Prevalence and correlates of walkable short car trips: A cross-sectional multilevel analysis
Introduction
Promotion of physical activity continues to be an international public health priority (Das et al., 2016; Lee et al., 2012). Evidence consistently highlights the role of integrating active living behaviors into daily routines as a key to increasing population levels of physical activity (Haskell et al., 2007, Rachele et al., 2015). The use of active modes of transport, in particular walking, is one way of incorporating physical activity into daily life. It has been shown that a large number of daily trips by car tend to be short: studies using household travel survey data in Sydney, Australia and in Phoenix, Arizona reported that about a quarter of car trips were five minutes or less in duration (Sugiyama et al., 2012a) or two miles or less in distance (Paul et al., 2013). Converting such short car trips into walking may be a potential strategy to increase physical activity at the population level (Maibach et al., 2009). It is thus important to estimate the prevalence of short car trips, and where and by whom such trips are made. Although some existing studies have examined short car trips, these are characterized by a number of limitations.
First, studies have applied one distance threshold for all participants to determine short car trips. For instance, a “walkable” distance has been defined as 1.6 km (Morency et al., 2014, Paul et al., 2013), 3 km (Vagane, 2007), or the distance covered by five minutes of driving (Olabarrio et al., 2012). However, the distance that can be walked is likely to vary between different age and gender groups (Harrison et al., 2013). Thus, the definition of short car trips may also vary between different sub-groups. Second, only a few studies have addressed the sequential nature of trips in identifying short car trips (Beckx et al., 2013, Morency et al., 2014, Vagane, 2007). Studies on short car trips often use household travel surveys, in which participants report their travel behaviors for each trip stage that has a single purpose and mode. A sequence of trips starting and ending at the same place (i.e., home or work) is considered as a trip chain. A trip chain can consist of two or more trips, depending on the number of destinations included in the trip chain. Thus, even if a single trip is short, it may not be walkable if the trip is part of a longer trip chain. In one study that considered the distance threshold for trip chains (Morency et al., 2014), a trip chain up to 6.4 km (four times the threshold for a single trip) was deemed to be walkable. However, it will take about 1 hour and 20 minutes to walk 6.4 km at a walking speed of 4.8 km/h (Bohannon, 1997), and the feasibility of converting such a distance into walking is not clear, particularly for some population groups such as older adults.
To address these limitations, we used an Australian household travel survey to examine the prevalence of short car trips that could be converted to walking trips, based on the age/gender-specific distance thresholds, and taking the distance of trip chains into account. We then determined individual-, household-, and area-level correlates of short car trips to identify sub-groups and areas where such short car trips are more common.
Section snippets
Household travel survey: study setting and survey design
The data used were from the 2009 South East Queensland Travel Survey (SEQTS). The SEQTS is a travel behavior survey administered by the Queensland Government Department of Transport and Main Roads, primarily for modelling travel behavior and informing state-level infrastructure and service investments. The survey covers the Sunshine Coast, Brisbane, and Gold Coast Statistical Divisions, which had a population of 2.9 million. The region has a diversity of built environments from high-density
Characteristics of car trips
The total number of car trips made on the survey day was 46,721. On average, participants made 3.2 car trips per day. The median car trip distance was 6.1 (25th–75th percentile: 2.9–12.7) km. Fourteen percent of car trips (n=6751) were within the single trip distance thresholds, and 7% (n=3299) were within the single trip and trip chain distance thresholds. As shown in Table 2, the prevalence of short car trips for the age/gender-specific groups ranged from 4% to 10% of the total car trips.
Discussion
Using a representative sample of Australian adults, we identified the prevalence and correlates of short car trips that could be replaced by walking. This is the first study to examine short car trips using the age/gender-specific distance criteria accounting for the trip chain distance. We found that more than one tenth of car users made at least one short car trip on the survey day, mainly for daily purposes such as shopping, going to work, and giving someone a lift. Converting such routine
Conclusions
The findings of this study suggest that there is a potential for some car trips to be converted into walking in Australia. Initiatives to replace car use with walking may be particularly effective in high density areas where more local destinations are available within a walking distance. Barriers that discourage walking (e.g., lack of pedestrian facilities, safety issues) need to be addressed to facilitate walking trips among older adults and in disadvantaged areas. Converting car trips to
Financial disclosure
Koohsari was supported by a Postdoctoral Fellowship from the National Heart Foundation of Australia [#100878] and a National Health and Medical Research Council (NHMRC) Program Grant [#569940]. Owen was supported by a NHMRC Program Grant [#569940] and a Senior Principal Research Fellowship [#1003960]. Koohsari and Owen were supported by the Victorian Government’s Operational Infrastructure Support Program.
Conflict of interest statement
None to report.
Acknowledgements
The authors would like to thank the Queensland Government Department of Transport and Main Roads for providing the SEQTS data used in the analyses of this study.
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