Editor’s note: The City of Portland has just released the discussion draft (PDF, 5.5MB) of their Freight Master Plan.

Last month in a commentary titled “Road funding scheme ignores constitution, physics,” Orval Etter charged that the Oregon Department of Transportation hasn’t been charging trucks their fair share for the costs of roads.

The Oregon Constitution requires that highway user tax rates ensure “fairness and proportionality” between light (up to 8,000-pound) and heavy (more than 8,000-pound) vehicles. According to Etter, heavy trucks inflict proportionally far more damage on roads than do light vehicles — the result of a “fourth power law.”

Orval Etter of Eugene is an emeritus associate professor of public affairs and administration at the University of Oregon.

But in a recent response titled “Oregon a pioneer in the just division of highway taxes,” John Merriss argued that trucks are paying their fair share for the costs of highways.

According to Merriss: “When all costs are considered, the past two Oregon studies have found light vehicles responsible for approximately two-thirds of total highway expenditures and heavy vehicles one-third. These results are generally in line with those of other recent state studies and the 1997 federal study. Therefore, in Oregon, we currently assign two-thirds of the costs of highways to light vehicles and one-third to heavy vehicles.”

John Merriss is manager of policy and economic analysis for the Oregon Department of Transportation.

But at its August meeting, the Oregon Transportation Commission approved Oregon Highway Plan. What such a designation means isn’t completely clear. But the general intent is to give priority to the needs of truck freight on highways designated as freight routes — even over the needs of local communities through which highways pass.

Can anyone shed additional light on this issue?