Federal Highway Administration Research and Technology Evaluation: National Household Travel Survey Program Final Report

1. Introduction

The Federal Highway Administration (FHWA) has initiated an effort to evaluate the Research and Technology (R&T) development program. Leaders of governmental transportation R&T programs need to be able to effectively communicate the impacts of their programs. The R&T evaluation program helps FHWA assess how well it is meeting its goals and objectives and provides useful data to inform future project selections.

1.1   Evaluation Objectives

One of the programs being evaluated under the R&T Evaluation Program is the NHTS, which is funded by FHWA through the Office of Highway Policy Information. This survey is conducted periodically (once every 6–8 years) and measures the daily travel behavior and transportation-related attitudes of a nationally representative sample of the American public. Given the massive scale of this data collection effort—a yearlong survey that reaches 150,000 households—and the associated costs of collecting these data, FHWA wants to better understand the impact of this program.

Identifying and measuring these impacts includes documenting how widely and for what purposes the NHTS data are used. Perhaps more important, however, is assessing the longer-term impacts of the availability and use of the survey data by identifying how NHTS data inform policy, program, and regulatory decisions. These types of impacts may be occurring at the Federal, State, or regional level across a range of fields and issues. Assessing the impacts of the NHTS enables FHWA to examine the value of this research program.

1.2   Identifying Key Outcomes and Impact Areas

The Volpe team identified key outcome and impact areas for the NHTS evaluation through initial discussions with members of the R&T Evaluation Team and NHTS staff. An iterative series of discussions led to the development of the NHTS logic model (see section 2.1). The model identifies the inputs, activities, and outputs from the NHTS Program, which produce a mix of short-term outcomes and long-term impacts.

Table 1. Evaluation outcome and impact areas.

1.2.1 Short-Term Outcomes

First, the evaluation assessed the short-term outcomes of the programs through an examination of the breadth and depth of NHTS data use in national, State, and regional contexts and across a range of users. The evaluation sought to uncover who the NHTS users are, what form of the NHTS data and outputs they use, and the purposes for which they use them.

Another short-term outcome measured challenges and lessons learned regarding the planning, administration, and outreach for NHTS. The main objectives of this analysis were to identify process-related hurdles or challenges and ways in which the process could be improved. The evaluation documented NHTS’s responsiveness to its user community, identifying the ways in which NHTS has collected information from its user community and whether and how this feedback was addressed by the program. Both the challenges and lessons learned and user responsiveness portions of the evaluation can provide guidance to future programs based on the experiences of the NHTS team.

1.2.2 Medium- and Long-Term Outcomes

The evaluation also identified whether the use of NHTS data have had an impact on policy and/or program decisionmaking, regulations, or other decisions. While it was not difficult to assess the breadth and depth of NHTS use, it was far more challenging to attribute policy, program, or regulatory decisions to NHTS. The focus of this effort was to document cases showing how NHTS data and outcomes informed such decisions.

1.3   Report Structure

This report is organized as follows:

• Chapter 1 explains the purpose of the evaluation and provides a high-level description of the project’s history.
  
  
• Chapter 2 explains the evaluation methodology, including data sources, data collection methods, and data analysis methods.
  
  
• Chapter 3 explains the findings of the evaluation.
  
  
• Chapter 4 explains Volpe’s recommendations for FHWA based on the findings of the evaluation.
  
  
• Chapter 5 explains the general conclusions that Volpe drew from the evaluation.

1.4   Project and Program Background

National travel surveys have been conducted by the FHWA for more than 45 years. The most recent surveys, known as NHTS, were conducted in 2009 and 2001. Prior surveys, known as the Nationwide Personal Transportation Surveys (NPTSs)⁾ were conducted in 1995, 1990, 1983, 1977, and 1969.⁽¹⁵⁾ The surveys are conducted periodically (once every 6–8 years) and measure daily household travel behavior while collecting data on transportation-related attitudes, household members, housing, vehicles, and other demographic information.

The surveys are the only data in the country that link individual personal travel behavior, household demographic and socioeconomic characteristics, vehicle ownership, and vehicle attributes. For each survey effort, data are collected over the course of a year, with sampled households providing information on household daily trips taken in a 24-h period. For each trip, respondents are asked to report trip purpose (e.g., work, school, shopping, recreation, etc.); mode of transportation (car, bus, walking, etc.); travel time; time of day; day of the week; vehicle occupancy; vehicle characteristics (make, model, and year); and respondent demographic characteristics (gender, age, education level, etc.).

In addition to the national sample, States and Metropolitan Planning Organizations (MPOs) may purchase additional or “Add-on” samples. With the more robust sample sizes provided by the Add-on sample, States and MPOs are able to perform more detailed analyses and to drill down to smaller geographic units, such as cities or counties. The 2009 NHTS consisted of a national sample of 25,000 households. Another 20 States and MPOs purchased Add-on samples, totaling 125,000 additional households. Overall, approximately 150,000 households and 300,000 individuals were surveyed. Currently, NHTS is planning its 2016 survey, which will include a national sample of approximately 26,000 households and an Add-on sample of approximately 103,000 additional households from 13 States or MPOs.

1.5   Survey Methodology and Updates

In 2001 and 2009, the NHTS was conducted primarily as a telephone survey, using a random-digit dialing (RDD) sampling frame and Computer-Assisted Telephone Interviewing (CATI) technology to recruit households and to retrieve their responses. During the household recruitment interview, each household was assigned a specific date as their “Travel Day” for which detailed data on travel were collected. All household members who completed the recruitment interview were sent diaries for their travel day. Each household received a reminder call on the day before their assigned travel day; phone calls to collect the diary information usually began the day after the travel day and continued for the next six days.

The 2016 NHTS will undergo significant design changes that include using an address-based sample (ABS), whereby respondents are recruited via mail and retrieval of travel day information is done using a web-based survey. Other changes to the methodology have been implemented, including a revamping of the incentive structure and a focus on activity at each place rather than trip purpose. Overall, the significant changes to the NHTS methodology were deemed necessary to ensure a more representative sample frame and to increase response rates.

1.6   Goals and Outputs

The primary goal of the NHTS is to provide a better understanding of travel behavior in the United States. The data are used for a wide variety of purposes including the following:

• Understanding characteristics of travel (e.g., modes used, purpose of travel, etc.).
  
  
• Quantifying the travel behavior of individuals and households.
  
  
• Monitoring and analyzing travel behavior over time (trends).
  
  
• Connecting the role of transportation to other aspects of people’s lives (e.g., health, environment, etc.).
  
  
• Examining the relationship between travel and demographics.
  
  
• Understanding the public’s perceptions of transportation systems.

In describing the goals of the NHTS Program, FHWA staff explained that it provides travel- and transportation-related data to inform decisionmaking in a variety of contexts and that it serves as the foundation for Federal policy and legislation enactments within transportation, as well as other fields, including health, energy, and the environment. According to one interviewee, for example, NHTS research on teen driving risks contributed to the Graduated Driver Licensing (GDL) Laws enacted by States in the 1990s. The NHTS Program also provides data and information to State and local government agencies and organizations, often serving as the only source of local travel behavior data. These data support transportation planning, including project, program, and policy development, as well as transportation evaluation.

The NHTS team is responsible for all aspects of the preparation and administration of this data collection effort. This includes conducting outreach to understand user needs, procuring a survey research firm, finalizing the survey instruments and methodology, submitting the information collection request (ICR) to the Office of Management and Budget for approval (per the Paperwork Reduction Act), managing the Add-on component, and monitoring the contractor and the overall administration of the survey. NHTS staff also collect and make publicly available the travel survey data and all associated user documentation (e.g., codebooks, user guides, etc.). They develop online modules to show users what they can do with the NHTS data and provide online analysis tools to help access the data. The NHTS team provides direct user support for the datasets, reports, and online analysis tools and coordinates outreach events and activities to support the use of the data and findings (e.g., NHTS User Conference, Transportation Research Board (TRB) sessions, etc.). In addition, NHTS develops publications based on the survey findings, including Summary Travel Trends, briefs, and reports.

1.7   Stakeholders

The NHTS is funded and housed in the USDOT’s Office of Policy, under the direction of Tianjia Tang. The survey is directly managed by a small team including the Program Manager (Adella Santos) and one part-time contractor. The NHTS effort, however, is supported by a broader team, including an analytic and website support team under contract to Oak Ridge National Laboratory (ORNL) and a survey research firm. In addition, the outreach efforts for the NHTS are also supported by the NHTS task force, made up of leaders in the transportation research community.