FEDERAL HIGHWAY ADMINISTRATION · OFFICE OF HIGHWAY INFORMATION MANAGEMENT
WASHINGTON, D.C. · (202) 366-0180

1995 NPTS Pretest

The Pretest for the 1995 Nationwide Personal Transportation Survey (NPTS) was conducted, in part, to test a number of different methods and questions for use in the full year-long survey. The most important of these methodological tests in the Pretest for the 1995 survey-which was conducted from November 1994 through January 1995-was a comparison of three data collection methods. In this test, participants from approximately one-third of the survey households were simply asked to recall their travel for the assigned travel day, the same retrospective collection method used for the 1990 survey. The other two-thirds of the households were mailed one of two different forms-one which was called a travel diary and a more abbreviated version, a memory jogger. Each person was asked to note in the diary information about each trip taken on the travel day. This information was then collected by the telephone interviewers in the same way as with the retrospective sample. Figures I and 2 show that the average number of trips and miles per person was lower for the sample population in the retrospective sample than in the two diary-type samples. Trips collected by the diary method were I 1 6 percent, and miles, I 1 8 percent, of those collected by the retrospective method; trips collected by the joggers were I 00 percent, and miles, 130 percent, of those from the retrospective sample. These increases are not uniform across trip purposes. The purposes that tend to be intermittent or discretionary show significant increases in trips and mileage for data collected by diary and jogger methods. However, "to and from work" or "school and church" purposes show little or no increase, suggesting that those trips are wellreported from memory.

Because it appears that the diaries have, overall, enhanced the accuracy of trip recall, the full survey has

been done using travel diaries. Although the more accurate reporting of trips attributed to the travel diaries will increase the overall accuracy qf the survey data, it may also create problems in comparing the data to that of previous surveys. NPTS project staff are investigating the impact on comparability of the data series and plan to provide guidance on comparing data from the 1995 NPTS to that of previous surveys.

For more information, contact Susan Liss, HPM-40, at (202) 366-5060 or Carol Harbaugh, HPM-40, at (202) 366-0076.

Sampling in the Collection of Local Government Highway Finance Data

"Administrators require sufficient and accurate data upon which to base decisions on broad public policies, as well as on day-to-day problems. Decisions must be made whether pertinent data are available or not. Therefore, data collection and data analyses are the ever-present concems of administrators." This statement was in an article titled "Sampling Techniques Applicable to the Collection of Economic Data" written by Nathan Lieder (Highway Needs and Economy Division, Bureau of Public Roads) and published in the December 1959 issue of Public Roads. It is as valid today as when it was written in 1959.

While many things have changed since the 1959 Public Roads article, current State DOT Administrators and the Federal Highway Administrator still need information to make policy decisions just as their counterparts did in 1959. Sufficient and quality data must still be analyzed into information. Information is necessary to make the informed decisions that manage present highway programs and shape future highway programs. Policy initiatives, policy studies, legislative proposals for State highway programs and reauthorization of the Federal highway program, and a variety of economic studies all depend on information. The ever-present problem in the decision process is having enough quality information at the right time. The problem with producing sufficient quality information is in collecting and analyzing data while coping with limited resources.

Resource limitations directly affect the accuracy and reliability of data and the information derived from that data. Resources are mainly limited by time, funding, and personnel. Sampling allows data to be gathered and processed into information in less time, using fewer personnel and at a lower level of funding than the alternative of a 100-percent effort of collecting and processing all possible data.

Even though FHWA is reducing its local reporting requirements (see the article on form FHWA 534 in the June 1996 issue of Highway Information Quarterly), sampling is still quite relevant in the local data collection required by Local Highway Finance Report (fon-n FHWA 536). As a matter of fact, the sampling technique FHWA uses as an example was initially set up for the form FHWA 536. With more than 30,000 units of govemment, sampling is applicable to those States that do not have a 100-percent local government reporting requirement. FHWA has long advocated the use of sampling in the collection of local government highway finance data. The sampling methodology can be adapted to the individual State's circumstances.

Instructions and an example are provided in A Guide To Reporting Highway Statistics for those States that choose to use sampling in the collection of local govemment highway finance data.

For more information on sampling and its use in the collection and reporting of local government highway finance data, contact Tom Benedict at (202) 366-5025.

Highway Statistics Steering Committee Meets

The Highway Statistics Steering Committee met in Washington, D.C. on June 26-27, 1996. The Committee, which provides suggestions and feedback to FHWA:s Office of Highway Information Management on its general highway information programs and policies, is comprised of transportation officials from State transportation agencies, FHWA and other U.S. Department of Transportation (DOT) staff, and other Federal agencies.

Presentations

Gloria J. Jeff, FHWA Associate Administrator for Policy, and Chris Bertram, House Transportation and Infrastructure Committee, discussed Federal legislative issues and approaches to Reauthorization. The Committee also heard presentations on a wide range of other transportation issues, including the U.S. DOT Conditions and Performance Report, SCOP and CTIPS updates, States' views of FHWA:s statistical programs, an update of the HPMS Steering Committee, an INTERNET demonstration, and an overview of Bureau of Transportation Statistics (BTS) programs.

Customer Survey

A brief summary of a Committee-recommended survey of highway information inquiries conducted by FHWNs Office of Highway Information Management was also presented. The customer survey shows a high volume of demand from a number of important sources for highway statistical information to support policy, planning, and business decisions at the Federal, State, and local levels as well as in the private sector. The survey, which covered four-week-long periods in late 1995 and early 1996, included more than 460 customer inquiries.

Significantly, some key findings on the survey on topics of interest and uses of data revealed the following:

Topics of Interest

(excluding "other") (see Figure 3)
  • About 30 percent of customer inquiries were on Finance/Fuel.
  • About 13 percent were on Drivers and Vehicles.
  • About 18 percent were on the HPMS.
  • About 33 percent were on VMT and traffic.
  • About 5 percent were on the Nationwide Personal Transportation Survey.

    Uses of Data

    (excluding "other") (see Figure 4)
  • About 18 percent were used for legislation and budget.
  • About 25 percent were for planning purposes. About 20 percent were for marketing urposes.
  • About 37 percent were for research purposes.·

    Committee Work

    The Committee reviewed FHWNs progress in implementing several key Committee recommendations made last year-including the decision to phase out the local government version of form FHWA 534. The following are several of the Committee's recommendations for further improvement of its statistical programs, for both data providers and data users:

  • Reviewing cuffent material in Highway Statistics on data comparability so that the user is sufficiently aware of data issues.
  • Publishing a brochure on Highway Statistics programs for the general reader similar to the HPMS brochure.
  • Providing more feedback to data providers and supporting them by compiling and distributing a Directory of State Data Providers.
    The Committee also agreed to monitor several other ongoing data issues.

    Next Meeting

    While no specific date was set for a meeting, the Committee asked FHWA to consider late Spring 1997 for its next meeting.

    For additional information call Teia McGee, HPM-10, at (202) 366-0170.

    Local Highway Finance

    The Summer 1996 issue of Public Roads contains an article written by Leonard S. Goldberg entitled "Local Govemment Highway Finance Trends: 1984-1993," on pages 24-27. Copies of the Summer 1996 Public Roads magazine can be obtained by calling the Editor, Bob Bryant, at (703) 285-2443.

    Conference on Household Travel Surveys: New Concepts and Research Needs

    Proceedings from the conference, Household Travel Surveys: New Concepts and Research Needs, are now available from Transportation Research Board (TRB). This conference, held in March 1995, sponsored by the Federal Highway Administration, the Federal Transit Administration, and the Bureau of Transportation Statistics, was an excellent forum for discussing the future of household travel surveys. Discussion papers and workshop summaries on non-response, stated response, survey methods, data collection instruments, and new technology provided practitioners with information on the state-of-the-art and directions for future surveys. Many of the research recommendations are now being implemented by the U.S. Department of Transportation. Copies are available for $34 from TRB Business Office, National Research Council, 2101 Constitution Avenue, NW, Washington, D.C. 20418, telephone (202) 334-3214.

    For more information, contact Elaine Murakami, HPM-40, at (202) 366-6971.

    Reporting Financial Data on the National Highway System (NHS)

    The National Highway System Act of 1995 (signed on November 28 by President Clinton) identified the 160,995 miles designated for the NHS. The NHS includes only 4 percent of the Nation's highways but carries 43 percent of total highway traffic. Its major components are the Interstate System, the Strategic Highway Corridor Network, congressionally designated highpriority corridors, and other highways that connect the system with major intermodal facilities.

    Due to the high visibility and importance of the NHS to U.S. transportation and economic growth, data users have requested financial highway information that is classified as on or off the actual, designated NHS. In a July 5, 1996, memorandum for State data providers, the Office of Highway Infon-nation Management reminded them that they will be required to report their 1996 State capital outlay and maintenance data as on or off the actual designated NHS rather than the interim NHS. The 1996 State capital outlay and maintenance reports are due in 1997.

    State reporting of capital outlay and maintenance data on the actual designated NHS enhances FHWA:s ability to satisfy the changing needs of our data customers and improves the data's relevance. It also reinforces one of the main missions of the Office of Highway Information Management, which is to report timely and accurate highway statistical data.

    For more information about the reporting of State capital outlay and maintenance data on the actual designated NHS, contact Leonard Goldberg, HPM-10, at (202) 366-5024.

    Directory of State Data Providers

    A draft Directory of State Data Providers containing names, addresses, and phone numbers of State data providers in most States was recently distributed through FHWA division offices and is also available on'request from FHWNs Office of Highway Information Management. This draft Directory, which was prepared as recommended by FHWNs Highway Statistics Steering Committee, should help State data preparers share information and ideas. It should be finalized this year. To receive a copy or to get additional information, please call (202) 366-0170.

    For additional information, contact Teia McGee or Brenda Ruffin, HPM-10, at (202) 366-0170.

    Toll Facilities in the United States

    The Office of Highway Information Management publishes a biennial report titled Toll Facilities in the United States: Bridges-Roads-Tunnels-Ferries. The report contains selected information on toll facilities in the United States (bridges, roads, tunnels, ferries), based on a survey of facilities in operation, financed, or under construction. The 1995 issue is currently being updated. The scheduled publication date for the 1997 issue is February 1997.

    For additional information call Connie Bell, HPM-20, at (202) 366-5068.

    Heaviest Truck Traffic Routes on the Interstate System

    Based on 1994 Highway Performance Monitoring System (HPMS) data, the heaviest truck traffic routes on the Interstate System are in or near large urbanized areas. The chart shows the heaviest truck volume segments among the sample sections. The percent of trucks ranges from a low of 9 percent on I-75 in atlanta to a high of 41 percent on 1-30 in Arkansas. These segments may not represent the highest percent trucks, highest total annual average daily traffic (AADT), or highest truck AADT because data are obtained from randomly sampled Interstate sections.

    Heaviest Truck Traffic Routes on the Interstate System1
    Urbanized Areas Interstate Route Truck AADT (1,000) Percent Trucks2 Total AAOT (1,000) State
    Chicago-Northwestern, IN 90 41,324 15% 275,498 Illinois
    Chicago-Northwestern, IN 55 35,695 26% 137,291 Illinois
    Chicago-Northwestern, IN 290 32,558 20% 162,794 Illinois
    Chicago-Northwestern, IN 94 32,145 29% 110,846 Illinois
    Chicago-Northwestern, IN 80 29,060 26% 111,771 Illinois
    New York-Northeastern, NJ 95 38,206 14% 272,903 New Jersey
    Los Angeles 15 36,270 26% 139,500 California
    Los Angeles 710 28,548 14% 203,900 California
    New Orleans 10 33,019 19% 173,789 Louisiana
    Indianapolis 70 29,580 18% 164,335 Indiana
    _3 95 29,546 22% 134,300 Maryland
    _3 30 28,165 41% 68,897 Arkansas
    Minneapolis-St. Paul 356 28,500 15% 190,000 Minnesota
    Minneapolis-St. Paul 94 26,400 15% 176,000 Minnesota
    Detroit 75 28,340 13% 218,000 Michigan
    Detroit 96 28,780 13% 208,000 Michigan
    Washington (DC-MD-VA) 95 27,600 11% 250,000 Virginia
    Washington (DC-MD-VA) 495 25,383 12% 211,525 Maryland
    Greensboro 85 27,347 23% 118,900 North Carolina
    Atlanta 75 27,270 9% 303,000 Georgia
    Louisville 66 26,780 26% 103,000 Kentucky
    Tucson 10 26,507 27% 98,175 Arizona
    Phoenix 10 26,312 13% 202,407 Arizona
    San Francisco-Oakland 880 25,830 14% 184,500 California
    Charlotte 85 26,674 22% 116,700 North Carolina
    Baton Rouge 10 25,330 20% 126,651 Louisiana
    1 Routes on the Interstate System with truck traffic of 25,000+ AAD'T.
    2 "Trucks" includes vehicles classified as 6 tire and above. Percent trucks is derived from classification counts conducted on sampled sections or similar roadway sections determined to have similar truck travel distributions.
    3 Nonurbanized section.
    For additional information, contact Janet Tiemey, HPM-20, at (202) 366-5021

    National Highway System (NHS) Annual Average Daily Traffic (AADT) Per Lane

    As Figure 5 shows, the AADT per lane on four-ormore-lane facilities exceeds the AADT per lane on twolane facilities in both rural and urban areas. In general, the urban NHS facilities carry 2 to 2 1/2 times as much AADT per lane as their rural counterparts. These differences probably reflect the larger population in the urban areas and a preference for use of multilane facilities by the driving public.

    For more information, contact Robert Rozycki at (202) 366-5059 or RROZYCKI@INTERGATE.DOT.GOV

    National Traffic Data Acquisition Conference-NATDAC '96

    The National Traffic Data Acquisition Conference (NATDAC) was held in Albuquerque, New Mexico, on May 6-9, 1996. Sponsored by the FHWA, the Alliance for Transportation Research, and the New Mexico State Highway and Transportation Department, it was attended by 400 participants from 48 States and 10 countries. FHWA speakers included Tony Kane, Executive Director, Christine Johnson, Director of the ITS Joint Program Office, and Gary Maring, Director of the Office of Highway Information Management. There were over 90 presentations in 3 general sessions and 27 concuffent sessions focusing on traffic data collection and analysis, including congestion monitoring, weigh-in-motion, and traffic data analysis. The Conference also included exhibits by 34 traffic monitoring equipment vendors. Much of this equipment was also demonstrated under actual traffic conditions at nearby sites.

    Panel discussions covered Traffic Data Collection Contracts, Traffic Monitoring Systems, Long-Term Pavement Perfonnance Survey, and Writing Specifications. Demonstrations were conducted of a Virtual Environment for Transportation Data (VETD) giving dynamic views of multidimensional data sets. A highlight of the Conference banquet was a presentation by management consultant Dr. John Steber who spoke about managing change.

    The next NATDAC is tentatively planned for the spring of 1998. The Office of Highway Information Management will be soliciting for a host State.

    For additional information, call Ralph Gillmann, HPM-30, at (202) 366-5042.

    "Keep the 'Long Form' for Census 2000"

    This was the consensus of the participants at the conference, Decennial Census Data for Transportation Planning: Case Studies and Strategiesfor 2000, held at the end of April. The Conference was sponsored by the Federal Highway Administration (FHWA), the Federal Transit Administration (FTA), and the Bureau of Transportation Statistics (BTS). Large and small Metropolitan Planning Organizations (MPO), State DOTS, universities, Federal agencies, and consulting firms were all represented. Although the current plan at the Bureau of the Census is to include the "long form," it is still unclear whether Congress will approve a budget which includes this component of the decennial Census for 2000. The long form includes the questions on vehicle availability, joumey-to-work, and income. By April 1, 1997, the Census Bureau must submit to Congress a list of topics to be included in the Census form.

    Martha Famsworth Riche, Director of the Bureau of the Census, gave the keynote address. The cuffent plan is to include the long form in 2000, to start a continuous measurement process in 1999 and to use administrative records in 2010. The goals for 2000 Census are to make it simpler, less costly, and more accurate. The strategies to meet these goals are partnership, simplicity, technology, and statistical methods.

    In the partnership area, Census is already working with local governments to update address lists and TIGER files. Transportation agencies with a stake in the data products need to be involved in this address information effort.

    The 20 case studies showed how decennial census data products-including Census Transportation Planning Package (CTPP), Summary Tape Files I and 3 (STFI and STF3), and Public Use Microdata Sample (PUMS)-are used. The number of census data users in the transportation profession has increased dramatically since the last census because the CTPP has a nationwide coverage and includes a statewide element added to the traditional urban element. CD-ROM technology and the ability to process the files using desktop computers have greatly improved data accessibility. The Conference provided many examples of using Census data for transit planning applications, quite a chartge from previous Census experience. TRB will compile these case studies into a TR Circular.

    Although the current plan is to conduct both a long form in 2000 and continuous measurement beginning in 1999, the Conference participants felt that it was unlikely that Congress would fund both. Therefore, much of the discussion hinged upon continuous measurement-now named the "American Community Survey"-as an alternative to the long form. The participants echoed the National Academy of Sciences Panel report, Modernizing the U.S. Census, and the BTS report, Implications of Continuous Measurementfor the Uses of Census Data in Transportation Planning, in which the group prefeffed to have small geographic area reporting (tracts and block groups, and traffic analysis zones) for one point in time rather than accumulations over 3 or 5 years. Changing to a method of accumulation was considered too risky because the transportation community has had no chance to evaluate such a replacement. Other potential problems identified by the conferees were that the profession would need to develop new models to use "averaged" data, and continuous measurement requires continuous funding from Congress.

    Altematives to the long form were determined to have several major flaws. If a nationwide survey is not conducted, there is lack of comparability of regional data. If each Federal agency develops and implements its own national survey, there will be no cost savings in data collection compared to the Census long fonn. If a nationwide survey is not conducted, there is a great potential for spending even more money at the State and local level.

    The Conference participants also developed a list of improvements to Census products if the long form is collected in 2000 and if it includes the joumey-to-work questions. Listed were such items as improving workplace coding and involving local governments in resolving coding problems, more timely release of the data, and provision of user-friendly data access tools.

    For additional information, contact Elaine Murakami, HPM-40, at (202) 366-6971.

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