Document Type


Publication Date



Transportation -- Planning -- Evaluation, Transportation -- Management, Transportation -- engineering

Physical Description

1 online resource (18 p.)


Oregon s weight-mile tax was amended in 1990 to provide for a lower tax rate for trucks weighing more than 80,000 pounds if they added axles. The additional axles within a weight class reduce the amount of road damage. The tax break was largely based on equity considerations, since trucks within a weight class tend to do less road damage if they have more axles; however, the tax reductions also created an economic incentive to add axles and thus reduce road damage. This article is a report on attempts to determine if the tax break actually led to an increase in the number of axles within weight classes and a reduction in the amount of road damage. Statistical data indicates that there has been a small increase in the number of axles in most weight classes and a large increase in mileage by the heaviest trucks with the most axles. This has reduced the damage per ton shipped on trucks subject to the axle incentive, but it is not possible to determine if this was due to the weight-mile tax. A series of structured interviews supplemented the statistical analysis and indicates that the tax incentive is not a major determinant of truck configuration. One reason is that regulatory constraints, particularly weight limits, limit the effectiveness of the tax incentives.


Catalog Number PR116.

Published by the Center for Urban Studies, College of Urban and Public Affairs, Portland State University.

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