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Travel Behavior Panel Surveys: Measuring the Impacts of Road Pricing in Seattle and Atlanta
Travel Survey Methods Committee MeetingJanuary 25, 2012
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Project Background
• USDOT Urban Partnership Agreement (UPA)/Congestion Reduction Demonstration (CRD) programs fund selected cities/ regions to implement a comprehensive, integrated approach to reducing congestion– The four T’s: Tolling; Transit;
Technology; Telecommuting
– Recipients: Atlanta, Seattle, Miami, Minneapolis, Los Angeles, San Francisco
• National Evaluation being conducted by Battelle
• FHWA funds Volpe Center to perform household panel survey
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Source: Wikipedia
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Seattle and Atlanta
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Evaluation Questions
How did travel times, vehicle miles traveled, and daily travel budgets change at the individual/household level?
Were there shifts in departure times or modes? In origin-destination patterns?
For those who used the priced facility less, where did the reduced trips go? Telework? Combined errands? Route diversion?Atlanta: How do 2-person carpools adapt to the new occupancy requirements?
What are the equity impacts of the road pricing policies?
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Overall Study Approach
• Household Panel Study: same households before and after road pricing
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Overview of Study Population
• Peak hour corridor drivers: sample through license plate capture with match to registered address
• Seattle: SR-520 and I-90• Atlanta: I-85 and Buford Highway
• Peak hour corridor transit users: In-person intercept • Seattle: bus stops, transit centers; park & rides; on-board
buses• Atlanta: park & rides in corridor: MARTA stations
• Corridor vanpool members: send email to vanpool participants
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Atlanta Sample Development (Drivers)
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Sample Development for Transit/Vanpools
• Seattle: in-person intercept October 18-21, 2010– on-board intercept (ipad) on buses crossing Lake Washington – Postcard handout: Redmond and Bellevue Transit Centers;
South Kirkland and Eastgate Park & Rides; on-board buses; downtown bus stops
• Atlanta: in-person intercept March 21-25, 2011– Postcard handout only: Discover Mills, Indian Trail, Mall of
Georgia, and I-985 Park and Rides, Doraville and Lindbergh MARTA Stations
• Vanpool recruitment: Georgia Regional Transportation Authority/King County sent an e-mail to registered vanpoolers who use the corridor inviting them to participate (~500)
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Survey Materials
• Memory Jogger• Reminder postcards and
emails
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Online survey tool• Household survey on demographics (completed by one person)• 2-day travel diary completed by all adult (18+) household members• Additional survey questions: typical commute behavior; typical use
of the facility; trip satisfaction; attitudes and values• Phone option available; Spanish version of materials in Atlanta
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Pilot Study• Purpose: Test all steps of survey administration
– Recruitment method (license plate capture and transit intercept; effectiveness of materials; incentive structure)
– Online tool: questionnaire design and functionality, survey duration
– Obtain estimate of response rate
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Modal Segment
SeattleResponse Rate
Atlanta Response Rate
Auto 9.6% (N=175) 8.9% (N=176)
Transit 18.3% (N=119) 14.7% (N=49)
294 households 225 households
NOTE: “Completion” defined as all adult members of the household complete their travel diary
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Pilot Study, continued
• Findings: Overall, no major issues or problems– Cut survey questions due to comments on length – Clarify several error messages/instructions – Add response categories for some questions
• Trip purpose: “exercise/gym”
– Increase automation• Pre-populate starting point for day 2 trip roster with ending point
from day 1
– Utilize $15 gift card incentive (resulted in 9.4% response) • $10 gift card: 7.0% response rate• $10 gift card with enclosed $1 bill: 9.8% response rate• $15 gift card with enclosed $1 bill: 11.8% response rate
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Incentives and Panel Maintenance
• Each household receives $15 gift card after wave 1 completion; $30 after wave 2 completion
• Approximately 3 contacts per household– graphic display of findings (~3 months after wave 1)– Seattle only: letter about wave 2 survey delay – After pricing: mini-survey to engage respondents and obtain
initial feedback on tolling– Household update survey (several weeks prior to wave 2 survey)
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Wave 1 Response
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ModalSegment
Wave 1: Total invitations distributed
Wave 1 Completions
Percentcompleted
Auto 31,282 2908 9.3%
Transit 2,513 396 15.8%
Vanpool 520 52 10%
Total 37,983 3356
NOTES: “Completion” = All adult members of the household completed all surveys
Household Completion Rates by Recruitment Mode
Seattle (November 2010)
Atlanta (April/May 2011)
Household Completion Rates by Recruitment Mode
Modal Segment
Goal for Wave 1
Goal for Wave 2
Auto 2600 1300
Transit + vanpool
400 200
Total 3000 1500
ModalSegment
Wave 1: Total invitations distributed
Wave 1 Completions
Percentcompleted
Auto 35,455 2090 5.8%
Transit 2,721 303 11.1%
Vanpool 477 19 3.9%
Total 38,653 2412
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Wave 1 Methodology Notes• Respondent Burden
– Rough estimates come from RSG data on respondents’ web-based survey times
– This does not include time for filling in Memory Joggers or other work– Averaged 4 minutes per household for initial screener– Approx. 10 minutes per person per day for diary and related questions– 44 minutes total for a typical 2-adult household
• Item Non-Response:– Essentially none due to design of online survey– ~10% selected “prefer not to answer” on income question
• Survey medium: – At least 95% of respondents used online tool, but telephone option was
available and used
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Methodology Notes, continued
• Non-response Bias:– Analyzed via comparison of completed surveys against
partial completions and external benchmarks (including other corridor studies, Census, and Acxiom data)
– Household size appears to be the only key variable with a bias – the achieved sample has fewer large households
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Lessons Learned
• Pilot your survey• Spend the extra time needed to develop a high quality
online survey; provide clear, concise directions– Pop-up windows, map of corridor
• Advance planning is critical– License plate capture process differs by state
• Be flexible– Added travel days in Atlanta to boost response rate
– Enhanced panel maintenance with “mini-survey” to engage respondents
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Next Steps
• Focus groups in Seattle (February 2012)
• Panel maintenance “mini-survey” in Seattle and Atlanta (January/February, 2012)
• Final version of wave 2 surveys
• Household update and wave 2 survey administration
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Comments? Questions?
Margaret Petrella, Social ScientistThe Volpe Center
Margaret.Petrella@dot.gov