133 white-collar workers residing in the Tokyo metropolitan area was conducted between April 2022 and March 2023. WFH frequency was evaluated through a self-report questionnaire, while SB and PA during weekdays were measured using a triaxial accelerometer. Linear regression models adjusting for potential confounders were used to examine the association of WFH frequency with PA and SB. Regardless of activity intensity, individuals who worked at home, even for 1 to 2days per week, demonstrated lower levels of PA and higher levels of SB as compared with those who did not (P < .05). For example, difference between never and ≥5days per week WFH was approximately 70minutes/day for total PA and about 4000 steps/day for step counts. Associations between WFH and decreased PA were more pronounced in workers who were older, female, less educated, in sales and service work, nonregular staff, and precontemplating changes in exercise and eating habits. We report that WFH was associated with decreased PA and increased SB in Japanese white-collar workers with pronounced associated in several subgroups.

The evolution of urban freight generation: a study of intra- and inter-city truck trips

The operations and spatial structure of logistics-related facilities has evolved with the growth of the global production network and the advancement of information and communication technology over the past several decades. Such logistics evolutions are thought to have occurred in tandem with changes in urban freight transportation systems. We estimate models for freight trip generation using the data from 2003 and 2013 in the Tokyo Metropolitan Area. The results suggest that the relationship between employment size and freight trip generation weakened during the study period and that the scale of freight generation and the generation of intercity freight trips became less connected.

An assessment of ashfall impacts and a study of measures in the Tokyo metropolitan area from an eruption of Mt. Fuji

An assessment of ashfall impacts and a study of measures in the Tokyo metropolitan area from an eruption of Mt. Fuji

A Study on the Sustainability of the Water Supply Service in Tokyo Metropolitan Area based on Estimated Future Cost by the Mesh Unit

A Study on the Sustainability of the Water Supply Service in Tokyo Metropolitan Area based on Estimated Future Cost by the Mesh Unit

A study on the achievements and issues of the Renovation Machizukuri in the suburbs of the Tokyo Metropolitan Area

A study on the achievements and issues of the Renovation Machizukuri in the suburbs of the Tokyo Metropolitan Area

Aging City and House Prices: Impact of Aging Condominium Stock on the Housing Market in the Tokyo- Metropolitan Area

Based on an analysis of the housing market in the Tokyo metropolitan area, this study focuses on the external diseconomies of aging condominiums. It is possible that the quality of the condominium stock deteriorates more rapidly than that of ordinary housing. This deterioration in quality leads to a reduction in the quality of housing services received by residents. Furthermore, this worsening of the residential environment may lead to external diseconomies. We run hedonic models to identify the external diseconomies of aging condominiums in the residential market of the Tokyo metropolitan area. The results of our estimated models indicate that such external diseconomies occur for detached housing in areas where detached houses and condominiums coexist. These external diseconomies exert downward pressure on prices. Specifically, detached housing prices are lowered by around 3.2% for each 1% increase in the proportion of total building floor area in neighborhoods where condominiums were built before 1990. In other words, aging condominiums begin to generate diseconomies in their vicinities approximately 20 years after they were built.

Associations Between Generativity and Social Asymmetry Among Older Adults in Japan.

Loneliness and social isolation are major public health concerns among older adults in Japan. Generativity, the concern for and commitment to future generations, may buffer older adults from loneliness. This study examined the cross-sectional and longitudinal associations between generativity and social asymmetry (the discrepancy between social isolation and loneliness) among older adults in Japan. Data were from 2 waves (2008 and 2012) of the Midlife in Japan survey, a nationally representative longitudinal study of 645 adults aged 30-79 residing in the Tokyo metropolitan area. Generativity was measured using the 6-item Loyola Generativity Scale. Social asymmetry was computed as the residual score from regressing loneliness onto social isolation. Higher generativity levels were associated with lower social asymmetry scores (B=-0.21, SE=0.04), but generativity change across waves did not predict social asymmetry 4 years later (B=-0.04, SE=0.06). Generativity may play a protective role in buffering older adults from the adverse effects of social isolation on loneliness. Promoting generativity among older adults may be a potential intervention strategy to reduce loneliness and improve well-being in aging populations in Japan.

Social segregation levels vary depending on activity space types: Comparison of segregation in residential, workplace, routine and non-routine activities in Tokyo metropolitan area

Given the dynamic spatial characteristics of modern cities, the issue of social segregation based on activity spaces has been gaining increased attention. However, few studies have performed a detailed comparison of the differences in social segregation at different types of activities space on the citywide scale with a relatively small granularity from both place and individual perspectives. To gain a better understanding of the intricate and dynamic aspects of human mobility and its patterns of segregation, it is necessary to conduct comparative research utilizing several activity segregation indices by exploring different contexts behind people's activities. Thus, in this study, we take the Tokyo metropolitan area as a case and classify the activity spaces into four categories: residential, working, routine activities, and non-routine activities, and then calculate the place income segregation and individual experienced income segregation under different activity contexts. Our findings show that the segregation levels vary depending on the activity contexts. For the place income segregation, the segregation level in residential and non-routine activity spaces tends to be higher than that in the working and routine activity spaces, respectively. In terms of spatial distribution, the values of segregation indicators in the suburbs deviate more from the regional mean. In addition, the main composition of the population in highly segregated areas is low- and middle-income class groups, and there are no super-rich activity areas that completely exclude other income groups in the Tokyo metropolitan area. For the individual experienced income segregation, the higher the household income, the lower the segregation level among all households except the poorest. Furthermore, the differences between individual income segregation indicators tend to be smaller near the central area and bigger in suburban areas. This work demonstrates the importance of comparing the differences in various activity segregation contexts in urban spaces instead of merely focusing on one specific perspective.

Cross-sectional study of factors related to COVID-19 vaccination uptake among university healthcare students.

Healthcare students are more likely to become infected than other university students as they may encounter patients with COVID-19 during clinical training. Vaccination uptake is essential to prevent infection. This study explored factors related to COVID-19 vaccination uptake among healthcare students. This cross-sectional study conducted online surveys of undergraduate and graduate nursing and healthcare graduate students from four medical universities in the Tokyo Metropolitan Area of Japan. Data were collected from June to August 2022, when the fourth vaccination program was initiated. Data from 1,169 students were analyzed (response rate = 37.3%). The mean age was 25.1 ± 7.6 years, and most were female (82.3%). Academic majors included nursing (68.0%), medicine (16.3%), dentistry (9.3%), and others (6.4%). Thirty students (2.6%) were not vaccinated, one student (0.1%) had received one vaccination, 997 (85.3%) had received three, and 27 (2.3%) had received four. The major reason for not being vaccinated was insufficient confirmation of its safety (n = 25). Students who had received at least one vaccination (n = 1,139), 965 (84.7%) reported experiencing adverse side effects, the most frequent being pain at the injection site (76.2%), followed by fever (68.3%). In the logistic regression, a greater number of vaccinations (3-4 times) was associated with older age (odds ratio, OR = 1.53), working (OR = 1.67), and more frequent infection-preventive behaviors (OR = 1.05). Significantly fewer students were vaccinated at University B than at University A (OR = 0.46). Additionally, those majoring in subjects other than nursing (OR = 0.28), and students from non-Asian countries (OR = 0.30) were less likely to be vaccinated. It is necessary to pay attention to and encourage the vaccination of students who engage in low levels of preventive behavior, students who are young, international, or unemployed, and those in non-healthcare professional majors.

Anthropogenic CO2 emission estimates in the Tokyo metropolitan area from ground-based CO2 column observations

Abstract. Urban areas are responsible for more than 40 % of global energy-related carbon dioxide (CO2) emissions. The Tokyo metropolitan area (TMA), Japan, one of the most populated regions in the world, includes various emission sources, such as thermal power plants, automobile traffic, and residential facilities. In order to infer a top–down emission estimate, we conducted an intensive field campaign in the TMA from February to April 2016 to measure column-averaged dry-air mole fractions of CO2 (XCO2) with three ground-based Fourier transform spectrometers (one IFS 125HR and two EM27/SUN spectrometers). At two urban sites (Saitama and Sodegaura), measured XCO2 values were generally larger than those at a rural site (Tsukuba) by up to 9.5 ppm, and average diurnal variations increased toward evening. To simulate the XCO2 enhancement (ΔXCO2) resulting from emissions at each observation site, we used the Stochastic Time-Inverted Lagrangian Transport (STILT) model driven by meteorological fields at a horizontal resolution of ∼1 km from the Weather Research and Forecasting (WRF) model, which was coupled with anthropogenic (large point source and area source) CO2 emissions and biogenic fluxes. Although some of the diurnal variation of ΔXCO2 was not reproduced and plumes from nearby large point sources were not captured, primarily because of a transport modeling error, the WRF–STILT simulations using prior fluxes were generally in good agreement with the observations (mean bias, 0.30 ppm; standard deviation, 1.31 ppm). By combining observations with high-resolution modeling, we developed an urban-scale inversion system in which spatially resolved CO2 emission fluxes at &gt;3 km resolution and a scaling factor of large point source emissions were estimated on a monthly basis by using Bayesian inference. The XCO2 simulation results from the posterior CO2 fluxes were improved (mean bias, −0.03 ppm; standard deviation, 1.21 ppm). The prior and posterior total CO2 emissions in the TMA are 1.026 ± 0.116 and 1.037 ± 0.054 Mt-CO2 d−1 at the 95 % confidence level, respectively. The posterior total CO2 emissions agreed with emission inventories within the posterior uncertainty, demonstrating that the EM27/SUN spectrometer data can constrain urban-scale monthly CO2 emissions.