National Academies Press: OpenBook

Interregional Travel: A New Perspective for Policy Making (2016)

Chapter: APPENDIX: Federal Highway Administration Trip Table Estimation Method

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Page 174
Suggested Citation:"APPENDIX: Federal Highway Administration Trip Table Estimation Method." National Academies of Sciences, Engineering, and Medicine. 2016. Interregional Travel: A New Perspective for Policy Making. Washington, DC: The National Academies Press. doi: 10.17226/21887.
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APPENDIX

Federal Highway Administration
Trip Table Estimation Method

In view of the unlikelihood of a new American Travel Survey (ATS) being undertaken soon, the U.S. Department of Transportation’s Federal Highway Administration (FHWA) partnered with other modal agencies to estimate the number of long-distance (≥100-mile) person trips made in 2008. The FHWA trip tables are based on data for actual (ticketed) trips made by airline and train and on estimates for trips made by automobile and bus (scheduled, tour, and charter). Counts of trips by airline and train are accurate because they are derived from records of ticket purchases; ground access surveys are used to assign the air and train trips to specific county origins and destinations. Long-distance trips made principally by automobile and bus are more difficult to estimate in the absence of actual or survey-derived trip data for these modes. To compensate for the lack of data, FHWA used the 1995 ATS data to estimate the number of automobile and bus trips made in 2008. Linear regression equations were developed that explained the 1995 ATS results on the basis of 1995 Census Bureau employment and demographic data. Estimates for 2008 were then made by using 2008 Census Bureau data as input for the explanatory variables in the equations.

According to the FHWA tables, about 2 billion long-distance person trips were made in 2008. As in 1995, more than three-quarters of long-distance trips were estimated to have been made by automobile, nearly 20 percent by air, and 3 to 4 percent by rail and bus. The 2 billion total trips in 2008 are a 100 percent increase since 1995 and a 50 percent increase since the 2001–2002 National Household Travel Survey. The amount of long-distance trip making by rail grew the most on a percentage basis, up nearly 250 percent from 1995 to 2008.

Page 175
Suggested Citation:"APPENDIX: Federal Highway Administration Trip Table Estimation Method." National Academies of Sciences, Engineering, and Medicine. 2016. Interregional Travel: A New Perspective for Policy Making. Washington, DC: The National Academies Press. doi: 10.17226/21887.
×

The updated FHWA trip tables are the only comprehensive data set from which estimates of intercity trips by mode can be made that take into account economic and demographic trends since 1995. The FHWA trip calculations for 2008 are examined in more detail below. The focus is on trip making in the most heavily traveled intercity markets in the 100- to 500-mile distance range.

AIR AND RAIL TRIPS

Airline and rail trips are estimated by using 2008 Amtrak station-to-station ticketing data and the U.S. Department of Transportation airline ticket sample (known as Databank 1B), which contains itinerary data for one in 10 tickets purchased.

AUTOMOBILE TRIPS

The following trip generation and distribution equations were developed by using 1995 Census Bureau population, household, and industry employment [Quarterly Census of Employment and Wages (QCEW)] data to explain the 1995 ATS results. To obtain results for 2008, 2008 Census Bureau data were used as inputs for the explanatory variables in the equations. Special generation models were developed to account for tourist and cross-border trip making in relevant locations.

Trip Generation Model

Linear regression models were estimated by using employment and population variables to predict 1995 ATS trips at the state level. The production and attraction equations by trip purpose are shown in Equations 1 to 4.

Business trip productions = 0.47692 × Census population

images

Nonbusiness trip productions = 2.19893 × Census population

images

Page 176
Suggested Citation:"APPENDIX: Federal Highway Administration Trip Table Estimation Method." National Academies of Sciences, Engineering, and Medicine. 2016. Interregional Travel: A New Perspective for Policy Making. Washington, DC: The National Academies Press. doi: 10.17226/21887.
×

Business trip attractions = 1.09773 × QCEW employment

images

Nonbusiness trip attractions = 6.573 × QCEW leisure and hospitality and service providing industry employment

images

Trip Distribution Model

The balanced productions were distributed by using a destination choice model. The multinomial logit formulation for each trip purpose is shown in Equations 5 and 6. The trips are distributed from zone i to zone j on the basis of the share of zone i among all possible zones in the choice set.

images

images

Special Generators

To estimate trips to national parks, at cross-border points, and to places such as Las Vegas and Orlando that attract a large portion of visitors not necessarily captured by the ATS, the models use data from the National Park Service; the Bureau of Transportation Statistics (for cross-border inbound trips); and visitors bureau data from Las Vegas, Niagara Falls, and Orlando. The generated values are allocated to their production and attraction zones on the basis of the nonbusiness trip distribution (Equation 6).

BUS TRIPS

To derive bus trips for 2008, the following trip generation and estimation equations were developed, and 2008 Census Bureau data on population, households, and industry employment were used as inputs for the explanatory variables. Special generation models were developed to account for tourist and cross-border trip making in relevant locations.

Page 177
Suggested Citation:"APPENDIX: Federal Highway Administration Trip Table Estimation Method." National Academies of Sciences, Engineering, and Medicine. 2016. Interregional Travel: A New Perspective for Policy Making. Washington, DC: The National Academies Press. doi: 10.17226/21887.
×

Trip Generation

Trip generation rates were estimated by using the 1995 ATS:

Age (years) Income Vehicles
0 1+
Under 18 <35,000 0.062 0.097
35,000–75,000 0.872 0.155
>75,000 0.868 0.156
18–64 <35,000 0.342 0.474
35,000–75,000 0.619 0.263
>75,000 0.411 0.151
65 and older <35,000 0.679 0.212
35,000–75,000 1.045 0.190
>75,000 1.051 0.097

Trip Distribution

The bus passenger destination choice model is formulated as follows and was estimated by using the 1995 ATS data:

images

where

images

Special Generators

Trips from the following two sources were added:

  1. Cross-border entry points between the United States and Canada and between the United States and Mexico. The actual number of border
Page 178
Suggested Citation:"APPENDIX: Federal Highway Administration Trip Table Estimation Method." National Academies of Sciences, Engineering, and Medicine. 2016. Interregional Travel: A New Perspective for Policy Making. Washington, DC: The National Academies Press. doi: 10.17226/21887.
×
  1. crossings by persons traveling by bus in 2008 is reported in the Bureau of Transportation Statistics–Transportation Security Administration database. On the basis of information from Statistics Canada about the destination state of Canadians entering the United States, the model developer used a factor of 0.75 to convert border crossings into long-distance trips.

  2. Trips destined for popular recreation locations outside of large metropolitan areas not likely to be addressed adequately by the ATS. The ATS indicates the state and metropolitan statistical area (MSA) of a trip end but does not indicate the location of trips outside of MSAs. Trips were added to account for travel to National Park Service locations and for a limited number of other destinations such as Niagara Falls, Orlando, and Las Vegas. On the basis of information from National Park Service visitor surveys, the model developer used a factor of 0.05 to estimate the total number of visitors arriving by bus and a factor of 0.88 to convert total visitations to long-distance trips.
Page 174
Suggested Citation:"APPENDIX: Federal Highway Administration Trip Table Estimation Method." National Academies of Sciences, Engineering, and Medicine. 2016. Interregional Travel: A New Perspective for Policy Making. Washington, DC: The National Academies Press. doi: 10.17226/21887.
×
Page 174
Page 175
Suggested Citation:"APPENDIX: Federal Highway Administration Trip Table Estimation Method." National Academies of Sciences, Engineering, and Medicine. 2016. Interregional Travel: A New Perspective for Policy Making. Washington, DC: The National Academies Press. doi: 10.17226/21887.
×
Page 175
Page 176
Suggested Citation:"APPENDIX: Federal Highway Administration Trip Table Estimation Method." National Academies of Sciences, Engineering, and Medicine. 2016. Interregional Travel: A New Perspective for Policy Making. Washington, DC: The National Academies Press. doi: 10.17226/21887.
×
Page 176
Page 177
Suggested Citation:"APPENDIX: Federal Highway Administration Trip Table Estimation Method." National Academies of Sciences, Engineering, and Medicine. 2016. Interregional Travel: A New Perspective for Policy Making. Washington, DC: The National Academies Press. doi: 10.17226/21887.
×
Page 177
Page 178
Suggested Citation:"APPENDIX: Federal Highway Administration Trip Table Estimation Method." National Academies of Sciences, Engineering, and Medicine. 2016. Interregional Travel: A New Perspective for Policy Making. Washington, DC: The National Academies Press. doi: 10.17226/21887.
×
Page 178
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 Interregional Travel: A New Perspective for Policy Making
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TRB Special Report 320: Interregional Travel: A New Perspective for Policy Making examines the demand for and supply of interregional transportation in the United States. Major additions to transportation infrastructure, including high-speed rail, are being considered for some of the country’s most heavily traveled 100- to 500-mile corridors. The availability and use of the automobile, airplane, and train for interregional travel are reviewed along with the rejuvenated intercity bus. U.S. interregional corridors and transportation options are contrasted with those in Japan and Europe, where substantial investments have been made in passenger rail.

Public investments in new, long-lived transportation infrastructure can be risky because of uncertainty about future demand and the development of new technologies and competing transportation services. Decisionmakers in interregional corridors face the added challenge of having to coordinate investments across multiple jurisdictions. The report recommends actions to reduce this uncertainty and create stronger institutional means for developing the country’s interregional corridors.

TR News 303 features an article on Interregional Travel: A New Perspective for Policy Making.

A video about the research is now available:

At the 2016 TRB Annual Meeting, January 10-14, 2016, a session entitled Interregional Travel: Policymaking from a New Perspective was webcast live. These videos provide an overview of various components of the project.

Introduction:

Part 1: Overview of Project Scope

Part 2: Data and Information Needs

Part 3: Intercity Bus Operations

Question and Answer Session

Presenters:

  • Tom Deen
  • Nancy McGuckin
  • Joe Schweiterman

Moderated by: Martin Wachs

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