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Currently, Oregon taxes trucks by means of a system called the weight-mile tax. It
evolved from a Aton-mile tax@ imposed in 1925. This tax was used to cover the responsibility
of the growing number of trucks and buses that were appearing on the public roadways
at that time.
Oregon’s first weight-mile tax was enacted in 1947 and implemented in 1948. The tax
applies to all commercial motor vehicles with registered gross weights in excess
of 26,000 pounds. It is based on the gross weight of the vehicle and the distance
it travels in Oregon.
The weight-mile tax is a use tax that takes the place of a fuel tax on heavy vehicles.
Although fuel consumption increases with vehicle size and weight, it does not increase
proportionately with cost responsibility. The per-mile cost responsibility of a typical
truck operating at 80,000 pounds, for example, is more than double that of a typical
truck operating at 60,000 pounds. The 80,000 pound truck, however, uses only about
five percent more fuel for the same amount of travel. Thus, fuel consumption alone
cannot adequately reflect the cost responsibility of vehicles of different sizes
and weights.
Vehicle registration fees and other charges unrelated to the amount of highway use
are even more seriously deficient in reflecting cost responsibilities. Such fees
cannot reflect variations in travel by the same vehicle from year-to-year or variations
in mileage between vehicles of the same type and weight.
The Oregon weight-mile tax system actually consists of a set of weight categories
and alternative flat-fee rates. There are separate categories for vehicles registered
at gross weights of 26,001-80,000 pounds, in increments of 2,000 pounds, and those
operated under special permit at weights above 80,000 pounds. Additionally, log,
sand and gravel, and wood chip haulers, along with farm truck operators, have the
option to pay monthly flat fees in lieu of the mileage tax.
Since 1990 carriers operating vehicles under special permit at gross weights in excess
of 80,000 pounds now pay a weight-mile tax based on a vehicle’s registered gross
weight and number of axles (ATable B@ rates). There are separate schedules for five,
six, seven, eight, and nine or more axle vehicles, with each schedule graduated by
gross weight. The rates are structured so that, at any registered gross weight, carriers
can qualify for a lower per-mile rate by utilizing additional axles.
In summary, Oregon has for many years been dedicated philosophically to a cost-based
approach to road finance known as cost responsibility. A balanced mix of registration,
fuel, and weight-mile taxes is used to capture the cost responsibility of vehicles
of different sizes and weights and to equitably charge both high and low mileage
vehicles.
[Most of this is repeated from the AOregon Highway Cost Allocation Study@ July 1,
1999 also presented in prior cost allocation studies.]
