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

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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

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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

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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

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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