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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 - PowerPoint PPT Presentation
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Combining Travel Surveys and Physical Activity StudiesCombining Travel Surveys and Physical Activity Studies
Michelle Lee, GISP
Jean Wolf, PhD
GeoStats LP
Atlanta, GA
May 2009
Michelle Lee, GISP
Jean Wolf, PhD
GeoStats LP
Atlanta, GA
May 2009
2
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
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
Presentation OverviewPresentation Overview
3
Household Travel Surveys - BackgroundHousehold 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
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GPS Use in Travel SurveysGPS 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
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GPS Use in Travel SurveysGPS 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.
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Old…Old…NewNew
GPS Data LoggersGPS Data Loggers
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GPS Data and Travel SurveysGPS 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)
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Map of GPS Trips Collected - VisualizationMap of GPS Trips Collected - Visualization
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Physical Activity StudiesPhysical Activity Studies
Comparison of Different Physical Activity Data Collection Methods
DiariesHeart Rate Monitors Pedometers Accelerometers
Cost to Implement Low Moderate Low Moderate to High
Measurement Type Subjective Objective Objective Objective
Accuracy of Data Varies GreatlyHigh when coupled with
basic health dataHigh High
Usefulness of Data
Varies greatly – all data subjective,
difficult to do cross
comparisons
Useful, but limited based on
environmental factors
Useful, but limited to step count
High, although dependent on
calibration
Ease of Data Analysis
Often requires interpretation and standardization
Data analysis can be automated
Data analysis can be automated
Data analysis can be automated
Health researchers need objective measurement of travel and physical activity; similar issues exist with self report methods.
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Accelerometer DataAccelerometer Data
Accelerometers are similar to pedometers, but in addition to step count they
provide the ability to measure intensity of physical activity.
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Accelerometer Travel Mode Profiles Accelerometer Travel Mode Profiles
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Combining GPS and PA DataCombining GPS and PA Data
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Physical Activity Project Website
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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
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
Studies Combining both TechnologiesStudies Combining both Technologies
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Case Study - FACES 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
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
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GPS Traces with PA LevelsGPS Traces with PA Levels
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Percent of Moderate to Vigorous Activity by LocationAge Group One - Project Activity Thresholds
0%
10%
20%
30%
40%
50%
60%
70%
Wednesday Thursday Friday Saturday Sunday
Travel Day
Home
School
Both
Other
Travel
MVPA breakdown by location, DOW MVPA breakdown by location, DOW
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Moderate to Vigorous Activity by Location Age Group 1
0
200
400
600
800
1000
1200
1400
Wed Thur Fri Sat Sun
Min
ute
s
Indoors
Outdoors
MVPA breakdown by I / O, DOW MVPA breakdown by I / O, DOW
20
Other Health-Related PA StudiesOther 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
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Physical Activity Studies Physical Activity Studies
FACES MA Trail Usage Study VA Mobility StudyAtlantic Station Health
Study
Duration 2 years 2 years 3 years 3 years
Timeline 2006 - 2008 2004-2006 2005 - 2008 2006 - 2009
Type School/Summer Single Deployment Before/After Before*/After
Deployment Period
5 days per phase 4 days 14 days per phase 5 days
Ages Children ages 7-18 Adults ages 18+Average Age 72; range
from 47-90Adults ages 18+
Sample Size150 participants
(87 deployed twice, 7 deployed thrice)
178 participants 198 participants 100 participants
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Summary 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
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Google Earth Visualizations of Travel & PAGoogle 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