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Combining Travel Surveys and Physical Activity Studies

Combining Travel Surveys and Physical Activity Studies. Michelle Lee, GISP Jean Wolf, PhD GeoStats LP Atlanta, GA May 2009. Presentation Overview. GPS in household travel surveys Accelerometers in physical activity studies

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Combining Travel Surveys and Physical Activity Studies

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  1. Combining Travel Surveys and Physical Activity Studies Michelle Lee, GISP Jean Wolf, PhD GeoStats LP Atlanta, GA May 2009

  2. Presentation Overview • GPS in household travel surveys • Accelerometers in physical activity studies • Use of both technologies to collect travel and physical activity • Review case studies for health/physical activity studies

  3. Household Travel Surveys - Background • Household travel surveys are conducted at regional, statewide, and national levels to collect information about daily travel patterns • In the US, traditional methods for conducting surveys are travel diary based, with telephone recruitment and data retrieval • Self-report methods for reporting travel are not always accurate as some people will misreport trips or trip details • The use of Global Positioning System (GPS) data collection in tandem with traditional household travel survey methods has become commonplace in the US over the last decade • Due to technology constraints, most GPS studies were vehicle-based • Examples include California Statewide, Pittsburgh, Laredo, St Louis, Kansas City, Reno, Chicago, Washington DC, Baltimore

  4. GPS Use in Travel Surveys • Vehicle methodology involves providing diaries to all household members and GPS data loggers for all household vehicles for a subsample of large survey effort • Vehicle trips measured by GPS are compared to trips reported by household members to estimate level and magnitude of misreported and underreported travel among larger survey sample • Other uses for GPS data have been secondary, exploratory • Air quality modeling, congestion analyses, independent assessments of trip rates, travel times, and VMT • As GPS data logger technology has improved (smaller, better battery and storage capacity), recent studies have shifted to person-based approach with all household members 16+ given a GPS logger

  5. GPS Use in Travel Surveys • Wearable approach allows for multi-modal focus, such as exploring walk, bike, and transit users • Example wearable GPS-enhanced travel surveys include: • Early tests: Atlanta, London, Portland • Recent / ongoing studies: Chicago, Indianapolis, Cincinnati • Upcoming studies: Boston, NYC, Jerusalem • Under consideration: Portland, Denver • Recent trends in GPS applications for travel surveys include using GPS to replace the use of travel diaries (to reduce respondent burden) • GPS-based prompted recall • GPS only using software to impute missing variables • Multi-day data collection also becoming more prevalent .

  6. GPS Data Loggers Old… New

  7. GPS Data and Travel Surveys • Most trip attributes can be derived from GPS data and other supporting information • Recruit information reported by households, GIS layers (road and transit network, landuse database, aerial imagery. Google Maps and Streetview)

  8. Map of GPS Trips Collected - Visualization

  9. Physical Activity Studies Health researchers need objective measurement of travel and physical activity; similar issues exist with self report methods. Comparison of Different Physical Activity Data Collection Methods

  10. Accelerometer Data Accelerometers are similar to pedometers, but in addition to step count they provide the ability to measure intensity of physical activity.

  11. Accelerometer Travel Mode Profiles

  12. Combining GPS and PA Data

  13. Physical Activity Project Website

  14. Studies Combining both Technologies Household Travel Surveys • The 2001-2002 Atlanta Regional Household Travel Survey (SMARTRAQ) deployed electronic travel diaries with GPS (implemented on a Palm handheld device) OR activity monitors to a subset of participants in the regional study to assess physical activity and travel • No other PA augments have been added to travel surveys since then (it was ahead of its time…) Health • There have been a handful of studies since 2004 deploying both GPS and accelerometers to capture both travel and physical activity data

  15. Case Study - FACES • Fresno Asthmatic Children’s Environment Study • Large 8-year epidemiological study of effects of air pollution on children with asthma led by UC-Berkeley School of Public Health • In 2006, passive monitoring component was added with GPS data loggers and accelerometers to collect details of location, time, and physical activity • 150 children of ages 8-17 participated in this portion of study • All children were deployed with devices during five days of school year (Wed-Sun) • Some children were deployed again during summer months • Objective was to examine amount of time spent indoors and outdoors, by location, and amount of physical activity obtained • Time spent riding in vehicles was also of interest

  16. GPS Traces with PA Levels

  17. MVPA breakdown by location, DOW

  18. MVPA breakdown by I / O, DOW

  19. Other Health-Related PA Studies • Trail Users in Massachusetts • Trail users instrumented to evaluate amount of physical activity obtained on trails versus other areas • Veteran’s Affairs Mobility Study • Before and after evaluation of cane orientation and mobility training for blind veterans (2-week before, 2-week after training) • Atlantic Station Health Study • Before and after evaluation of improvements in health, reduction in vehicle travel for residents moving to new urbanism development in Atlanta • Includes environmental assessment of ‘walkability’ factors

  20. Physical Activity Studies

  21. Summary • Use of GPS and accelerometer technologies allows for: • Objective, passive measurement of travel and physical activity • Reduced participant burden while collecting high resolution, high accuracy data for multi-day periods • Rich and robust data which can be used for a range of purposes • Data visualization further improves understanding of observed / measured behaviors • Applications for Transportation and Health • Standard travel surveys with improved travel mode imputation • Bike and pedestrian facilities – usage, before and after (traffic calming) • Transit usage – access modes, PA benefits • Built environment – factors influencing physical activity either as secondary to transport mode or for exercise / recreation

  22. Google Earth Visualizations of Travel & PA GPS traces with height based on physical activity, height (m) = PA (counts) / 10 GPS traces with height based on speed, height (m) = speed (mph) * 10

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