Background and Purpose
Walking for transportation, which can include walking that takes place at the beginning or end of a trip taken by public transportation, can provide individuals with the opportunity to meet recommended levels of physical activity. Previous studies have demonstrated that individuals who walk to and from public transportation stops engage in more daily physical activity than those who do not.[1-5] More evidence is needed, however, to better understand the relationship between walking for transportation and public transportation use and more specifically, the mechanisms through which this relationship occurs.[5] A growing body of evidence has also suggested that perceptions of built environment characteristics can influence walking for transportation.[6-8] Despite this evidence, little is known about how these perceived environmental factors influence public transportation use.

Objectives
The aims of this study were to: (1) further assess the relationship between individual factors, public transportation use, and walking for transportation, specifically in a low-income community of color; and (2) examine the association among individual and perceived environmental factors and public transportation use.

Methods
This cross-sectional study was conducted in 2012. We used questionnaire data from 772 adults living in St. Louis, Missouri. We used the International Physical Activity Questionnaire long form to assess walking for transportation and public transportation use. The abbreviated Neighborhood Environment Walkability Scale was used to examine perceptions of the environment. Two different models were tested using multinomial logistic regression with walking for transportation and public transportation use as the outcome variables. Model 1 examined the association between individual factors and public transportation use with walking for transportation. Model 2 examined the association between individual and perceived environmental factors with public transportation use.

Results
Most participants were women and adults less than 50 years old. The majority of the sample was employed outside of the home and 27% had an annual income less than $10,000.

Multinomial logistic regression analyses revealed that the odds of walking for transportation for 1-149 minutes/previous week and =150 minutes/previous week (OR=2.11, CI=1.31-3.40 and OR=2.08, CI=1.27-3.42, respectively) were higher for individuals who reported using public transportation 1-4 days in the previous week in comparison to individuals who did not use public transportation. Similarly, the use of public transportation for five or more days in the previous week was positively related to walking for transportation. Compared to individuals who did not use public transportation, individuals who used public transportation for five or more days in the previous week were 3.47 times more likely to walk for transportation for 1-149 minutes/previous week and 8.61 times more likely to walk for transportation for more than 150 minutes/previous week (CI=1.47-8.19 and CI=3.87-19.20, respectively).

Model 2 revealed that the odds of using public transportation more than once a week (1-4 days/previous week) was greater among individuals between 50-59 years old (OR=1.98, CI=1.06-3.70) in comparison to individuals between 18-29 years old. However, adults over 60 years old were less likely to use public transportation five or more days in the previous week (OR=.34, CI=.14-.86) compared to individuals between 18-29 years old. Employed individuals were less likely than unemployed individuals to use public transportation more than once a week (1-4 days/previous week: OR=.56, CI=.35-.92).

Participants who reported high traffic speed and high crime in their neighborhood were less likely to use public transportation. More specifically, individuals who reported that traffic exceeded the posted speed limits in their neighborhood were less likely to use public transportation for 1-4 days in the previous week (OR=.54, CI=.36-.81) compared to those who did not report high traffic speed in their neighborhood. Similarly, individuals who perceived high crime in their neighborhood had lower odds of using public transportation for more than five days in the previous week (OR=.50, CI=.28-.87) compared to those who did not report high crime.

Conclusions
Using a diverse sample of adults where many participants were unemployed and used public transportation as their primary mode of transport, we found that individuals that use public transportation more frequently are more likely to meet physical activity recommendations by walking for transportation. Our study results are consistent with earlier research demonstrating that regular public transportation use is associated with increased physical activity and that walking for transportation appears to occur in combination with public transportation.[1-5] Of the perceived environmental factors assessed, our study results indicated that high traffic speed and high neighborhood crime were negatively associated with public transportation use. To our knowledge, no studies to date have investigated the relationship between perceived built environment attributes and public transportation use.

Implications for Practice and Policy
Programs, policies, and infrastructure changes to improve the perception and actual safety from traffic and crime may be an important investment to increase public transportation use in similar urban communities, and thereby increase levels of walking.

References

1. Besser LM, Dannenberg AL, 2005. Walking to public transit: steps to help meet physical activity recommendations. Am J Prev Med 29: 273-280.
2. Frank LD, Greenwald MJ, Winkelman S, Chapman J, Kavage S, 2010. Carbonless footprints: promoting health and climate stabilization through active transportation. Prev Med 50: S99-105.
3. Freeland AL, Banerjee SN, Dannenberg AL, Wendel AM, 2013. Walking associated with public transit: moving toward increased physical activity in the United States. Am J Public Health 103: 536-542.
4. Lachapelle U, Frank L, Saelens BE, Sallis JF, Conway TL, 2011. Commuting by public transit and physical activity: where you live, where you work, and how you get there. J Phys Act Health 8: S72-82.
5. Wener RE, Evans GW, 2007. A morning stroll: levels of physical activity in car and mass transit commuting. Environ Behav 39: 62-74.
6. Bauman AE, Reis RS, Sallis JF, Wells JC, Loos RJF, Martin BW, 2012. Correlates of physical activity: why are some people physically active and others not? Lancet 380: 258-271.
7. Duncan MJ, Spence JC, Mummery WK, 2005. Perceived environment and physical activity: a meta-analysis of selected environmental characteristics. Int J Behav Nutr Phys Act 2: 11.
8. Van Dyck D, Cerin E, Conway TL, De Bourdeaudhuij I, Owen N, Kerr J, Cadon G, Frank LD, Saelens BE, Sallis JF, 2012. Perceived neighborhood environmental attributes associated with adults’ transport-related walking and cycling: Findings from the USA, Australia, and Belgium. Int J Behav Nutr Phys Act 9: 70.

Support / Funding Source
This study was supported by the International Center for Advanced Renewable Energy and Sustainability at Washington University in St. Louis, Missouri (1660-94758A) and the John Hopkins Global Center on Childhood Obesity (2001656847).