The National Household

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The National Household Travel Survey
Heather Contrino US Department of
Transportation Federal Highway Administration Offi
ce of Highway Policy Information
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Outline of Todays Presentation

• About the NHTS
• Methods and Data
• Data Applications
• NHTS Products and Tools

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About the NHTS
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About the NHTS

• Only national data source on travel demand and
  travel behavior of the American public.
• Measures travel by US households for all modes
  and all purposes
• Survey conducted since 1969

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The NHTS obtains information on the publics use
of the transportation system
Highway Statistics, 2001
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The NHTS Program Two Components

• National Study
• Serves the department, congress, and
  administration
• Sample size of 25,000 households
• Add-On Program
• Allows States and MPOs to purchase additional
  samples for their local area
• Program participation has doubled every survey
  year
• (Sample size of 125,000 households for 2008)

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NHTS Program Structure
NHTS Program
Add-On Program n 125,000 List Assisted
RDD Some Additional Questions
National Study n 25,000 List Assisted RDD
Cell Only n 1,250 National coverage
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2008 Add-On Program Participants
125,000 Add-On Samples
Vermont DOT
Wisconsin DOT
South Dakota DOT
New York State DOT
Cedar Rapids, IA
Iowa DOT
Indiana DOT
Omaha, Nebraska
California DOT
Virginia DOT
North Carolina DOT
Tennessee DOT
Piedmont Region
Maricopa, AZ
South Carolina DOT
Pima, AZ
Georgia DOT
Texas DOT
Florida DOT
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NHTS Add-On Program Benefits

• What We Get
• Leadership in household travel survey data
• Larger program, visibility, stakeholders and
  users
• Greater analysis power
• What They Get
• Administrative Functions (program management,
  contracting, and quality assurance)
• Comparability
• Legitimacy
• Partnership

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NHTS Program Features

• Adding questions each Add-On allowed five
  additional questions
• Sample plan area specific sample plans (within
  the constraints of overall sample methodology)
• Quality Assurance On-line access to status
  reports and monthly progress reports to Add-Ons

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Study Design and Data
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Study Design

• National list assisted RDD with CATI
• Population of interest - US Households with
  telephones
• Advance letter with incentives
• Multi-stage design

Travel Data Retrieval
Diary Mailing
Advance Letter
Household Recruitment
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Study Design (continued)

• Single day travel period for all household
  members age 5
• All trips by all modes of travel, including walk
  and bike and access and egress modes
• NHTS covers all days of the year with day of week
  and month of year balance

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Study Design - New for 2008

• Minimum State samples (n250)
• Cell Phone only sample
• Add-On specific questionnaire content
• New data items for national study
• Improvements in weighting and adjustments

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NHTS uses a classic travel diary as a memory
jogger
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And obtains trips from one address to another by
all modes
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NHTS links households, people, vehicles, and
trips
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NHTS Core Data Content

• Households
• Income, composition, location
• Persons
• Age, sex, race, ethnicity, worker and student
  status, citizenship, education
• Geography
• High level geography urban, rural, suburban,
  state and national analyses
• Vehicles
• Make, model, year, mileage, alternative fuels,
  commercially licensed
• Trips
• Mode, time of day, purpose, vehicle occupancy,
  distance, trip length

Major Contribution Linkage between people,
travel and vehicles
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New 2008 NHTS Content

• Congestion
• Interstate use and tolling
• Telecommuting opportunity and frequency
• Work arrival time and flexibility
• Safety
• Safe Travel to School
• Travel impacts of disability
• Energy and Environment
• Shopping by Internet and deliveries to the
  household
• Hybrid/Alternative fuel vehicles
• Fuel costs by vehicle type and travel behavior
• Vehicle age, odometer reading, and annual mileage
• Alternative Modes
• Access (to transit) travel party size
• Frequency of walk and bike
• Motorcycle ownership and use

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Data Applications
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Trend Data - There has been amazing growth in
travel since 1969Growth in Travel and Related
Issues, 1969 - 2001
Base NHTS series since 1969
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Travel Demand But in the last decade, total
trips have leveled off
Base NHTS data series, travelers 16
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Congestion - Non-work Travel Adds to Peak Period
Congestion
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Mobility and impacts on access and travel options
This is the daily range of travel for a high
income African American
This is the daily range of travel for a
low-income African American
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NHTS is used to develop daytime populations for
security research
Number of workers at work, visitors, people in
motion and people at home 200 pm
Tuesday Memphis, TN
Source 2001 NHTS, Nate Erlbaum, NY DOT
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And for special studies (example Florida DOT)

• Hurricane Evacuation Planning
• Weekend and Holiday Travel Planning
• Seasonal Resident Impact

Broward County, Florida
Source ACS 1999-2002, U.S. Census Bureau
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Changes in population growth effect
transportation demand
Estimated on current VMT/person from NHTS and
Census population forecast
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The driving population is agingProjections
show a doubling of VMT by 2040 for drivers aged
65 and over
BaseCensus projections and VMT/person from NHTS
2001
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Which has safety implications as older drivers
are more likely to be in a fatal accident
Base NHTS data on driver miles by age and FARS
fatalities
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Reliable data on walk trips
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Which are used for Safety Planning

• Pedestrian Fatalities per Mile of Exposure

Source 2001 FARS pedestrian Fatalities and NHTS
2001 miles walked
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And to help understand the link between
transportation and health
Is increased vehicle use related to reduced
walking and biking?
Mode Share to Walk/Bike
VMT Per Driver
Source Matt Coogan
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Transit planners can use NHTS to understand who
uses transit
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And how transit is used(not just commuting)
Percent of Transit Trips by Purpose
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What if scenarios for climate change
Source McGuckins analysis based on NHTS 2001
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And cold and hot starts for air quality analysis

• Vehicle Starts, Trip Lengths by Time of Day and
  Vehicle Utilization

Source 2001 NHTS, Nate Erlbaum, NY DOT
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We also include and track gas costs in our
dataset
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Which allows us a unique perspective on the
economics of travel
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NHTS Status and Schedule
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2008 NHTS Schedule

• Data collection completed April 2009
• Final weighted data file October 2009
• Public Use file January 2010
• Methods Research (for next NHTS) and work for
  reauthorization is ongoing

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Future Design Goals

• Methods
• Coverage and Response Rates
• Cellular phones and non-contacts
• Periodicity
• Real time reporting environment
• Continuous study design/annual reporting
• Relevant Content
• Establishing regular, reliable performance
  measures
• Maintaining trends while addressing new policy
  and planning questions

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NHTS Program Goals

• Institutionalize the Study
• Specific program authorization and regular
  funding cycle
• Maintain Add-On Program
• Regular State and MPO participation federal,
  local and community gains
• Serve User Community
• Clear link to policy and planning questions
• National and State travel indicators
• On-line Analyses
• Annual reporting of Key Measures
• Modeling and data integration to provide annual
  estimates
• Annual/continuous data collection
• Feed into performance measurement, annual
  reporting to Congress (CP), and other data
  programs (e.g. FARS)

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NHTS Products and Tools
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NHTS Products

• State Profiles
• Policy Briefs
• Trends Database
• Transferability
• On-line Analysis Tool
• Risk Assessment Tool
• AAA Traffic Safety Foundation

NHTS Trends CD-ROM
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Policy Briefs
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State Profiles
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NHTS Website
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On-line Analysis Tools
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Table Designer Tool
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Local Area Estimation
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Accessing NHTS Products
Contact Heather Contrino, FHWA

• State Profiles
• Policy Briefs http//ornl.gov/publications.shtml
  issueBriefs
• Trends Database To be posted soon
• Local area estimation
• http//fmip.ornl.gov/nhts/
• Risk Assessment Tool
• http//www.aaafoundation.org/trafficSTATS/
• On-line Analysis Tool http//nhts.ornl.gov
• SAS Data Set http//nhts.ornl.gov/download.shtml

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Thank You! Heather Contrino Heather.Contrino_at_dot.
gov