Does the built environment matter for active travel among older adults: Insights from Chiba City, Japan
Introduction
Population ageing is significant in both post-industrial and developing countries. According to the United Nations (2019), in 2019 one in eleven people were an older person (aged 65 and above). It is predicted that the ratio will reach one in six by 2050 (United Nations, 2019), and that the world ageing population will experience a higher growth rate than the younger population (He et al., 2016). Japan in particular tops the global population ageing list with an expected ageing rate of 40% by 2055 (Sasaki et al., 2017). With a growing ageing population, the mobility needs of older people have been widely documented in relation to their social participation, physical health, quality of life, and well-being (Banister and Bowling, 2004; Chen et al., 2021; Kroesen and De Vos, 2020; Metz, 2000). Active travel (e.g., walking and cycling) is increasingly considered to contribute to physical mobility levels and thereby having positive effects on the ageing population to reduce physical risk, and ensure the quality of life (Banister and Bowling, 2004; Pucher et al., 2010; Vale et al., 2015). In particular, active travel is documented to reduce the risks of chronic diseases, such as obesity (Flint and Cummins, 2016), high blood pressure, and other ageing related risk of chronic diseases, leading to better physical conditions and significant health care cost savings per year (Jarrett et al., 2012). Active travel also associates with a higher degree of travel satisfaction and subjective well-being, compared to mechanised travel (De Vos et al., 2016). Hence, understanding the patterns of active travel behaviour and how to encourage active travel among older adults have drawn increasing attention by scholars in recent years.
In the literature, socio-demographic characteristics and built environment factors are often used to explain active travel of older adults (Cheng et al., 2019, Cheng et al., 2020; Yang et al., 2018, Yang et al., 2021). Significant heterogeneity among older adults in active travel patterns has been demonstrated, varying by individual attributes (e.g., age, gender, work status), and household attributes, such as the number of household members, and availability of transport resources. Age is negatively related to older adults' trip generation (Böcker et al., 2017; Yang et al., 2018). Prins et al. (2014) indicated that elderly aged 75 and above walk more frequently than cycling, while the opposite occurs for those aged under 75. Older females are observed to generate more and shorter active trips (Cheng et al., 2019). Cheng et al. (2019) also uncovered that education level negatively influences active trip making. A similar finding has been noted by a study in the Netherlands that high educated seniors tend to be less likely to ride active modes (Schwanen et al., 2001). A recent study in China also indicates that older people holding a driver license prefer to make a longer active trip (Cheng et al., 2019). Furthermore, having a job has been found to be negatively associated with older people’ active travel (Schwanen et al., 2001).
In addition to the effects of individual characteristics, household attributes also exert significant effects on active travel behaviour of older adults. Studies in China have revealed a negative effect of larger households on active travel among older people (Cheng et al., 2019; Z. Liu et al., 2021a, Liu et al., 2021b). Yang et al. (2018) and Cheng et al. (2019) both reported that older adults with higher household income level conduct more active trips. With regard to availability of transport resources, studies in the U.S. (Yang et al., 2018), the Netherlands (Böcker et al., 2017), and China (Cheng et al., 2019) revealed that car ownership poses a significant negative effect on active travel among older adults. Unsurprisingly, bicycle ownership has a significant positive impact on active travel (in particular, cycling) among older adults (Cheng et al., 2019; Zhang et al., 2016).
Relationship between built environment and active travel among older adults has also been detected in previous research, wherein the D factors have been of particular interest, including density, diversity (e.g., land use mixture) and design (e.g., neighbourhood design) (Cervero and Kockelman, 1997) and later, distance to public transport, and destination accessibility (Ewing and Cervero, 2010).From the findings, a recurrent observation appears to be that the probability of active travel use by older people tends to be higher in denser, and more diverse urbanised surroundings (Cheng et al., 2019; Hatamzadeh and Hosseinzadeh, 2020; Zhang et al., 2016). This might be attributed to that areas with the high density and mixed land use are associated with better spatial proximity to diverse facilities, allowing walking and cycling to be a feasible alternative, in particular for older people (Moniruzzaman and Páez, 2016). Neighbourhood design has been identified as one important factor influencing active travel for older adults. For example, green residential environment (Kemperman and Timmermans, 2009), availability of gardens and shops (Borst et al., 2009), as well as the presence of pavements (Hess et al., 1999), correlate positively with active travel. Studies by Rodríguez et al. (2009) and Shigematsu et al. (2009) indicated that proximity to destinations/facilities provide an opportunity to promote active travel (in particular, walking) for older people. This finding is illustrated by later studies that older adults are inclined to make an active travel in activity friendly environments to ensure safety and easy access to services and amenities (Borst et al., 2009; Ewing et al., 2015; Hirsch et al., 2014). The findings of effects of distance to public transport on active travel are often positive (Cheng et al., 2019; Yang et al., 2021; Zhang et al., 2016). A possible explanation is that public transport usage requires walking or cycling as a feeder mode (Bopp et al., 2015).
Geographically, despite the known studies on the relationship between the determinants (socio-demographics and built environment) and active travel for older adults, the existing research has drawn disproportionally on the dataset in European and American countries (Nagel et al., 2008; Yang et al., 2018). The insights on active travel of older adults in the rest of the world are limited, especially in Japan, where the socio-cultural context differs significantly from that of the Western world, as well as other parts of Asia. A point worth noting is that these findings on active travel in a Western context also cannot be necessarily transferred to an Asian context (Van Cauwenberg et al., 2011). Thus, an investigation of older adults in Japan will offer valuable insights for policymakers towards Japan's hyper-ageing context, contributing to an ageing-friendly society.
Among other factors, socio-cultural norms exert a profound influence on individual psychological factors such as lifestyle habits and attitudes, thus leading to individual differences on travel behaviour (Scheiner, 2010). In Japan, familial integration across different generations is highly valued in Japan, leading to intergenerational co-residence household structure that is different from the Western context (Feng, 2017; Takagi and Silverstein, 2006). However, over recent years, the ratio of intergenerational co-residence households decreases – resulting in a scenario of partly intergenerational co-residence. The dynamic co-residence transforming leads to a shift in the travel patterns among a certain proportion of older people in Japan, for example, switching from sharing household affair activities (e.g., daily shopping) to personal affair activities (e.g., physical exercise, visiting friends). Moreover, the traditional gender norms in Japan lead to males undertaking more responsibility for household income, while females are more likely to take care of household affairs – resulting in different travel patterns before retirements. However, with the retirement of older males, such travel pattern differences have changed within households and their travel patterns have converged with those of their spouses. In addition, different preferences for recreational activities lead to differentiated patterns of active travel. For example, to fill their time in retirement, older adults in Japan prefer to walk their dogs in parks (Koohsari et al., 2020), while older adults in China prefer to play Tai Chi or dance in parks (Feng, 2017). Apparently, the socio-cultural norms in Japan could exert profound effects on older adults' travel patterns.
In addition, Japanese older adults may face their own transport problems. A growing number of drivers' license holders aged 65 and over have been increasing annually, reaching 18.85 million in 2019–22.9% of Japan's driving license holders (National Police Agency Bureau of Traffic, 2020). However, the proportion of at-fault drivers aged 65 and older in motor vehicle crashes has increased by 24% during the past decade (Ichikawa et al., 2016). Today, older drivers are encouraged to giving up their driving licenses by the National Policy Agency and local governments. Driving cessation, however, poses a challenge for older adults, as their basic daily mobility depends mostly on driving. Active modes, as the feasible alternatives, would play a more important role in meeting short-distance travel demands for older adults. According to the national data (Ministry of Health Labour and Welfare Japan, 2017) and a research data (Amagasa et al., 2017), the active mobility for Japanese older adults remains a serious gap, for example, under 30% of older people satisfy the WHO recommendation of 150 min of moderate to physical activity per week. Evidently, promoting active travel for older adults in Japan comes as a matter of critical mobility need.
In sum, studies of active travel among older people in the special context of Japan are limited from quantitative, geographic, and socio-cultural dimensions. It is believed that these particular attributes in the Japanese context will have a profound implication for older adults' active travel behaviour in an ageing society. Therefore, taking Chiba city, Japan, as a case, this study aims to explore the determinants of active travel patterns of older adults. We pay particular attention to urban built environment factors, which might generate strategies for urban planners and transport operators to adjust land use, urban amenity, and transport facility distributions, as well as the disaster preparedness transport planning and implementations, to better facilitate the travel needs and improve the health conditions of older adults. In our research, we measure active travel patterns, particularly walking and cycling, by daily travel frequency and travel time. The research framework is shown in Fig. 1. In doing so, this study provides the first insight and robust evidence into active travel patterns of older adults under the background of hyper-ageing in Japan.
The remaining of this paper is structured as follows. The ensuing section introduces the dataset and Chiba city as the study context. Section 3 describes research methodologies in our study. In Section 4, we elaborate on key results and discussion, followed by Section 5 in which main conclusions and possible policy implications are made.
Section snippets
Personal trip survey data
The 6th Tokyo Metropolitan Area Person Trip Survey (PTS) was conducted in the Greater Tokyo area during September to November in 2018 on a normal weekday by Tokyo Metropolitan Transportation Planning Council. The survey involved approximately 160 thousand households and 300 thousand individuals aged over 5 years old. The Tokyo metropolitan area includes Tokyo Metropolis, Kanagawa prefecture, Saitama prefecture, Chiba prefecture and southern Ibaraki prefecture. In the PTS, each individual was
Ordered logistic model
The first objective of this study is to identify the determinants of older adults' trip frequency by active travel modes. To achieve this objective, each older respondent in PTS is viewed as being able to generate active trips on the survey day. The number of active trips that an individual made on the survey day is a count dataset. An ordered logistic model offers a technique to obtain an estimate of the regression model for this sort of data. As a count variable, it has also been
Results and discussion
Prior to model specification, we tested the issue of multicollinearity among the explanatory variables. In particular, we examined the variance inflation factor (VIF), of which a larger value indicates a more serious issue of multicollinearity (Craney and Surles, 2002). As indicated by the VIF values in our data, all explanatory variables have VIF values ranging from 1.12 to 2.26, with the majority of values under 2.0, suggesting that there is no multicollinearity issue. In addition, for the
Conclusions
Population ageing has been a notable and common demographic phenomenon in many cities worldwide (United Nations, 2019), and Japan is the world's most aged country (S. Liu et al., 2021). Given that active travel has multiple social and health benefits for older adults, understanding the influence factor of active travel behaviour of older people is of paramount importance for building an age-friendly society in Japan. Specifically, an emphasis is placed on how the built environment factors
CRediT authorship contribution statement
Yongjiang Yang: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Software, Writing – original draft. Kuniaki Sasaki: Data curation, Writing – review & editing, Supervision, Project administration. Long Cheng: Writing – review & editing. Sui Tao: Writing – review & editing.
Acknowledgement
We gratefully acknowledge for the data support from Tokyo Metropolitan Region Transportation Planning Comission.u
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