Accounting for Commercial Vehicles in Urban Transportation Models

Summary Report

4.0 Data Sources

The effort to quantify the magnitude and distribution of commercial vehicle travel relied on a series of data sources that provided data on vehicles, trips, trip lengths, and/or vehicle miles traveled in each of 12 commercial vehicle categories. Based on these data, commercial vehicle travel was estimated for 13 urban areas in the United States, as shown in Table 4.1.

Most of the data sources provided data for multiple categories of commercial vehicles (such as the registration data and the commercial vehicle surveys) but some data sources were category-specific (such as the school bus fleet data, the taxi fact book, the National Transit Database for Paratransit Vehicles (formerly FTA section 15 data). The primary data sources and the urban areas available in each are provided below in the following sections.

4.1 Commercial Vehicle Surveys

Inventory and Use Survey

The 1997 Vehicle Inventory and Use Survey (VIUS) is a probability sample of private and commercial trucks registered (or licensed) in the United States as of July 1, 1997. This survey excludes vehicles owned by Federal, state, or local governments; ambulances; buses; motor homes; farm tractors; unpowered trailer units; and trucks reported to have been sold, junked, or wrecked by the respondents prior to July 1, 1996. A sample of about 131,000 trucks was surveyed to measure the characteristics of nearly 75 million trucks registered in the United States.

Many states allow pickups, small vans, and sport utility vehicles to be registered as either cars or commercial vehicles. Therefore, during the development of the VIUS sampling frame, passenger car registration files were searched and appropriate vehicles were included. Some vehicles, such as "off-highway" trucks used exclusively on private property, do not have to be registered. These vehicles were not included in the sampling frame.

Vehicle Surveys by City

Commercial vehicle survey data for Detroit, Atlanta, Denver, and the Piedmont-Triad area (Winston-Salem, Greensboro, and High Point) were obtained from the relevant authority and analyzed for this study. A brief description of the data is given below:

• Atlanta Area Commercial Vehicle Survey - NuStats International conducted the Atlanta Area Commercial Vehicle Survey for the Atlanta Regional Commission (ARC) in the spring of 1996.^4-1 The primary objective of the survey was to provide insight into truck movements in the Atlanta region. Specifically, the goals of the study were to determine the number of trips per truck and the average truck trip length, and to develop a truck trip table that would provide critical information for the regional travel demand model.
• Denver Commercial Vehicle Survey - The Denver Regional Council of Governments (DRCOG), in partnership with the Regional Transportation District, the Colorado Department of Transportation, and the Regional Air Quality Council, initiated the Regional Travel Behavior Inventory (TBI) in 1996.^4-2 The TBI was undertaken to provide a snapshot of travel patterns and characteristics of travelers in the Denver region and to collect the data needed to develop and "freshen" traditional travel models, while providing for the possible development of new modeling techniques.
• Detroit Commercial Vehicle Survey - The Southeast Michigan Council of Governments (SEMCOG) Commercial Vehicle Survey (CVS) collected detailed information on truck travel within the seven-county area of Southeast Michigan, for use in SEMCOG's Regional Travel Forecast Model.^4-3 The information also will assist with other intermodal and freight planning activities. The universe for the commercial vehicles is from a data file from the Michigan Secretary of State containing the universe of commercial vehicles registered within the region. A supplemental business survey was conducted to determine the proportion of businesses located within the region that have commercial vehicles, registered at locations outside the region, but which operate within the region for business purposes on a regular basis.
• Piedmont-Triad Commercial Vehicle Survey - The Piedmont-Triad Commercial Vehicle Survey was conducted to estimate truck trips and trips made by commercial cars in the Triad region (Greensboro, High Point, and Winston-Salem) of North Carolina.^4-4 A database of employers in the Triad region, including the number of employees and whether or not commercial vehicles are garaged at the employment location, was used as the universe of sampling commercial vehicles in the region. Eligible vehicles were those having a commercial license and being garaged at a non-residential location overnight. The definition of eligible vehicles eliminates company cars that are driven home by employees and effectively eliminates a large share of vehicles that may otherwise have been placed into the personal services commercial vehicle category. Also, missing from the survey are non-commercially licensed vehicles that are used for commercial purposes.

4.2 Vehicle Registration

State Motor Vehicle Departments

State registration databases contain only basic data related to the use of the vehicle (e.g., commercial versus non-commercial, or whether the vehicle is part of a public fleet). Other use information could be inferred by looking at the owner of the vehicle in conjunction with vehicle characteristics, but this level of analysis would require significant effort as well as access to confidential data. As a result, state registration databases were found to have little value for determining the numbers or usage of commercial vehicles by service use, except the California database.

Vehicle registration databases that are maintained by a state, as evidenced by the experience in California, have the potential to yield useful information on the number of commercial vehicles existing within a particular geographic area. Experience has shown, though that it is time-consuming, costly, and difficult to use these vehicle registration databases for reasons other than those for which they originally were developed. Consequently, the only example of a vehicle registration database that has been successfully used to produce information on commercial vehicle travel that was able to be identified was for California. Nonetheless, it is recommended that other states explore and develop the same kind of multi-year cooperative arrangement that exists in California so that, over time, vehicle registration data can be used to support transportation planning, including, but not limited to, the movement of commercial vehicles.

Processed California Department of Motor Vehicles (DMV) data was obtained from the California Energy Commission and extracted for four urban areas: San Francisco, Los Angeles, San Diego, and Sacramento.^4-5 To compare the commercial VMT with the total VMT, the total number of personal vehicles was obtained from the DMV. The average number of daily miles traveled for personal vehicles was calculated from the National Highway Travel Survey (NHTS)^4-6 for MSAs in California. These data were not available for specific cities, and so the calculation was based on MSAs between one and three million population (for Sacramento and San Diego) and MSAs over three million population (for San Francisco and Los Angeles). The total VMT calculation, therefore, was an estimate based not only on local data within each MSA.

Other Registration Sources

We reviewed two other registration databases as follows:

• Inspection and Maintenance Programs - Many states collect data for their I/M programs that include the vehicle identification number (VIN) and odometer reading. A VIN decoder is a computer software program that is used to determine the make and model of the vehicle. Other emissions-related data also are collected, such as chassis, engine, emissions control system, fuel control system, etc. Odometer readings from at least two cycles of I/M inspection can be used to get vehicle activity (miles/year). I/M databases often identify whether the vehicle is commercial and include the gross vehicle weight rating (GVWR).
• R.L. Polk & Co. - R.L. Polk & Co.,^4-7 a privately held consumer marketing information company, started motor vehicle statistics operations in 1922. Polk maintains comprehensive vehicle databases on both new and used vehicles in various formats, some of which are potentially useful for this study. Polk develops custom-built reports for customers and data are available by ZIP code, Metropolitan Statistical Area (MSA), county, state, or entire USA. However, these data are not free; they must be purchased from Polk.

4.3 Vehicle Count Data

We reviewed three sets of vehicle count databases, described below:

• Highway Performance Monitoring System - The HPMS data as published in Highway Statistics were obtained for all metropolitan areas in the United States and summarized to identify the total VMT for all vehicles. These data were intended to be used as an estimate of overall VMT so that commercial VMT could be assessed as a percent of the total and compared across different cities.
• Freight Analysis Framework - The results of the Freight Analysis Framework (FAF) have been made available as a database file on the FHWA's FAF web site. The database file can be mapped to geographic information system (GIS) shape files of highways in the lower 48 states. The shape files allow the specification of highway links within specific urban areas. The database file includes mileage and functional classification information for each link in the FAF network. Because the links in the FAF database do not include all roadways, the FAF VMT does not represent the full universe of VMT although the FAF does include non-freight trucks. The one anomaly in these data is the non-freight trucks on minor arterials, which has a very high percentage of VMT compared to expectations.
• Vehicle Classification Counts - Vehicle classification count data, which classifies the vehicles according to FHWA's 13-axle-based classes, are generally available from the state DOTs. Source information was obtained and examined for two states (Georgia and Florida). Summary information was examined on several state DOT web sites (Maine, Ohio, New Jersey, Massachusetts, Virginia, Pennsylvania, Delaware, and Indiana).

4.4 Other Data Sources

There are five databases that provide data directly for a specific vehicle category, such as paratransit vehicles, mail delivery vans, school buses, taxis, and airport shuttle services. These databases are summarized below:

• The National Transit Database for Paratransit Vehicles - The Federal Transit Administration (FTA) collects and disseminates data on the state of mass transportation via the National Transit Database (NTD) program. Over 600 of the nation's transportation providers submit data on vehicle miles traveled, passenger miles and passenger trips to the NTD annually. The National Transit Database for paratransit vehicles was available for all 13 urban areas in our study (Los Angeles, San Francisco, Detroit, Atlanta, San Diego, Houston, Denver, Portland, Sacramento, Orlando, Winston-Salem, Greensboro, and High Point). In these cities, paratransit vehicles' total VMT as a percentage of the total VMT in the region varies from 0.003 to 0.035 percent.
• United States Postal Service Data - United States Postal Service provided data on fleet size and vehicle miles traveled for specific city districts, based on zip codes. The average daily VMT per vehicle is about 25 miles although it is much lower in urbanized areas (about five to six miles) and higher in suburban areas. In urbanized areas, daily postal delivery vehicles typically stop every block, after which the postal worker walks to deliver the mail. Fleet size and VMT data were obtained from the United States Postal Service (USPS) for seven urban areas (Atlanta, Denver, Detroit, Houston, Greensboro, Orlando, and Portland). In these cities, postal service vehicles' total VMT as a percentage of the total VMT in the region varies from 0.04 to 0.09 percent.
• School Bus Fleet Survey - Schoolbusfleet.com^4-8 is an information service of the magazine School Bus Fleet, a trade publication serving school transportation professionals in the United States and Canada. School Bus Fleet provides information on the management and maintenance of school bus fleets operated by school districts, private schools, Head Start agencies and childcare centers. These data include the number of buses in operation, the students transported on a daily basis, and the annual route mileage. School bus fleet surveys were available for the largest 100 school districts, including 10 of the urban areas in our study (Los Angeles, Detroit, Atlanta, San Diego, Houston, Denver, Portland, Winston-Salem, and Greensboro). In these cities, school bus total VMT as a percentage of the total VMT in the region varies from 0.01 to 0.55 percent.
• Taxi Fact Book - The National Association of Taxicab Operators was established in 1917 in Washington, D.C. In 1991, the Taxicab, Limousine & Paratransit Association (TLPA) was established with five membership divisions, including the Taxicab Division. TLPA publishes the magazine Transportation Leader quarterly and the Taxicab Division Fact Book annually. These data include nationwide statistics by the size of the fleet on the average annual total miles per taxi, the average distance per paid taxi trip (miles), the average annual paid trips per taxi, the average annual passengers per taxi and the average passengers per paid trip. These data also include annual mileage and number of licenses for each city. The Taxi Fact Book was available for all major cities in the United States, including all 13 urban areas in our study (Los Angeles, San Francisco, Detroit, Atlanta, San Diego, Houston, Denver, Portland, Sacramento, Orlando, Winston-Salem, Greensboro, and High Point).^4-9 In these cities, taxi total VMT as a percentage of the total VMT in the region varies from 0.15 to 1.19 percent.
• The Airport Ground Access Planning Guide - The Airport Ground Access Planning Guide presents the results of the first phase of a project jointly sponsored by the Federal Highway Administration and the Federal Aviation Administration.^4-10 It outlines the process for planning ground access to airports within the context of current laws, regulations, and procedures. These data include information on mode split, average trip length and vehicle miles traveled. The Airport Ground Access Planning Guide was available for 27 cities in the United States, including five cities in our study (Los Angeles, San Francisco, Houston, Portland, and Orlando). In these cities, shuttle service VMT as a percentage of the total VMT in the region varies from 0.00 to 0.04 percent.

In addition to the vehicle-specific databases, there are several surveys that contain some relevant data for commercial vehicles; these are described below:

• Travel Surveys - The 1995 National Personal Transportation Survey^4-11 (NPTS) and the new 2000 NHTS^4-12 are potential sources of information on certain kinds of commercial vehicles. The 1995 NPTS contains the following modes, which may be relevant to this study: Pickup truck; Other truck; Other privately owned vehicle (excluding autos, vans, sport utility vehicles, and recreational vehicles); Taxicab; and School bus.
• Other Surveys - There are a number of other types of surveys that we discovered during the literature review that are relevant to different types of commercial vehicles. In Washington,^4-13 the Department of Transportation conducted a survey of 5,000 tow trucks to determine response times and types of incidents in the region. The original survey data on incident response and additional data on feedback to the survey are available from the WSDOT. In St. Louis, the East-West Gateway Coordinating Council^4-14 conducted a survey of paratransit operators to collect data on trip purpose, service area, service hours, unused vehicle miles, operating and capital budgets, and other information. In addition, 431 vehicles were surveyed to estimate trips per vehicle.

4.5 Individual Contacts

In addition to all of the data sources discussed, individual firms and agencies in both the public and private sectors and in all 12 urban areas were contacted. We did not expect to receive totals for all commercial vehicles operated by the firms contacted and commercial vehicle mileages in each city, but we wanted to capture a snapshot of the typical mileages that are driven by commercial vehicles of different industries in support of the other data sources. Although we contacted all 12 cities in some cases, only a few cities responded to our request for information.

Footnotes

4-1. NuStats International, Atlanta Area Commercial Vehicle Survey. Draft Final Report. 1996.

4-2. Parsons Transportation Group, Commercial Vehicle Survey Report, prepared for Denver Regional County of Governments, 2001.

4-3.  Wilbur Smith Associates, Commercial Vehicle Survey, prepared for Southeast Michigan County of Governments, 1999.

4-4. Barton-Ashman Associates, Inc., Piedmont Triad Area Commercial Vehicle Survey, prepared for the North Carolina Department of Transportation, January 1996.

4-5. California Energy Commission, processed California Department of Motor Vehicle Database, 2002.

4-6. http://nhts.ornl.gov/2001/index.shtml

4-7. R.L. Polk & Co., 26955 Northwestern Hwy, Southfield, MI 48034.

4-8. http://www.schoolbusfleet.com

4-9. Taxicab, Limousine and Paratransit Association, Taxicab Division Fact Book, 2002.

4-10. Airport Ground Access Planning Guide First Phase, Federal Highway Administration Intermodal Division, Washington, D.C. 20590. http://ntl.bts.gov/DOCS/AGAPP.html

4-11. http://www-cta.ornl.gov/npts/1995/Doc/publications.shtml

4-12. http://www.bts.gov/nhts/

4-13. Nee, Jennifer and Hallenbeck, Mark E., Washington State Transportation Center (TRAC), University of Washington, Seattle. Evaluation of the Service Patrol Program in the Puget Sound Region, Washington State DOT and US DOT, FHWA Research Project TI803, Task 37, August 2000 to January 2001.

4-14. East-West Gateway Coordinating Council, Social Service Transportation Assets in the St. Louis, Missouri Area, ftp://ftp.ewgateway.org/library/sst.pdf