Oregon Revised Statutes Revenue and Taxation § 308.570

(1) In the assessment of the property of any company conducting transportation or operating over rail lines, the Department of Revenue shall determine the value of each branch line of the company located within this state and the mileage of each branch line, including miles of main tracks, spurs, yard and sidetracks.

(2) The department shall determine the values per mile of a branch line by dividing the value of the line by the mileage of the line.

(3) The department shall deduct the total value of branch lines of the company from the total value of all centrally assessed property of the company. The department shall then determine the values per mile of the main line of the company by dividing the remainder by the number of miles of the main line, taking into consideration miles of main tracks, spurs, yard and sidetracks. Each mile of spurs, yard and sidetracks shall be valued at not to exceed 50 percent of the value per mile assigned to the main track of the branch or main line with which the spurs, yard and sidetracks are connected.

(4) This section does not apply to small private railcar companies.