The modelers determined that the Vehicle Inventory and use Survey (VIUS) was the best source of data on the share of light trucks used off-road for recreational purposes. The VIUS had been conducted by the U.S. Bureau of the Census about every five years (called the Truck Inventory and Use Survey (TIUS) through 1997). After the 2002 VIUS was performed, the Census Bureau discontinued the program. The latest survey data available is from 2002. FY 2009 is the first year that the 2002 VIUS was incorporated into the RTP apportionments. The 1997 TIUS was the basis for estimates from FY 2002 through 2008, and the 1992 TIUS was the basis for estimates for 1998 through 2001.

 There are several reasons that the VIUS was chosen as the estimator for these data. VIUS respondents were asked to provide the percentage of miles that the vehicle was operated off-road, and the primary use of the truck (personal, business, or mixed). Respondents whose primary use of the vehicle was mixed (both business and personal) were asked to provide the percentage of business use vs. personal use. It is important to separate business use from personal use due to the fact that some off-road light truck travel is not for recreational purposes (i.e. vehicles used by the lumber industry). Information about the truck weight, body type, and configuration is also available so that pickup trucks and sport utility vehicles under 10,000 pounds gross vehicle weight can be identified.

 The VIUS did not specifically collect information on the vehicle miles used off-road for recreational purposes. FHWA and its contractor assumed that the product of the percent miles used off-road and the percent personal use would be a reasonable proxy of the probability that a truck would be used off-road for recreational purposes. Because light trucks travel both on road and off-road, the number of off-road recreational light trucks is counted in full vehicle equivalents (FVE). For example, if a vehicle is driven 30 percent of its annual miles off-road for recreational purposes, then the vehicle is counted as 0.30 of a full vehicle equivalent.

 The 2002 VIUS data exhibited a significant decline in off-road light truck activity compared to the 1997 TIUS data. Under the category of Vehicular and Operational Characteristics and the subcategory Primary Range of Operation, Off-the-Road, the summary statistics comparing the 1997 and 2002 surveys show a 61.3 percent drop in off the road operation mileage. See the 2002 Economic Census Vehicle Inventory and Use Survey at www.census.gov/prod/ec02/ec02tv-us.pdf (page 14). HTML: www.census.gov/svsd/www/vius/2002.html.

It is not clear to FHWA or ORNL why the 2002 data exhibits this decline. The same question was asked on the 1997 TIUS and the 2002 VIUS survey.

FHWA staff previously hypothesized that respondents to the 1997 TIUS may have overestimated off-road light truck use, based on comparing how States managed their Off Highway Vehicle programs. Many States have active ATV, OHM, and snowmobile programs, but few States have organized programs for light trucks or four-wheel drive vehicles. However, there are no data to document this conjecture, and this conjecture does not explain why respondents answered the same question with lower estimates in 2002.

 Lacking any other reason for the decline, FHWA concludes that fewer respondents to the survey reported off-road use of their vehicle, and considers the 2002 VIUS the most reasonable estimate of nonhighway light truck use.  

Further Results of the Change in the Estimate of Light Truck Use

 The estimate of nonhighway recreational fuel use by light trucks in the 2002 VIUS is much lower than the previous estimate under the 1997 TIUS. Therefore, the share of nonhighway recreational fuel use attributable to light trucks is much smaller, resulting in larger shares for ATVs, OHMs, and snowmobiles. ATVs and motorcycles are dispersed widely across the nation, relatively proportionate to State population, and larger shares of fuel use attributable to ATVs and OHMs would not necessarily result in large proportional differences among the States. However, snowmobile use is concentrated in northern States. Therefore, FY 2009 RTP apportionments for States with more snowmobile use generally increased significantly, while apportionments for most southern States decreased significantly.

The change in the estimate of light truck use also changes the estimate of total nonhighway recreational fuel use in the United States.

Comparison of Nonhighway Recreational Fuel Use Estimates for FY 2008 and FY 2009

 The Federal excise tax on gasoline is 18.4 cents per gallon. Of this, 2.86 cents goes to the Mass Transit account and 0.1 cents goes to the Leaking Underground Storage Trust fund. The Federal Highway Trust Fund (HTF) receives 15.44 cents.

 One of the original concepts for the Recreational Trails Program was that program should return a portion of HTF revenue attributable to nonhighway recreational fuel use to the trail users paying into the system.

 Based on the 1997 TIUS, the HTF revenue attributable to nonhighway recreational fuel use (at 15.44 cents per gallon) was $290,879,354.

 Based on the 2002 VIUS, the HTF revenue attributable to nonhighway recreational fuel use (at 15.44 cents per gallon) was $87,684,567. This figure does not account for likely increasing amounts of ATV and OHM use in recent years, because FHWA has not been able to obtain updated information for these uses since 2003.